Brain mitochondrial injury in human immunodeficiency virus-seropositive (HIV+) individuals taking nucleoside reverse transcriptase inhibitors

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.

When Do Children Convert from Liquid Antiretroviral to Solid Formulations?

BACKGROUND

Liquid formulations are usually regarded as the gold standard in paediatric formulation; but sometimes, liquid formulations have stability and taste problems as well as being inconvenient for travelling. Therefore, for the management of long-term illness, some older children, parents and clinicians would prefer to use solid formulations. However, there is a lack of studies to investigate the age at which children are converted from liquid to solid formulations.

OBJECTIVES

(1) To investigate the age range at which children convert from liquid antiretroviral drug formulations to solid formulations, the formulations are abacavir, didanosine, lamivudine, stavudine, and zidovudine. (2) To calculate how long children stay on each of five UK liquid formulations (retention time) and factors affecting the retention times of the above liquid formulations.

METHOD

This was a retrospective medical records survey at Great Ormond Street Hospital for Children, London, United Kingdom. Patients' treatment details were entered into SPSS for Windows v. 11.0 and the retention times for the above liquid formulations were calculated i.e., from initiation of the liquid treatment to conversion to solid preparation. The retention times of different preparations were then compared using Cox regression analysis.

RESULTS

A total of 92 patients are included in the analysis. The overall average age at conversion was 7.3 years (95% CI 6.3-8.2). Patients on stavudine were more likely to switch to the corresponding solid dose form than the other four medicines (P < 0.001); more than 50% of patients on stavudine switched to solid formulation after nine months of treatment, however, less than 25% of patients on other formulations switched during the same period.

CONCLUSION

Children taking antiretroviral liquid preparations change to solid dose forms at approximately seven years of age. However, for stavudine, children are more likely to take the solid form at an earlier age.

Pharmacokinetics of nevirapine in HIV-infected children receiving an adult fixed-dose combination of stavudine, lamivudine and nevirapine

OBJECTIVE

To evaluate the steady state pharmacokinetics of nevirapine (NVP) in HIV-infected children receiving a fixed-dose combination of stavudine, lamivudine and NVP.

METHODS

This cross-sectional study enrolled 34 children (18 girls) who had received GPO-VIR S30 (30 mg stavudine, 150 mg lamivudine and 200 mg NVP) for at least 8 weeks. Tablets were divided into quarter fractions (1/4, 1/2, 3/4 or 1 tablet) to attain the NVP dosages of 120-200 mg/m every 12 h. Plasma NVP levels were measured at predose, and at 2 and 6 h after drug administration.

RESULTS

The median age was 8.4 years (range, 3-15). Median CD4 lymphocyte count and percentage at study entry was 576 x 10 cells/l and 20.25%, respectively. The median pharmacokinetics parameters were area under the curve at 12 h, 78.4 h x mug/ml; minimum plasma drug concentration, 5.98 microg/ml; plasma half-life, 25.5 h; apparent oral clearance, 0.079 l/kg per h; and volume of distribution, 2.95 l/kg. Only one child had a minimum plasma drug concentration < 3.4 microg/ml (2.57 microg/ml). Of the 13 children who received GPO-VIR as their first-line regimen, 12 had plasma HIV-1 RNA < 400 copies/ml at 6-18 months, with a median CD4 lymphocyte increase of 216 and 433 x 10 cells/l at 6 and 12 months of treatment, respectively.

CONCLUSIONS

The administration of GPO-VIR S30 fixed-dose combination tablets in fractions or as a whole tablet to children resulted in appropriate NVP exposure and satisfactory virological and immunological benefit. This finding confirms the effectiveness of using a fixed-dose combination as a "transitional option" while waiting for a paediatric fixed-dose combination drug formulation.

[Ester derivatives of nucleoside inhibitors of reverse transcriptase: II. Molecular systems for combined therapy with 3'-azido-3'-deoxythymidine and 2',3'-didehydro-3'-deoxythymidine]

The methods of synthesis of conjugates of anti-HIV nucleosides with various compounds, such as protease inhibitors, peptides, polysaccharides, and bicyclames, are considered; they are designated for the combined therapy of HIV.

Management of HIV-1 Infection With a Combination of Nevirapine, Stavudine, and Lamivudine

OBJECTIVE

To evaluate treatment outcome in the first 12 months among HIV-positive patients managed with a combination of nevirapine + stavudine + lamivudine under the current national antiretroviral (ARV) program in Nigeria.

DESIGN

This was a prospective observational, cohort study on 50 ARV-naive patients who met the inclusion criteria for the program and had given informed consent. All patients were in stage 2 or stage 3 periods of infection based on World Health Organization clinical classification. The patients were treated with the generic brands of ARVs and treatment consisted of oral nevirapine (Nevimal, Cipla, Mumbai, India), 200 mg daily, lamivudine (Lamivir, Cipla), 150 mg twice daily, and stavudine (Stavir, Cipla), 40 mg twice daily. Prior to initiation of treatment, the clinical history and baseline data for each patient were documented. The levels of plasma HIV-1 RNA, CD4 cell counts, frequency of opportunistic infections, and estimated body mass index were recorded at baseline and subsequently at intervals during treatment. Data obtained at the various sampling times for each parameter were compared against their baseline values.

RESULTS

Data on the plasma HIV-1 RNA levels indicated that between baseline and week 24, the median viral load of the patients decreased by 1.79 log(10) copies/mL. Equally between baseline and week 48 the median CD4 cell counts increased by 186 x 10(6) cells/L, the frequency of opportunistic infections decreased by 82%, the median body mass index increased by 4.8 kg/m(2), and 36% experienced side effects, which were minor and transient. The most prevalent side effect recorded was skin rash associated with nevirapine. Good adherence to this triple regimen was recorded in >85% of the patients.

CONCLUSIONS

The overall results within the 12-month treatment period indicated an effective suppression of viral replication, the reconstitution of the immune system, and improvement of the physical well-being of the study population. Though there may be differences in global distribution of the infecting HIV-1 subtypes, the clinical and biologic results of this study compared favorably to those documented in cohorts treated with branded and generic ARV drugs in some developed and developing countries. The cumulative data in this study further confirmed that the correct use of generic brands of ARVs is a feasible option in HIV care and support programs in resource-poor countries.

Three-year durability of dual-nucleoside versus triple-nucleoside therapy in a Thai population with HIV infection

We compared the long-term immunologic and virologic efficacy of the dual- and triple-nucleoside therapy for HIV infection. This was a retrospective analysis of 2 randomized clinical trials in antiretroviral-naive patients. In the dual-nucleoside group, 15 started with didanosine (ddI) monotherapy and then added stavudine (d4T) after 24 weeks, 63 started with various doses of d4T and ddI, and 53 started with zidovudine (ZDV) and lamivudine (3TC). In the triple-nucleoside group, 53 started with ZDV, 3TC, and ddI. After 48 weeks, patients who were not failing were randomized to immediate (before treatment failure) versus delayed (at the time of virologic failure) switching from ddI and d4T to ZDV and 3TC or vice versa and from ZDV, 3TC, and ddI to d4T, 3TC, and abacavir (ABC). Failure was defined as a plasma HIV-1 RNA level>or=1 log10 above nadir or >or=10,000 copies/mL when nadir was <500 copies/mL. Patients failing therapy before week 48 received the new treatment as in the immediate switching group. Hydroxyurea was added to the last treatment regimen if patients failed after week 96. CD4 count and plasma HIV-1 RNA level (branched DNA assay with a cutoff point of 50 copies/mL) at week 144 were analyzed by intention to treat. Compared with the dual-nucleoside group, the triple-nucleoside group had a higher proportion of patients with <50 copies/mL at 144 weeks (60% vs. 18%; P<0.001), higher median CD4 count (388 cells/microL vs. 346 cells/microL; P=0.018), and longer duration of response, defined as the time from onset of viral suppression (<500 copies/mL) to the time of treatment failure (the first of 2 consecutive HIV-1 RNA measurements >500 copies/mL never followed by 2 consecutive visits showing suppressible viremia to <500 copies/mL) or discontinuation from the study (144 weeks vs. 104 weeks; P=0.002). Multivariate regression analyses showed that significant predictors for treatment success, defined as a plasma viral load <50 copies/mL at week 144, were asymptomatic clinical status at enrollment, a baseline plasma viral load <or=30,000 copies/mL, treatment with triple nucleosides, and a viral load response of <500 copies/mL by week 12. Triple-nucleoside therapy with ZDV, 3TC, and ddI or d4T, 3TC, and ABC in patients with HIV infection is more effective in inducing a sustained virologic response than the dual combinations of ZDV and 3TC or ddI and d4T.

HIV leucoencephalopathy and TNFalpha expression in neurones

BACKGROUND

Human immunodeficiency virus (HIV) leucoencephalopathy (HIVL) is an uncommon and rapidly progressive form of AIDS dementia complex (ADC) that has remained poorly understood. Tumour necrosis factor alpha (TNFalpha), which has been implicated in the pathogenesis of ADC, is predominantly localised in macrophages in the HIV infected brain, although in vitro studies indicate that neurones can express this cytokine.

OBJECTIVE

To examine the clinical/neuroradiological features of HIVL and the expression of TNFalpha in HIVL.

METHODS

Six patients who presented with rapidly progressive dementia within four to 12 weeks of the primary manifestation of their HIV infection were evaluated. Clinical history, treatment regimens, and imaging studies were reviewed, and brain samples from three of the patients were studied by means of immunohistochemistry.

RESULTS

Imaging studies showed diffuse bilateral deep white matter changes in all six patients. Clinical and imaging abnormalities improved in five of the six patients within weeks after initiation of antiretroviral treatment. Brain biopsies of two showed pronounced microglia/macrophage activation, but only scant viral protein (gp41) expression. Staining for TNFalpha was found in microglia/macrophages, and surprisingly, in neurones also. Postmortem analysis of a third patient also showed TNFalpha expression in neurones of the frontal cortex and basal ganglia.

CONCLUSION

This study provides the first demonstration of staining for TNFalpha in the neurones of the HIV infected brain, and suggests that the process underlying this rapidly progressive form of ADC may reflect indirect mechanisms mediated by host factors, particularly TNFalpha.

Microdialysis evaluation of the brain distribution of stavudine following intranasal and intravenous administration to rats

Intranasal (IN) administration as a potential route of enhancing brain delivery of stavudine (d4T) was investigated in rats using microdialysis as a sampling technique. Sprague-Dawley rats were divided into two groups (n = 7 per group). One group of animals received IN administration of 5 mg/kg d4T (50 microL); the other group was dosed intravenously (IV) at the same dose. Following IN administration, d4T was rapidly and completely absorbed into the systemic circulation with a T(max) of 14 min and an IN bioavailability of 105%. The brain/plasma AUC ratios in the lateral ventricle, caudate putamen, and frontal cortex in the anesthetized and nasal surgery-operated rats were 0.36 +/- 0.090, 0.47 +/- 0.089, and 0.41 +/- 0.087, respectively, whereas they were 0.63 +/- 0.077, 0.62 +/- 0.17, 0.60 +/- 0.13, respectively, following IV dosing to sham animals. The half-life of d4T in the various brain regions was significantly longer than that in plasma (p < 0.05). Moreover, the systemic clearance of d4T was significantly reduced in these anesthetized and nasal surgery-operated animals. Further studies of the effect of anesthesia suggest the additive role of anesthesia, possibly in additional to nasal surgery, in decreasing the systemic clearance. The extent of the brain distribution, however, was not significantly affected by anesthesia. Lack of enhancement of the brain delivery of d4T following IN administration over systemic dosing cannot be attributed to its absorption into systemic circulation, since direct nose-brain transport, if fully functional and effective, should be a parallel and competing process with systemic absorption. The current study results along with several physiological considerations raise a question regarding the overall effectiveness of IN administration for direct delivery of small molecules into brain tissues, particularly where passive diffusion predominates.

Better maintained adherence on switching from twice-daily to once-daily therapy for HIV: a 24-week randomized trial of treatment simplification using stavudine prolonged-release capsules

BACKGROUND

Adherence to antiretroviral therapy is critical to treatment outcomes. Adherence studies in other therapeutic areas of medicine suggest that once-daily regimens support improved adherence when compared to twice-daily therapy. An expansion in the range of once-daily antiretrovirals is making once-daily therapy possible for persons with HIV infection.

METHODS

A 24-week randomized open-label simplification study of twice-daily regimens based on stavudine immediate release or zidovudine to an all once-daily regimen based on the stavudine prolonged-release capsule (PRC), in persons with complete virological suppression on regimens also including efavirenz and lamivudine, was carried out. Subjects were assessed for adherence [using the Medication Event Monitoring System (MEMS) cap; Aardex Corporation, Union City, CA, USA], quality of life, tolerability and efficacy.

RESULTS

Forty-three patients were randomly assigned: 21 remained on their original regimen and 22 switched to once-daily therapy with stavudine PRC. Although high levels of adherence and good quality of life were present at study enrollment, adherence declined to a significantly lesser extent at week 24 in the group that switched to once-daily therapy. Efficacy was maintained in both groups and there were no differences in tolerability or toxicity.

CONCLUSIONS

Subjects switching from twice-daily therapy to once-daily therapy demonstrate less of a decline in adherence over 24 weeks. A once-daily regimen including stavudine PRC is as effective and tolerable as a regimen containing the twice-daily formulation.

Aplastic anemia in an HIV infected child

Hematologic manifestations of HIV in children are common and include anemia, neutropenia, lymphocytopenia, thrombocytopenia that may occur due to many reasons. However, aplastic anemia due to HIV infection is rare and even more so in children. Though anemia is seen with advanced disease and associated with poor prognosis it is treated with various therapeutic modalities. Our patient with aplastic anemia due to HIV infection responded to antiretroviral therapy.

Lowering the dose of hydroxyurea minimizes toxicity and maximizes anti-HIV potency

The goal of this study was to optimize the hydroxyurea dosage in HIV-infected patients, and to minimize the toxicity and maximize the antiviral efficacy of the hydroxyurea-didanosine combination. In a randomized, open-label study (RIGHT 702, a multicenter trial performed in private and institutional practices), three daily doses (600 microg, 800-900 microg, and 1200 microg) of hydroxyurea were administered in combination with didanosine and stavudine to 115 chronically HIV-infected patients, one-third antiretroviral drug naive, with viremia between 5000 and 200,000 copies/ml regardless of CD4+ cell count. The primary efficacy end point was the proportion of patients with plasma HIV-1 RNA levels below 400 copies/ml after 24 weeks of therapy. In the RIGHT 702 intent-to-treat population the lowest (600 mg) dose of hydroxyurea was better tolerated, associated with fewer adverse events, and more potent by all efficacy parameters, including the primary end point (76 versus 60% patients with viremia<400 copies/ml at week 24 for the 600-mg and 800- to 900-mg dose groups, respectively; p=0.027), the mean area under the curve (60.3 versus 65.8; p=0.016), and the mean log10 decrease (-1.95 versus -0.77; p=0.001). Patients receiving 600 mg of hydroxyurea daily also had the highest CD4+ cell count, CD4+/CD8+ cell ratio, and lowest CD8+ cell count and percentage (p=0.035). The RIGHT 702 trial provides an explanation for the increased toxicity and decreased efficacy of hydroxyurea when it was used at high dosage (1200 mg daily). At the optimal dosage of 600 mg daily, hydroxyurea, in combination with didanosine, deserves reevaluation for the long-term management of HIV/AIDS worldwide, because of its excellent resistance profile, durability, and affordability.

Increased adipocyte apoptosis in lipoatrophy improves within 48 weeks of switching patient therapy from Stavudine to abacavir or zidovudine

OBJECTIVES

Lipoatrophy is an important manifestation of the lipodystrophy syndrome and is particularly associated with stavudine exposure. Increased apoptosis has been suggested as a possible mechanism of lipoatrophy. We assessed the degree and reversibility of adipocyte apoptosis in patients with lipoatrophy before and 48 weeks after substituting abacavir or zidovudine for stavudine.

METHODS

Apoptotic adipocytes were identified using terminal transferase dUTP nick end labeling and quantified using video image analysis.

RESULTS

Fat biopsy specimens were obtained from patients before (n = 15) and 48 weeks after (n = 10) switching from stavudine and from 20 HIV-uninfected controls. More apoptotic cells were seen in fat samples from patients with lipoatrophy treated with stavudine than in specimens from controls (P < 0.0001). Forty-eight weeks after switching from stavudine to abacavir or zidovudine, there was a reduction in apoptotic cells per unit area (P = 0.01) and as a proportion of all adipocytes present (P = 0.02) in patient biopsy specimens. Levels of adipocyte apoptosis in the 48-week biopsy specimens were no longer significantly different from those seen in control biopsy specimens (P > 0.1).

CONCLUSIONS

Increased apoptosis is present in fat samples from patients with lipoatrophy treated with stavudine. This improves toward normal within 48 weeks of switching from stavudine to abacavir or zidovudine, suggesting a causative role for stavudine in this process.

Gender differences in health-related quality of life in patients with HIV/AIDS

BACKGROUND

In studies evaluating the general US population, patients in primary care, and patients with chronic conditions, women consistently report poorer health-related quality of life (HRQoL) than men; however, studies evaluating HRQoL in patients with HIV/AIDS have not completely corroborated those findings. The objective of this study was to evaluate gender differences in HRQoL for participants in a large randomized trial comparing antiretroviral regimens.

METHODS

AIDS Clinical Trials Group (ACTG) 320 was a randomized, blinded, placebo-controlled trial comparing the 3-drug regimen of indinavir + zidovudine (or stavudine) + lamivudine with the 2-drug combination of zidovudine (or stavudine) + lamivudine in subjects with CD4 cell counts less than 200 cells/microl and no prior treatment with protease inhibitors. Nine quality of life domains scored on 0-100 scales were assessed using the ACTG QOL 601-602 Health Survey at 3 points in the trial: baseline, 24 weeks and 40 weeks. Differences between men and women in HRQoL scores were assessed using the Wilcoxon rank-sum test and generalized estimating equation (GEE) models.

RESULTS

Overall, 202 females and 976 males were randomized to one of two treatment arms. Female participants were more likely to be black or Hispanic and tended to be younger. At baseline, females reported lower HRQoL scores than males in all of the domains except social functioning, and at week 40, women scored lower in all of the domains except overall health. In repeated measures models, women were found to score lower in all HRQoL domains except overall health, with significant differences of 3.5-6.7 points in 3 of the 9 quality of life domains: physical functioning, pain, and energy/fatigue. HRQoL scores improved for participants in the study over time and in response to potent treatment, and the improvements were similar for men and women.

CONCLUSIONS

Women with HIV/AIDS report substantially poorer HRQoL than men with HIV/AIDS in several HRQoL domains. However, changes in domain scores over time and in response to treatment do not differ significantly by gender, implying that changes in domain scores may be better HRQoL outcomes to compare between HIV-infected men and women in clinical trials than mean domain scores.

Impact of dyslipidemia associated with Highly Active Antiretroviral Therapy (HAART) on cardiovascular risk and life expectancy

We investigated the effect of dyslipidemia associated with highly active antiretroviral therapy on cardiovascular risk and life expectancy among patients who had the human immunodeficiency virus. Dyslipidemia estimates were based on results from a phase 2 randomized trial that compared lipid changes after 32 weeks of therapy with atazanavir with those with nelfinavir (each in combination with stavudine and lamivudine). The resultant increased coronary risk was estimated using Framingham risk equations, and change in life expectancy (after adjustment for mortality due to human immunodeficiency virus) was based on the cardiovascular life expectancy model, which is based on a published Markov's model. Levels of total cholesterol and low-density lipoprotein cholesterol increased significantly more among patients who used nelfinavir (+24% and +28%) than among those who used atazanavir (+4% and +1%). This dyslipidemia increased the risk of coronary disease by 50% over 10 years. The absence of dyslipidemia was estimated to preserve life expectancy 0.15 to 1.53 additional years depending on a patient's age, gender, and other risk factors. There are increasing reports of dyslipidemia and cardiovascular events associated with highly active antiretroviral therapy. Significant increases in blood lipid levels observed with some protease inhibitors are associated with an increase in calculated 10-year coronary risk. Accordingly, minimizing dyslipidemia associated with highly active antiretroviral therapy may preserve life expectancy among adults who have the human immunodeficiency virus.

Stavudine Entry into Cerebrospinal Fluid After Single and Multiple Doses in Patients Infected with Human Immunodeficiency Virus

STUDY OBJECTIVE

To establish the pharmacokinetics of stavudine within the cerebrospinal fluid (CSF) of patients infected with human immunodeficiency virus (HIV).

DESIGN

Pharmacokinetic study.

SETTING

General clinical research center.

PATIENTS

Thirty-six patients infected with HIV; 21 were receiving long-term stavudine therapy, 15 were not (single-dose treatment group).

INTERVENTION

After an overnight fast, all patients received a single dose of stavudine 40 mg. Fifteen patients in the long-term treatment group and all 15 patients in the single-dose treatment group were randomized to undergo lumbar puncture 2, 4, or 6 hours after dosing (five patients for each time point from each group). The six other patients in the long-term treatment group underwent lumbar puncture 0 or 8 hours after dosing.

MEASUREMENTS AND MAIN RESULTS

Serum stavudine concentrations were obtained just before dosing, 1 hour after dosing (approximate peak), and at the time of lumbar puncture. The CSF was also analyzed for cell counts, protein, and glucose levels. The mean peak serum stavudine concentration in the long-term treatment group was estimated to be 580.7 ng/ml (2.59 micromol/L), occurring approximately 1.3 hours after dosing. The CSF concentrations over 0-8 hours were 0.0-109.9 ng/ml (0.00-0.49 micromol/L) with an overall mean of 51.6 ng/ml (0.23 micromol/L). Mean peak CSF concentration was estimated to be 62.8 ng/ml (0.28 micromol/L), occurring 4.7 hours after dosing. For the 15 patients not taking stavudine, both the serum and the CSF estimated peaks were significantly lower than those of the long-term group: 475.3 ng/ml (2.12 micromol/L) and 40.4 ng/ml (0.18 micromol/L), respectively. However, time to peak was similar at 1.2 hours and 5.0 hours, respectively. In both groups, no correlation was found between CSF and baseline or peak serum stavudine concentrations, CSF white blood cell count, baseline CD4 + lymphocyte count, or plasma viral load.

CONCLUSION

Mean CSF stavudine concentrations equaled or exceeded the mean concentration producing 50% of the maximal effect in vivo (EC 50 ) for HIV. The CSF concentrations were higher in the stavudine-experienced patients, indicating that concentrations rise with progressive doses until steady state is reached.

Efficacy and safety of indinavir/ritonavir 400/100 mg twice daily plus two nucleoside analogues in treatment-naive HIV-1-infected patients with CD4+ T-cell counts <200 cells/mm3: 96-week outcomes

OBJECTIVE

To evaluate the efficacy and safety of indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily in antiretroviral-therapy-naive Thai HIV-1-infected patients.

METHODS

This was an open-label, non-randomized single arm study. Antiretroviral-naive patients (n=80) with CD4+ cell count < 200 x 10(6)/l were started on stavudine and lamivudine plus indinavir/ritonavir 400/100 mg twice daily. CD4+ cell count and HIV RNA were determined at week 0, 12, 24, 48 and 96. HIV RNA was measured to a level of 50 copies/ml by RT-PCR assay. Primary analysis was statistically performed as intent to treat. The primary endpoint was the percentage of patients with plasma HIV RNA below 50 copies/ml at week 96.

RESULT

Eighty antiretroviral-therapy-naive patients with median CD4+ cell count 19 x 10(6)/l (range: 2 - 197 x 10(6)/l) and median baseline plasma HIV RNA of 174,000 copies/ml (range 16,800-750,000 copies/ml) were enrolled. In the intent-to-treat analysis at week 96, the proportion of patients with HIV RNA of <50 copies/ml was 68.8% (95% confidence interval [CI]: 68.3-69.3), whereas it was 88.7% (95% CI: 88.1-89.3) in the on-treatment analysis at week 96. The regimen was well tolerated. Hyperglycaemia, hypercholesterolaemia and hypertriglyceridaemia were found in 8.3, 33.3 and 37.0% of the patients, respectively. Treatment was stopped in 18 patients; two from intolerance, two switched therapy, four as a result of serious adverse event-related death, and ten were lost to follow-up.

CONCLUSION

Our study demonstrates that indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily, the least expensive boosted protease inhibitor, appears to be effective and safe up to 96 weeks despite high baseline viraemia and low CD4+ cell count in antiretroviral-naive patients.

Nevirapine and efavirenz pharmacokinetics and covariate analysis in the 2NN study

OBJECTIVE

The aim of this 2NN pharmacokinetic substudy was to investigate the population pharmacokinetics of nevirapine and efavirenz.

METHODS

Treatment-naive, HIV-1-infected patients received nevirapine (once or twice daily), efavirenz or a combination with lamivudine and stavudine. Blood samples were collected on day 3 and weeks 1, 2, 4, 24 and 48. Using non-linear mixed effects modelling, pharmacokinetics of nevirapine and efavirenz and factors involved in the inter-individual variability were investigated.

RESULTS

Clearance of nevirapine in the induction phase (<14 days) and at steady state (>28 days) were 2.02 I/h and 2.81 I/h, respectively. Volume of distribution and absorption rate constant were 77.0 l and 1.66 h(-1), respectively. Clearance of nevirapine was lower in females (13.8%) and in patients with hepatitis B (19.5%). Patients from South America and Western countries had higher clearance of nevirapine compared with Thai and South African patients. The clearances of efavirenz in the induction phase and at steady state were 7.95 l/h and 8.82 l/h, respectively. The volume of distribution and absorption rate constant were 4181 and 0.287 h(-1), respectively. Concomitant use of nevirapine increased clearance of efavirenz (43%). Patients from Thailand had lower clearance than the rest of the population.

CONCLUSIONS

The population pharmacokinetics of nevirapine and efavirenz were assessed in the 2NN trial. For both drugs, an induction phase was distinguished from the steady-state phase. Gender, hepatitis B and geographical region were involved in the variability of the pharmacokinetics of nevirapine. Region and concomitantly used nevirapine were determinants of the pharmacokinetics of efavirenz.

Mitochondrial effects of a 24-week course of pegylated-interferon plus ribavirin in asymptomatic HCV/HIV co-infected patients on long-term treatment with didanosine, stavudine or both

BACKGROUND

It has been suggested that the addition of ribavirin (RBV) as a part of the treatment for chronic hepatitis C virus (HCV) in HIV co-infected patients on didanosine (ddI) or stavudine (d4T) might increase the nucleoside-induced impairment of mitochondrial function.

DESIGN

Comparative study to investigate the impact on mitochondrial function of adding RBV to a long-term treatment with ddI, d4T or both in HCV/HIV non-cirrhotic, asymptomatic patients. We included 26 patients: 16 continued with their current antiretroviral therapy (control group) and 10 patients received a concomitant 24-week course of RBV plus pegylated interferon (PEG-IFN) alpha-2b therapy (HCV-treated group).

METHODS

We assessed peripheral blood mononuclear cells mitochondrial DNA (mtDNA) content and mitochondrial respiratory chain (MRC) function at baseline and at 24 weeks of follow-up. In the HCV-treated group we performed additional determinations at 12 weeks during anti-HCV therapy and 24 weeks after finishing anti-HCV therapy.

RESULTS

Times on ddI or d4T exposure were 194 +/- 54.9 and 131 +/- 66.5 weeks in the HCV-treated and control groups, respectively. There were no differences either in mtDNA content, the enzyme activity of MRC complexes or clinical parameters at baseline. Throughout the study, mitochondrial measurements remained stable within groups and without differences when we compared HCV-treated and control groups.

CONCLUSIONS

In our study, the addition of RBV and PEG-IFN during a 24-week period in HCV/HIV non-cirrhotic, asymptomatic patients on long-term ddI, d4T or both had no impact on mitochondrial function. These findings could suggest that additional triggers are required to achieve a critical threshold in the degree of mitochondrial damage needed for symptoms to develop.

Short communication: benefits in the lipid profile after substitution of abacavir for Stavudine: a 48-week prospective study

Stavudine (d4T) has been associated with lipoatrophy and hyperlactatemia. In recent studies, d4T has also been related to both hypercholesterolemia and hypertriglyceridemia. Replacing d4T with another nucleoside analogue such as abacavir (ABC) may reduce lactate levels and improve lipoatrophy in the long term. However, the impact of this strategy on the lipid profile is still unclear. In a prospective and randomized study, fasting lipids were examined over 48 weeks in 112 subjects on d4T regimens, 49 of whom replaced d4T with ABC. The substitution of ABC for d4T was found to be safe and provided a reduction in both LDL cholesterol and the total cholesterol (TC)/HDLc ratio, which might impact favorably on cardiovascular risk.

Tenofovir: new indication. For first-line antiretroviral therapy: wait and see

(1) First-line antiretroviral combinations generally include, in addition to a protease inhibitor or a non nucleoside reverse transcriptase inhibitor, two nucleoside reverse transcriptase inhibitors, namely zidovudine + didanosine, stavudine + lamivudine, or zidovudine + lamivudine. (2) Tenofovir disoproxil (referred to simply as tenofovir below) is a nucleotide HIV reverse transcriptase inhibitor. Previously recommended for second-line treatment in case of virological failure, it is now approved for first-line therapy in adults. (3) This licence extension is based on a double-blind trial comparing tenofovir + lamivudine + efavirenz with stavudine + lamivudine + efavirenz in 602 patients. After 96 weeks, three-quarters of patients had undetectable viral load (<50 copies/ml), and there was no statistically significant difference among the groups. (4) The number of serious adverse effects was similar in the two groups. Relative to the stavudine combinations, there were fewer reports of lipodystrophy (1% versus 12%), fewer peripheral neuropathies (3% versus 10%) and fewer prescriptions of lipid-lowering therapy (2% versus 10%) among patients taking tenofovir. Tenofovir seemed to have a worse effect on renal function and bone metabolism, however. (5) Tenofovir is taken only once a day, but so are didanosine and lamivudine. (6) In practice, there is not yet enough evidence to support the routine use of tenofovir in first-line antiretroviral combinations. Tenofovir is, however, an interesting alternative when stavudine is poorly tolerated.

Effects of zidovudine, stavudine and beta-aminoisobutyric acid on lipid homeostasis in mice: possible role in human fat wasting

OBJECTIVE

Although mitochondrial DNA (mtDNA) depletion could play a role in nucleoside reverse transcriptase inhibitor-induced lipoatrophy, poor correlations between fat mtDNA levels and lipoatrophy suggest additional mechanism(s). Stavudine (d4T), zidovudine (AZT) and the thymine catabolite, beta-aminoisobutyric acid (BAIBA), but not zalcitabine (ddC) or didanosine (ddI), can increase fatty acid oxidation in liver mitochondria and plasma ketone bodies in mice. Since fat oxidation in non-adipose tissue can influence body adiposity, we sought to determine whether d4T, AZT and BAIBA can cause lipoatrophy in mice by this catabolic mechanism.

METHODS

Lean or obese ob/ob mice were treated for 6 weeks with d4T, AZT or BAIBA, and lean mice with ddC or ddI. Body fat mass was assessed by dual energy X-ray absorptiometry, and mtDNA by Slot blot hybridization in epididymal fat.

RESULTS

Whereas ddC or ddI did not change plasma beta-hydroxybutyrate and body fat mass, d4T, AZT and BAIBA increased plasma beta-hydroxybutyrate in lean mice suggesting increased hepatic fatty acid oxidation and ketogenesis. Despite unchanged food consumption, a supra-pharmacological dose of d4T tended to decrease, whilst AZT and BAIBA decreased body fat mass. Fat mtDNA and plasma triglycerides, cholesterol, glucose, insulin, leptin and adiponectin levels were unchanged. In obese mice, d4T, AZT and BAIBA did not increase plasma beta-hydroxybutyrate, and only AZT decreased body fat mass without reducing fat mtDNA.

CONCLUSIONS

d4T and AZT can enhance hepatic fat oxidation and cause fat wasting, without decreasing adipose tissue mtDNA and without causing insulin resistance in mice. BAIBA, a thymine catabolite, reproduces these effects. These catabolic effects could play a role in the lipoatrophy, which can occur in AZT- or d4T-treated patients.

Antiretroviral treatment. HIV infection in adults: better-defined first-line treatment

(1) There is still no cure for HIV infection. The short-term treatment aims are to drive viral load below the current detection limit and to increase the CD4+ T cell count, in order to reduce morbidity and prolong survival. (2) Early initiation of treatment has both advantages and disadvantages. If the patient is symptomatic or if the CD4+ T cell count is below 200 per mm3, antiretroviral treatment should be started immediately. If the patient is asymptomatic, the CD4+ T cell count is above 350 per mm3, and viral load is below 50 000 copies/ml, antiretroviral treatment can often be deferred. Other situations should be considered case by case. (3) The benefits of treating symptomatic primary infection have not been adequately documented, and current recommendations diverge. (4) The advent of new antiretroviral drugs has increased the choice, but cross-resistance often limits treatment options. The new antiretroviral family to have emerged since 1999 is the fusion inhibitor; the only representative of this class, enfuvirtide, is reserved for patients with multiple treatment failure. (5) There is broad agreement on the principles of first-line antiretroviral treatment. It should combine at least two nucleoside (or nucleotide) inhibitors of HIV reverse transcriptase and one non nucleoside inhibitor, or at least one HIV protease inhibitor. Comparative studies have now identified the most effective combinations in terms of virological efficacy and tolerability. The combination should be chosen according to its established efficacy, adverse effects, risks of interactions, and convenience. There is no reference combination suitable for all patients. Among the combinations containing a non nucleoside inhibitor, those based on efavirenz are the most effective after 48 weeks of follow-up. There is less agreement on the optimal treatment of pregnant women. (6) Among the HIV protease inhibitor-based combinations, those containing nelfinavir or the lopinavir + ritonavir combination must be taken during meals. The lopinavir + ritonavir combination showed better virological efficacy than nelfinavir in a comparative trial. Experience and safety evaluation are in favour of nelfinavir, but recent American guidelines issued in November 2003 recommend the lopinavir + ritonavir combination. (7) There is no major difference in virological efficacy between non nucleoside inhibitors and protease inhibitors as first line therapy. (8) In combination with protease inhibitors or non nucleoside inhibitors, the best-assessed nucleoside inhibitors (effective for several years) are lamivudine + zidovudine and lamivudine + stavudine. For first-line treatment, combinations consisting of only three nucleoside (or nucleotide) inhibitors are less effective than combinations containing HIV protease inhibitors or non nucleoside inhibitors. (9) Efficacy is monitored on the basis of changes in viral load and the CD4+ T cell count, one month after the beginning of treatment, then about every three months. Attention must be paid to adverse effects, which may necessitate the replacement of the causative antiviral drug, treatment of the adverse effect, treatment modification or, in extreme cases, treatment withdrawal. (10) Treatment failures must be carefully investigated: the cause(s) may include poor adherence, drug interactions, and inadequate plasma drug concentrations. Ongoing antiretroviral regimens do not always have to be modified if treatment failure occurs. (11) Resistance tests can help to determine the most effective alternative in case of virological failure due to drug resistance. The choice of back-up treatments is complex, and is limited by cross-resistance. Multiple lines of treatment fail in about 3% to 4% of patients.

HIV-1 drug resistance in subjects with advanced HIV-1 infection in whom antiretroviral combination therapy is failing: a substudy of AIDS Clinical Trials Group Protocol 388

We evaluated phenotypic and genotypic markers of drug resistance in human immunodeficiency virus type 1 (HIV-1) at the time of virologic failure (VF) in subjects in the AIDS Clinical Trials Group Protocol 388 (ACTG 388) who received lamivudine-zidovudine (or lamivudine-stavudine) and either indinavir, efavirenz-indinavir, or nelfinavir-indinavir. At VF, phenotypically susceptible HIV-1 was found in 55% of subjects in the nelfinavir-indinavir arm, compared with 22% in the indinavir arm (P=.006). Phenotypic resistance to lamivudine was less common in the efavirenz-indinavir arm (33% of subjects; P=.002) and the nelfinavir-indinavir arm (43%; P=.003), compared with the indinavir arm (78%). Isolated phenotypic resistance to efavirenz at VF occurred in HIV-1 recovered from 33% of subjects in the efavirenz-indinavir arm; 24% of the subjects had HIV-1 with both efavirenz and lamivudine resistance. Results of genotypic tests were similar. The lower frequency of resistance in the nelfinavir-indinavir arm likely reflects decreased drug exposure that is due to intolerance, which is consistent with the lower potency and tolerability of this combination in ACTG 388. The lower frequency of lamivudine resistance in the efavirenz-indinavir arm is consistent with reports in other studies of potent regimens. Thus, although dual resistance to efavirenz and lamivudine occurred at VF in the efavirenz-indinavir arm, this risk was relatively low when evaluated in the context of the potency and tolerability of this regimen.