Lack of association between plasma levels of non-nucleoside reverse transcriptase inhibitors & virological outcomes during rifampicin co-administration in HIV-infected TB patients.

Background & objectives: Among patients with HIV-associated tuberculosis (TB), reduced plasma non-nucleoside reverse transcriptase inhibitors (NNRTI) concentrations during rifampicin (RMP) co-administration could lead to HIV treatment failure. This study was undertaken to examine the association between plasma nevirapine (NVP) and efavirenz (EFV) concentrations and virological outcomes in patients infected with HIV-1 and TB. Methods: This was a nested study undertaken in a clinical trial of patients with HIV-1 and TB, randomized to two different once-daily antiretroviral treatment (ART) regimens along with anti-TB treatment (ATT). Trough concentrations of plasma NVP and EFV were estimated at months 1 (during ATT and ART) and 6 months (ART only) by HPLC. Plasma HIV-1 RNA level >400 copies/ml or death within 6 months of ART were considered as unfavourable outcomes. Genotyping of CYP2B6 516G>T polymorphism was performed. Results: Twenty nine per cent of patients in NVP arm had an unfavourable outcome at 6 months compared to 9 per cent in EFV arm (P<0.08). The mean NVP and EFV levels estimated at 1 and 6 months did not significantly differ between favourable and unfavourable responders. Logistic regression analysis showed CYP2B6 516G>T polymorphism significantly associated with virologic outcome in patients receiving EFV–based regimen. Interpretation & conclusions: Trough plasma concentrations of NVP and EFV did not show any association with response to ART in patients on ATT and once-daily ART. CYP2B6 516G>T polymorphism was associated with virologic outcome among patients on EFV.

Emergence of drug resistant mutations after single dose nevirapine exposure in HIV-1 infected pregnant women in south India.

Background & objectives: Resistance to nevirapine (NVP) has been described with single dose preventive regimens in other populations. Our aim was to study the pattern and prevalence of HIV drug resistance (DR) at baseline (during pregnancy) and after delivery among antenatal women exposed to single dose NVP for prevention of parent to child transmission (PPTCT). Methods: HIV-infected, ART-naive primigravidae between 18-25 years of age, attending government antenatal clinics in Chennai, Vellore or Madurai were recruited. Drug resistance testing was carried out during pregnancy and after Sd-NVP treatment (one month after delivery) by Viroseq sequencing. HIV-1 testing by DNA PCR was done in newborns at 30 days. Results: Thirty one women were enrolled but only twenty six plasma specimens were analyzable (24 paired and two postnatal only). No major mutations were observed in any drug class at baseline though many polymorphisms were observed in both the reverse transcriptase and protease genes. Mutations to non-nucleoside reverse transcriptase inhibitors (NNRTI) were observed post-delivery in 33 per cent of women who were treated with Sd-NVP. None of the infants were HIV-positive. Interpretation & conclusions: Among pregnant ART-naïve women, baseline HIV drug resistance was not observed. A high rate of development of NNRTI class resistance among women treated with single-dose NVP was observed. Our results emphasize the need to implement more effective PPTCT regimens, minimizing emergence of drug resistance and thereby preserving long-term treatment options for HIV-infected women in India.