Pharmacokinetics and safety of a raltegravir-containing regimen in HIV-infected children aged 2-12 years on rifampicin for tuberculosis

Abstract

Objectives: Drug-drug interactions limit current antiretroviral treatment options for HIV-infected children with tuberculosis (TB). Rifampicin (RIF) induces UDP-glucuronosyltransferase activity, accelerating the clearance of raltegravir (RAL). We sought to establish an optimal and well tolerated dose of RAL when administered with RIF to HIV and TB co-infected children.

Design: P1101 is a phase I/II open-label dose-finding study of RAL with RIF for children 2 to less than 12 years of age beginning treatment for HIV and active TB.

Setting: Four sites in South Africa.

Methods: Chewable RAL was given at 12 mg/kg per dose twice daily (twice the usual pediatric dose) with two nucleoside reverse transcriptase inhibitors. Intensive RAL pharmacokinetic sampling was conducted 5 to 8 days after antiretroviral therapy was initiated; a fourth antiretroviral agent was then added.

Results: Children were recruited into two age-defined groups: cohort 1 (2 to <6 years old) and cohort 2 (6 to <12 years old). Pharmacological targets [geometric mean (GM) AUC12 h of 14-45 μmol/l h and GM C12 h ≥75 nmol/l) were reached in both cohort 1 (28.8 μmol/l h and 229 nmol/l) and cohort 2 (38.8 μmol/l h and 228 nmol/l). The RAL-based ART was well tolerated by most participants: one participant discontinued treatment because of grade 4 hepatitis that was possibly treatment-related. At week 8, 22 of 24 participants (92%) had HIV RNA concentrations below 400 copies/ml; 19 of 24 (79%) were below 50 copies/ml.

Conclusion: Giving 12 mg/kg twice daily of the chewable RAL formulation achieved pharmacokinetic targets safely in HIV-infected children receiving RIF for TB.

Figure 1

Pharmacokinetic profiles of raltegravir in children receiving RAL concurrently with RIF based therapy for tuberculosis. Left Panel: data for children in Cohort 1 (2 to <6 years of age, n=12). Right Panel: Cohort 2 (6 to <12 years of age, n=14). The solid line is median for the group and dashed lines are 10^th and 90^th percentiles.

Figure 2

Viral Load Response By 8 Weeks of Treatment With RAL Note: The median (interquartile range) change in plasma log₁₀ HIV-RNA (copies/mL) from baseline was −3.17 (−3.80 to −2.56) for Cohort 1 and −2.79 (−3.42 to −2.09) for Cohort 2.