indinavir-sulfate and amprenavir

Molecular mechanisms behind the defects in insulin production and secretion associated with antihuman immunodeficiency virus (anti-HIV) therapy and the development of HIV-associated lipodystrophy syndrome (HALS) are discussed in this article. Data suggesting insulin resistance on the beta cell and defects in first-phase insulin release of HALS patients are presented. Hepatic extraction of insulin, nonglucose insulin secretagogues and insulin-like growth factor release may exert influence on the demand of circulating insulin and on insulin secretion in HIV-infected patients. Finally, the paucity in understanding the incretin effects in HIV and HIV therapy in relation to insulin secretion is highlighted.

Topics: Carbamates; Furans; HIV Protease Inhibitors; HIV-Associated Lipodystrophy Syndrome; Humans; Indinavir; Insulin; Insulin Resistance; Insulin Secretion; Insulin-Secreting Cells; Nelfinavir; Ritonavir; Sulfonamides

Protease inhibitors (PIs) are potent competitive inhibitors of the human immunodeficiency virus (HIV) widely used in the treatment of the acquired immune deficiency syndrome (AIDS) and prescribed in combination with other antiretroviral drugs. So far ten PIs were approved by the United States Food and Drug Administration (FDA) for the treatment of HIV infection. In this mini review, quality control methods of each PI are discussed on the basis of analytical techniques published in the literature. Special attention is given to summarize the LC methods described for the analysis of the selected PIs in both drug substances and products with the available literature till date.

Topics: Anti-HIV Agents; Atazanavir Sulfate; Carbamates; Chromatography, Liquid; Darunavir; Drug Contamination; Furans; HIV Protease Inhibitors; Indinavir; Lopinavir; Nelfinavir; Oligopeptides; Organophosphates; Pyridines; Pyrimidinones; Pyrones; Quality Control; Ritonavir; Saquinavir; Sulfonamides

There are currently (July, 2002) six protease inhibitors approved for the treatment of HIV infection, each of which can be classified as peptidomimetic in structure. These agents, when used in combination with other antiretroviral agents, produce a sustained decrease in viral load, often to levels below the limits of quantifiable detection, and a significant reconstitution of the immune system. Therapeutic regimens containing one or more HIV protease inhibitors thus provide a highly effective method for disease management. The important role of protease inhibitors in HIV therapy, combined with numerous challenges remaining in HIV treatment, have resulted in a continued effort both to optimize regimens using the existing agents and to identify new protease inhibitors that may provide unique properties. This review will provide an overview of the discovery and clinical trials of the currently approved HIV protease inhibitors, followed by an examination of important aspects of therapy, such as pharmacokinetic enhancement, resistance and side effects. A description of new peptidomimetic compounds currently being investigated in the clinic and in preclinical discovery will follow.

Topics: Anti-HIV Agents; Atazanavir Sulfate; Carbamates; Clinical Trials as Topic; Dipeptides; Furans; HIV; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Models, Molecular; Molecular Mimicry; Molecular Structure; Nelfinavir; Oligopeptides; Organophosphates; Peptides; Phenylbutyrates; Pyridines; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides; Urethane

Topics: Carbamates; Drug Resistance, Microbial; Furans; HIV; HIV Infections; HIV Protease; HIV Protease Inhibitors; Humans; Indinavir; Mutation; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides

The dimeric aspartyl protease of HIV has been the subject of intense research for almost a decade. Knowledge of the substrate specificity and catalytic mechanism of this enzyme initially guided the development of several potent peptidomimetic small molecule inhibitors. More recently, the solution of the HIV protease structure led to the structure-based design of improved peptidomimetic and non-peptidomimetic antiviral compounds. Despite the qualified success of these inhibitors, the high mutation rate associated with RNA viruses continues to hamper the long-term clinical efficacy of HIV protease inhibitors. The dimeric nature of the viral protease has been conducive to the investigation of dominant-negative inhibitors of the enzyme. Some of these inhibitors are defective protease monomers that interact with functional monomers to form inactive protease heterodimers. An advantage of macromolecular inhibitors as compared to small-molecule inhibitors is the increased surface area of interaction between the inhibitor and the target gene product. Point mutations that preserve enzyme activity but confer resistance to small-molecule inhibitors are less likely to have an adverse effect on macromolecular interactions. The use of efficient retrovirus vectors has facilitated the delivery of these macromolecular inhibitors to primary human lymphocytes. The vector-transduced cells were less susceptible to HIV infection in vitro, and showed similar levels of protection compared to other macromolecular inhibitors of HIV replication, such as RevM10. These preliminary results encourage the further development of dominant-negative HIV protease inhibitors as a gene therapy-based antiviral strategy.

Topics: Amino Acid Sequence; Carbamates; Furans; Genetic Therapy; Genetic Vectors; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Lentivirus; Models, Molecular; Molecular Structure; Nelfinavir; Retroviridae; Ritonavir; Saquinavir; Sulfonamides; Transfection

This review deals with clinical applications of compounds that inhibit the action of the protease encoded within the genome of human immunodeficiency virus (HIV). The HIV-protease is essential for viral maturation and represents an important therapeutic target in the fight against AIDS. Following a brief overview of the enzyme structure and function, the article focuses on a number of peptide and non-peptide based HIV-protease inhibitors that are in current clinical use. These drugs are discussed both with respect to their efficacy in treatment of AIDS, and to problems related to insurgence of viral resistance and side effects seen to date in patient populations.

Topics: Acquired Immunodeficiency Syndrome; Anti-HIV Agents; Binding Sites; Carbamates; Clinical Trials as Topic; Computer-Aided Design; Crystallography, X-Ray; Drug Design; Drug Resistance, Microbial; Drug Therapy, Combination; Furans; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Nelfinavir; Oligopeptides; Pyridines; Pyrones; Randomized Controlled Trials as Topic; Ritonavir; Saquinavir; Sulfonamides

The development of antiretrovirals has led to a revolution in the care of patients infected with HIV. What was once a uniformly fatal syndrome has become a more treatable, chronic, infectious disease. Central to this revolution have been the protease inhibitors, a class of drugs with potent antiretroviral activity. The first member of this class was approved for use in 1995 and there are now five protease inhibitors approved by the US Food and Drug Administration (FDA): amprenavir, indinavir, nelfinavir, ritonavir and saquinavir. As a result of the magnitude of the HIV pandemic coupled with the clinically proven efficacy of protease inhibitors, there are currently hundreds of ongoing clinical trials with these agents. Trial designs include comparisons between the various licensed protease inhibitors, comparisons of protease inhibitors to other classes of potent antiretroviral drugs, investigations with new protease inhibitors, investigations of protease inhibitor-related toxicities and attempts at simplifying current dosing regimens.

Topics: Carbamates; Clinical Trials as Topic; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides; United States; United States Food and Drug Administration

Deaths related to the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome and the incidence of opportunistic infections have been drastically decreased in the industrialized world. These reductions are mainly due to recent advances in the management of HIV infection, including the availability of new therapies. Until November 1995, the antiretroviral drugs available and approved by the Food and Drug Administration for clinical use in the United States consisted of only four nucleoside analogue reverse transcriptase inhibitors: zidovudine, zalcitabine, didanosine, and stavudine. Since then, 2 new classes of agents and 10 new agents have been approved; thus, the number of available antiretroviral drugs has more than tripled. Additional drugs and newer classes of antiretrovirals are in various stages of development. Because of the availability of more drugs, the complexity of HIV treatment has increased. Selecting an appropriate antiretroviral therapeutic regimen involves addressing multiple interdependent issues, including patient adherence, pharmacokinetic properties of the drugs (including food effects and drug-drug interactions), drug resistance, and overlapping adverse effects.

Topics: Adolescent; Adult; Alkynes; Anti-HIV Agents; Benzoxazines; Carbamates; Cyclopropanes; Delavirdine; Didanosine; Dideoxynucleosides; Female; Furans; HIV Infections; Humans; Indinavir; Lamivudine; Nelfinavir; Nevirapine; Oxazines; Pregnancy; Pregnancy Complications, Infectious; Protease Inhibitors; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Stavudine; Sulfonamides; Zalcitabine; Zidovudine

Topics: Carbamates; Drug Resistance; Furans; HIV Protease; HIV Protease Inhibitors; Indinavir; Nelfinavir; Pyridines; Pyrones; Ritonavir; Saquinavir; Structure-Activity Relationship; Sulfonamides

The effect of HIV type-1 (HIV-1) subtype on in vitro susceptibility and virological response to darunavir (DRV) and lopinavir (LPV) was studied using a broad panel of primary isolates, and in recombinant clinical isolates from treatment-naive, HIV-1-infected patients in the Phase III trial, AntiRetroviral Therapy with TMC114 ExaMined In naive Subjects (ARTEMIS).. Patients received DRV/ritonavir (DRV/r) 800/100 mg once daily (n=343) or LPV/ritonavir (LPV/r) 800/200 mg total daily dose (n=346), plus a fixed daily dose of emtricitabine and tenofovir disoproxil fumarate.. DRV demonstrated high antiviral activity against a broad panel of HIV-1 major group (M) and outlier group (O) primary isolates in peripheral blood mononuclear cells, with a median 50% effective concentration (EC(50)) of 0.52 nM. Most (61%) patients in ARTEMIS harboured HIV-1 subtype B; other prevalent subtypes were C (13%) and CRF01_AE (17%); 9% harboured other subtypes. Median EC(50) values (interquartile range) for DRV were 1.79 nM (1.3-2.6) for subtype B, 1.12 nM (0.8-1.4) for C and 1.27 nM (1.0-1.7) for CRF01_AE. Virological response to DRV/r (HIV-1 RNA<50 copies/ml [intent-to-treat, time-to-loss of virological response algorithm]) was 81%, 87% and 85% for patients with subtype B, C and CRF01_AE infections, respectively. Similar results were observed in the LPV/r treatment group.. In vitro susceptibility to DRV was comparable across HIV-1 subtypes in a broad panel of primary isolates and in recombinant clinical isolates. Once daily DRV/r 800/100 mg and LPV/r 800/200 mg were highly effective in ARTEMIS irrespective of the HIV-1 subtype studied, confirming their broad anti-HIV-1 activity.

Topics: Adamantane; Adult; Analysis of Variance; Atazanavir Sulfate; Carbamates; Darunavir; Drug Resistance, Viral; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Lopinavir; Microbial Sensitivity Tests; Molecular Typing; Nelfinavir; Neuraminidase; Oligopeptides; Pyridines; Pyrimidinones; Pyrones; Saquinavir; Sulfonamides; Viral Load

The effects of different HIV protease inhibitors (PIs) on peripheral insulin resistance have been described, but less is known about their effects on insulin suppression of endogenous glucose production (EGP).. We tested the acute effects of 3 PIs, indinavir, ritonavir, and amprenavir, on EGP quantified by stable isotope techniques during the hyperinsulinemic, euglycemic clamp in 3 similar placebo-controlled protocols.. EGP was higher with indinavir in the hyperinsulinemic state than with placebo (4.1 +/- 1.3 vs. 2.2 +/- 0.8 microg x kg(-1) x min(-1), P = 0.04). A trend toward higher EGP was seen with ritonavir (3.6 +/- 0.3 vs. 3.0 +/- 0.5 microg x kg(-1) x min(-1), P = 0.08). There was no evidence that amprenavir blunted insulin suppression of EGP compared with placebo (2.9 +/- 0.04 vs. 3.2 +/- 0.7 microg x kg(-1) x min(-1), P = 0.63).. Some PIs can acutely blunt the ability of insulin to suppress EGP, but, as with insulin resistance, the effects of PIs on EGP are drug-specific, not class-specific.

Topics: Carbamates; Furans; Glucose; HIV Protease Inhibitors; Human Experimentation; Humans; Indinavir; Insulin; Male; Placebos; Ritonavir; Sulfonamides

Some HIV protease inhibitors (PIs) have been shown to induce insulin resistance in vitro but the degree to which specific PIs affect insulin sensitivity in humans is less well understood.. In two separate double-blind, randomized, cross-over studies, we assessed the effects of a single dose of ritonavir (800 mg) and amprenavir (1200 mg) on insulin sensitivity (euglycemic hyperglycemic clamp) in healthy normal volunteers.. Ritonavir decreased insulin sensitivity (-15%; P = 0.008 versus placebo) and non-oxidative glucose disposal (-30%; P = 0.0004), whereas neither were affected by amprenavir administration.. Compared to previously performed studies of identical design using single doses of indinavir and lopinavir/ritonavir, a hierarchy of insulin resistance was observed with the greatest effect seen with indinavir followed by ritonavir and lopinavir/ritonavir, with little effect of amprenavir.

Topics: Adult; Aged; Blood Glucose; Carbamates; Double-Blind Method; Energy Metabolism; Furans; Glucose Clamp Technique; HIV Protease Inhibitors; Humans; Indinavir; Insulin; Insulin Resistance; Lactic Acid; Lopinavir; Male; Middle Aged; Pyrimidinones; Ritonavir; Sulfonamides

HIV-infected subjects who have lipodystrophy and insulin resistance on prolonged antiretroviral therapy have elevated levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) antigens, markers of impaired thrombolysis that are associated with hyperinsulinemia and increased cardiovascular risk. We studied HIV-infected, protease inhibitor (PI)-naive adults treated with indinavir (n = 11) or amprenavir (n = 14) plus two nucleoside reverse transcriptase inhibitors enrolled in two independent prospective trials. Antiretroviral and immune responses were similar in both studies. Over 8 wk, indinavir was associated with decreased insulin sensitivity, whereas amprenavir was not. Levels of tPA antigen declined by approx 25% with both treatments (p < 0.05 for each); levels of PAI-1 antigen did not change. Levels of the inflammatory marker soluble tumor necrosis factor-alpha receptor II (sTNFr2) correlated positively with tPA antigen (r = 0.33, p = 0.02), and mean (SD) plasma concentrations of sTNFr also declined with treatment (4.44 +/- 1.11 ng/mL pretherapy, 3.75 +/- 1.21 posttherapy, p = 0.007). Short-term improvement in a marker of impaired thrombolysis and increased vascular risk can occur during PI-based antiretroviral therapy, perhaps as a consequence of improvement in HIV-related inflammation. This improvement occurred independent of development of insulin resistance, which occurred only with indinavir.

Topics: Adult; Biomarkers; Blood Glucose; Carbamates; Drug Therapy, Combination; Female; Fibrinolysis; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Inflammation; Insulin Resistance; Male; Plasminogen Activator Inhibitor 1; Prospective Studies; Reverse Transcriptase Inhibitors; Stavudine; Sulfonamides; Tissue Plasminogen Activator

Pharmacokinetic interactions are expected when human immunodeficiency virus (HIV) protease inhibitors are coadministered because many are both substrates for and inhibitors of CYP3A4. The goal of this model-based pharmacokinetic analysis was to describe the differences observed in amprenavir pharmacokinetics among treatment arms in the Adult AIDS Clinical Trial Group (AACTG) study protocol 398 and to propose mechanisms to account for them.. One hundred seventy-six HIV-positive subjects receiving 1200 mg amprenavir twice daily as part of AACTG protocol 398 were included in the pharmacokinetic study. All patients also received background medications efavirenz, adefovir dipivoxil, and abacavir and, depending on the study arm, placebo or one of the following protease inhibitors: nelfinavir, indinavir, or saquinavir. A population pharmacokinetic model was fitted to a total of 565 amprenavir concentration measurements. The blood samples for concentration measurements were drawn at week 2 (12-hour pharmacokinetic study, approximately 7 samples per study; 46 patients) and at week 24 (6-hour pharmacokinetic study, approximately 5 samples per study; 10 patients). In addition, samples were collected at 1 or more follow-up visits (population pharmacokinetic study, 1 to 3 occasions per patient; 150 patients).. Amprenavir intrinsic clearance was significantly reduced relative to placebo by nelfinavir (-41%) and indinavir (-54%) but not by saquinavir. The absolute magnitude of amprenavir intrinsic clearance suggests that CYP3A4 inhibition by nelfinavir and indinavir is balanced by enzymatic induction in the presence of the background drug(s), most likely efavirenz. Amprenavir intrinsic clearance apparently increases by more than 30% between weeks 2 and 24, possibly because of the time course of CYP3A4 induction.

Topics: Adult; Biological Availability; Carbamates; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme Inhibitors; Drug Administration Schedule; Drug Therapy, Combination; Female; Furans; HIV Protease Inhibitors; Humans; Indinavir; Male; Middle Aged; Mixed Function Oxygenases; Nelfinavir; Saquinavir; Sulfonamides

Management of antiretroviral treatment failure in patients receiving protease inhibitor (PI)-containing regimens is a therapeutic challenge.. To assess whether adding a second PI improves antiviral efficacy of a 4-drug combination in patients with virologic failure while taking a PI-containing regimen.. Multicenter, randomized, 4-arm trial, double-blind and placebo-controlled for second PI, conducted between October 1998 and April 2000, for which there was a 24-week primary analysis with extension to 48 weeks.. Thirty-one participating AIDS (acquired immunodeficiency syndrome) Clinical Trials Units in the United States.. A total of 481 human immunodeficiency virus (HIV)-infected persons with prior exposure to a maximum of 3 PIs and viral load above 1000 copies/mL.. Selectively randomized assignment (per prior PI exposure) to saquinavir (n = 116); indinavir (n = 69); nelfinavir (n = 139); or placebo twice per day (n = 157); in combination with amprenavir, abacavir, efavirenz, and adefovir dipivoxil.. Primary efficacy analysis involved the proportion with viral load below 200 copies/mL at 24 weeks. Other measures were changes in viral load and CD4 cell count from baseline, adverse events, and HIV drug susceptibility.. Of 481 patients, 148 (31%) had a viral load below 200 copies/mL at week 24. The proportions of patients with a viral load below 200 copies/mL in the saquinavir, indinavir, nelfinavir, and placebo arms were 34% (40/116), 36% (25/69), 34% (47/139), and 23% (36/157), respectively. The proportion in the combined dual-PI arms was higher than in the amprenavir-plus-placebo arm (35% [112/324] vs 23% [36/157], respectively; P =.002). Overall, a higher proportion of nonnucleoside reverse transcriptase inhibitor (NNRTI)-naive patients had a viral load below 200 copies/mL compared with NNRTI-experienced patients (43% [115/270] vs 16% [33/211], respectively; P<.001). Baseline HIV-1 hypersusceptibility to efavirenz (< or = 0.4-fold difference in susceptibility compared with reference virus) was associated with suppression of viral load at 24 weeks to below 200 copies/mL (odds ratio [OR], 3.49; 95% confidence interval [CI], 1.62-7.33; P =.001), and more than 10-fold reduction in efavirenz susceptibility, with less likelihood of suppression at 24 weeks (OR, 0.28; 95% CI, 0.09-0.87; P =.03).. In this study of antiretroviral-experienced patients with advanced immunodeficiency, viral load suppression to below 200 copies/mL was achieved in 31% of patients with regimens containing 4 or 5 new drugs. Use of 2 PIs, being naive to NNRTIs, and baseline hypersusceptibility to efavirenz were associated with a favorable outcome.

Topics: Adenine; Adult; Alkynes; Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Benzoxazines; Carbamates; CD4 Lymphocyte Count; Cyclopropanes; Dideoxynucleosides; Disease Progression; Double-Blind Method; Drug Resistance, Viral; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Male; Nelfinavir; Organophosphonates; Oxazines; Proportional Hazards Models; Reverse Transcriptase Inhibitors; Saquinavir; Sulfonamides; Treatment Failure; Viral Load

This prospective, multicenter, open-label study was designed to determine the antiretroviral activity and safety of a 4-drug regimen: 1000 mg indinavir every 8 h with 200 mg nevirapine, 40 mg stavudine, and 150 mg lamivudine, each given twice daily in amprenavir-experienced subjects. The primary end points of the study were the human immunodeficiency virus (HIV) RNA level and CD4 cell count responses. Fifty-six subjects were enrolled and were changed from amprenavir-containing regimens to the 4-drug regimen. Overall, at week 48, 33 (59%) of 56 subjects had HIV RNA levels <500 copies/mL (intent-to-treat analysis, where missing values equal > or =500 copies/mL) and CD4 cell counts increased by 94 cells/mm(3) from baseline. Subjects who had previously taken amprenavir combination therapy were more likely to experience virologic failure than those who had taken amprenavir monotherapy (odds ratio, 7.7; P=.0012). In this study, most subjects who had taken amprenavir-based regimens and who changed to a 4-drug regimen achieved subsequent durable virologic suppression.

Topics: Adult; Anti-HIV Agents; Carbamates; CD4 Lymphocyte Count; Cross-Over Studies; Dose-Response Relationship, Drug; Female; Furans; HIV Infections; Humans; Indinavir; Lamivudine; Male; Nevirapine; Odds Ratio; Prospective Studies; RNA, Viral; Safety; Stavudine; Sulfonamides; Time Factors; Treatment Outcome; Viral Load

In an open-label, randomized, multicenter, multiple-dose pharmacokinetic study, we determined the steady-state pharmacokinetics of amprenavir with and without coadministration of indinavir, nelfinavir, or saquinavir soft gel formulation in 31 human immunodeficiency virus type 1-infected subjects. The results indicated that amprenavir plasma concentrations were decreased by saquinavir soft gel capsule (by 32% for area under the concentration-time curve at steady state [AUC(ss)] and 37% for peak plasma concentration at steady state [C(max,ss)]) and increased by indinavir (33% for AUC(ss)). Nelfinavir significantly increased amprenavir minimum drug concentration at steady state (by 189%) but did not affect amprenavir AUC(ss) or C(max,ss). Nelfinavir and saquinavir steady-state pharmacokinetics were unchanged by coadministration with amprenavir compared with the historical monotherapy data. Concentrations of indinavir, coadministered with amprenavir, in plasma decreased in both single-dose and steady-state evaluations. The changes in amprenavir steady-state pharmacokinetic parameters, relative to those for amprenavir alone, were not consistent among protease inhibitors, nor were the changes consistent with potential interactions in CYP3A4 metabolism or P-glycoprotein transport. No dose adjustment of either protease inhibitor in any of the combinations studied is needed.

Topics: Adult; Area Under Curve; Carbamates; CD4 Lymphocyte Count; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme Inhibitors; Drug Interactions; Enzyme Inhibitors; Female; Furans; HIV Protease Inhibitors; HIV Seropositivity; Humans; Indinavir; Male; Mixed Function Oxygenases; Nelfinavir; Orosomucoid; Saquinavir; Sulfonamides

The extent to which human immunodeficiency virus (HIV) type 1 drug resistance compromises therapeutic efficacy is intimately tied to drug potency and exposure. Most HIV-1 protease inhibitors maintain in vivo trough levels above their human serum protein binding-corrected IC(95) values for wild-type HIV-1. However, these troughs are well below corrected IC(95) values for protease inhibitor-resistant viruses from patients experiencing virologic failure of indinavir and/or nelfinavir. This suggests that none of the single protease inhibitors would be effective after many cases of protease inhibitor failure. However, saquinavir, amprenavir, and indinavir blood levels are increased substantially when each is coadministered with ritonavir, with 12-h troughs exceeding corrected wild-type IC(95) by 2-, 7-, and 28-79-fold, respectively. These indinavir and amprenavir troughs exceed IC(95) for most protease inhibitor-resistant viruses tested. This suggests that twice-daily indinavir-ritonavir and, to a lesser extent, amprenavir-ritonavir may be effective for many patients with viruses resistant to protease inhibitors.

Topics: Carbamates; Drug Resistance, Microbial; Drug Synergism; Drug Therapy, Combination; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Nelfinavir; Phenotype; Protein Binding; Ritonavir; Saquinavir; Sulfonamides

Topics: Acquired Immunodeficiency Syndrome; Adult; Carbamates; Furans; HIV Protease Inhibitors; Humans; Indinavir; Reverse Transcriptase Inhibitors; Sulfonamides

141W94 (VX-478) is a novel HIV-1 protease inhibitor with an IC50 of 0.08 microM against HIV-1 (strain IIIB) and a mean IC50 of 0.012 microM against six HIV clinical isolates. 141W94 was synergistic on the basis of isobologram analysis with each of the following reverse transcriptase inhibitors: AZT, 935U83, 524W91, 1592U89 and ddl, 141W94 was also synergistic with saquinavir and additive with either indinavir or ritonavir. Resistance to 141W94 has been reported in vitro passage experiments. The binding of 141W94 to human alpha 1-acid glycoprotein was relatively weak (Kd = 4 microM) and the off-rate for the drug is very fast (> or = 100 s-1). Only a 2-fold reduction of in vitro antiviral activity was observed in the presence of 45% human plasma. No serious drug associated adverse experiences were reported in a Phase I placebo-controlled, single-dose escalation, pharmacokinetic and safety study. The average concentration of 141W94 at 8 and 12 h after single doses of 900 and 1200 mg, respectively, was in excess of 10 times the IC50. As 141W94 is synergistic with a variety of anti-HIV-1 agents and exhibits a unique cross resistance profile compared to other protease inhibitors, 141W94 is considered a good candidate for combination therapy.

Topics: Carbamates; Drug Resistance, Microbial; Drug Synergism; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Isoquinolines; Pyridines; Quinolines; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sulfonamides; Thiazoles; Valine

Infection by human immunodeficiency virus type 1 (HIV-1) not only destroys the immune system bringing about acquired immune deficiency syndrome (AIDS), but also induces serious neurological diseases including behavioral abnormalities, motor dysfunction, toxoplasmosis, and HIV-1 associated dementia. The emergence of HIV-1 multidrug-resistant mutants has become a major problem in the therapy of patients with HIV-1 infection. Focusing on the wild type (WT) and G48T/L89M mutated forms of HIV-1 protease (HIV-1 PR) in complex with amprenavir (APV), indinavir (IDV), ritonavir (RTV), and nelfinavir (NFV), we have investigated the conformational dynamics and the resistance mechanism due to the G48T/L89M mutations by conducting a series of molecular dynamics (MD) simulations and free energy (MM-PBSA and solvated interaction energy (SIE)) analyses. The simulation results indicate that alterations in the side-chains of G48T/L89M mutated residues cause the inner active site to increase in volume and induce more curling of the flap tips, which provide the main contributions to weaker binding of inhibitors to the HIV-1 PR. The results of energy analysis reveal that the decrease in van der Waals interactions of inhibitors with the mutated PR relative to the wild-type (WT) PR mostly drives the drug resistance of mutations toward these four inhibitors. The energy decomposition analysis further indicates that the drug resistance of mutations can be mainly attributed to the change in van der Waals and electrostatic energy of some key residues (around Ala28/Ala28' and Ile50/Ile50'). Our work can give significant guidance to design a new generation of anti-AIDS inhibitors targeting PR in the therapy of patients with HIV-1 infection.

Topics: Anti-HIV Agents; Carbamates; Drug Resistance; Furans; HIV Protease; Indinavir; Molecular Conformation; Molecular Dynamics Simulation; Mutation; Nelfinavir; Protein Binding; Ritonavir; Sulfonamides

Human immunodeficiency virus (HIV)-1 protease is one of the most promising drug target commonly utilized to combat Acquired Immune Deficiency Syndrome (AIDS). However, with the emergence of drug resistance arising from mutations, the efficiency of protease inhibitors (PIs) as a viable treatment for AIDS has been greatly reduced. I50V mutation as one of the most significant mutations occurring in HIV-1 protease will be investigated in this study. Molecular dynamics (MD) simulation was utilized to examine the effect of I50V mutation on the binding of two PIs namely indinavir and amprenavir to HIV-1 protease. Prior to the simulations conducted, the electron density distributions of the PI and each residue in HIV-1 protease are derived by combining quantum fragmentation approach molecular fractionation with conjugate caps and Poisson-Boltzmann solvation model based on polarized protein-specific charge scheme. The atomic charges of the binding complex are subsequently fitted using delta restrained electrostatic potential (delta-RESP) method to overcome the poor charge determination of buried atom. This way, both intraprotease polarization and the polarization between protease and the PI are incorporated into partial atomic charges. Through this study, the mutation-induced affinity variations were calculated and significant agreement between experiments and MD simulations conducted was observed for both HIV-1 protease-drug complexes. In addition, the mechanism governing the decrease in the binding affinity of PI in the presence of I50V mutation was also explored to provide insights pertaining to the design of the next generation of anti-HIV drugs.

Topics: Carbamates; Furans; HIV Infections; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Molecular Dynamics Simulation; Point Mutation; Protein Binding; Sulfonamides

1.  Transient benign unconjugated hyperbilirubinemia has been observed clinically with several drugs including indinavir, cyclosporine, and rifamycin SV. Genome-wide association studies have shown significant association of OATP1B1 and UGT1A1 with elevations of unconjugated bilirubin, and OATP1B1 inhibition data correlated with clinical unconjugated hyperbilirubinemia for several compounds. 2.  In this study, inhibition of OATP1B3 and UGT1A1, in addition to OATP1B1, was explored to determine whether one measure offers value over the other as a potential prospective tool to predict unconjugated hyperbilirubinemia. OATP1B1 and OATP1B3-mediated transport of bilirubin was confirmed and inhibition was determined for atazanavir, rifampicin, indinavir, amprenavir, cyclosporine, rifamycin SV and saquinavir. To investigate the intrinsic inhibition by the drugs, both in vivo Fi (fraction of intrinsic inhibition) and R-value (estimated maximum in vivo inhibition) for OATP1B1, OATP1B3 and UGT1A1 were calculated. 3.  The results indicated that in vivo Fi values >0.2 or R-values >1.5 for OATP1B1 or OATP1B3, but not UGT1A1, are associated with previously reported clinical cases of drug-induced unconjugated hyperbilirubinemia. 4.  In conclusion, inhibition of OATP1B1 and/or OATP1B3 along with predicted human pharmacokinetic data could be used pre-clinically to predict potential drug-induced benign unconjugated hyperbilirubinemia in the clinic.

Topics: Antirheumatic Agents; Atazanavir Sulfate; Bilirubin; Carbamates; Cyclosporine; Furans; Glucuronosyltransferase; HIV Protease Inhibitors; Hyperbilirubinemia; In Vitro Techniques; Indinavir; Liver-Specific Organic Anion Transporter 1; Oligopeptides; Organic Anion Transporters; Organic Anion Transporters, Sodium-Independent; Pyridines; Rifampin; Rifamycins; Saquinavir; Solute Carrier Organic Anion Transporter Family Member 1B3; Sulfonamides

Aspartic peptidase inhibitors have shown antimicrobial action against distinct microorganisms. Due to an increase in the occurrence of Chagas' disease/AIDS co-infection, we decided to explore the effects of HIV aspartic peptidase inhibitors (HIV-PIs) on Trypanosoma cruzi, the etiologic agent of Chagas' disease.. HIV-PIs presented an anti-proliferative action on epimastigotes of T. cruzi clone Dm28c, with IC50 values ranging from 0.6 to 14 µM. The most effective inhibitors, ritonavir, lopinavir and nelfinavir, also had an anti-proliferative effect against different phylogenetic T. cruzi strains. The HIV-PIs induced some morphological alterations in clone Dm28c epimastigotes, as reduced cell size and swollen of the cellular body. Transmission electron microscopy revealed that the flagellar membrane, mitochondrion and reservosomes are the main targets of HIV-PIs in T. cruzi epimastigotes. Curiously, an increase in the epimastigote-into-trypomastigote differentiation process of clone Dm28c was observed, with many of these parasites presenting morphological alterations including the detachment of flagellum from the cell body. The pre-treatment with the most effective HIV-PIs drastically reduced the interaction process between epimastigotes and the invertebrate vector Rhodnius prolixus. It was also noted that HIV-PIs induced an increase in the expression of gp63-like and calpain-related molecules, and decreased the cruzipain expression in epimastigotes as judged by flow cytometry and immunoblotting assays. The hydrolysis of a cathepsin D fluorogenic substrate was inhibited by all HIV-PIs in a dose-dependent manner, showing that the aspartic peptidase could be a possible target to these drugs. Additionally, we verified that ritonavir, lopinavir and nelfinavir reduced drastically the viability of clone Dm28c trypomastigotes, causing many morphological damages.. The results contribute to understand the possible role of aspartic peptidases in T. cruzi physiology, adding new in vitro insights into the possibility of exploiting the use of HIV-PIs in the clinically relevant forms of the parasite.

Topics: Animals; Anti-HIV Agents; Aspartic Acid Proteases; Carbamates; Furans; Host-Parasite Interactions; Indinavir; Insect Vectors; Lopinavir; Microscopy, Electron, Transmission; Nelfinavir; Protease Inhibitors; Ritonavir; Saquinavir; Sulfonamides; Trypanocidal Agents; Trypanosoma cruzi

The emergence of HIV-1 drug-resistant mutations is the major problem against AIDS treatment. We employed molecular dynamics (MD) calculations and free energy (MM-PBSA and thermodynamic integration) analyses on wild-type (WT) and mutated HIV-1 protease (HIV-1 PR) complexes with darunavir, amprenavir, indinavir, and saquinavir to clarify the mechanism of resistance due to the I50V flap mutation. Conformational analysis showed that the protease flaps are increasingly flexible in the I50V complexes. In the WT, stabilization of the HIV-1 PR structure is achieved via interflap and water-mediated hydrogen-bonding interactions between the flaps. Furthermore, hydrogen bonds between drugs and binding cavity residues (Asp29/29'/30/30') are crucial for effective inhibition. All these interactions were significantly diminished (or absent) in the mutated forms, thus denoting their importance toward binding. Thermodynamic integration calculations reproduced the experimental data to within ≈1 kcal mol⁻¹ and showed that the I50V mutation results in weaker binding free energies for all analyzed complexes with respect to the WT. It was observed that the loss in binding energy upon mutation was mostly enthalpically driven in all complexes, with the greatest effect coming from the reduction of van der Waals interactions. Our results motivated us to test two novel compounds that have been synthesized to maximize interactions with HIV-1 PR. MM-PBSA and TI calculations showed that compound 3c (Ghosh et al. Bioorg. Med. Chem. Lett. 2012, 22, 2308) is a promising protease inhibitor, which presents very effective binding to the WT PR (ΔG(MM-PBSA) = -17.2 kcal mol⁻¹, ΔG(exp) = -16.1 kcal mol⁻¹). Upon I50V mutation, the complex binding free energy was weakened by a ΔΔG(TI) of 1.8 kcal mol⁻¹, comparable to the marketed inhibitors. This predicts that I50V may confer low resistance to 3c. This computational comparative study contributes toward elucidation of the I50V drug-resistance mechanism in HIV-1 PR.

Topics: Anti-HIV Agents; Carbamates; Cluster Analysis; Darunavir; Drug Resistance, Viral; Furans; HIV Protease; HIV Protease Inhibitors; HIV-1; Hydrogen Bonding; Indinavir; Molecular Dynamics Simulation; Mutation; Protein Conformation; Saquinavir; Sulfonamides; Thermodynamics

The highly active antiretroviral therapy (HAART) can cause a metabolic syndrome consisting of lipodystropy/lipoatrophy, dyslipidemia, and type 2 diabetes mellitus with an increased cardiovascular risk. The pathogenetic bases of HAART-associated lipodystrophy are poorly known. A genetic screen was used to evaluate proteins that are modulated in HIV-1-infected patients with or without lipodystrophy syndrome, that are routinely treated with HAART regimens. The most significant modulation was represented by FAP48 expression. Stable over-expression of FAP48 was able to alter, in vitro, adipogenesis, acting both on calcineurin and glucocorticoid pathways. Finally, we demonstrated that FAP48 over-expression was able to influence the capacity of some HIV drugs, Saquinavir and Efavirenz, but not Stavudine, Amprenavir, and Indinavir to inhibit adipocyte formation. In conclusion, this molecule could be a potential target for novel therapeutic approaches to the HAART related lipodystrophy in HIV patients.

Topics: Adaptor Proteins, Signal Transducing; Adipocytes; Alkynes; Animals; Antiretroviral Therapy, Highly Active; Benzoxazines; Calcineurin; Carbamates; Cell Differentiation; Cell Line; Cyclopropanes; Furans; Gene Expression; Glucocorticoids; HIV-1; HIV-Associated Lipodystrophy Syndrome; Humans; Indinavir; Mice; Saquinavir; Signal Transduction; Stavudine; Sulfonamides; Transfection

Patterns of HIV-1 protease inhibitor (PI) resistance-associated mutations (RAMs) and effects on PI susceptibility associated with the L76V mutation were studied in a large database. Of 20,501 sequences with ≥1 PI RAM, 3.2% contained L76V; L76V was alone in 0.04%. Common partner mutations included M46I, I54V, V82A, I84V, and L90M. L76V was associated with a 2- to 6-fold decrease in susceptibility to lopinavir, darunavir, amprenavir, and indinavir and a 7- to 8-fold increase in susceptibility to atazanavir and saquinavir.

Topics: Antiviral Agents; Carbamates; Darunavir; Furans; HIV Protease; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Mutation; Pyrimidinones; Sulfonamides

Hepatotoxicity has been reported as a side-effect in some patients on HIV protease inhibitors (PI). Since transporter interaction has been implicated as a mechanism underlying drug-mediated hepatotoxicity and drug-drug interactions, the interaction of PI with the hepatic canalicular efflux transporter ABCC2 (MRP2; multidrug resistance associated protein-2) was studied. Interaction with ABCC2/Abcc2 was evaluated in human and rat sandwich-cultured hepatocytes using 5(6)-carboxy-2',7'-dichlorofluorescein (CDF) as substrate. In rat hepatocytes, interaction with estradiol-17-beta-D-glucuronide (E17G) efflux was also studied. In human hepatocytes, saquinavir, ritonavir and atazanavir were the most efficient inhibitors of ABCC2-mediated biliary excretion of CDF, whereas in rat hepatocytes indinavir, lopinavir and nelfinavir were the most efficient. No species-similarity was found for ABCC2/Abcc2 inhibition. In rat hepatocytes, the effects on Abcc2 were substrate-dependent as inhibition of biliary excretion of E17G was most pronounced for saquinavir (completely blocked), amprenavir (82% inhibition) and indinavir (68% inhibition). In conclusion, several HIV PI showed substantial ABCC2 inhibition, which, combined with the effects of PI on other hepatobiliary disposition mechanisms, will determine the clinical relevance of these in vitro interaction data.

Topics: Animals; Anti-HIV Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Carbamates; Cells, Cultured; Fluoresceins; Furans; Hepatocytes; HIV Protease Inhibitors; Humans; Indinavir; Liver; Multidrug Resistance-Associated Protein 2; Multidrug Resistance-Associated Proteins; Nelfinavir; Rats; Rats, Wistar; Ritonavir; Saquinavir; Sulfonamides

The importance of the active site region aspartyl residues 25 and 29 of the mature HIV-1 protease (PR) for the binding of five clinical and three experimental protease inhibitors [symmetric cyclic urea inhibitor DMP323, nonhydrolyzable substrate analog (RPB) and the generic aspartic protease inhibitor acetyl-pepstatin (Ac-PEP)] was assessed by differential scanning calorimetry. DeltaT(m) values, defined as the difference in T(m) for a given protein in the presence and absence of inhibitor, for PR with DRV, ATV, SQV, RTV, APV, DMP323, RPB, and Ac-PEP are 22.4, 20.8, 19.3, 15.6, 14.3, 14.7, 8.7, and 6.5 degrees C, respectively. Binding of APV and Ac-PEP is most sensitive to the D25N mutation, as shown by DeltaT(m) ratios [DeltaT(m)(PR)/DeltaT(m)(PR(D25N))] of 35.8 and 16.3, respectively, whereas binding of DMP323 and RPB (DeltaT(m) ratios of 1-2) is least affected. Binding of the substrate-like inhibitors RPB and Ac-PEP is nearly abolished (DeltaT(m)(PR)/DeltaT(m)(PR(D29N)) > or = 44) by the D29N mutation, whereas this mutation only moderately affects binding of the smaller inhibitors (DeltaT(m) ratios of 1.4-2.2). Of the nine FDA-approved clinical HIV-1 protease inhibitors screened, APV, RTV, and DRV competitively inhibit porcine pepsin with K(i) values of 0.3, 0.6, and 2.14 microM, respectively. DSC results were consistent with this relatively weak binding of APV (DeltaT(m) 2.7 degrees C) compared with the tight binding of Ac-PEP (DeltaT(m) > or = 17 degrees C). Comparison of superimposed structures of the PR/APV complex with those of PR/Ac-PEP and pepsin/pepstatin A complexes suggests a role for Asp215, Asp32, and Ser219 in pepsin, equivalent to Asp25, Asp25', and Asp29 in PR in the binding and stabilization of the pepsin/APV complex.

Topics: Atazanavir Sulfate; Binding Sites; Binding, Competitive; Calorimetry, Differential Scanning; Carbamates; Crystallography, X-Ray; Darunavir; Furans; HIV Protease; HIV Protease Inhibitors; Humans; Indinavir; Kinetics; Lopinavir; Models, Molecular; Molecular Structure; Mutation; Nelfinavir; Oligopeptides; Pepsin A; Protein Binding; Protein Structure, Tertiary; Pyridines; Pyrimidinones; Pyrones; Ritonavir; Saquinavir; Sulfonamides

Most HPLC-UV methods for therapeutic drug monitoring of anti-HIV drugs have long run times, which reduce their applicability for high-throughput analysis. We developed an ultra-performance liquid chromatography (UPLC)-diode array detection method for the simultaneous quantification of the HIV-protease inhibitors (PIs) amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, and tipranavir (TPV), and the nonnucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz and nevirapine.. Solid-phase extraction of 1 mL plasma was performed with Waters HLB cartridges. After 3 wash steps, we eluted the drugs with methanol, evaporated the alcohol, and reconstituted the residue with 50 microL methanol. We injected a 4-microL volume into the UPLC system (Waters ACQUITY UPLC BEH C8 column maintained at 60 degrees C) and used a linear gradient of 50 mmol/L ammonium acetate and 50 mmol/L formic acid in water versus acetonitrile to achieve chromatographic separation of the drugs and internal standard (A-86093). Three wavelengths (215, 240, and 260 nm) were monitored.. All drugs were eluted within 15 min. Calibration curves with concentrations of 0.025-10 mg/L (1.875-75 mg/L for TPV) showed coefficients of determination (r(2)) between 0.993 and 0.999. The lower limits of quantification were well below the trough concentrations reported in the literature. Inter- and intraassay CVs and the deviations between the nominal and measured concentrations were <15%. The method was validated by successful participation in an international interlaboratory QC program.. This method allows fast and simultaneous quantification of all commercially available PIs and NNRTIs for therapeutic drug monitoring.

Topics: Alkynes; Atazanavir Sulfate; Benzoxazines; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Nevirapine; Oligopeptides; Pyridines; Pyrimidinones; Pyrones; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sensitivity and Specificity; Solid Phase Extraction; Sulfonamides

Human immunodeficiency virus type 2 (HIV-2) contains numerous natural polymorphisms in its protease (PR) gene that are implicated in drug resistance in the case of HIV-1. This study evaluated emergent PR resistance in HIV-2. Three HIV-2 isolates were selected for resistance to amprenavir (APV), nelfinavir (NFV), indinavir (IDV), and tipranavir (TPV) in cell culture. Genotypic analysis determined the time to the appearance of protease inhibitor (PI)-associated mutations compared to HIV-1. Phenotypic drug susceptibility assays were used to determine the levels of drug resistance. Within 10 to 15 weeks of serial passage, three major mutations--I54M, I82F, and L90M--arose in HIV-2 viral cultures exposed to APV, NFV, and IDV, whereas I82L was selected with TPV. After 25 weeks, other cultures had developed I50V and I84V mutations. In contrast, no major PI mutations were selected in HIV-1 over this period except for D30N in the context of NFV selective pressure. The baseline phenotypes of wild-type HIV-2 isolates were in the range observed for HIV-1, except for APV and NFV for which a lower degree of sensitivity was seen. The acquisition of the I54M, I84V, L90M, and L99F mutations resulted in multi-PI-resistant viruses, conferring 10-fold to more than 100-fold resistance. Of note, we observed a 62A/99F mutational motif that conferred high-level resistance to PIs, as well as novel secondary mutations, including 6F, 12A, and 21K. Thus, natural polymorphisms in HIV-2 may facilitate the selection of PI resistance. The increasing incidence of such polymorphisms in drug-naive HIV-1- and HIV-2-infected persons is of concern.

Topics: Amino Acid Sequence; Carbamates; Drug Resistance, Viral; Furans; HIV Protease; HIV Protease Inhibitors; HIV-1; HIV-2; Humans; Indinavir; Molecular Sequence Data; Mutation; Nelfinavir; Polymorphism, Genetic; Pyridines; Pyrones; Sulfonamides

A simple, accurate and fast method was developed for determination of the commonly used HIV protease inhibitors (PIs) amprenavir, indinavir, atazanavir, ritonavir, lopinavir, nelfinavir, M8-nelfinavir metabolite and saquinavir in human plasma. Liquid-liquid extraction was used with hexane/ethylacetate from buffered plasma samples with a borate buffer pH 9.0. Isocratic chromatographic separation of all components was performed on an Allsphere hexyl HPLC column with combined UV and fluorescence detection. Calibration curves were constructed in the range of 0.025-10 mg/l. Accuracy and precision of the standards were all below 15% and the lowest limit of quantitation was 0.025 mg/l. Stability of quality control samples at different temperature conditions was found to be below 20% of nominal values. The advantages of this method are: (1) inclusion and determination of the newly approved atazanavir, (2) simultaneous isocratic HPLC separation of all compounds and (3) increased specificity and sensitivity for amprenavir by using fluorescence detection. This method can be used for therapeutic drug monitoring of all PIs currently commercialised and is now part of current clinical practice.

Topics: Atazanavir Sulfate; Calibration; Carbamates; Chromatography, High Pressure Liquid; Drug Monitoring; Drug Stability; Fluorescence; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Oligopeptides; Pyridines; Pyrimidinones; Reproducibility of Results; Ritonavir; Saquinavir; Sensitivity and Specificity; Sulfonamides; Ultraviolet Rays

An efficient, isocratic high performance liquid chromatography (HPLC) method for determining human immunodeficiency virus (HIV) non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) in plasma is advantageous for laboratories participating in clinical trials and therapeutic drug monitoring (TDM) programs, or conducting small animal research. The combination of isocratic reversed phase chromatography using an S-3, 3.0 mm x 150 mm column along with low plasma volume (200 microl), rapid liquid-liquid extraction, and detection at a single wavelength (212 nm) over a short run time makes this method valuable. Within and between assay variability ranges from 0.8 to 3.5% and 1.2-6.2%, respectively. Accuracy ranges from 91.0 to 112.8% for four quality controls (50, 100, 1000, and 10,000 ng/ml) for all drugs measured (efavirenz, nevirapine, amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir).

Topics: Alkynes; Atazanavir Sulfate; Benzoxazines; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Nevirapine; Oligopeptides; Pyridines; Pyrimidinones; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Spectrophotometry, Ultraviolet; Sulfonamides

An accurate, sensitive and simple reverse-phase (RP) high-performance liquid chromatography (HPLC) assay has been developed and validated for the simultaneous quantitative determination of tipranavir with nine other antiretroviral drugs in plasma. A liquid-liquid extraction of the drugs in tert-butylmethylether (TBME) from 200 microL of plasma is followed by a reversed phase gradient HPLC assay with UV detection at 210 nm. The standard curve for the drug was linear in the range of 80-80,000 ng/mL for tipranavir; 10-10,000 ng/mL for nevirapine, indinavir, efavirenz, and saquinavir; and 25-10,000 ng/mL for amprenavir, atazanavir, ritonavir, lopinavir, and nelfinavir. The regression coefficient (r(2)) was greater than 0.998 for all analytes. This method has been fully validated and shown to be specific, accurate and precise. Due to an excellent extraction procedure giving good recovery and a clean baseline, this method is simple, rapid, accurate and provides excellent resolution and peak shape for all analytes. Thus this method is very suitable for therapeutic drug monitoring.

Topics: Alkynes; Anti-HIV Agents; Atazanavir Sulfate; Benzoxazines; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Drug Stability; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Molecular Structure; Nelfinavir; Nevirapine; Oligopeptides; Oxazines; Pyridines; Pyrimidinones; Pyrones; Reproducibility of Results; Ritonavir; Saquinavir; Sensitivity and Specificity; Spectrophotometry, Ultraviolet; Sulfonamides; Time Factors

The effects of five HIV protease inhibitors (amprenavir, indinavir, nelfinavir, ritonavir and saquinavir) on cytochrome P450 (CYP) 3A4, 3A5 and 3A7 activities were studied in vitro using testosterone 6beta-hydroxylation in recombinant CYP3A4, CYP3A5 and CYP3A7 enzymes. The protease inhibitors showed differential inhibitory effects on the three CYP3A forms. Ritonavir and saquinavir were non-selective and preferential inhibitors of CYP3A4 and CYP3A5 (K(i) 0.03 microM and 0.6-0.8 microM for ritonavir and saquinavir, respectively), and weaker inhibitors of CYP3A7 (K(i) 0.6 microM and 1.8 microM, respectively). Nelfinavir was a potent and non-selective inhibitor of all three CYP3A forms (K(i) 0.3-0.4 microM). Amprenavir and indinavir preferentially inhibited CYP3A4 (K(i) 0.1 microM and 0.2 microM, respectively), with weaker inhibitory effects on CYP3A5 (K(i) 0.5 microM and 2.2 microM, respectively) and CYP3A7 (K(i) 2.1 microM and 10.6 microM, respectively). In conclusion, significant differences exist in the inhibitory potency of protease inhibitors for different CYP3A forms. Ritonavir, nelfinavir, saquinavir and amprenavir seem to be prone to drug-drug interactions by inhibiting both CYP3A4 and CYP3A5. Especially nelfinavir and ritonavir also have a potential to inhibit foetal CYP3A7-mediated drug metabolism and some endogenous pathways that may be crucial to normal foetal development, while indinavir has the lowest potential to inhibit CYP3A5 and CYP3A7.

Topics: Aryl Hydrocarbon Hydroxylases; Carbamates; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Dose-Response Relationship, Drug; Drug Interactions; Furans; HIV Protease Inhibitors; Humans; Hydroxylation; In Vitro Techniques; Indinavir; Isoenzymes; Kinetics; Nelfinavir; Recombinant Proteins; Ritonavir; Saquinavir; Sulfonamides; Testosterone

The internal motions of proteins may serve as a "gate" in some systems, which controls ligand-protein association. This study applies Brownian dynamics simulations in a coarse-grained model to study the gated association rate constants of HIV-1 proteases and drugs. The computed gated association rate constants of three protease mutants, G48V/V82A/I84V/L90M, G48V, and L90M with three drugs, amprenavir, indinavir, and saquinavir, yield good agreements with experiments. The work shows that the flap dynamics leads to "slow gating". The simulations suggest that the flap flexibility and the opening frequency of the wild-type, the G48V and L90M mutants are similar, but the flaps of the variant G48V/V82A/I84V/L90M open less frequently, resulting in a lower gated rate constant. The developed methodology is fast and provides an efficient way to predict the gated association rate constants for various protease mutants and ligands.

Topics: Carbamates; Computer Simulation; Enzyme Activation; Furans; HIV Protease; HIV Protease Inhibitors; Indinavir; Ligands; Models, Molecular; Mutation; Saquinavir; Sulfonamides

Mutation proI47A has recently been associated with lopinavir/ritonavir (LPV/r) resistance. Only four out of 1859 specimens (0.2%) sent for drug resistance testing (219 drug-naive and 1650 antiretroviral-experienced) showed I47A. All belonged to patients failing LPV/r. The prevalence among protease inhibitor-experienced patients was 0.6%. Phenotypic testing showed that proI47A caused high-level lopinavir resistance (> 100-fold) and cross-resistance to amprenavir, whereas it caused hypersusceptibility to saquinavir. ProI47A should thus be considered the primary lopinavir resistance mutation.

Topics: Carbamates; Codon; Drug Resistance, Viral; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Lopinavir; Mutation; Nelfinavir; Phenotype; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides

The clearance of cytomegalovirus viraemia in HIV-1-infected patients may partly result from the inhibition of cytomegalovirus protease by HIV-1 protease inhibitors contained in highly active antiretroviral therapy. We used a computational method to calculate the binding affinity of six HIV-1 protease inhibitors to cytomegalovirus protease based on its X-ray crystallography structure. The calculations showed that amprenavir and indinavir occupy the substrate-binding site of the cytomegalovirus protease with high affinity, and may be implicated in alleviating cytomegalovirus infection.

Topics: AIDS-Related Opportunistic Infections; Antiretroviral Therapy, Highly Active; Binding Sites; Carbamates; Crystallography, X-Ray; Cytomegalovirus; Cytomegalovirus Infections; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Molecular Structure; Peptide Hydrolases; Sulfonamides

Several studies suggest that therapeutic drug monitoring of protease inhibitors and nonnucleoside reverse transcriptase inhibitors may contribute to the clinical outcome of HIV-infected patients. Because of the growing number of antiretroviral drugs and of drug combinations than can be administered to these patients, an accurate high-performance liquid chromatographic (HPLC) method allowing the simultaneous determination of these drugs may be useful. To date, the authors present the first simultaneous HPLC determination of the new protease inhibitor atazanavir with all the others currently in use (M8 nelfinavir metabolite included) and the 2 widely used nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine. This simple HPLC method allows the analysis all these drugs at a single ultraviolet wavelength following a 1-step liquid-liquid extraction procedure. A 500-muL plasma sample was spiked with internal standard and subjected to liquid-liquid extraction using by diethyl ether at pH 10. HPLC was performed using a Symmetry Shield RP18 and gradient elution. All the drugs of interest and internal standard were detected with ultraviolet detection at 210 nm. Calibration curves were linear in the range 50-10,000 ng/mL. The observed concentrations of the quality controls at plasma concentrations ranging from 50 to 5000 ng/mL for these drugs showed that the overall accuracy varied from 92% to 104% and 92% to 106% for intraday and day-to-day analysis, respectively. No metabolites of the assayed compounds or other drugs commonly coadministered to HIV-positive patients were found to coelute with the drugs of interest or with the internal standard. This assay was developed for the purpose of therapeutic monitoring (TDM) in HIV-infected patients.

Topics: Alkynes; Atazanavir Sulfate; Benzoxazines; Calibration; Carbamates; Chromatography, Liquid; Cyclopropanes; Drug Stability; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Nevirapine; Oligopeptides; Oxazines; Pyridines; Pyrimidinones; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Specimen Handling; Spectrophotometry, Ultraviolet; Sulfonamides

Intensification therapy adding a boosted protease inhibitor (PI) to a failing regimen has the potential to worsen the resistance profile. Sixty-six patients included in four different boosted PI intensification studies were assessed and resistance mutations in the reverse transcriptase and protease genes were evaluated at baseline and 4 weeks after the initiation of the intensification strategy. Only one of the 66 patients developed changes in their pattern of mutations able to generate or increase resistance to new drugs.

Topics: Antiretroviral Therapy, Highly Active; Carbamates; Drug Resistance, Multiple, Viral; Follow-Up Studies; Furans; HIV Infections; HIV Protease; HIV Protease Inhibitors; HIV Reverse Transcriptase; HIV-1; Humans; Indinavir; Lopinavir; Mutation; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides; Treatment Failure; Viral Load

HIV protease inhibitors (PIs) have been implicated to cause cardiovascular complications. Previous studies demonstrated that the PI ritonavir (RTV) caused endothelial dysfunction in porcine arteries. This study investigated and compared the effects of 5 commonly used PIs on vasomotor function, endothelial nitric oxide synthase (eNOS) expression, and oxidative stress in porcine coronary arteries. Vessel rings were incubated with 15 microM of RTV, amprenavir (APV), saquinavir (SQV), indinavir (IDV), or nelfinavir (NFV) for 24 hours. Vasomotor function was studied using a myograph system. The contractility of the rings was significantly reduced for RTV and SQV. In response to bradykinin at 10(-5) M, the endothelium-dependent relaxation was significantly reduced for RTV, APV, and SQV. The eNOS mRNA levels were significantly reduced for RTV, APV, and SQV. Furthermore, the superoxide anion (O(2)(-)) levels of the vessels were significantly increased for RTV and APV. It was found that nitric oxide production was decreased, whereas the level of nitrotyrosine proteins was increased in RTV-treated vessels. Furthermore, antioxidant seleno-L-methionine (SeMet) reversed RTV-induced O(2)(-) production and vasomotor dysfunction. Thus, the HIV PIs RTV, APV, and SQV at 15 microM have more potent in vitro effects on vasomotor dysfunction, eNOS downregulation, and O(2)(-) production than IDV and NFV. The antioxidant SeMet can block these adverse effects of RTV. The results suggest that antioxidant therapy may have applications for controlling PI-associated cardiovascular complications.

Topics: Animals; Bradykinin; Carbamates; Coronary Vessels; Down-Regulation; Furans; HIV Protease Inhibitors; Indinavir; Methionine; Muscle Contraction; Muscle, Smooth, Vascular; Myography; Nelfinavir; Nitric Oxide Synthase; Organ Culture Techniques; Ritonavir; RNA, Messenger; Saquinavir; Selenium Compounds; Sulfonamides; Superoxides; Swine; Vasomotor System

The purpose of this study was to investigate placental transfer and amniotic fluid concentrations of protease inhibitors when they are given to pregnant women who are infected with human immunodeficiency virus.. Fifty-eight mothers who received antiretroviral therapy that included > or =1 protease inhibitors for clinical indications at the time of delivery were enrolled in the study. Maternal blood samples and amniotic fluid were obtained during delivery or cesarean delivery, and paired cord blood samples were obtained by venipuncture immediately after the delivery. Drug concentrations were measured with high performance liquid chromatography.. Most maternal protease inhibitor plasma concentrations (38/66 concentrations) were below the trough concentrations that are recommended for therapeutic drug monitoring. Cord blood concentrations were below the assay limit of detection in 10 of 40 samples for nelfinavir and 25 of 40 samples for its metabolite M8, 9 of 11 samples for ritonavir, 4 of 6 samples for indinavir, 5 of 6 samples for saquinavir but were detectable in 3 of 3 samples for amprenavir. Among the 24 amniotic fluid samples that were available, the concentrations below the detection limit were 10 of 16 samples for nelfinavir, 11 of 16 samples for M8, 1 of 3 samples for indinavir, 4 of 4 samples for ritonavir, and 0 of 1 samples for amprenavir. There were significant correlations between cord blood and maternal concentrations of nelfinavir and its metabolite M8.. Placental transfer of the human immunodeficiency virus protease inhibitors is generally low; however, it may differ greatly according to the molecule.

Topics: Adult; Amniotic Fluid; Carbamates; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Maternal-Fetal Exchange; Nelfinavir; Pregnancy; Pregnancy Complications, Infectious; Ritonavir; Saquinavir; Sulfonamides

The mechanism by which chronic treatment with HIV (human immunodeficiency virus)-1 protease inhibitors leads to a deterioration of glucose metabolism appears to involve insulin resistance, and may also involve impaired insulin secretion. Here we investigated the long-term effects of HIV-1 protease inhibitors on glucose-stimulated insulin secretion from beta cells and explored whether altered insulin secretion might be related to altered insulin signaling. INS-1 cells were incubated for 48 h with different concentrations of amprenavir, indinavir, nelfinavir, ritonavir or saquinavir, stimulated with 20 mM d-glucose, and insulin determined in the supernatant. To evaluate insulin signaling, cells were stimulated with 100 nM insulin for 2 min, and insulin-receptor substrate (IRS)-1, -2 and Akt phosphorylation determined. Incubation for 48 h with ritonavir, nelfinavir and saquinavir resulted in impaired glucose-induced insulin secretion at 2.5, 5 and 5 microM respectively, whereas amprenavir or indinavir had no effects even at 20 and 100 microM respectively. The impaired insulin secretion by ritonavir, nelfinavir and saquinavir was associated with decreased insulin-stimulated IRS-2 phosphorylation, and, for nelfinavir and saquinavir, with decreased insulin-stimulated IRS-1 and Thr308-Akt phosphorylation. No such effects on signaling were observed with amprenavir or indinavir. In conclusion, certain HIV-1 protease inhibitors, such as ritonavir, nelfinavir and saquinavir, not only induce peripheral insulin resistance, but also impair glucose-stimulated insulin secretion from beta cells. With respect to the long-term effect on beta-cell function there appear to be differences between the protease inhibitors that may be clinically relevant. Finally, these effects on insulin secretion after a 48 h incubation with protease inhibitor were associated with a reduction of the insulin-stimulated phosphorylation of insulin signaling parameters, particularly IRS-2, suggesting that protease inhibitor-induced alterations in the insulin signaling pathway may contribute to the impaired beta-cell function.

Topics: Carbamates; Cell Line; Furans; Glucose; HIV Protease Inhibitors; Humans; Indinavir; Insulin; Insulin Receptor Substrate Proteins; Insulin Secretion; Intracellular Signaling Peptides and Proteins; Islets of Langerhans; Nelfinavir; Phosphoproteins; Phosphorylation; Ritonavir; Saquinavir; Signal Transduction; Stimulation, Chemical; Sulfonamides; Time Factors

To elucidate drug interaction between human immunodeficiency virus (HIV) protease inhibitors (PIs), the effect of indinavir (IDV) on the intestinal exsorption of other HIV PIs, amprenavir (APV), saquinavir (SQV) and nelfinavir (NFV) was investigated in rats using an in situ single perfusion method. IDV in the intestinal perfusate inhibited the exsorption of rhodamine 123 (Rho123), a known P-glycoprotein (P-gp) substrate, from blood into intestinal lumen in a concentration-dependent manner, and the inhibitory potency of 10 micro M IDV in the perfusate was close to that of 10 micro M cyclosporin A (CsA) in the perfusate. Ten micro M of IDV in the intestinal perfusate also decreased significantly the exsorption clearance of Rho123 after intravenous administration. The IDV concentration in this system was not likely to cause hepatic interaction between HIV PIs, because the plasma IDV concentration was far below its inhibition constants for other HIV PIs in the liver microsomes. Thus, 10 micro M of IDV was chosen to investigate the effect of this inhibition on the exsorption of APV, SQV and NFV. IDV in the intestinal perfusate markedly increased the exsorbed amounts of SQV and NFV but not APV after intravenous administrations. Their exsorption clearances, however, showed only a slight increasing tendency or remained unchanged. These findings suggest that in addition to P-gp inhibition, other factors such as CYP3A inhibition might be important in the drug interaction of IDV with APV, SQV and NFV after intravenous administration in rat small intestine. The results obtained in this study will provide useful information to discuss the interactions among PIs when a double protease therapy is used for in HIV-infected patients.

Topics: Animals; Carbamates; Drug Interactions; Furans; Indinavir; Infusions, Intravenous; Intestinal Absorption; Male; Microsomes, Liver; Nelfinavir; Rats; Rats, Wistar; Saquinavir; Sulfonamides

The increasing interest in applying therapeutic drug monitoring (TDM) to antiretroviral therapy is related to the observed interindividual variation in antiretroviral pharmacokinetics that results in a wide range of drug exposure from fixed-dosing regimens and the rapid evolution in the availability of phenotypic assays that generate a target 50% inhibitory concentration (e.g., IC(50)) as a basis for adjusting individual antiretroviral dosages. To facilitate the application of TDM, a method for the simultaneous determination of eight species has been developed. This method is used to quantitate efavirenz and the following protease inhibitors: amprenavir, indinavir, lopinavir, nelfinavir and its active metabolite (M8), ritonavir, and saquinavir. The method using reversed-phase high-performance liquid chromatography (RP-HPLC) was validated. Detection is effected using a photodiode-array detector (PDA) scanning at four different wavelengths. This method allows for detection of all analytes to a lower limit of quantitation of 0.1 to 0.2 microg/mL with an interday variation in CV ranging from 3.5% to 10.4%. The method is being applied to a TDM program that is currently being implemented in the authors' laboratory.

Topics: Alkynes; Anti-HIV Agents; Benzoxazines; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Furans; Heparin; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Oxazines; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides

HIV protease inhibitors (PIs) acutely and reversibly inhibit the insulin-responsive glucose transporter Glut 4, leading to peripheral insulin resistance and impaired glucose tolerance. Minimal modeling analysis of glucose tolerance tests on PI-treated patients has revealed an impaired insulin secretory response, suggesting additional pancreatic beta-cell dysfunction. To determine whether beta-cell function is acutely affected by PIs, we assayed glucose-stimulated insulin secretion in rodent islets and the insulinoma cell line MIN6. Insulin release from MIN6 cells and rodent islets was significantly inhibited by the PI indinavir with IC(50) values of 1.1 and 2.1 micro mol/l, respectively. The uptake of 2-deoxyglucose in MIN6 cells was similarly inhibited (IC(50) of 2.0 micro mol/l), whereas glucokinase activity was unaffected at drug levels as high as 1 mmol/l. Glucose utilization was also impaired at comparable drug levels. Insulin secretogogues acting downstream of glucose transport mostly reversed the indinavir-mediated inhibition of insulin release in MIN6 cells. Intravenous infusion of indinavir during hyperglycemic clamps on rats significantly suppressed the first-phase insulin response. These data suggest that therapeutic levels of PIs are sufficient to impair glucose sensing by beta-cells. Thus, together with peripheral insulin resistance, beta-cell dysfunction likely contributes to altered glucose homeostasis associated with highly active antiretroviral therapy.

Topics: Animals; Carbamates; Cells, Cultured; Furans; Glucose; HIV Protease Inhibitors; Indinavir; Insulin; Insulin Secretion; Islets of Langerhans; Kinetics; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Nelfinavir; Ritonavir; Sulfonamides

The objective of this study was to investigate the long-term effects of anti-retroviral protease inhibitors (PIs) on 2-deoxy-d -glucose (2-DG) transport in L6 cells in vitro. Exposure of L6 cells to saquinavir, ritonavir, indinavir and amprenavir resulted in significant increases in 2-DG transport using PI concentrations of 1-10 microM with continual exposure to PI. After removal of the PI for up to 48 h, 2-DG transport increases did not change and remained at pre-reversal levels. These changes in 2-DG transport were not related to stress-induced sugar transport or to apoptosis. The examination of glucose transporter (GLUT) 1, 3 or 4 translocation with subcellular fractionation indicated that insulin (i.e. 67 nM) could induce the translocation of all the GLUTs to the plasma membrane. Also, ritonavir (10 microM), which leads to a 2-fold increase in 2-DG transport, demonstrated increased GLUT (i.e. 1, 3 or 4) presence in the plasma membrane fraction, in the presence or absence of insulin. This increased 2-DG transport involved transporter presence in plasma membrane preparations and did not affect the ability of insulin to stimulate 2-DG transport with continual PI exposure. The mechanism(s) involved indicates ready reversibility of PI effects on transporters. The mechanism(s) why reversibility of PI-induced 2-DG transport was similar plus or minus PI was not apparent.

Topics: Biological Transport; Blotting, Western; Carbamates; Cell Membrane; Cells, Cultured; Deoxyglucose; Furans; Glucose Transporter Type 1; Glucose Transporter Type 3; Glucose Transporter Type 4; HIV Protease Inhibitors; Humans; Indinavir; Insulin; Monosaccharide Transport Proteins; Muscle Proteins; Myoblasts; Nerve Tissue Proteins; Ritonavir; Saquinavir; Sulfonamides

Lipodystrophy is a major side effect of HIV protease inhibitor (PI) antiretroviral therapy. It has been shown that protease inhibitors interfere in vitro with adipocyte differentiation. However, there is no evidence that PIs accumulate into preadipocytes and adipocytes and that intra-cellular accumulation is sufficient to alter differentiation. We assessed the effect of six different PIs on the differentiation of cells from four clonal lines. We also studied the capacity of ritonavir to accumulate both into drug-sensitive and drug-resistant cultured adipocytes.. Adipocyte differentiation of mouse 3T3-F442A, 3T3-L1 and Ob1771 cells as well as embryonic stem cells were investigated at pharmacological concentrations of indinavir, saquinavir, ritonavir, amprenavir, nelfinavir and lopinavir. We used a sensitive ELISA to determine intracellular concentration of ritonavir from 3T3-L1 and Ob1771 preadipocytes.. Nelfinavir and lopinavir inhibited adipocyte differentiation whereas amprenavir was ineffective. Indinavir, saquinavir and ritonavir inhibited differentiation of 3T3-L1 and 3T3-F442A cells but did not alter differentiation of either Ob1771 or embryonic stem cells. We showed that ritonavir accumulated in preadipocytes and fully differentiated 3T3-L1 adipocytes as a function of its extracellular concentration. Although Ob1771 cells were resistant and 3T3-L1 cells were sensitive to ritonavir, the drug accumulated to similar levels in both cases.. Protease inhibitors inhibit adipocyte differentiation depending on the cell model used. We showed for the first time that ritonavir accumulates into preadipocytes and adipocytes, suggesting a direct effect on intracellular targets. However, intracellular accumulation was clearly not sufficient as Ob1771 cells remained resistant to the inhibitory effect of ritonavir.

Topics: 3T3 Cells; Adipocytes; Animals; Carbamates; Cell Differentiation; Cell Line; Enzyme-Linked Immunosorbent Assay; Furans; HIV Protease Inhibitors; Indinavir; Lopinavir; Mice; Mice, Inbred Strains; Nelfinavir; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides

To study whether HIV protease inhibitors could induce nuclear lamina alterations in adipocytes as observed in a genetic form of lipodystrophy due to lamin A/C mutation.. We have previously observed that indinavir (IDV) impairs adipocyte differentiation and sterol regulatory element-binding protein-1 (SREBP-1) nuclear localization in 3T3-F442A adipocytes. We compared here the effects of IDV with that produced by two other PIs, nelfinavir (NFV) and amprenavir (APV) on adipose conversion, cellular localization of SREBP-1, nuclear morphology, and maturation and stability of the lamina network.. IDV and NFV, but not APV, altered adipose cell differentiation, as shown by lipid staining and protein expression of SREBP-1, CAAAT/enhancer binding protein (C/EBP)alpha and fatty acid synthase (FAS). In IDV-treated cells, 50-60 % of the nuclei could not accumulate SREBP-1. Twenty percent of these SREBP-negative nuclei were grossly dysmorphic, with blebs and prominent herniations, and showed an altered distribution of lamin A/C and lamin B. In IDV-treated cells, nuclear fragilization was shown by the abnormal extractibility of lamina proteins and SREBP-1, and the accumulation of prelamin A. NFV similarly altered lamin A/C maturation whereas APV was almost ineffective.. We show in an adipose cell line that IDV and NFV induced alterations at the nuclear level by promoting defects in lamin A/C maturation, organization and stability. We suggest that these lamina network alterations might be responsible for SREBP-1 nuclear mislocalization therefore resulting in altered adipocyte differentiation.

Topics: 3T3 Cells; Adipocytes; Animals; Blotting, Western; Carbamates; CCAAT-Enhancer-Binding Proteins; Cell Differentiation; Cell Nucleus; DNA-Binding Proteins; Furans; HIV Protease Inhibitors; Indinavir; Lamin Type A; Mice; Microscopy, Confocal; Nelfinavir; Sterol Regulatory Element Binding Protein 1; Sulfonamides; Transcription Factors

To elucidate the aspects of pharmacokinetic interactions among HIV protease inhibitors (PIs), we investigated the effects of indinavir (IDV) on the hepatic and intestinal first-pass metabolism of other HIV PIs, amprenavir (APV), saquinavir (SQV) and nelfinavir (NFV), in rats. After oral co-administration with IDV, the area under the concentration versus time curves (AUC) of APV, SQV and NFV increased significantly by 1.6-, 9.5- and 2.3-fold, respectively, compared with mono-administration. After intravenous administration, the AUC of APV, SQV and NFV also increased in the presence of IDV by 1.4-, 1.2- and 1.5-fold, respectively. Mean concentrations of APV, SQV and NFV in the liver extracellular fluid, measured using a liver microdialysis method, were very low compared with their Michaelis constants regardless of co-administration of IDV, suggesting that APV, SQV and NFV metabolism follows linear kinetics in the liver. This finding also indicates that metabolism of PIs depended on the metabolic clearance rate in the liver microsomes. The oral bioavailability of SQV in the presence of IDV increased markedly by 8.5-fold, and that of APV and NFV also increased by 1.2- and 1.5-fold, respectively. On the basis of the well-stirred model, the hepatic availabilities of APV, SQV and NFV in the presence of IDV increased by 1.1-, 1.4- and 1.5-fold, and the intestinal availabilities increased by 1.1-, 6.2- and 1.1-fold, respectively. These results suggest that both hepatic and intestinal metabolism were essentially involved in the interactions between IDV and other HIV PIs, and the degree of those contributions varied with each combination of HIV PIs.

Topics: Animals; Area Under Curve; Carbamates; Drug Interactions; Drug Therapy, Combination; Furans; Half-Life; HIV Protease Inhibitors; Indinavir; Intestinal Mucosa; Liver; Male; Microsomes, Liver; Nelfinavir; Rats; Rats, Wistar; Saquinavir; Sulfonamides

A sensitive and rapid liquid chromatography tandem mass spectrometry (LC-MS-MS) method has been developed to measure the levels of five HIV protease inhibitors nelfinavir (NFV), indinavir (IDV), ritonavir (RTV), saquinavir (SQV) and amprenavir (APV) in human plasma. The analytes and internal standard are isolated from plasma by a simple acetonitrile precipitation of plasma proteins followed by centrifugation. LC-MS-MS in positive mode used pairs of ions at m/z of 568.4/330.0, 614.3/421.2, 720.9/296.0, 671.1/570.2 and 505.9/245.0 for NFV, IDV, RTV, SQV and APV, respectively and 628/421 for the internal standard. Two 1/x weighted linear calibration curves for each analyte were established for quantitation with the low curve ranging from 5 to 1000 ng/ml and while the high curve ranging from 1000 to 10,000 ng/ml. Mean inter- and intra-assay coefficients of variation (CVs) over the ranges of the standard curves were less than 10%. The overall recovery of NFV, IDV, RTV, SQV and APV were 88.4, 91.4, 92.2, 88.9 and 87.6%, respectively.

Topics: Carbamates; Chromatography, Liquid; Furans; Gas Chromatography-Mass Spectrometry; HIV Protease Inhibitors; Indinavir; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides

The drug interactions between a new human immune deficiency virus (HIV) protease inhibitor, amprenavir, and four other protease inhibitors which are presently used have been characterized by in-vitro metabolic studies using rat liver microsomal fractions and in-vivo oral administration studies. The metabolic clearance rates (Vmax/Km) of amprenavir, saquinavir, indinavir and nelfinavir in rat liver microsomes were 50.67+/- 3.77, 170.88 +/- 15.34, 73.01 +/- 2.76 and 126.06 +/- 6.23 microLmin(-1) (mg protein)(-1), respectively, and the degree of metabolicclearance was in the order of saquinavir > nelfinavir > indinavir > amprenavir > ritonavir. The inhibition constants (Ki) of ritonavir for amprenavir, indinavir, nelfinavir and saquinavir were 2.29, 0.95, 1.01 and 1.64 microM, respectively, and that of indinavir for amprenavir was 0.67, indicating that amprenavir metabolism in rat liver microsomes was strongly inhibited by indinavir. The Ki values of amprenavir for indinavir, nelfinavir and saquinavir were 7.41, 2.13 and 16.11 microM, respectively, and those of nelfinavirand saquinavirforamprenavirwere 9.15 and 34.57 microM, respectively. The area under the concentration vs time curve (AUC) of amprenavir after oral co-administration with saquinavir, indinavir, nelfinavir or ritonavir (20 mg kg(-1) for each oral dose in rats) was increased by 1.6-, 2.0-, 1.2- and 9.1-fold, respectively. The AUC values of saquinavir, indinavir and nelfinavir by co-administration with amprenavir showed about 7.3-, 1.3-, and 7.9-fold increase, respectively. These observations suggested that the oral bioavailability of amprenavir was not so affected by co-administration with saquinavir, nelfinavir or indinavir, compared with ritonavir, whereas amprenavir markedly affected the oral bioavailability of saquinavir and nelfinavir. In addition, the in-vivo effects after co-administration of two kinds of HIV protease inhibitors cannot always be predicted from in-vitro data, suggesting the presence of other interaction processes besides metabolism in the liver. However, these results provide useful information for the treatment of AIDS patients when they receive a combination therapy with two kinds of HIV protease inhibitor.

Topics: Administration, Oral; Animals; Area Under Curve; Biological Availability; Carbamates; Chromatography, High Pressure Liquid; Drug Interactions; Furans; HIV Protease Inhibitors; In Vitro Techniques; Indinavir; Male; Microsomes, Liver; Nelfinavir; Rats; Rats, Wistar; Saquinavir; Sulfonamides; Time Factors

Topics: Anti-HIV Agents; Blood; Carbamates; Cerebrospinal Fluid; Drug Resistance, Viral; Drug Therapy, Combination; Female; Furans; Genitalia; Genotype; HIV; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Male; Mutation; Phenotype; Randomized Controlled Trials as Topic; Retrospective Studies; Ritonavir; Sulfonamides; Time Factors; Viral Load

A sensitive and selective liquid chromatographic assay has been developed for the determination of the six currently protease inhibitors approved by the U.S. Food & Drug Administration (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir) plus the M8 active metabolite of nelfinavir and the nonnucleoside reverse transcription inhibitor efavirenz in a single run. Pretreatment of 1-mL plasma sample spiked with internal standard was made by a solid-phase extraction procedure using a polymeric reversed-phase sorbent. Liquid chromatography was performed using a narrow-bore C18 reversed-phase column and gradient elution. Double ultraviolet detection at 265 nm (amprenavir) and at 210 nm (all other assayed drugs and internal standard) was used. Calibration curves were linear in the range 25 to 10,000 ng/mL, and the assay has been validated over the range 25 to 5,000 ng/mL. Average accuracies at four concentrations were in the range 92.4% to 103.0% and 94.4% to 103.0% for within-day and between-day, respectively, and the coefficients of variation were less than 8%. Mean absolute recoveries varied from 72.8% (ritonavir) to 93.7% (indinavir). No metabolite of the protease inhibitors was found to coelute with the drugs of interest or with the internal standard. At this time, among the tested drugs, especially all the currently licensed nucleosides and the other nonnucleoside reverse transcription inhibitor nevirapine that can be used in combination with the protease inhibitors, none was found to interfere with the assay.

Topics: Alkynes; Benzoxazines; Carbamates; Chromatography, Liquid; Cyclopropanes; Drug Monitoring; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Oxazines; Pyrimidinones; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sulfonamides

Human immunodeficiency virus (HIV) therapies have been associated with alterations in fat metabolism and bone mineral density. This study examined the effects of HIV protease inhibitors (PIs) on bone resorption, bone formation, and adipocyte differentiation using ex vivo cultured osteoclasts, osteoblasts, and adipocytes, respectively. Osteoclast activity, measured using a rat neonatal calvaria assay, increased in the presence of nelfinavir (NFV; 47.2%, p = 0.001), indinavir (34.6%, p = 0.001), saquinavir (24.3%, p = 0.001), or ritonavir (18%, p < 0.01). In contrast, lopinavir (LPV) and amprenavir did not increase osteoclast activity. In human mesenchymal stem cells (hMSCs), the PIs LPV and NFV decreased osteoblast alkaline phosphatase enzyme activity and gene expression significantly (p < 0.05). LPV and NFV diminished calcium deposition and osteoprotegrin expression (p < 0.05), whereas the other PIs investigated did not. Adipogenesis of hMSCs was strongly inhibited by saquinavir and NFV (>50%, p < 0.001) and moderately inhibited by ritonavir and LPV (>40%, p < 0.01). Expression of diacylglycerol transferase, a marker of adipocyte differentiation, decreased in hMSCs treated with NFV. Amprenavir and indinavir did not affect adipogenesis or lipolysis. These results suggest that bone and fat formation in hMSCs of bone marrow may be coordinately down-regulated by some but not all PIs.

Topics: Adipocytes; Animals; Animals, Newborn; Bone and Bones; Calcium; Carbamates; Cells, Cultured; Down-Regulation; Fats; Furans; Glycoproteins; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Mesoderm; Nelfinavir; Osteoblasts; Osteoclasts; Osteoprotegerin; Pyrimidinones; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Ritonavir; Saquinavir; Skull; Stem Cells; Sulfonamides

Topics: Carbamates; Drug Evaluation; Furans; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides

A selective and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the determination of the six human immunodeficiency virus (HIV)-protease inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir) and the non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine) in a single run. After a liquid-liquid extraction with diethyl ether, the six protease inhibitors and the two non-nucleoside reverse transcriptase inhibitors are separated on a Stability RP18 column eluted with a gradient of acetonitrile and phosphate buffer 50 mmol/L pH 5.65. A sequential ultraviolet detection (5-minute sequence set at 240 nm for nevirapine acquisition, 22-minute sequence set at 215 nm for other antiretroviral drugs acquisition followed by a sequence set at 260 nm for internal standard acquisition) allowed for simultaneous quantitation of the six protease inhibitors, nevirapine, and efavirenz. Calibration curves were linear in the range 100 ng/mL to 10,000 ng/mL. The limit of quantitation was 50 ng/mL for all drugs except nevirapine (100 ng/mL). Average accuracy at four concentrations ranged from 88.2% to 110.9%. Both interday and intraday coefficients of variation were less than 11% for all drugs. The extraction recoveries were greater than 62%. This method is simple and shows a good specificity with respect to commonly co-prescribed drugs. This method allows accurate therapeutic monitoring of amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, efavirenz, and nevirapine.

Topics: Alkynes; Benzoxazines; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Drug Monitoring; Furans; HIV Infections; Humans; Indinavir; Lopinavir; Nelfinavir; Nevirapine; Oxazines; Protease Inhibitors; Pyrimidinones; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sulfonamides

To investigate the involvement of P-glycoprotein (Pgp) and the multidrug resistance-associated protein (MRP) on the active transport of the HIV protease inhibitors amprenavir, ritonavir and indinavir.. The transport behaviour of ritonavir, indinavir and amprenavir in the presence and absence of Pgp modulators and probenecid was investigated in an in vitro blood--brain barrier (BBB) co-culture model and in monolayers of LLC-PK1, LLC-PK1:MDR1, LLC-PK1:MRP1 and Caco-2 cells.. All three HIV protease inhibitors showed polarized transport in the BBB model, LLC-PK1:MDR1 and Caco-2 cell line. The Pgp modulators SDZ-PSC 833, verapamil and LY 335979 inhibited polarized transport, although their potency was dependent on both the cell model and the HIV protease inhibitor used. Ritonavir and indinavir also showed polarized transport in the LLC-PK1 and LLC-PK1:MRP1 cell line, which could be inhibited by probenecid. HIV protease inhibitors were not able to inhibit competitively polarized transport of other HIV protease inhibitors in the LLC-PK1:MDR1 cell line.. Amprenavir, ritonavir and indinavir are mainly actively transported by Pgp, while MRP also plays a role in the transport of ritonavir and indinavir. This indicates that inhibition of Pgp could be useful therapeutically to increase HIV protease inhibitor concentrations in the brain and in other tissues and cells expressing Pgp. The HIV protease inhibitors were not able to inhibit Pgp-mediated efflux when given simultaneously, suggesting that simultaneous administration of these drugs will not increase the concentration of antiretroviral drugs in the brain.

Topics: Animals; Astrocytes; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP-Binding Cassette Transporters; Biological Transport, Active; Blood-Brain Barrier; Caco-2 Cells; Carbamates; Cattle; Cell Line, Transformed; Cells, Cultured; Coculture Techniques; Cyclosporins; Dibenzocycloheptenes; Endothelium, Vascular; Furans; HIV Protease Inhibitors; Humans; Indinavir; LLC-PK1 Cells; Multidrug Resistance-Associated Proteins; Probenecid; Quinolines; Rats; Rats, Wistar; Ritonavir; Sulfonamides; Swine; Verapamil

A reversed-phase high-performance liquid chromatographic method for the simultaneous quantitative determination of five HIV protease inhibitors (i.e. indinavir, amprenavir, saquinavir, ritonavir and nelfinavir) in human plasma is described. An aliquot of 500 microl plasma was extracted with 0.5 ml of 0.1 M NH4OH and 5 ml of methyl tert.-butyl ether. After evaporating, the residue was dissolved in eluent mixture of acetonitrile and 50 mM KH2PO4 adjusted to pH 5.6 with 50 mM Na2HPO4 (43:57, v/v). Subsequently, the eluent was washed with hexane. Chromatography was performed using a C18 reversed-phase column. Ultraviolet detection at 215 nm was used. Linearity of the method was obtained in the concentration range of 0.05-20 microg ml(-1) for all five protease inhibitors. Our method is now in use to analyse plasma samples from patients treated with co-administration of HIV protease inhibitors.

Topics: Adult; Calibration; Carbamates; Chromatography, High Pressure Liquid; Furans; HIV Protease Inhibitors; Humans; Indinavir; Male; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides

A rapid, simple and sensitive high-performance liquid chromatographic (HPLC) assay has been developed for the simultaneous quantification of the HIV-protease inhibitors indinavir, amprenavir, ritonavir, saquinavir and nelfinavir in human plasma. The method involved the solid-phase extraction of the five drugs and the internal standard (I.S., verapamil) from 400 microl of human plasma. The HPLC analysis used a reversed-phase C18 analytical column and a mobile phase consisting of a gradient with 15 mM phosphate buffer (pH 5.75)-acetonitrile and UV monitoring. The method was linear over the therapeutic concentration range for the five HIV-protease inhibitors. The accuracy of the method ranged from 98.2 to 106.7% and the precision values ranged from 1.4 to 8.1% for intra-day precision and from 3.1 to 6.4% for the inter-day values.

Topics: Carbamates; Chromatography, High Pressure Liquid; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Reference Standards; Reproducibility of Results; Ritonavir; Saquinavir; Sensitivity and Specificity; Spectrophotometry, Ultraviolet; Sulfonamides

An analytical technique using liquid chromatography (LC) coupled with electrospray-mass spectrometry (ESI--MS) has been developed for the simultaneous determination of five protease inhibitors (PIs): saquinavir, indinavir, ritonavir, nelfinavir, and amprenavir; and three non-nucleoside reverse transcriptase inhibitors (NNRTIs): nevirapine, delavirdine, and efavirenz, in human plasma. This assay allows the elution and identification of these drugs in a single run (10 minutes) using a linear gradient with water and acetonitrile. The procedure involves liquid--liquid extraction. High-performance liquid chromatography (HPLC) separation was achieved on a C18 reversed-phase column, with a linear gradient elution followed by mass spectrometry detection. The calibration curves, obtained by automatic process peak area integration, show a good linearity in a range of concentrations between 20 and 10,000 ng/mL (40--10,000 ng/mL for efavirenz). The limit of detection was approximately 10 ng/mL for seven drugs (25 ng/mL for efavirenz). The coefficients of variation (CV) were always less than 15% for both intraday and interday precision for each compound. The recovery of the eight drugs ranged from 88.5% to 100%. This novel LC/ESI--MS assay provides an excellent method for simultaneous quantitative monitoring of different components of the highly active antiretroviral treatments (HAARTs) in patients treated simultaneously with PIs and NNRTIs, and it has been successfully applied to therapeutic drug monitoring and pharmacokinetic studies.

Topics: Alkynes; Benzoxazines; Carbamates; Chromatography, Liquid; Cyclopropanes; Delavirdine; Drug Monitoring; Furans; HIV Protease Inhibitors; Humans; Indinavir; Mass Spectrometry; Nelfinavir; Nevirapine; Oxazines; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sensitivity and Specificity; Sulfonamides

A single HPLC assay was developed for therapeutic drug monitoring of 5 HIV protease inhibitors (indinavir, amprenavir, saquinavir, ritonavir, nelfinavir) and a non-nucleoside reverse transcriptase inhibitor (nevirapine) in human plasma. After liquid-liquid extraction in a mixture ethyl acetate-hexane, compounds are separated on a C18 column with a gradient elution of solvent A [acetonitrile and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))] and solvent B [methanol and 0.025 M tetramethylammonium perchlorate in 0.2% aqueous trifluoroacetic acid (55:45 (v/v))]. The compounds are detected at various wavelengths: 320 nm (nevirapine), 259 nm (indinavir), 254 nm (amprenavir, nelfinavir, saquinavir) and 239 nm (ritonavir). The intra-day and inter-day precision and accuracy are lower than 15%. The limits of quantitation are 0.05 mg/l (amprenavir), 0.2 mg/l (indinavir, saquinavir, nelfinavir) and 0.4 mg/l (ritonavir, nevirapine). This method which allows to estimate simultaneously plasma levels of protease inhibitors and nevirapine can be used for therapeutic drug monitoring.

Topics: Calibration; Carbamates; Chromatography, High Pressure Liquid; Furans; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Nevirapine; Reference Standards; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sensitivity and Specificity; Sulfonamides

Protease inhibitors are known by their inhibition of a viral protease that leads to production of immature and non-infectious virus particles. The novel protease inhibitor KALETRA is a co-formulation of lopinavir and ritonavir. Ritonavir reduces the metabolization of lopinavir by the cytochrome P450 3A4 isoenzyme which leads to markedly increased plasma levels of lopinavir(4). A new rapid and sensitive HPLC method for the simultaneous determination of lopinavir, indinavir, amprenavir, saquinavir, ritonavir and nelfinavir in human plasma has been developed. An aliquot of 500 microl plasma, spiked with internal standard, was extracted with 500 microl 0.1 M ammonium hydroxide solution and 5 ml tert. -butyl ether. After drying under a nitrogen stream, the residue was redissolved in an eluent consisting of 50 mM phosphate buffer, pH 5.40 and acetonitrile (50:50, v/v). Chromatographic separation was accomplished on a C-18 column using a non-linear gradient elution and ultraviolet detection at 215 nm.

Topics: Carbamates; Chromatography, High Pressure Liquid; Drug Interactions; Drug Monitoring; Drug Therapy, Combination; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Nelfinavir; Pyrimidinones; Reproducibility of Results; Ritonavir; Saquinavir; Sulfonamides

Topics: Adenocarcinoma; ATP Binding Cassette Transporter, Subfamily B, Member 1; Carbamates; Cell Line, Transformed; Colonic Neoplasms; Drug Resistance, Multiple; Furans; Gene Expression Regulation, Neoplastic; HIV Protease Inhibitors; Humans; Indinavir; Ivermectin; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides; Tumor Cells, Cultured; Verapamil; Vinblastine

Clinical cohort studies suggest that as many as 60% of patients experience virologic failure of a first-line antiretroviral regimen. Second-line and rescue (or salvage) regimens have a poorer success record: Most studies presented to date show a short-term virologic response rate of only approximately 30% in treatment-experienced individuals. That rate will improve with better understanding of what causes initial virologic failure, continued development of new antiretroviral agents (including drugs with new mechanisms of action) and new treatment strategies (including dual-protease inhibitor regimens), and more widespread use of resistance testing. Further clinical research is needed to improve salvage options, and physicians should consider enrolling treatment-experienced patients in clinical trials.

Topics: Anti-HIV Agents; Carbamates; CD4 Lymphocyte Count; Dideoxynucleosides; Drug Therapy, Combination; Furans; HIV Protease Inhibitors; Humans; Indinavir; Lopinavir; Microbial Sensitivity Tests; Mutation; Nelfinavir; Practice Guidelines as Topic; Pyrimidinones; Retroviridae; Retroviridae Infections; Reverse Transcriptase Inhibitors; Sulfonamides; Time Factors; Treatment Failure; Viral Load

As part of an on-going study on the suitability of a formal therapeutic drug monitoring (TDM) of antiviral drugs for improving the management of HIV infection, a high-performance liquid chromatography method has been developed to quantify simultaneously in plasma five HIV protease inhibitors (PIs) (i.e., indinavir, amprenavir, saquinavir, ritonavir, nelfinavir) and the novel non-nucleoside reverse transcriptase inhibitor efavirenz. After viral inactivation by heat (60 degrees C for 60 min), plasma (600 microl), with clozapine added as internal standard, is diluted 1:1 with phosphate buffer, pH 7 and subjected to a solid-phase extraction on a C18 cartridge. Matrix components are eliminated with 2 x 500 microl of a solution of 0.1% H3PO4 neutralised with NaOH to pH 7. PIs and efavirenz are eluted with 3 x 500 microl MeOH. The resulting eluate is evaporated under nitrogen at room temperature and is reconstituted in 100 microl 50% MeOH. A 40-microl volume is subjected to HPLC analysis onto a Nucleosil 100, 5 microm C18 AB column, using a gradient elution of MeCN and phosphate buffer adjusted to pH 5.15 and containing 0.02% sodium heptanesulfonate: 15:85 at 0 min-->30:70 at 2 min-->32:68 at 8 min-->42:58 at 18 min-->46:54 at 34 min, followed by column cleaning with MeCN-buffer, pH 5.15 (90:10), onto which 0.3% AcOH is added. Clozapine, indinavir, amprenavir, saquinavir, ritonavir, efavirenz and nelfinavir are detected by UV at 201 nm at a retention time of 8.2, 13.0, 16.3, 21.5, 26.5, 28.7 and 31.9 min, respectively. The total run time for a single analysis is 47 min, including the washing-out and reequilibration steps. The calibration curves are linear over the range 100-10,000 ng/ml. The absolute recovery of PIs/efavirenz is always higher than 88%. The method is precise with mean inter-day relative standard deviations within 2.5-9.8% and accurate (range of inter-day deviations -4.6 to +4.3%). The in vitro stability of plasma spiked with PIs/efavirenz at 750, 3000 and 9000 ng/ml has been studied at room temperature, -20 degrees C and +60 degrees C. The method has been validated and is currently applied to the monitoring of PIs and efavirenz in HIV patients. This HPLC assay may help clinicians confronted to questionable compliance, side effects or treatment failure in elucidating whether patients are exposed to adequate circulating drug levels. The availability of such an assay represents an essential step in elucidating the utility of a formal TDM for the opt

Topics: Alkynes; Benzoxazines; Calibration; Carbamates; Chromatography, High Pressure Liquid; Cyclopropanes; Drug Stability; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Oxazines; Reproducibility of Results; Reverse Transcriptase Inhibitors; Ritonavir; Saquinavir; Sulfonamides

Human immunodeficiency virus (HIV) protease inhibitors (PI) may alter lipid metabolism in patients with acquired immunodeficiency syndrome (AIDS). However, the influence of dietary fat on the metabolic effects of PI therapy remains unknown. AKR/J mice were fed high or low fat diets and treated with the PI indinavir (IDV), nelfinavir (NFV), saquinavir (SQV) or amprenavir (APV) by subcutaneous delivery for 2 wk. Serum concentrations of glucose, insulin, triglyceride, free fatty acid, glycerol, pancreatic lipase, bilirubin, alkaline phosphatase, blood urea nitrogen and PI, and interscapular and epididymal fat weights were determined. Some metabolic effects of PI were dependent on diet. IDV- and NFV-treated mice had greater serum glucose concentration and body weight; IDV-treated mice had lower serum insulin; NFV-treated mice had greater interscapular fat mass; and SQV treated mice had lower serum triglyceride concentration than control mice fed the low but not the high fat diet. In contrast, NFV- and IDV-treated mice had greater triglyceride concentration and blood urea nitrogen, and SQV treated mice had greater serum cholesterol than control mice fed the high but not the low fat diet. The serum concentration of SQV was lower in mice fed the high fat compared with the low fat diet. Other effects were not dependent on diet. IDV- and NFV-treated mice had greater fatty acids, and IDV-treated mice had greater pancreatic lipase, bilirubin and alkaline phosphatase than control mice fed either diet. APV treatment had little effect on these serum measurements. Thus, changes in dietary fat can influence some but not all of the effects of PI on metabolism. Furthermore, each PI produces different effects in vivo, indicating that various PI affect distinct metabolic pathways.

Topics: Adipose Tissue; Animals; Blood Glucose; Body Weight; Carbamates; Dietary Fats; Drug Interactions; Furans; HIV Protease Inhibitors; Indinavir; Injections, Subcutaneous; Insulin; Liver; Male; Mice; Mice, Inbred AKR; Nelfinavir; Saquinavir; Sulfonamides

Although numerous mutations that confer resistance to protease inhibitors (PRI) have been mapped for HIV-1 subtype B, little is known about such substitutions for the non-B viruses, which globally cause the most infections.. To determine the prevalence of PRI-associated mutations in PRI-naive individuals worldwide.. Using the polymerase chain reaction, protease sequences were amplified from 301 individuals infected with HIV-1 subtypes A (79), B (95), B' (19), C (12), D (26), A/E (23), F (26), A/G (11), and H (3) and unclassifiable HIV-1 (7). Amplified DNA was directly sequenced and translated to amino acids to analyze PRI-associated major and accessory mutations.. Of the 301 sequences, 85% contained at least one codon change giving substitution at 10, 20, 30, 36, 46, 63, 71, 77, or 82 associated with PRI resistance; the frequency of these substitutions was higher among non-B (91%) than B (75%) viruses (P < 0.0005). Of these, 25% carried dual and triple substitutions. Two major drug resistance-conferring mutations, either 20M or 30N, were identified in only three specimens, whereas drug resistance accessory mutations were found in 252 isolates. These mutations gave distinct prevalence patterns for subtype B, 63P (62%) > 77I (19%) > 10I/V/R (6%) = 361 (6%) = 71T/V (6%) > 20R (2%), and non-B strains, 36I (83%) > 63P (17%) > 10I/V/R (13%) > 20R (10%) > 77I (2%), which differed statistically at positions 20, 36, 63, 71, and 77.. The high prevalence of PRI-associated substitutions represent natural polymorphisms occurring in PRI-naive patients infected with HIV-1 strains of subtypes A-H. The significance of distinct mutation patterns identified for subtype B and non-B strains warrants further clinical evaluation. A global HIV-1 protease database is fundamental for the investigation of novel PRI.

Topics: Amino Acid Sequence; Amino Acid Substitution; Carbamates; Codon; Drug Resistance, Microbial; Furans; Global Health; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Molecular Sequence Data; Mutation; Nelfinavir; Phylogeny; Ritonavir; Saquinavir; Sulfonamides

AIDS therapies employing HIV protease inhibitors (PIs) are associated with changes in fat metabolism. However, the cellular mechanisms affected by PIs are not clear. Thus, the affects of PIs on adipocyte differentiation were examined in vitro using C3H10T1/2 stem cells. In these cells the PIs, nelfinavir, saquinavir, and ritonavir, reduced triglyceride accumulation, lipogenesis, and expression of the adipose markers, aP2 and LPL. Histological analysis revealed nelfinavir, saquinavir and ritonavir treatment decreased oil red O-staining of cytoplasmic fat droplets. Inhibition occurred in the presence of the RXR agonist LGD1069, indicating the inhibitory effects were not due to an absence of RXR ligand. Moreover, these three PIs increased acute lipolysis in adipocytes. In contrast, two HIV PIs, amprenavir and indinavir, had little effect on lipolysis, lipogenesis, or expression of aP2 and LPL. Although, saquinavir, inhibited ligand-binding to PPARgamma with an IC(50) of 12.7+/-3.2 microM, none of the other PIs bound to the nuclear receptors RXRalpha or PPARgamma, (IC(50)s>20 microM), suggesting that inhibition of adipogenesis is not due to antagonism of ligand binding to RXRalpha or PPARgamma. Taken together, the results suggest that some, but not all, PIs block adipogenesis and stimulate fat catabolism in vitro and this may contribute to the effects of PIs on metabolism in the clinic.

Topics: Adipocytes; Animals; Azo Compounds; Bexarotene; Carbamates; Carrier Proteins; Cell Differentiation; Cells, Cultured; Coloring Agents; Fatty Acid-Binding Proteins; Furans; HIV Protease Inhibitors; Indinavir; Insulin; Lipolysis; Lipoprotein Lipase; Nelfinavir; Neoplasm Proteins; Receptors, Cytoplasmic and Nuclear; Receptors, Retinoic Acid; Retinoid X Receptors; Ritonavir; RNA, Messenger; Rosiglitazone; Saquinavir; Stem Cells; Sulfonamides; Tetrahydronaphthalenes; Thiazoles; Thiazolidinediones; Transcription Factors; Triglycerides

The therapeutic success of an antiretroviral salvage regimen containing protease inhibitors (PI) is limited by PI-resistant viral strains exhibiting various degrees of resistance and cross-resistance. To evaluate the extent of cross-resistance to the new PI amprenavir, 155 samples from 132 human immunodeficiency virus type 1-infected patients were analyzed for viral genotype by direct sequencing of the protease gene. Concomitantly, drug sensitivity to indinavir, saquinavir, ritonavir, nelfinavir, and amprenavir was analyzed by a recombinant virus assay. A total of 111 patients had been pretreated with 1-4 PI, but all were naive to amprenavir. A total of 105 samples (67.7%) were sensitive to amprenavir; 25 samples (16.1%) were intermediately resistant, and another 25 samples were highly resistant (4- to 8-fold- and >8-fold-reduced sensitivity, respectively). The mutations 46I/L, 54L/V, 84V, and 90M showed the strongest association with amprenavir resistance (P < 0. 0001). The scoring system using 84V and/or any two of a number of mutations (10I/R/V/F, 46I/L, 54L/V, and 90M) predicted amprenavir resistance with a sensitivity of 86.0% and a specificity of 81.0% within the analyzed group of samples. Of 62 samples with resistance against 4 PI, 23 (37.1%) were still sensitive to amprenavir. In comparison, only 2 of 23 samples (8.7%) from nelfinavir-naive patients with resistance against indinavir, saquinavir, and ritonavir were still sensitive to nelfinavir. Amprenavir thus appears to be an interesting alternative for PI salvage therapy.

Topics: Carbamates; Drug Resistance, Microbial; Drug Resistance, Multiple; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Ritonavir; Saquinavir; Sulfonamides

To optimize the conditions for determining Caco-2 permeation of HIV protease inhibitors and other lipophilic compounds, and to compare cyclic urea HIV protease inhibitors with marketed compounds.. Absorptive and secretory Caco-2 membrane permeation studies were performed with HIV protease inhibitors and various reference compounds, examining the effects of adding the solubilizing agents dimethylacetamide (DMAC) and albumin in donor and reservoir compartments, respectively.. DMAC was useful as an additive in the donor vehicles, increasing the dissolved concentrations of poorly water-soluble HIV protease inhibitors, and enabling more reliable determination of P(app) values. Donor vehicles containing up to 5% DMAC could be used without altering Caco-2 barrier function, as indicated by the lack of effect on permeabilities of reference compounds with diverse absorption characteristics. The utilization of a reservoir containing albumin resulted in marked increases in absorptive Papp values for some HIV protease inhibitors as well as other lipophilic, highly protein bound compounds, consistent with albumin increasing the release of these compounds from the cell monolayer.. Poorly soluble, lipophilic, highly bound compounds may require using solubilizing agents in the donor and reservoir compartments of Caco-2 permeation experiments for estimating in vivo absorption potential. If the reservoir does not provide adequate sink conditions, cellular retention could over-emphasize the contributions of secretory transport. The cyclic ureas, DMP 450, DMP 850, and DMP 851, have Caco-2 permeabilities suggestive of moderate-to-high oral absorption potential in humans.

Topics: Acetamides; Albumins; Azepines; Caco-2 Cells; Carbamates; Cell Membrane Permeability; Furans; HIV Protease Inhibitors; Humans; Indinavir; Intestinal Absorption; Nelfinavir; Ritonavir; Solvents; Structure-Activity Relationship; Sulfonamides; Urea

Patients with AIDS who are receiving therapy with HIV protease inhibitors have been widely reported to be afflicted with a syndrome characterized by lipodystrophy (fat redistribution favoring the accumulation of abdominal and cervical adipose tissue), hyperlipidemia, and insulin resistance. HIV protease inhibitors have been suggested to have a direct role in modulating adipocyte differentiation. To address this hypothesis, several HIV protease inhibitors were studied for their ability to either augment or inhibit the differentiation of murine 3T3-L1 preadipocytes. Dose-responsive inhibition of adipogenesis by several protease inhibitors was noted as measured by reduced triglyceride accumulation and attenuated induction of three differentiation marker genes -- aP2, lipoprotein lipase, and Adipo Q. Potential mechanisms for altered adipocyte function, including direct binding to PPARgamma or inhibition of PPARgamma-mediated gene transcription were effectively excluded.

Topics: 3T3 Cells; Adipocytes; Adiponectin; Animals; Carbamates; Carrier Proteins; Cell Differentiation; Dose-Response Relationship, Drug; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; Furans; Gene Expression; Glycoproteins; HIV Protease Inhibitors; Humans; Indinavir; Intercellular Signaling Peptides and Proteins; Lipoprotein Lipase; Mice; Myelin P2 Protein; Nelfinavir; Neoplasm Proteins; Nerve Tissue Proteins; Proteins; Receptors, Cytoplasmic and Nuclear; Recombinant Proteins; Ritonavir; Stem Cells; Sulfonamides; Transcription Factors; Triglycerides; Tumor Suppressor Proteins

To examine the relationship between HIV protease genotype and altered protease inhibitor sensitivity of isolates from patients after therapy with saquinavir (SQV) in its hard gelatin formulation.. Forty-one post-therapy isolates and corresponding baseline samples were obtained from 37 patients in four different clinical trials after therapy with SQV for 16-147 weeks. Post-therapy isolates were selected on the basis of preliminary sequence or drug sensitivity data.. Fifteen out of 17 isolates without detectable Val-48 or Met-90 mutations retained sensitivity to SQV. (The remaining isolates showed only a marginal increase in median inhibitory concentration.) In addition, three out of 15 isolates with Met-90 retained sensitivity to all other protease inhibitors tested (indinavir, ritonavir, amprenavir, nelfinavir). Of the isolates showing reduced sensitivity to SQV, six out of 22 retained sensitivity to all other protease inhibitors, whereas only four out of 22 showed broad cross-resistance to all protease inhibitors tested. The reduction in sensitivity correlated closely with the presence of Val-48 or Met-90. Subsequent accessory substitutions were also linked to reduced sensitivity. However, significant linkage was observed only between mutations at residues 48 and 82 and between those at residues 82 and 74.. Recruitment of Val-48/Met-90 mutations was not found to be synonymous with cross-resistance. Indeed, the majority of isolates with these mutations retained sensitivity to at least one protease inhibitor (Val-48, 86%; Met-90, 77%). The recruitment of accessory mutations may occur only after the selection of key resistance mutations. Furthermore, Met-90 was found to be a poor marker of cross-resistance in SQV-treated patients.

Topics: Amino Acid Substitution; Carbamates; Clinical Trials as Topic; Databases, Factual; DNA, Viral; Furans; Genetic Linkage; Genotype; HIV Infections; HIV Protease; HIV Protease Inhibitors; Humans; Indinavir; Methionine; Nelfinavir; Phenotype; Polymerase Chain Reaction; Ritonavir; Saquinavir; Sulfonamides; Valine

Topics: Acquired Immunodeficiency Syndrome; Anti-HIV Agents; Carbamates; Dideoxynucleosides; Drug Therapy, Combination; Furans; HIV Protease Inhibitors; Humans; Indinavir; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides; Viral Load

Topics: Anti-HIV Agents; Carbamates; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Lamivudine; Saquinavir; Sulfonamides; Viral Load; Zidovudine

New anti-HIV drugs that are expected to become available in the future are discussed. The potent protease inhibitor amprenavir (Agenerase) is expected to be available in pharmacies by early 1999. Results of a study of treatment-naive, HIV-positive people showed that those taking amprenavir as part of a three-drug combination therapy, with AZT and 3TC, had better viral reduction than those using AZT and 3TC alone. In a French study of the non-nucleoside reverse transcriptase inhibitor Nevirapine, and a similar study of Delavirdine, a majority of participants had HIV RNA levels below the limit of detection. Further comparative studies are needed between Nevirapine, Delavirdine and the more costly, highly publicized competitor, efavirenz. Several studies of regimens that include protease inhibitors compare dosing twice daily to three times a day. A Canadian study describes salvage therapies, for people who have failed previous treatment with protease inhibitors, that can include up to nine drugs. Because there is a shortage in the development of new types of HIV drugs, people are encouraged to carefully consider when to begin treatment and what medical options are available.

Topics: Anti-HIV Agents; Carbamates; Delavirdine; Dideoxynucleosides; Drug Resistance, Microbial; Drug Therapy, Combination; Drugs, Investigational; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Nevirapine; Reverse Transcriptase Inhibitors; Salvage Therapy; Sulfonamides

Protein binding can impair the potency of human immunodeficiency virus (HIV) protease inhibitors. Therefore, the activity of a novel compound, CGP 61755, was studied in the absence or presence of alpha1-acid glycoprotein (alpha1AGP). In MT-2 cells, the activity loss was 4-fold (EC90 without alpha1AGP, 29 nM vs. 122 nM with alpha1AGP). In primary lymphocytes, the loss was 8-fold (EC90, 45 nM vs. 364 nM). In identical experiments, the activity loss in MT-2 cells and lymphocytes was 2- and 3-fold, respectively, for indinavir, 11- and 10-fold for saquinavir, and 11- and 48-fold for ritonavir. For SC-52151, a 17-fold loss was seen in MT-2 cells, whereas no EC90 with alpha1AGP was reached in lymphocytes. This study demonstrates that the impact of alpha1AGP on in vitro activity varies greatly among different HIV protease inhibitors. The magnitude of such differences is greater in human lymphocytes than in a standard cell line.

Topics: Anti-HIV Agents; Carbamates; Cell Line; Cells, Cultured; Ethylenes; Furans; HIV Protease Inhibitors; HIV Seronegativity; HIV-1; Humans; Indinavir; Kinetics; Lymphocytes; Orosomucoid; Ritonavir; Saquinavir; Sulfonamides; Urea; Virus Replication

Passage of human immunodeficiency virus type-1 (HIV-1) in T-lymphocyte cell lines in the presence of increasing concentrations of the hydroxylethylamino sulfonamide inhibitor VX-478 or VB-11328 results in sequential accumulation of mutations in HIV-1 protease. We have characterized recombinant HIV-1 proteases that contain these mutations either individually (L10F, M46I, I47V, I50V) or in combination (the double mutant L10F/I50V and the triple mutant M46I/I47V/I50V). The catalytic properties and affinities for sulfonamide inhibitors and other classes of inhibitors were determined. For the I50V mutant, the efficiency (kcat/Km) of processing peptides designed to mimic cleavage junctions in the HIV-1 gag-pol polypeptide was decreased up to 25-fold. The triple mutant had a 2-fold higher processing efficiency than the I50V single mutant for peptide substrates with Phe/Pro and Tyr/Pro cleavage sites, suggesting that the M46I and I47V mutations are compensatory. The effects of mutation on processing efficiency were used in conjunction with the inhibition constant (Ki) to evaluate the advantage of the mutation for viral replication in the presence of drug. These analyses support the virological observation that the addition of M46I and I47V mutations on the I50V mutant background enables increased survival of the HIV-1 virus as it replicates in the presence of VX-478. Crystal structures and molecular models of the active site of the HIV-1 protease mutants suggest that changes in the active site can selectively affect the binding energy of inhibitors with little corresponding change in substrate binding.

Topics: Amino Acid Sequence; Binding Sites; Carbamates; Furans; Genetic Variation; HIV Protease; HIV Protease Inhibitors; HIV-1; Hydrolysis; Indinavir; Isoquinolines; Kinetics; Models, Molecular; Molecular Sequence Data; Mutation; Oligopeptides; Pyridines; Quinolines; Saquinavir; Selection, Genetic; Substrate Specificity; Sulfonamides

Site-specific substitutions of as few as four amino acids (M46I/L63P/V82T/I84V) of the human immunodeficiency virus type 1 (HIV-1) protease engenders cross-resistance to a panel of protease inhibitors that are either in clinical trials or have recently been approved for HIV therapy (Condra, J. H., Schleif, W. A., Blahy, O. M. , Gadryelski, L. J., Graham, D. J., Quintero, J. C., Rhodes, A., Robbins, H. L., Roth, E., Shivaprakash, M., Titus, D., Yang, T., Teppler, H., Squires, K. E., Deutsch, P. J., and Emini, E. A. (1995) Nature 374, 569-571). These four substitutions are among the prominent mutations found in primary HIV isolates obtained from patients undergoing therapy with several protease inhibitors. Two of these mutations (V82T/I84V) are located in, while the other two (M46I/L63P) are away from, the binding cleft of the enzyme. The functional role of these mutations has now been delineated in terms of their influence on the binding affinity and catalytic efficiency of the protease. We have found that the double substitutions of M46I and L63P do not affect binding but instead endow the enzyme with a catalytic efficiency significantly exceeding (110-360%) that of the wild-type enzyme. In contrast, the double substitutions of V82T and I84V are detrimental to the ability of the protease to bind and, thereby, to catalyze. When combined, the four amino acid replacements institute in the protease resistance against inhibitors and a significantly higher catalytic activity than one containing only mutations in its active site. The results suggest that in raising drug resistance, these four site-specific mutations of the protease are compensatory in function; those in the active site diminish equilibrium binding (by increasing Ki), and those away from the active site enhance catalysis (by increasing kcat/KM). This conclusion is further supported by energy estimates in that the Gibbs free energies of binding and catalysis for the quadruple mutant are quantitatively dictated by those of the double mutants.

Topics: Carbamates; Clinical Trials as Topic; Furans; Fusion Proteins, gag-pol; HIV Protease; HIV Protease Inhibitors; Humans; Hydrolysis; Indinavir; Kinetics; Mutagenesis; Ritonavir; Sulfonamides

Mutations in the human immunodeficiency virus (HIV) protease (L90M, G48V, and L90M/G48V) arise when HIV is passaged in the presence of the HIV protease inhibitor saquinavir. These mutations yield a virus with less sensitivity to the drug (L90M > G48V >> L90M/G48V). L90M, G48V, and L90M/G48V proteases have 1/20, 1/160, and 1/1000 the affinity for saquinavir compared to WT protease, respectively. Therefore, the affinity of mutant protease for saquinavir decreased as the sensitivity of the virus to saquinavir decreased. Association rate constants for WT and mutant proteases with saquinavir were similar, ranging from 2 to 4 x 10(7) M-1 s-1. In contrast, the dissociation rate constants for WT, L90M, G48V, and L90M/G48V proteases complexed with saquinavir were 0.0014, 0.019, 0.128, and 0. 54 s-1, respectively. This indicated that the reduced affinity for mutant proteases and saquinavir is primarily the result of larger dissociation rate constants. The increased dissociation rate constants may be the result of a decrease in the internal equilibrium between the bound inhibitor with the protease flaps up and the bound inhibitor with the flaps down. Interestingly, the affinity of these mutant proteases for VX-478, ABT-538, AG-1343, or L-735,524 was not reduced as much as that for saquinavir. Finally, the catalytic constants of WT and mutant proteases were determined for eight small peptide substrates that mimic the viral cleavage sites in vivo. WT and L90M proteases had similar catalytic constants for these substrates. In contrast, G48V and L90M/G48V proteases had catalytic efficiency (kcat/Km) values with TLNF-PISP, RKIL-FLDG, and AETF-YVDG that were 1/10 to 1/20 the value of WT protease. The decreased catalytic efficiencies were primarily the result of increased Km values. Thus, mutations in the protease decrease the affinity of the enzyme for saquinavir and the catalytic efficiency with peptide substrates.

Topics: Antiviral Agents; Carbamates; Drug Resistance, Microbial; Furans; HIV Protease; HIV Protease Inhibitors; Humans; Indinavir; Isoquinolines; Kinetics; Mutagenesis; Nelfinavir; Ritonavir; Saquinavir; Sulfonamides; Sulfonic Acids

A controversy has developed, initiated by a paper in the April 1995 issue of Nature, over the use of protease inhibitors among AIDS patients. The article, written by Jon Condra and Emilio Emini, reported that HIV developed resistance to indinavir (Merck & Co.'s protease inhibitor), and all other protease inhibitors as well. In response to the study on Merck's product, Roche released information suggesting that their protease inhibitor, saquinavir, does not cause resistance nearly as quickly or as much. Merck is currently studying the combination of indinavir and AZT, and Abbott Laboratories is examining the effects of AZT, ddC, and ritonavir. These studies imply that optimal multi-drug combination therapy should delay drug resistance as well as cross-resistance. The implications are promising for patients with HIV and AIDS. Pharmaceutical companies are conducting additional studies to develop new reverse transcriptase inhibitors and to determine the effectiveness of the combination of two or more protease inhibitors. Each drug trial demonstrates the relationship between dosing and resistance; patients are advised to adhere completely to dosing instructions.

Topics: Acquired Immunodeficiency Syndrome; Antiviral Agents; Carbamates; Didanosine; Drug Resistance, Microbial; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Indinavir; Isoquinolines; Lamivudine; Nelfinavir; Pyridines; Quinolines; Saquinavir; Sulfonamides; Zalcitabine; Zidovudine

An overview of the Fourth International Workshop on HIV Drug Resistance held in 1995 is presented. Topics concern the dual resistance to AZT and 3TC, viral resistance to protease inhibitors, and recent laboratory findings on viral resistance patterns that have provided impetus for the design of clinical studies to evaluate rational combinations of protease inhibitors. VX-478, indinavir, and ritonavir study data are presented.

Topics: Antiviral Agents; Carbamates; CD4 Lymphocyte Count; Drug Resistance, Microbial; Furans; HIV; HIV Infections; HIV Protease Inhibitors; Humans; Indinavir; Isoquinolines; Lamivudine; Pyridines; Quinolines; Ritonavir; Saquinavir; Sulfonamides; Thiazoles; Valine; Viremia; Zalcitabine; Zidovudine