Nevirapine plasma concentrations are associated with virologic response and hepatotoxicity in Chinese patients with HIV infection

Background: Limited information is available on the relationship between nevirapine plasma concentrations and virologic response or liver toxicity in Chinese patients with HIV infection. The objective of this prospective study was to test this relationship and to determine the minimal therapeutic trough concentration of nevirapine for Chinese patients. Methods: A total of 227 HIV-infected, treatment naïve patients were enrolled into this study. Blood samples were taken at C _trough (12 hr postdose) and C ₂ (2 hr postdose) for measurement of nevirapine concentrations 6 months after treatment initiation. Therapeutic outcomes, viral load and CD4 cell count, were assessed at 3 and 6 months after starting therapy, while the evaluation of hepatotoxicity was undertaken 12 months after nevirapine treatment. Results: A significant correlation between nevirapine trough concentrations and viral load was noticed after 6 months of treatment, particularly in patients with partial response and viral failure (p<0.01). The therapeutic C _trough of nevirapine for Chinese patients was determined to be 3.9 μg/ml using the receiver operating characteristic curve. Virologic failure was observed in 21% (6/29) of patients with low nevirapine concentrations (<3.9 μg/ml) versus 5% (4/87) in patients with concentrations higher than 3.9 μg/ml (p = 0.015). Hepatotoxicity was significantly associated with the median nevirapine trough concentrations among male patients (8.20 vs. 5.48 μg/ml, p = 0.015) and hepatitis C virus co-infection (p = 0.039). Conclusions: Among Chinese patients with HIV infection, the therapeutic C _trough of nevirapine was 3.9 μg/ml, higher than the recommended 3.0 μg/ml. The correlation between nevirapine concentrations, efficacy and hepatotoxicity suggests the benefit of dosage adjustment based on therapeutic drug monitoring among Chinese HIV-infected patients to optimize nevirapine containing antiretroviral therapy.