didanosine and Mitochondrial-Diseases

Nucleoside reverse transcriptase inhibitors (NRTIs) suppress human immunodeficiency virus (HIV) replication, but are often associated with mitochondrial toxicity. Although well studied outside of the central nervous system, no investigation has examined the effects of these drugs on brain mitochondria of individuals living with HIV. The authors used proton magnetic resonance spectroscopy to evaluate NRTI-related changes in brain mitochondria. N-acetylaspartate (NAA; sensitive to alterations in mitochondrial integrity) was measured in frontal lobe white and gray matter of 18 HIV+ individuals taking didanosine and/or stavudine (two NRTIs likely to cause mitochondrial toxicity), 14 HIV+ individuals taking zidovudine and lamivudine, 16 HIV+ individuals not currently taking antiretrovirals, and 17 HIV- controls. The HIV+ groups were comparable on demographic measures, estimates of illness severity, and estimated length of HIV infection. Those taking didanosine and/or stavudine had a significant 11.4% decrease in concentrations of frontal white matter NAA compared to HIV- controls, whereas NAA levels of the other HIV+ groups were intermediate. Group differences in metabolites were not found in frontal gray matter. Lower levels of frontal white matter NAA were associated with longer periods of didanosine and/or stavudine treatment (r = -.41, P = .06). Levels of NAA were not related to length of zidovudine/lamivudine treatment (r = -.04, P = .44). Furthermore, taking more than one of stavudine, didanosine, and abacavir increased the likelihood of having reduced NAA. The results are consistent with previous studies finding HIV-related changes in neuronal integrity. However, because NRTIs can injure mitochondria, we propose that the observed reductions in NAA in individuals taking didanosine and/or stavudine may be the result of depleted brain mitochondria and/or alterations in cellular respiration. Measurement of brain metabolites sensitive to impairments in energy metabolism, including NAA, may aid in early detection of subclinical NRTI-mediated mitochondrial toxicity.

Topics: Adult; Aspartic Acid; Brain; Cell Respiration; Didanosine; Female; HIV Infections; Humans; Lamivudine; Magnetic Resonance Spectroscopy; Male; Middle Aged; Mitochondria; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; Stavudine; Treatment Outcome; Zidovudine

NRTIs are essential components of HIV therapy with well-documented, long-term mitochondrial toxicity in hepatic cells, but whose acute effects on mitochondria are unclear. As acetaminophen-induced hepatotoxicity also involves mitochondrial interference, we hypothesized that it would be exacerbated in the context of ART.. We evaluated the acute effects of clinically relevant concentrations of the most widely used NRTIs, alone or combined with acetaminophen, on mitochondrial function and cellular viability.. The purine analogues abacavir and didanosine produced an immediate and concentration-dependent inhibition of oxygen consumption and complex I and III activity. This inhibition was accompanied by an undermining of mitochondrial function, with increased production of reactive oxygen species and reduction of mitochondrial membrane potential and intracellular ATP levels. However, this interference did not compromise cell survival. Co-administration with concentrations of acetaminophen below those considered hepatotoxic exacerbated the deleterious effects of both compounds on mitochondrial function and compromised cellular viability, showing a clear correlation with diminished glutathione levels.. The simultaneous presence of purine analogues and low concentrations of acetaminophen significantly potentiates mitochondrial dysfunction, increasing the risk of liver injury. This new mechanism is relevant given the liver's susceptibility to mitochondrial dysfunction-related toxicity and the tendency of the HIV infection to increase oxidative stress.

Topics: Acetaminophen; Analgesics, Non-Narcotic; Anti-HIV Agents; Cell Line; Chemical and Drug Induced Liver Injury; Didanosine; Dideoxynucleosides; Electron Transport Chain Complex Proteins; Glutathione; Humans; Mitochondria, Liver; Mitochondrial Diseases; Oxygen Consumption; Reactive Nitrogen Species

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Blepharoptosis; Didanosine; DNA, Mitochondrial; Genetic Predisposition to Disease; HIV Infections; Humans; Lipodystrophy; Male; Middle Aged; Mitochondria; Mitochondrial Diseases; Muscle, Skeletal; Mutation; Oculomotor Muscles; Ophthalmoplegia; Ophthalmoplegia, Chronic Progressive External; Recovery of Function; Risk Factors; Time

Tenofovir disoproxil fumarate (tenofovir DF) use has been associated with renal dysfunction and Fanconi syndrome. Tenofovir is taken up into renal tubules by anion transporters where high intracellular drug concentration may induce a functionally relevant depletion of mitochondrial DNA (mtDNA). We investigated if tenofovir may induce renal mtDNA depletion and respiratory chain dysfunction.. Rats (n = 8) were gavaged daily with 100 mg x kg(-1) x d(-1) of tenofovir DF or didanosine. Kidneys and livers were examined after 8 weeks of treatment.. The tenofovir group had significantly lower body and kidney weights than rats exposed to water or didanosine. Proximal but not distal tubules were of increased diameter and contained small lipid droplets. Tubular mitochondria were enlarged, and their crystal architecture was disrupted. Tenofovir-exposed kidneys contained low mtDNA copy numbers and impaired expression of mtDNA-encoded cytochrome c oxidase (COX) I but not nucleus-encoded COX IV subunits. Histochemistry demonstrated low tubular COX and nicotinamide adenine dinucleotide dehydrogenase (NADH-DH) activities, whereas succinate dehydrogenase activity was preserved. COX activity was preserved in the glomeruli of tenofovir-exposed rats. Didanosine did not elicit renal effects but, unlike tenofovir, depleted mtDNA in liver (by 52%).. Tenofovir DF induces an organ-specific nephrotoxicity with mtDNA depletion and dysfunction of mtDNA-encoded respiratory chain subunits. The data do not support nephrotoxicity of didanosine.

Topics: Adenine; Animals; Anti-HIV Agents; Didanosine; DNA, Mitochondrial; Electron Transport; Electron Transport Complex IV; Kidney Tubules, Proximal; Male; Microscopy, Electron, Transmission; Mitochondria; Mitochondrial Diseases; NADH Dehydrogenase; Organophosphonates; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Inhibitors; Tenofovir

The normal metabolism of mitochondria in T lymphocytes is unknown, as are the effects from nucleoside-analogue reverse-transcriptase inhibitors that impair mitochondrial polymerase- gamma . We isolated peripheral-blood CD4 and CD8 T lymphocytes from 6 healthy men and stimulated them with anti-CD3 and anti-CD28 antibodies, in the presence and in the absence of didanosine (ddI). In the absence of ddI, mitosis of T lymphocytes was paralleled by a transient up-regulation of both mtDNA and production of lactate. In CD4 lymphocytes, 10-day incubation with ddI at concentrations of 11.8 mu mol/L, 35.4 mu mol/L, 59.0 mu mol/L, and 118.0 mu mol/L induced (1) a concentration-dependent reduction of both mtDNA (to 73%, 29%, 24%, and 23%, respectively, of the levels in control samples) and subunit II of mtDNA-encoded cytochrome c oxidase (to 86%, 81%, 55%, and 31%, respectively, of the levels in control samples) and (2) a concentration-dependent increase in production of lactate (to 139%, 222%, 276%, and 312%, respectively, of the levels in control samples). Activation of lymphocytes (which was measured in terms of expression of CD25) was unaffected. Mitochondrial depolarization (assessed by staining with JC-1) was observed as early as day 7 of incubation. All changes were time dependent and also were observed in isolated CD8 lymphocytes. Electron microscopy revealed enlarged mitochondria with vacuoles, inclusions, and reduced electron density. ddI at a concentration of 11.8 mu mol/L induced changes that bordered statistical significance. After stimulation, there was a wide range in the change of mtDNA content in lymphocytes. Therefore, mtDNA measurements in blood are not necessarily a marker for the mitochondrial toxicity of ddI. Nevertheless, ddI does lead to depletion of mtDNA in lymphocytes and to functional impairment.

Topics: Adult; Anti-HIV Agents; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Didanosine; DNA, Mitochondrial; Humans; Lymphocyte Activation; Male; Mitochondria; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; T-Lymphocytes

To evaluate if nucleoside analogue reverse transcriptase inhibitors (NRTIs) and polymerase-gamma inhibitors deplete mitochondrial DNA (mtDNA) in cultured primary lymphocytes and if such depletion might be associated with functional defects.. Primary peripheral blood CD4 and CD8 lymphocytes were purified from six healthy humans (three male and three female), stimulated mitotically (CD3/CD28) and cultured for 10 days in the presence or absence of NRTIs. Lymphocyte proliferation, mtDNA content, the expression of mtDNA-encoded cytochrome c-oxidase II (COXII) and lactate production were assessed.. In CD4 lymphocytes, 10-day exposure to zalcitabine (1.77 microM), didanosine (118 microM) and stavudine (361 microM) induced a time-dependent decline of mtDNA. Compared with controls, residual mtDNA levels were 25%, 21% and 40%, respectively. COXII was reduced to 55%, 35% and 70% of control values. Lactic acid production was increased (by 214%, 294% and 175%, respectively). At day 10, lymphocyte counts were reduced (to 60%, 51%, and 41%, respectively). Zidovudine (71 microM) also reduced lymphocyte counts to 34% and increased lactic acid production by 170%, but did not induce mtDNA and COXII depletion. All these changes were highly significant. Lower NRTI concentrations (0.177 microM of zalcitabine, 11.8 microM of didanosine, 3.6 microM of stavudine and 7.1 microM of zidovudine) had effects at the border of significance. Similar observations were made in CD8 lymphocytes.. In human lymphocytes, zalcitabine, didanosine and stavudine induce dose- and time-dependent mtDNA depletion, which is associated with decreased cell proliferation and increased lactate production. Zidovudine impairs lymphocyte division without inducing mtDNA depletion.

Topics: CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cells, Cultured; Didanosine; DNA, Mitochondrial; Female; Humans; Lactic Acid; Lymphocyte Activation; Male; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; Stavudine; Zalcitabine

Most toxicities associated with nucleoside analogue reverse transcriptase inhibitors (NRTIs) are thought to result from mitochondrial toxicity. These toxicities include peripheral neuropathy, pancreatitis, lactic acidosis, and peripheral lipoatrophy. Unfortunately, there are no validated laboratory markers for clinically assessing, let alone predicting, the onset of mitochondrial toxicity associated with NRTI therapy.. To provide preliminary evidence of the potential clinical utility of an assay which has been developed for quantifying mitochondrial DNA (mtDNA) in clinical samples from HIV-infected patients.. A single-tube duplex real-time DNA-nucleic acid sequence-based amplification (NASBA) assay (Mitox, Primagen, Amsterdam, the Netherlands) was used to quantify mtDNA in cryopreserved peripheral blood mononuclear cells (PBMC) obtained from HIV-1-infected patients during their prior participation in a randomized placebo-controlled trial comparing zidovudine (ZDV) monotherapy with combinations of ZDV plus either dideoxycytidine (ddC) or didanosine (ddI) (the Delta trial). Patients were antiretroviral naïve prior to entering the trial. Samples obtained during the initial 48 weeks of treatment were tested.. A significant decline of mtDNA, both in an intent-to-treat and in an as-treated analysis, was observed in patients treated with ZDV+ddC and ZDV+ddI, but not with ZDV alone, consistent with the results expected from the degree of mtDNA depletion described for each of these drugs in vitro.. This single-tube duplex real-time DNA-NASBA assay was shown to measure mtDNA accurately in PBMC. Treatment with a combination of two NRTIs was associated with greater reductions in mtDNA than obtained for ZDV monotherapy. The relevance of these results in predicting treatment toxicity requires further evaluation.

Topics: Analysis of Variance; Anti-HIV Agents; Didanosine; DNA, Mitochondrial; Drug Combinations; HIV Infections; Humans; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; Self-Sustained Sequence Replication; Sensitivity and Specificity; Zalcitabine; Zidovudine

Topics: Adult; Child; Diagnosis, Differential; Didanosine; DNA, Mitochondrial; Female; HIV Seropositivity; Humans; Medicine, African Traditional; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; Reye Syndrome; Rwanda; Stavudine

Nucleoside analogues may induce mitochondrial toxicity, particularly didanosine. Ribavirin increases didanosine exposure, which might be clinically relevant when coadministered in HIV/HCV-coinfected patients.. To evaluate, among 89 patients receiving highly active antiretroviral therapy (HAART) and therapy for chronic hepatitis C, clinically relevant mitochondrial toxicity in those treated with concomitant ribavirin and didanosine (n=35, 39%).. From January 2000 to July 2002 longitudinal analysis of the incidence and clinical course of didanosine-related hyperamylasaemia, pancreatitis, hyperlactataemia/lactic acidosis or neuropathy. Risk factors were evaluated using univariate and multivariate Cox's proportional hazards model.. Among 35 patients who received concomitant didanosine (400 mg/day in 86%) and ribavirin (> or = 10 mg/kg/day in 91%), 20 (57%) developed one or more adverse events after a mean of 87 days. Most frequent laboratory abnormalities were hyperamylasaemia (18 patients, 51%) and hyperlactataemia (eight patients, 23%). Acute pancreatitis and symptomatic hyperlactataemia developed in 10 (28%) and six (17%) patients, respectively. Two patients (6%) with pancreatitis and severe lactic acidosis died; the other patients recovered uneventfully despite continuation of anti-HCV therapy in 83% after didanosine withdrawal in 40%. In the Cox's model higher baseline amylase levels (HR: 1.04, 95% CI: 1.02-1.06, P=0.001) and three nucleoside reverse transcriptase inhibitor-based HAART (HR: 5.3, 95% CI: 1.73-16.24, P=0.003) were significantly associated to toxicity.. The coadministration of didanosine and ribavirin should be avoided in HIV/HCV-coinfected patients, due to a high rate of clinically significant toxicity, particularly in triple nucleoside-based HAART. Amylase levels should be strictly monitored, especially if elevated at baseline.

Topics: Adult; Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Antiviral Agents; Didanosine; Female; Hepatitis C; HIV Infections; Humans; Incidence; Male; Middle Aged; Mitochondria; Mitochondrial Diseases; Proportional Hazards Models; Ribavirin

During 27 months treatment with 400 mg didanosine and 80 mg stavudine daily but no protease inhibitor therapy, a 50-y-old HIV-positive woman gradually lost 13 kg in weight, her arms, legs and buttocks decreased in volume and she experienced fatigue and polyneuropathy. Laboratory tests showed slight increases in plasma lactate and liver enzyme levels. Eighteen months after withdrawal of antiretroviral drug, the patient was free of fatigue and polyneuropathy and had regained 7 kg in weight as well as most of the volume of her arms, legs and buttocks.

Topics: Anti-HIV Agents; Antiretroviral Therapy, Highly Active; Didanosine; Female; HIV Infections; Humans; Middle Aged; Mitochondrial Diseases; Reverse Transcriptase Inhibitors; Stavudine