Liver toxicity caused by nevirapine.

Nevirapine plasma levels were measured in 70 HIV-infected patients, 33 of whom developed transaminase elevations. Higher nevirapine levels and hepatitis C virus infection were found to be independent predictors of liver toxicity. Moreover, in individuals with chronic hepatitis C, nevirapine concentrations greater than 6 microg/ml were associated with a 92% risk of liver toxicity. Therefore, monitoring nevirapine levels, especially in individuals with chronic hepatitis C, may be warranted.