Tenofovir (TDF) is part of the WHO recommended first-line antiretroviral therapy (ART); however, there are limited data comparing TDF to other nucleoside reverse transcriptase inhibitors in resource-limited-settings. Using a routine workplace and community-based ART cohort in South Africa, we assessed single drug substitution, HIV RNA suppression, CD4 count increase, loss-from-care, and mortality between TDF, stavudine (d4T) 30 mg dose, and zidovudine (AZT).In a prospective cohort study we included ART naïve patients aged ≥17 years-old who initiated ART containing TDF, d4T, or AZT between 2007 and 2009. For analysis of single drug substitutions we used a competing-risks time-to-event analysis; for loss-from-care, mixed-effect Poisson modeling; for HIV RNA suppression, competing-risks logistic regression; for CD4 count slope, mixed-effects linear regression; and for mortality, proportional hazards modeling.Of 6,196 patients, the initial drug was TDF for 665 (11%), d4T for 4,179 (68%), and AZT for 1,352 (22%). During the first 6 months of ART, the adjusted hazard ratio for a single drug substitution was 2.3 for d4T (95% confidence interval [CI]: 0.27, 19) and 5.2 for AZT (95% CI: 1.1, 23), compared to TDF; whereas, after 6 months, it was 10 (95% CI: 5.8, 18) and 4.4 (95% CI: 2.5, 7.8) for d4T and AZT, respectively. Virologic suppression was similar by agent; however, CD4 count rise was lowest for AZT. The adjusted hazard ratio for loss-from-care, when compared to TDF, was 1.5 (95% CI: 1.1, 1.9) for d4T and 1.2 (95% CI: 1.1, 1.4) for AZT. The adjusted hazard ratio for mortality, when compared to TDF, was 2.7 (95% CI: 2.0, 3.5) and 1.4 (95% CI: 1.3, 1.5) and for d4T and AZT, respectively.In routine care, TDF appeared to perform better than either d4T or AZT, most notably with less drug substitution and mortality than for either other agent.

Among 30 human immunodeficiency virus type 1 (HIV-1)-infected women who received single-dose nevirapine (NVP), 17 (57%) had NVP-resistant HIV-1 detected in breast milk. NVP resistance in breast milk persisted for at least 8 months postpartum and was apparently transmitted to at least 1 infant. NVP resistance was detected less often in women who also received zidovudine.

Objective.

 Nevirapine is metabolized by cytochrome P450 (CYP) 2B6 and CYP3A4, We characterized relationships between clinical parameters, human genetics, pharmacokinetics, and HIV-1 drug resistance mutations in pregnant women following single-dose intrapartum nevirapine.Methods. In AIDS Clinical Trials Group study A5207, women received nevirapine at onset of labor, and were randomized to lamivudine/zidovudine, emtricitabine/tenofovir, or lopinavir/ritonavir, for 7 or 21 days. Plasma nevirapine was quantified at post-partum day 1 and weeks 1, 3 and 5. We assayed 214 polymorphisms in CYP2B6 and other genes and evaluated associations with pharmacokinetic parameters included elimination constant, time to protein-adjusted 50% inhibitory concentration (IC50), and week 5 nevirapine below quantification limit.

Results.

 Among 301 women with evaluable pharmacokinetic and genotype data, lower body mass index and randomization to lopinavir/ritonavir were associated with more rapid nevirapine elimination. Among those of African ancestry, longer time to IC50 was associated with CYP2B6 983T→C (p=0.004) but not with CYP2B6 516G→T (p=0.8). Among Indians, slower nevirapine elimination was associated with CYP2B6 516G→T (p=0.04). Emergent resistance was infrequent and not associated with pharmacokinetics or CYP2B6 genotype.

Conclusions.

 Effects on plasma drug exposure following single-dose nevirapine may be greater for CYP2B6 983T→C than 516G→T, and are less pronounced than at steady state.

Although muscle diseases are relatively rare, several treatable myopathies must be recognized by the clinician to maximize the possibility of restoring strength in affected patients. The inflammatory myopathies, including polymyositis, dermatomyositis, inflammatory necrotizing myopathy, and myositis in association with mixed connective tissue disease, typically respond well to immunosuppressive treatment. Inclusion body myositis, a myopathy that has features of both inflammation and primary degeneration, may not be treatable at this time, but treatments are actively being sought. Muscle dysfunction caused by toxins must also be recognized because removal of the offending toxin usually results in restoration of normal muscle function. Important muscle toxins include cholesterol-lowering medications, colchicine, zidovudine, corticosteroids, emetine, and ethanol.

The nucleoside reverse transcriptase inhibitor zidovudine (3'-azido-3'-dexoythymidine, AZT) can be incorporated into DNA and cause DNA damage. Previously, we determined that the human hepatocellular carcinoma HepG2 cells are more susceptible to AZT-induced toxicities than the immortalized normal human liver THLE2 cells and the nucleotide excision repair (NER) pathway plays an essential role in the response to AZT-induced DNA damage. We have now investigated if the effects of AZT treatment on the expression levels of genes related to DNA damage and repair pathways contribute to the differences in sensitivity to AZT treatment between HepG2 cells and THLE2 cells. Of total 84 genes related to DNA damage and repair, two, five, and six genes were up-regulated more than 1.5-fold at 50, 500, and 2,500 µM AZT groups compared with that of control THLE2 cells. Seven genes showed a decreased expression of more than 1.5-fold following the 2,500 µM AZT treatment. Two-sided multivariate analysis of variance indicated that the change in expression of genes involved in apoptosis, cell cycle, and DNA repair pathways was significant only at 2,500 µM AZT. Statistically significant dose-related increases were identified in XPC gene expression and GTF2H1 protein level after the AZT treatments, which implicated the NER pathway in response to the DNA damage induced by AZT. In contrast, AZT treatment did not alter significantly the expression of the APE1 gene or the levels of APE1 protein. These results indicate that the NER repair pathway is involved in AZT-induced DNA damage response in immortalized human hepatic THLE2 cells.

OBJECTIVES:

We evaluated the emergence of drug resistance in patients failing first-line regimens containing one nonnucleoside reverse transcriptase inhibitor (NNRTI) administered with zidovudine (ZDV) + lamivudine (the ZDV group) or non-thymidine analogues (non-TAs) (tenofovir or abacavir, + lamivudine or emtricitabine; the non-TA group).

METHODS:

Three hundred HIV-1-infected patients failing a first-line NNRTI-containing regimen (nevirapine, n = 148; efavirenz, n = 152) were included in the analysis. Virological failure was defined as viraemia ≥ 400 HIV-1 RNA copies/mL for the first time at least 6 months after starting the NNRTI-based regimen. For each patient, a genotypic resistance test at failure was available. The presence of drug-resistance mutations in HIV-1 reverse transcriptase was evaluated by comparing patients treated with NNRTI + zidovudine + lamivudine vs. those treated with NNRTI + non-TA.

RESULTS:

A total of 208 patients were failing with NNRTI + zidovudine + lamivudine and 92 with NNRTI + non-TA. No significant differences were observed between the non-TA group and the ZDV group regarding the time of virological failure [median (interquartile range): 12 (8-25) vs. 13 (9-32) months, respectively; P = 0.119] and viraemia [median (interquartile range): 4.0 (3.2-4.9) vs. 4.0 (3.3-4.7) log10 copies/mL, respectively; P = 0.894]. Resistance to reverse transcriptase inhibitors (RTIs) occurred at a significant lower frequency in the non-TA group than in the ZDV group (54.3 vs. 75.5%, respectively; P = 0.001). This difference was mainly attributable to a significantly lower prevalence of NNRTI resistance (54.3 vs. 74.0%, respectively; P = 0.002) and of the nucleoside reverse transcriptase inhibitor (NRTI) mutation M184V (23.9 vs. 63.5%, respectively; P < 0.001) in the non-TA group compared with the ZDV group. As expected, the mutation K65R was found only in the non-TA group (18.5%; P < 0.001).

CONCLUSIONS:

At first-line regimen failure, a lower prevalence of RTI resistance was found in patients treated with NNRTI + non-TA compared with those treated with NNRTI + zidovudine + lamivudine. These results confirm that the choice of backbone may influence the prevalence of drug resistance at virological failure.

OBJECTIVES:

: Zidovudine (AZT) is recommended for first-line antiretroviral therapy (ART) in resource limited settings. AZT may, however, lead to anemia and impaired immunological response. We compared CD4 counts over 5 years between patients starting ART with and without AZT in Southern Africa.

DESIGN:

: Cohort study.

METHODS::

Patients aged ≥16 years who started first-line ART in South Africa, Botswana, Zambia or Lesotho were included. We used linear mixed-effect models to compare CD4 cell count trajectories between patients on AZT-containing regimens and patients on other regimens, censoring follow-up at first treatment change. Impaired immunological recovery, defined as a CD4 count below 100 cells/μl at 1 year, was assessed in logistic regression. Analyses were adjusted for baseline CD4 count and haemoglobin level, age, gender, type of regimen, viral load monitoring and calendar year.

RESULTS::

72 597 patients starting ART, including 19 758 (27.2%) on AZT, were analysed. Patients on AZT had higher CD4 cell counts (150 vs.128 cells/μl) and haemoglobin level (12.0 vs. 11.0 g/dl) at baseline, and were less likely to be female than those on other regimens. Adjusted differences in CD4 counts between regimens containing and not containing AZT were -16 cells/μl (95% CI -18 to -14) at 1 year and -56 cells/μl (95% CI -59 to -52) at 5 years. Impaired immunological recovery was more likely with AZT compared to other regimens (odds ratio 1.40, 95% CI 1.22-1.61).

CONCLUSIONS::

In Southern Africa AZT is associated with inferior immunological recovery compared to other backbones. Replacing AZT with another NRTI could avoid unnecessary switches to second-line ART.

A 46 years old HIV reactive patient developed Stevens Johnson syndrome (SJS) probably due to nevirapine and/or co-trimoxazole. Patient was on zidovudine + lamivudine + nevirapine along with Co-trimoxazole since last two months. After 15 days, zidovudine was replaced with stavudine due to development of anemia. All these drugs were stopped after development of reaction. Temporal association was found between stavudine, lamivudine, nevirapine, cotrimoxazole and development of the reaction. Nevirapine and Co-trimoxazole were suspected to cause this reaction most probably due to associated hepatotoxicity and their common potential to cause SJS. In our case, patient died despite stopping of all medications.

This study aimed to test the hypothesis that the paediatric fixed-dose combination granule for reconstitution (comprising lamivudine/zidovudine/nevirapine 30/60/50 mg per 5 ml) as a test product is bioequivalent to the coadministered single entities of the referenced products. Fixed-dose combination anti-retroviral therapy provides adequate suppression of HIV-1 replication, provides barrier to the development of resistance, simplifies dosage regimen and improves adherence.An open label, randomized, two-way crossover study was conducted on 24 health adults under fasted conditions, with a washout period of 14 days between treatments. A total of 15 blood samples were collected before dosing and up to 96 h post dosing. The drugs were extracted from plasma and anlaysed using a validated high performance liquid chromatography- ultraviolet method. Non- compartmental pharmacokinetic (PK) analysis was performed to obtain the PK parameters, maximum plasma concentration (C max), area under the curve of plasma concentration-time curves from the time zero to last measurable concentration (AUC0-t) and the area under the curve extrapolated to infinity (AUC 0-∞) ANOVA test was performed to determine the effect of model factors on the PK parameters. The two one-sided t-tests were performed on the log-transformed data to determine the 90% CL for the ratio of test to reference PK parameters.The drugs were well tolerated and safe with minimal adverse events. The ANOVA test indicated the absence of any significant effects ( P>0.05) due to the model parameters. The 90% Cl for the geometric mean ratio of the test/reference for the Cmax, AUC0-t and the AUC0-∞ for lamivudine, zidovudine and nevirapine were within 80-125% bioequivalence limits.This single dose randomized study found that the test and reference products met the criteria for bioequivalence in the fasting healthy adult volunteers.