Effect of rifampicin on lopinavir pharmacokinetics in HIV-infected children with tuberculosis.

OBJECTIVE: Rifampicin dramatically reduces plasma lopinavir concentrations (coformulated with ritonavir in a 4:1 ratio). A study in healthy adult volunteers showed that this reduction could be ameliorated if additional ritonavir is given. We evaluated the effect of additional ritonavir on plasma lopinavir concentrations in HIV-infected children receiving rifampicin-based treatment for tuberculosis.

METHODS: We measured plasma lopinavir concentrations in 2 parallel groups receiving combination antiretroviral therapy that included lopinavir-ritonavir, with and without rifampicin-based antitubercular treatment. Additional ritonavir was given (lopinavir/ritonavir ratio of 1:1) during antitubercular treatment. Lopinavir concentrations were determined using liquid chromatography-tandem mass spectrometry.

RESULTS: There were 15 children (aged 7 months to 3.9 years) in each group. Lopinavir pharmacokinetic measures (median [interquartile range]) for children with and without rifampicin, respectively, were maximum concentration (Cmax) of 10.5 [7.1 to 14.3] versus 14.2 [11.9 to 23.5] mg/L (P = 0.018), area under the curve from 0 to 12 hours (AUC0-12) of 80.9 [50.9 to 121.7] versus 117.8 [80.4 to 176.1] mg/h/L (P = 0.036), and trough concentration (Cmin) of 3.94 [2.26 to 7.66] versus 4.64 [2.32 to 10.40] mg/L (P = 0.468). Thirteen of 15 children receiving antitubercular treatment (87%) had a lopinavir Cmin greater than the recommended minimum therapeutic concentration (1 mg/L).

CONCLUSIONS: The effect of rifampicin-based antitubercular treatment on lopinavir concentrations was attenuated by adding ritonavir to rifampicin. Although the median Cmax and AUC0-12 were lowered by 26% and 31%. respectively, the Cmin was greater than the minimum recommended concentration in most children.