pyrimidinones and amprenavir

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, Viral; Furans; Genetic Linkage; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Mutation; Phenotype; Pyrimidinones; 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 inhibitory quotient (IQ) of human immunodeficiency virus (HIV) protease inhibitors (PIs), which is the ratio of drug concentration to viral susceptibility, is considered to be predictive of the virological response. We used several approaches to calculate the IQs of amprenavir and lopinavir in a subset of heavily pretreated patients participating in the French National Agency for AIDS Research (ANRS) 104 trial and then compared their potentials for predicting changes in the plasma HIV RNA level. Thirty-seven patients were randomly assigned to receive either amprenavir (600 mg twice a day [BID]) or lopinavir (400 mg BID) plus ritonavir (100 or 200 mg BID) for 2 weeks before combining the two PIs. The 90% inhibitory concentration (IC(90)) was measured using a recombinant assay without or with additional human serum (IC(90+serum)). Total and unbound PI concentrations in plasma were measured. Univariate linear regression was used to estimate the relation between the change in viral load and the IC(90) or IQ values. The amprenavir phenotypic IQ values were very similar when measured with the standard and protein binding-adjusted IC(90)s. No relationship was found between the viral load decline and the lopinavir IQ. During combination therapy, the amprenavir and lopinavir genotypic IQ values were predictive of the viral response at week 6 (P = 0.03). The number of protease mutations (< 5 or > or = 5) was related to the virological response throughout the study. These findings suggest that the combined genotypic IQ and the number of protease mutations are the best predictors of virological response. High amprenavir and lopinavir concentrations in these patients might explain why plasma concentrations and the phenotypic IQ have poor predictive value.

Topics: Adult; Aged; Carbamates; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Therapy, Combination; Female; France; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Male; Middle Aged; Phenotype; Prognosis; Pyrimidinones; Ritonavir; RNA, Viral; Sulfonamides; Treatment Outcome; Viral Load

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Brazil; Carbamates; CD4 Lymphocyte Count; Drug Resistance, Viral; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Pilot Projects; Prospective Studies; Pyrimidinones; Ritonavir; Saquinavir; Sulfonamides; Treatment Outcome

We report the results of the extended follow-up at one year of a randomized trial evaluating the virological efficacy of a salvage therapy combining lopinavir and amprenavir with either 200 or 400 mg/day ritonavir, along with optimized nucleoside reverse transcriptase inhibitors, in patients carrying multidrug-resistant isolates. The combination of amprenavir, lopinavir and ritonavir (400 mg/day) is durably potent, yielding a sustained virological response (HIV RNA < 50 copies) in 39% of cases.

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Carbamates; Drug Resistance, Multiple, Viral; Follow-Up Studies; Furans; HIV Infections; HIV-1; Humans; Lopinavir; Pyrimidinones; Ritonavir; Salvage Therapy; Sulfonamides

Amprenavir (APV), fosamprenavir (FPV), lopinavir (LPV), ritonavir (RTV) and efavirenz (EFV) are to varying degrees substrates, inducers and inhibitors of CYP3A4. Coadministration of these drugs might result in complex pharmacokinetic drug-drug interactions.. Two prospective, open-label, non-randomized studies evaluated APV and LPV steady-state pharmacokinetics in HIV-infected patients on APV 750 mg twice daily + LPV/RTV 533/133 mg twice daily with EFV (n=7) or without EFV (n=12) + background nucleosides (Study 1) and after switching FPV 1,400 mg twice daily for APV (n=10) (Study 2).. In Study 1 EFV and non-EFV groups did not differ in APV minimum plasma concentration (Cmin; 1.10 versus 1.06 microg/ml, P = 0.89), area under the concentration-time curve (AUC; 17.46 versus 24.34 microg x h/ml, P = 0.22) or maximum concentration (Cmax; 2.61 versus 4.33 microg/ml, P = 0.08); for LPV there was no difference in Cmin, (median: 3.66 versus 6.18 microg/ml, P = 0.20), AUC (81.84 versus 93.75 microg x h/ml, P = 0.37) or Cmax (10.36 versus 10.93 microg/ml, P = 0.61). In Study 2, after switching from APV to FPV, APV Cmin increased by 58% (0.83 versus 1.30 microg/ml, P = 0.0001), AUC by 76% (19.41 versus 34.24 micorg x h/ml, P = 0.0001), and Cmax by 75% (3.50 versus 6.14, P = 0.001). Compared with historical controls, LPV and RTV pharmacokinetics were not changed. All treatment regimens were well tolerated. Seven of eight completers (88%) maintained HIV-1 RNA <400 copies/ml 12 weeks after the switch (1 lost to follow up).. EFV did not appear to significantly alter APV and LPV pharmacokinetic parameters in HIV-infected patients taking APV 750 mg twice daily + LPV 533/133 mg twice daily. Switching FPV 1400 mg twice daily for APV 750 mg twice daily resulted in an increase in APV Cmin, AUC, and Cmax without changing LPV or RTV pharmacokinetics or overall tolerability.

Topics: Adult; Alkynes; Anti-HIV Agents; Benzoxazines; Carbamates; Cyclopropanes; Drug Interactions; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Organophosphates; Pyrimidinones; 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

To evaluate fosamprenavir/lopinavir (LPV)/ritonavir (RTV), fosamprenavir/RTV, or LPV/RTV in antiretroviral treatment-experienced patients. Lack of drug interaction data prompted a pharmacokinetic substudy to minimize subject risk.. Multi-center, open-label, selectively randomized, steady-state pharmacokinetic study in HIV-infected subjects.. A planned independent interim review occurred after at least eight subjects were randomized to each arm. Subjects received twice daily LPV/RTV 400/100 mg (arm A; n = 8); fosamprenavir/RTV 700/100 mg (arm B; n = 8) or LPV/RTV/fosamprenavir 400/100/700 mg (arm C; n = 17). Plasma samples were collected over 12 h between study weeks 2 and 4. Pharmacokinetic parameters were compared based on a one-sided t-test on log-transformed data with a Peto stopping boundary (P < 0.001).. Amprenavir mean area under the curve over 12 h (AUC0-12 h) and concentration at 12 h (C12 h) (microg/ml) were, respectively, 42.7 microg x h/ml (range, 33.1-55.1) and 2.4 microg/ml (range, 1.4-3.2) in arm B and 17.4 microg x h/ml (range, 4.6-41.3) and 0.9 microg/ml (range, 0.2-2.7) in arm C: geometric mean ratio (GMR) arm C:B was 0.36 [99.9% upper confidence boundary (UCB), 0.64] and 0.31 (99.9% h UCB, 0.61), respectively (P < or = 0.0001). Lopinavir AUC0-12 h and C12 h were, respectively, 95.3 microg x h/ml (range, 60.3-119.3) and 6.3 microg/ml (range, 2.2-9.2) in arm A and 54.4 microg x h/ml (range, 23.5-112.2) and 3.0 microg/ml (range, 0.4-7.9) in arm C: GMR arm C:A of 0.52 (99.9% UCB, 0.89) and 0.39 (99.9% UCB, 0.98), respectively (P < or = 0.0008). Ritonavir exposure was not significantly different between arms.. APV and LPV exposures are significantly reduced using LPV/RTV/fosamprenavir, possibly increasing the risk of virologic failure. Consequently, A5143 was closed to enrollment.

Topics: Adult; Carbamates; Drug Interactions; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Organophosphates; Pyrimidinones; Ritonavir; Salvage Therapy; Sulfonamides; Treatment Outcome

In a controlled, prospective study, the efficacy of ritonavir 200 mg twice daily (bid) in inhibiting the decrease of amprenavir plasma concentrations caused by co-administration of lopinavir was assessed. Twelve HIV-seropositive patients were enrolled, and nine patients completed the 28-day study. At day 14, plasma concentrations of amprenavir 600 mg bid and ritonavir 200 mg bid were determined over 12 h. At day 15, lopinavir 400 mg bid was added. At day 28, plasma concentrations of amprenavir, ritonavir and lopinavir were assessed. Co-administration of lopinavir was found to decrease the amprenavir concentration, determined as the median area under the curve over 12 h (AUC12), by 25% (AUC12 24.9 microg/h/mL vs. 18.5 microg/h/mL; P<0.01), despite the presence of ritonavir 200 mg bid. Eight participants discontinued the study regimen during the first 6 weeks because of adverse gastrointestinal events. In conclusion, gastrointestinal tolerance of a regimen containing an increased dose of ritonavir 200 mg bid was low, while the regimen did not prevent a decrease of amprenavir and possibly lopinavir plasma concentrations.

Topics: Anti-HIV Agents; Carbamates; Drug Interactions; Drug Therapy, Combination; Furans; HIV Protease Inhibitors; HIV Seropositivity; Humans; Lopinavir; Prospective Studies; Pyrimidinones; Ritonavir; Sulfonamides

Coadministration of amprenavir (APV) with small doses of ritonavir (RTV) results in a significant increase in APV plasma concentrations. Viruses showing resistance to other protease inhibitors (PI) may remain susceptible to APV, supporting a role for this drug in salvage therapy. We enrolled 35 patients who began a rescue intervention based on APV/RTV 600/100 mg twice daily. Their median viral load before beginning APV/RTV was 4.15 logs and their median CD4 count was 247 cells per microliter. The median prior PI exposure was of 43 months. At baseline, the median number of PI resistance mutations was 7. A significant virologic response (VR) (>1 log drop in plasma HIV-RNA and/or to <50 copies per milliliter) was recorded in 21.7% (5/23) of treated patients at week 48 (14.3% in the intent-to-treat analysis). The VR was significantly more frequent among subjects with less than 5 PI resistance mutations (66.6% vs. 5.8%; p = 0.008). Patients with prior exposure to lopinavir showed VR significantly less frequently than those not exposed to that drug (11% versus 60%; p < 0.05). The mean APV plasma trough concentration at week 12 was 1.3 microg/mL, and did not differ significantly comparing subjects having or not having VR. A trend toward a higher VR rate at week 48 was noticed among subjects with high genotypic inhibitory quotients (GIQ). In summary, HIV genotyping but not drug levels might be helpful to predict which patients would benefit from a rescue intervention based on APV/RTV 600/100 twice daily.

Topics: Adult; Antiretroviral Therapy, Highly Active; Area Under Curve; Carbamates; CD4 Lymphocyte Count; Drug Administration Schedule; Drug Resistance, Viral; Female; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Male; Mutation; Patient Selection; Phenotype; Predictive Value of Tests; Prospective Studies; Pyrimidinones; Ritonavir; RNA, Viral; Salvage Therapy; Sulfonamides; Treatment Outcome; Viral Load

This pharmacokinetic study was designed to characterize interactions between amprenavir and the lopinavir-ritonavir combination in patients infected with human immunodeficiency virus in whom previous antiretroviral therapy had failed.. Twenty-seven patients included in a randomized clinical trial (ANRS [National Agency for AIDS Research] Protocol 104) participated in this study. They were randomized to receive ritonavir at a dose of either 100 mg twice daily or 200 mg twice daily. For the first 2 weeks of therapy, they were randomly assigned to receive lopinavir (400 mg twice daily) and ritonavir (100 mg twice daily), amprenavir (600 mg twice daily) plus ritonavir (100 mg twice daily), lopinavir (400 mg twice daily) and ritonavir (100 mg twice daily) plus additional ritonavir (100 mg twice daily), or amprenavir (600 mg twice daily) plus ritonavir (200 mg twice daily). From week 3 onward, all patients received amprenavir plus lopinavir-ritonavir with or without an additional ritonavir dose (100 mg twice daily). The pharmacokinetics of the 3 drugs was studied in weeks 2 and 6 of therapy.. Median amprenavir concentrations decreased by 54% (P =.004) when lopinavir was added to the amprenavir-ritonavir regimen. Lopinavir weakly displaced amprenavir from plasma proteins: The average unbound fraction of amprenavir was 0.089 in week 2 and 0.114 in week 6 (P =.03), but this did not fully account for the observed interaction. Increasing the ritonavir dose did not affect the amprenavir concentration. The relationship between lopinavir and ritonavir concentrations fitted a maximum effect (E(max)) model;the average concentration of ritonavir that yielded a lopinavir concentration of 8119 ng/mL (50% of E(max)) was 602 ng/mL (coefficient of variation, 22%). There was a significant relationship between the lopinavir inhibitory quotient and the virologic response in week 2 (P =.005).. Lopinavir markedly decreases the amprenavir concentration during amprenavir and lopinavir-ritonavir combination therapy. The inhibitory quotients were more predictive of the short-term virologic response than was the level of drug exposure.

Topics: Administration, Oral; Adult; Antiretroviral Therapy, Highly Active; Biological Availability; Carbamates; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Interactions; Drug Therapy, Combination; Female; Follow-Up Studies; Furans; HIV Infections; Humans; Lopinavir; Male; Maximum Tolerated Dose; Middle Aged; Probability; Pyrimidinones; Risk Assessment; Ritonavir; Salvage Therapy; Severity of Illness Index; Single-Blind Method; Statistics, Nonparametric; Sulfonamides; Survival Rate; Treatment Outcome; Viral Load

The safety, efficacy, and mutual interactions of combination amprenavir with lopinavir/ritonavir as deep salvage treatment were investigated in a prospective 24-week pilot study. HIV-infected patients (n = 22) with virologic failure to nucleoside reverse transcriptase inhibitors (NRTIs), non-NRTIs, and at least 2 protease inhibitors received 400/100 mg of lopinavir/ritonavir with 600 mg of amprenavir every 12 hours combined with NRTIs. Patients receiving the same doses of lopinavir/ritonavir (n = 10) or amprenavir with ritonavir (n = 8) were chosen as controls for pharmacokinetic analyses. Mean changes from baseline HIV RNA levels and CD4 counts after 24 weeks were -1.13 log10 copies/mL and +88 x 10 cells/L, respectively. The mean plasma trough concentration (Cmin)and peak concentration (Cmax) of amprenavir were 104% and 228% lower and the Cmin of lopinavir was 46% lower in patients in whom the drugs were coadministered than in controls. There were 4 permanent drug discontinuations because of toxicity. An inhibitory quotient (IQ) of amprenavir higher than 0.8 was the best predictor of virologic outcome at 24 weeks, even after adjusting for amprenavir Cmin or phenotypic susceptibility. Deep salvage therapy using lopinavir/ritonavir with amprenavir is sufficiently safe and shows partial efficacy. When these drugs are coadministered, therapeutic drug monitoring should be employed and the IQ can be used to determine target drug levels.

Topics: Adult; Anti-HIV Agents; Carbamates; CD4 Lymphocyte Count; Drug Resistance, Viral; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV-1; Humans; Lopinavir; Male; Middle Aged; Pilot Projects; Pyrimidinones; Ritonavir; RNA, Viral; Salvage Therapy; Sulfonamides

To compare the antiviral efficacy of a salvage therapy combining lopinavir and amprenavir with 200 mg/d or 400 mg/d ritonavir, together with nucleoside reverse transcriptase inhibitors, over a 26-week period in HIV-infected patients in whom multiple antiretroviral regimens had failed.. Phase IIb, randomized, open-label, multicentre trial. Patients were eligible if they had <500 CD4+ cells/mm3 and >4 log10 copies/ml HIV-RNA after treatment with at least two protease inhibitors (PIs) and one non-nucleoside reverse transcriptase inhibitor.. At baseline (n=37), the median CD4+ cell count was 207/mm3 and the median plasma HIV-1 RNA level was 4.7 log10 copies/ml; the median number of PI mutations was seven and the median decrease in phenotypic susceptibility to lopinavir and amprenavir was 9.7 and 2.6, respectively. The mean number of antiretrovirals received prior to randomization was 7.7. The fall in the median HIV-1 RNA level at week 26 was -1.4 log10 copies/ml in the 200 mg/d ritonavir group and -2.5 log10 copies/ml in the 400 mg/d group (P=0.02). Viral load fell below 50 copies/ml in 32% and 61% of patients, respectively (P=0.07). After adjustment for the ritonavir dose, a smaller number of PI mutations was the only baseline characteristic associated with a better virological response at week 26. Amprenavir concentrations were significantly lower in presence of lopinavir. The lopinavir inhibitory quotient at week 6 correlated weakly with the change in the HIV-RNA level at week 26.. Combination of amprenavir, lopinavir and 400 mg/d ritonavir shows significant virological efficacy without increased toxicity in HIV-infected patients in whom multiple antiretroviral regimens have failed.

Topics: Adult; Aged; Carbamates; Drug Administration Schedule; Drug Therapy, Combination; Female; France; Furans; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Male; Middle Aged; Pyrimidinones; Ritonavir; RNA, Viral; Salvage Therapy; Sulfonamides; Viral Load

Human immunodeficiency virus (HIV) protease inhibitor (PI)-induced adverse effects have become a serious clinical problem. In addition to their metabolic and cardiovascular complications, these drugs also frequently cause severe gastrointestinal disorders, including mucosal erosions, epithelial barrier dysfunction, and diarrhea. However, the exact mechanisms underlying gastrointestinal adverse effects of HIV PIs remain unknown. This study investigated whether HIV PIs disrupt intestinal epithelial barrier integrity by activating endoplasmic reticulum (ER) stress.. The most commonly used HIV PIs (lopinavir, ritonavir, and amprenavir) were used; their effects on ER stress activation and epithelial paracellular permeability were examined in vitro as well as in vivo using wild-type and CHOP(-)/(-) mice.. Treatment with lopinavir and ritonavir, but not amprenavir, induced ER stress, as indicated by a decrease in secreted alkaline phosphatase activities and an increase in the unfolded protein response. This activated ER stress partially impaired the epithelial barrier integrity by promoting intestinal epithelial cell apoptosis. CHOP silencing by specific small hairpin RNA prevented lopinavir- and ritonavir-induced barrier dysfunction in cultured intestinal epithelial cells, whereas CHOP(-)/(-) mice exhibited decreased mucosal injury after exposure to lopinavir and ritonavir.. HIV PIs induce ER stress and activate the unfolded protein response in intestinal epithelial cells, thus resulting in disruption of the epithelial barrier integrity.

Topics: Animals; Apoptosis; Carbamates; Cell Line; Cell Membrane Permeability; Endoplasmic Reticulum; Furans; HIV Infections; HIV Protease Inhibitors; Intestinal Mucosa; Lopinavir; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Pyrimidinones; Ritonavir; Stress, Physiological; Sulfonamides; Transcription Factor CHOP

HIV protease inhibitors (HIV PI) reduce morbidity and mortality of HIV infection but cause multiple untoward effects. Because certain HIV PI evoke production of reactive oxygen species (ROS) and volume-sensitive Cl(-) current (I(Cl,swell)) is activated by ROS, we tested whether HIV PI stimulate I(Cl,swell) in ventricular myocytes. Ritonavir and lopinavir elicited outwardly rectifying Cl(-) currents under isosmotic conditions that were abolished by the selective I(Cl,swell)-blocker DCPIB. In contrast, amprenavir, nelfinavir, and raltegravir, an integrase inhibitor, did not modulate I(Cl,swell) acutely. Ritonavir also reduced action potential duration, but amprenavir did not. I(Cl,swell) activation was attributed to ROS because ebselen, an H(2)O(2) scavenger, suppressed ritonavir- and lopinavir-induced I(Cl,swell). Major ROS sources in cardiomyocytes are sarcolemmal NADPH oxidase and mitochondria. The specific NADPH oxidase inhibitor apocynin failed to block ritonavir- or lopinavir-induced currents, although it blocks I(Cl,swell) elicited by osmotic swelling or stretch. In contrast, rotenone, a mitochondrial e(-) transport inhibitor, suppressed both ritonavir- and lopinavir-induced I(Cl,swell). ROS production was measured in HL-1 cardiomyocytes with C-H(2)DCFDA-AM and mitochondrial membrane potential (ΔΨ(m)) with JC-1. Flow cytometry confirmed that ritonavir and lopinavir but not amprenavir, nelfinavir, or raltegravir augmented ROS production, and HIV PI-induced ROS production was suppressed by rotenone but not NADPH oxidase blockade. Moreover, ritonavir, but not amprenavir, depolarized ΔΨ(m). These data suggest ritonavir and lopinavir activated I(Cl,swell) via mitochondrial ROS production that was independent of NADPH oxidase. ROS-dependent modulation of I(Cl,swell) and other ion channels by HIV PI may contribute to some of their actions in heart and perhaps other tissues.

Topics: Action Potentials; Animals; Carbamates; Chloride Channels; Furans; HIV Integrase Inhibitors; HIV Protease Inhibitors; Ion Channel Gating; Lopinavir; Membrane Potential, Mitochondrial; Mitochondria; Myocytes, Cardiac; Nelfinavir; Pyrimidinones; Pyrrolidinones; Rabbits; Raltegravir Potassium; Reactive Oxygen Species; Ritonavir; Sulfonamides; Time Factors

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

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

Topics: Adult; Anti-HIV Agents; Carbamates; Drug Therapy, Combination; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Organophosphates; Pyrimidinones; Ritonavir; 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

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

Cross-contamination among wells of a high-throughput, high-density assay is a risk that cannot be detected or controlled by the performance of calibration standards and quality control samples. In the current practice, carryover and cross-contamination is detected only when analytes are detected in blank, zero, placebo, pre-dose samples, in a low standard or low quality control sample. There is no mechanism that allows bioanalytical scientists to determine if cross-contamination has occurred among other samples. As a result, erroneous results can be released to clients even though a batch meets the acceptance criteria. We tested a new approach that quantifies the cross-contamination of each sample and allows the scientist to make quality decisions with documentation. The approach will also detect carryover in over 90% of the wells. Briefly, two additional analytes were added as contamination markers. The markers were added to a multi-well plate alternatively creating a pattern of a checkerboard. The spiked multi-well plate was then used to perform the assay. If both markers were detected in a well, the sample was considered contaminated. The amount of the unexpected marker detected in a well measures the degree of contamination and may be used to make deactivation decisions. Depending on the relative impact of the contamination, a scientist can choose to tolerate the bias, reject the sample, reject the batch or raise the lower limit of quantitation for the batch. A guideline for rejection decisions is presented for discussion.

Topics: Biomarkers; Carbamates; Chemistry Techniques, Analytical; Chromatography, High Pressure Liquid; Drug Contamination; Furans; Humans; Lopinavir; Pyrimidinones; Quality Control; Reproducibility of Results; Ritonavir; Saquinavir; Sensitivity and Specificity; Sulfonamides; Tandem Mass Spectrometry

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

The need for a potent HIV protease inhibitor (PI) to combat emerging PI-resistant viruses is anticipated. Analogs formulated from the combination of structural fragments of Ritonavir, Lopinavir, and Amprenavir were synthesized. Analogs containing the oxime pharmacophore were found to have improved activities against both wild type and resistant (A17) viruses. The synthesis and structure-activity relationships (SAR) based upon the in vitro IC50 of this series of compounds are reported.

Topics: Binding Sites; Carbamates; Drug Design; Furans; HIV Protease; HIV Protease Inhibitors; Kinetics; Lopinavir; Models, Molecular; Molecular Conformation; Pyrimidinones; Ritonavir; 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

The clinical use of HIV protease inhibitors (PIs) is associated with the development of peripheral insulin resistance. The incidence and degree of impaired glucose tolerance observed in treated patients vary considerably between drugs, however. To compare the ability of HIV PIs to alter peripheral glucose disposal acutely in a genetically identical model system at therapeutically relevant drug levels, healthy lean male rats previously naive to PI exposure were given ritonavir, amprenavir, lopinavir/ritonavir (4:1), or atazanavir by continuous intravenous infusion to achieve steady state drug levels of 10 or 25 muM rapidly. Under euglycemic hyperinsulinemic clamp conditions, a dose-dependent reduction in the peripheral glucose disposal rate (Rd) was observed with all the PIs except atazanavir. The rank order of sensitivity was ritonavir, lopinavir, and then amprenavir. Changes in skeletal muscle and heart 2-deoxyglucose (2-DOG) uptake correlated with reductions in Rd. All 3 of these PIs also produced significant reductions in 2-DOG uptake into primary rat adipocytes in vitro. Atazanavir had no effect on glucose uptake in vitro or in vivo. The in vivo potency of PIs to impair peripheral glucose disposal acutely correlates with the degree of insulin resistance observed in HIV-infected patients receiving these drugs. Preclinical testing of novel candidate PIs in a rodent model system may be useful in identifying the future risk of altering glucose homeostasis.

Topics: Adipocytes; Animals; Atazanavir Sulfate; Carbamates; Deoxyglucose; Dose-Response Relationship, Drug; Furans; Glucose; Glucose Clamp Technique; HIV Protease Inhibitors; Infusions, Intravenous; Insulin Resistance; Lopinavir; Male; Models, Animal; Muscle, Skeletal; Myocardium; Oligopeptides; Pyridines; Pyrimidinones; Rats; Ritonavir; Sulfonamides

Topics: Adult; AIDS-Associated Nephropathy; Antiretroviral Therapy, Highly Active; Carbamates; Drug Monitoring; Female; Furans; Humans; Lopinavir; Pyrimidinones; Renal Dialysis; Sulfonamides

Despite the increasing number of antiretroviral compounds, the number of useful drug regimens is limited owing to the high frequency of cross-resistance.. We studied in vitro two-drug combinations using three protease inhibitors (PIs), tipranavir, amprenavir and lopinavir, on isolates (003 and 004) derived from patients with resistance to multiple PIs compared with the drug-susceptible isolate 14aPre in peripheral blood mononuclear cells. Drug interactions were determined by median dose-effect analysis, with the combination index calculated at several inhibitory concentrations (IC).. In 14aPre experiments, the combination tipranavir + lopinavir demonstrated synergy at low concentrations (IC(50)), an additive effect at IC(75) and antagonism at IC(90)-IC(95); tipranavir + amprenavir were antagonistic at all concentrations except IC(95), where they were synergic; and the lopinavir + amprenavir combination was always antagonistic. In 003 and 004 infections, tipranavir + lopinavir and tipranavir + amprenavir combinations were antagonistic, and lopinavir + amprenavir were synergic, at all concentrations, with the exception of being additive at IC(95).. Our in vitro experiments did not show any advantage in combining second generation PIs as a therapeutic strategy in naive or multi-treatment failure subjects, with the exception of tipranavir + amprenavir at IC(95) in infections by a wild-type isolate.

Topics: Carbamates; Drug Resistance, Viral; Enzyme-Linked Immunosorbent Assay; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Pyridines; Pyrimidinones; Pyrones; RNA, Viral; Sulfonamides

Genotypes in nine highly protease inhibitor (PI)-experienced patients were studied before and after lopinavir/ritonavir (LPV/r) treatment. Resistance to amprenavir was the rule both before and after LPV/r treatment. Treatment with LPV/r can select for the 50 V mutation. In this setting, significant differences in the inference of the amprenavir phenotype from genotype were observed when using different algorithms.

Topics: Adult; Anti-Retroviral Agents; Carbamates; CD4 Lymphocyte Count; Drug Resistance, Viral; Drug Therapy, Combination; Female; Furans; Genotype; HIV; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Mutation; Pyrimidinones; Retrospective Studies; Ritonavir; RNA, Viral; Sulfonamides

This study aimed at identifying HIV-1 protease amino acid changes associated with protease inhibitor (PI) exposure and susceptibility. New amino acid substitutions were correlated with the number of experienced PIs, reaching statistical significance only for those at positions 3, 44, and 74. The correspondence multivariate model demonstrated that > or =3 experienced PIs and substitutions or mutations at positions 3, 46, 54, 73, 74, and 84 were correlated with PI cross-resistance, including resistance for lopinavir and amprenavir in this cohort of patients who were naive for these drugs.

Topics: Amino Acid Substitution; Carbamates; Cohort Studies; Drug Resistance, Multiple, Viral; Furans; Genes, Viral; Genotype; HIV Infections; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Multivariate Analysis; Mutation; Phenotype; Pyrimidinones; Regression Analysis; Sulfonamides

Since 1999 an ongoing international interlaboratory quality control program has analyzed antiretroviral drugs in plasma. Results of the third round of this program are presented. Quality control samples were prepared by spiking drug-free plasma with varying concentrations of the currently available protease inhibitors and the nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine. Thirty-three laboratories participated in the program and were requested to analyze the quality control samples. Results were from 30 laboratories. Of all measurements, 82% were performed within 80%-120% accuracy limits. Only 3 laboratories performed all their measurements within these limits, and 12 participants reported at least 90% of their analyses within the acceptance range. Mean accuracy for low drug concentrations was worse than for medium and high concentrations. The percentage of satisfactory measurements for the 6 laboratories that participated for the third time in the program increased from 54% in the first round to 85% in the third round. The program revealed a large variability in the laboratories' ability to measure antiretroviral drugs accurately. This variability may have important implications for therapeutic drug monitoring of these drugs and for pharmacokinetic studies. Interlaboratory testing is useful to alert laboratories to previously undetected analytical problems.

Topics: Alkynes; Australia; Benzoxazines; Canada; Carbamates; Cyclopropanes; Europe; Furans; HIV Protease Inhibitors; Humans; International Cooperation; Laboratories; Lopinavir; Nevirapine; Oxazines; Pyrimidinones; Quality Control; Reference Standards; Reproducibility of Results; Reverse Transcriptase Inhibitors; Sulfonamides; United States

Current genotypic algorithms suggest that the HIV-1 protease inhibitors (PI) lopinavir (LPV) and amprenavir (APV) have distinct resistance profiles. However, phenotypic data indicate that cross-resistance is more common than expected.. Protease genotype (GT) and phenotype (PT) from 1418 patient viruses with reduced PI susceptibility and/or resistance-associated mutations (training data) were analyzed. Samples were classified as LPV resistant by GT (GT-R) if six or more LPV mutations were present, and by PT (PT-R) if the 50% inhibitory concentration (IC(50)) fold-change (FC) was over 10.. There were 182 samples (13%) that were GT-S but PT-R for LPV. A comparison of the mutation prevalence in PT-R/GT-S samples with that in PT-S/GT-S samples identified mutations associated with LPV PT-R. Several previously defined LPV mutations were found to have a stronger than average effect (e.g., M46I/L, I54V/T, V82A/F), and new variants at known positions (e.g., I54A/M/S, V82S) were identified. Other mutations, including known APV resistance mutations, were found to contribute to reduced LPV susceptibility. A new LPV genotypic interpretation algorithm was constructed that improved overall genotypic/phenotypic concordance from 80% to 91%. The algorithm demonstrated a concordance rate of 90% when tested on 523 new samples. Cross-resistance between APV and LPV was greater in samples with primary APV resistance mutations than in those lacking them.. The current LPV mutation score does not fully account for many resistant viruses. Consequently, cross-resistance between LPV and APV is underappreciated. Phenotypic results from large and diverse patient virus populations should be used to guide the development of more accurate GT interpretation algorithms.

Topics: Algorithms; Carbamates; Drug Resistance, Viral; Furans; Genotype; HIV Infections; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Mutation; Phenotype; Pyrimidinones; Sulfonamides

Topics: Anti-HIV Agents; Carbamates; Drug Resistance, Viral; Furans; Genotype; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Phenotype; Pyrimidinones; 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

A panel of 245 clinical samples with known treatment histories was retrospectively evaluated for cross-resistance to new protease inhibitors (PI). Samples with resistance to previously approved PI displayed high cross-resistance to atazanavir, whereas cross-resistance to amprenavir was considerably lower. A similar cross-resistance profile was observed for lopinavir, if a higher cut-off for resistance (9.5-fold) was applied. The enhanced efficacy of boosted PI is discussed with respect to clinically relevant cut-offs for drug resistance.

Topics: Atazanavir Sulfate; Carbamates; Drug Resistance, Multiple, Viral; Furans; HIV; HIV Protease Inhibitors; Humans; Lopinavir; Oligopeptides; Pyridines; Pyrimidinones; Retrospective Studies; 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

Topics: Acquired Immunodeficiency Syndrome; Adult; Anti-HIV Agents; Carbamates; Drug Interactions; Female; Furans; HIV-1; Humans; Lopinavir; Male; Middle Aged; Pyrimidinones; Retrospective Studies; Salvage Therapy; Sulfonamides

Genotypic correlates of reduced phenotypic susceptibility to amprenavir (APV) and lopinavir (LPV) were examined in 271 HIV isolates from 207 protease inhibitor (PI)-experienced subjects. All samples were from LPV-naive subjects; two were from APV-experienced subjects. Using a fold resistance (FR) of <2.5, 179 (66%) were APV susceptible. Using FRs of <2.5 and <10, 107 (39%) and 194 (72%), respectively, were LPV susceptible. The I84V mutation was the strongest APV resistance marker in PI-experienced subjects in both univariate and multivariate analyses, with an increased relative incidence (RI) of 6.9 with >2.5 FR. Mutations L10I (RI, 1.7), M46I (RI, 2.3), and L90M (RI, 1.9, but 65% linked with the I84V) were associated with decreased APV susceptibility in the univariate analysis (p < 0.001). Mutations L10I, G48V, I54T, I54V, and V82A were significantly associated with decreased LPV susceptibility (p < 0.001 for each) and had increased RIs of 2.2, 4.4, 13, 4.6, and 3.2, respectively. Decreased susceptibility to LPV (FR, >or=10) was significantly associated with prior exposure to the following PIs: ritonavir (RTV) (p < 0.001), saquinavir (SQV) (p < 0.001), nelfinavir (NFV) (p = 0.008), and indinavir (IDV) (p = 0.028). Decreased APV susceptibility (FR, >or=2.5) was significantly associated with prior exposure to RTV (p = 0.009), NFV (p = 0.003), and IDV (p = 0.021) but not with prior SQV (p = 0.103). These results suggest that APV and LPV have different cross-resistance mutation patterns that may help determine choice of PI therapy after therapy failure.

Topics: Carbamates; Cross-Sectional Studies; Drug Resistance, Viral; Furans; Genotype; HIV Infections; HIV Protease; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Microbial Sensitivity Tests; Mutation; Phenotype; Pyrimidinones; Retrospective Studies; RNA, Viral; Sulfonamides; Viremia

Topics: Carbamates; Drug Synergism; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Pilot Projects; Pyrimidinones; Ritonavir; Sulfonamides

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

To evaluate protease inhibitor (PI) cross-resistance and reductions in replication capacity conferred by amprenavir-selected mutations.. HIV-1IIIB variants derived from passage in increasing concentrations of amprenavir were studied, as well as 3'Gag/protease recombinants derived from them. These strains progressively accumulated mutations at codons 10, 46, 47, 50 and 84 in the protease as well as a p1/p6 cleavage site mutation at codon 449 in Gag. Their susceptibility (IC50) to various PI and their corresponding replication capacities were evaluated by a single-cycle growth assay and compared with measures using competitive cultures and p24 antigen production.. Amprenavir susceptibility decreased with increasing numbers of protease mutations. Changes in lopinavir susceptibility paralleled changes in amprenavir susceptibility. Certain amprenavir-selected mutants conferred greater than 10-fold cross-resistance to lopinavir, including PrL10F/M46I/I50V-GagL449F (19-fold) and PrL10F/M46I/I47V/I50V-GagL449F (31-fold). Moreover, one isolate with only two mutations in the protease (L10F/84V) and GagL449F displayed a 7.7-fold increase in lopinavir IC50. Low-level cross-resistance to ritonavir and nelfinavir was also observed. The replication capacity of viruses containing either I84V or I50V was at least 90% lower than the reference virus in the single-cycle assay. The order of relative replication capacity was wild-type > L10F > L10F/I84V > L10F/M46I/I50V > L10F/M46I/I47V/I50V.. These results indicate that until more comprehensive genotype-phenotype correlations between amprenavir and lopinavir susceptibility are established, phenotypic testing may be preferable to genotyping to detect cross-resistance, and should be considered when switching patients from a failing amprenavir-containing regimen. This study also provides data on the concordance of replication capacity measurements generated using rapid single-cycle growth and competition assays.

Topics: Carbamates; Codon; Drug Resistance, Multiple, Viral; Furans; Genes, gag; HIV Protease; HIV Protease Inhibitors; HIV-1; Lopinavir; Mutation; Phenotype; Pyrimidinones; Recombination, Genetic; Sulfonamides; Virus Replication

Topics: Carbamates; Dose-Response Relationship, Drug; Drug Interactions; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Pyrimidinones; Ritonavir; Salvage Therapy; Sulfonamides

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Carbamates; Delavirdine; Drug Synergism; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Pyrimidinones; Reverse Transcriptase Inhibitors; Ritonavir; 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

Topics: Adult; Carbamates; Drug Therapy, Combination; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Male; Middle Aged; Pyrimidinones; 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: Aged; Carbamates; CD4 Lymphocyte Count; Dideoxynucleosides; Drug Resistance, Microbial; Drug Therapy, Combination; Furans; HIV Infections; Humans; Lopinavir; Male; Patient Compliance; Pyrimidinones; Ritonavir; Stavudine; Sulfonamides; Viral Load

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Carbamates; CD4 Lymphocyte Count; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Nevirapine; Pyrimidinones; Reverse Transcriptase Inhibitors; Sulfonamides; Viral Load

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

Many at the 6th Conference on Retroviruses and Opportunistic Infections expressed concern regarding the significant amount of drug resistance that is developing among treatment-naive patients. The threat of drug failure has created an acute need for new treatments that are not affected by resistance to older treatments. Three promising drugs that are on the horizon are discussed. Amprenavir (Agenerase) is expected to receive marketing approval in the next few months, and ABT-378 and T-20 are in phase II trials and should be available in the next 2 years. Additional information on these drugs is presented.

Topics: Anti-HIV Agents; Carbamates; Congresses as Topic; Drug Resistance, Microbial; Drug Therapy, Combination; Drugs, Investigational; Enfuvirtide; Furans; HIV Envelope Protein gp41; HIV Infections; HIV Protease Inhibitors; HIV-1; Humans; Lopinavir; Peptide Fragments; Pyrimidinones; Salvage Therapy; Sulfonamides; Viral Load; Virus Replication

Updates are provided for new anti-HIV drugs currently in development. ABT-378, Tipranavir, and DMP-450 are among the new protease inhibitors discussed. Drugs from other classes that are discussed include emivirine (Coactinon, formerly MKC-442), FTC (emtricitabine, Coviracil), adefovir (Preveon), and pentafuside (T-20). A small study has found that women using Ritonavir (Norvir) may be at a greater risk for anemia (a decrease in red blood cells), caused by excessive menstrual bleeding or hypermenorrhea. New formulations of Ritonavir and ddI (Didanosine, Videx) are described.

Topics: Adverse Drug Reaction Reporting Systems; Anti-HIV Agents; Capsules; Carbamates; Chemistry, Pharmaceutical; Didanosine; Drug Synergism; Drug Therapy, Combination; Drugs, Investigational; Female; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Lopinavir; Menorrhagia; Pyrimidinones; Reverse Transcriptase Inhibitors; Ritonavir; Sulfonamides

Current treatment strategies need to be planned carefully, because there is an inadequate supply of new types of drugs available to treat people who have failed previous therapies. It is important to fully use existing therapies so as not to limit future options. Drugs in development include: ABT-378, a protease inhibitor from Abbott Laboratories; tipranavir (PNU-140690), a protease inhibitor by Pharmacia & Upjohn; and S-1153, a non-nucleoside reverse transcriptase inhibitor from Agouron Pharmaceuticals. All were effective and well-tolerated in recent trials. A warning was issued for adefovir, a nucleoside reverse transcriptase inhibitor, regarding the development of kidney toxicity for people taking the drug more than 20 weeks. Information on expanded access programs for abacavir, adefovir, amprenavir, and efavirenz is provided.

Topics: Adenine; Alkynes; Anti-HIV Agents; Benzoxazines; Carbamates; CD4 Lymphocyte Count; Clinical Trials as Topic; Cyclopropanes; Dideoxynucleosides; Drug Therapy, Combination; Drugs, Investigational; Furans; HIV Infections; HIV Protease Inhibitors; Humans; Imidazoles; Kidney Diseases; Lopinavir; Oxazines; Pyridines; Pyrimidinones; Reverse Transcriptase Inhibitors; Sulfonamides; Viral Load

The 12th World AIDS Conference in Geneva brought together AIDS researchers, medical care providers, advocates, and people living with HIV to discuss implications related to providing global access to care. New drugs have decreased deaths and opportunistic infections in developed countries, but developing countries are becoming overwhelmed by the number of new patients. The World Health Organization estimates that the majority of the 30.6 million people infected with HIV/AIDS worldwide will die within a decade unless a cure is found or treatments are made accessible to them. Researchers are no longer optimistic about the feasibility of viral eradication, and instead are looking for strategies to overcome the virus that continues to live in latent reservoirs in the body. Descriptions are given of several new drugs currently being studied, including abacavir, amprenavir, efavirenz, ABT 378, and Hydroxyurea. Progress is also highlighted about dosing regimens, antiretroviral resistance, and reconstitution of the immune system.

Topics: Acquired Immunodeficiency Syndrome; AIDS-Related Opportunistic Infections; Alkynes; Anti-HIV Agents; Benzoxazines; Carbamates; CD4-Positive T-Lymphocytes; Clinical Trials as Topic; Congresses as Topic; Cyclopropanes; Dideoxynucleosides; Drug Resistance, Microbial; Drug Therapy, Combination; Enzyme Inhibitors; Furans; Health Services Accessibility; HIV Protease Inhibitors; Humans; Hydroxyurea; Lopinavir; Oxazines; Patient Care Planning; Pyrimidinones; Remission Induction; Reverse Transcriptase Inhibitors; Sulfonamides; Switzerland; Virus Replication