Lopinavir exposure is insufficient in children given double doses of lopinavir/ritonavir during rifampicin-based treatment for tuberculosis

Background: Coadministration of rifampicin dramatically reduces the concentrations of protease inhibitors. A pharmacokinetic study in healthy adults showed that doubling the dose of coformulated lopinavir/ritonavir was able to overcome the inducing effect of rifampicin. We evaluated this strategy in children treated with rifampicin-based antituberculosis therapy attending antiretroviral clinics in South Africa. Methods: Plasma concentrations of lopinavir were measured in children (aged 0.64-2.43 years) established on antituberculosis treatment who commenced antiretroviral therapy comprising double the usual recommended dose of lopinavir/ritonavir oral solution (460/115 mg/m(2) twice daily) plus two nucleoside reverse transcriptase inhibitors. Control children (0.57-4.23 years old) without tuberculosis received standard doses of lopinavir/ritonavir (230/57.5 mg/m(2) twice daily). Results: Pre-dose lopinavir concentrations were reduced by >80% in children with tuberculosis (median 0.7 mg/l, IQR 0.1-2.0) compared with controls (4.2 mg/l, IQR 3.4-8.1; P<0.001) and were below the minimum recommended concentration of 1 mg/l in 12 of 20 (60%) children with tuberculosis versus 2 of 24 (80%) controls (P<0.001). Conclusions: Double doses of coformulated lopinavir/ritonavir results in inadequate lopinavir concentrations in young children treated concurrently with rifampicin. Suitable regimens are urgently needed for treating young children with HIV-associated tuberculosis.