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To determine nevirapine (NVP) plasma levels during the postpartum period after a single intrapartum NVP dose for the prevention of mother-to-child transmission.Plasma samples at delivery and during days 8 to 45 postpartum were obtained from HIV-infected Thai women who received an intrapartum NVP dose in the Perinatal HIV Prevention Clinical Trial-2 (PHPT-2) for the prevention of perinatal HIV transmission. These data were combined with NVP concentration data from 2 phase 1 studies of NVP for a population analysis.The median NVP level fell to 68 ng/mL (range:50-228, n = 43) 8 to 14 days after dosing and to 51 ng/mL (range:50-166, n = 25) between 15 and 21 days. During the second and third weeks postpartum, NVP levels were below the limit of quantitation in 23% and 44% of samples, respectively. Between 21 and 45 days, no sample had a quantifiable NVP concentration. A simulation derived from the population analysis predicts that NVP concentration falls to less than 10 ng/mL in 5% of women by 11 days, in 50% of women by 17.5 days, and in 95% of women by 28 days.Significant NVP concentrations remained for up to 20 days in these Thai women. To ensure that coverage is maintained until NVP concentrations fall to nonsuppressive levels, 1 month of additional antiretroviral treatment after delivery should be considered to prevent the emergence of resistant viruses.

Objectives: To assess the steady-state pharmacokinetics of two reduced doses of indinavir boosted with ritonavir (indinavir/ritonavir) in HIV-infected Thai patients. Patients and methods: Thirteen immunocompromised antiretroviral-naive patients (6 males, 7 females) initiated 600/100 mg indinavir/ritonavir, zidovudine and lamivudine, every 12 h. After 1 month, blood samples were taken at pre-dose, and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 h after drug intake. Indinavir dosing was then reduced to 400 mg (twice daily) and 1 week later an identical series of samples were drawn. Patients then resumed 600 mg of indinavir. HIV-1 RNA viral load was determined at 8, 24 and 48 weeks. Indinavir plasma levels were determined by HPLC and pharmacokinetic parameters by non-compartmental analysis. Results: Median (range) weight was 58 kg (51-73) for men and 53 kg (46-59) for women. On 600 mg of indinavir, median indinavir AUC, C-max and C-min were 39.3 mg(.)h/L (20.6-50.5), 6.2 mg/L (3.7-9.0) and 0.41 mg/L (0.12-0.77), respectively, and on indinavir 400 mg, 18.3 mg(.)h/L (11.1-33.0), 3.8 mg/L (2.2-7.8) and 0.17 mg/L (0.10-0.39), respectively. No renal complications were observed. At 48 weeks, 6/13 (46%) patients had stopped 600 mg of indinavir due to intolerability (gastrointestinal and cutaneous), and 5/7 (71%) patients had a HIV-1 viral load < 50 copies/mL. Conclusions: Reduced doses of indinavir/ritonavir maintained adequate indinavir plasma levels compared to current guidelines suggesting that these doses are efficacious in this setting. Considering the poor tolerability of 600 mg of indinavir, the 400 mg of indinavir may be preferred due to its lower exposure indices but long-term efficacy data are needed.