Population pharmacokinetic analysis of raltegravir pediatric formulations in HIV-infected children 4 weeks to 18 years of age

P1066 is an open-label study of raltegravir in HIV positive youth, ages 4 weeks-18 years. Here we summarize P1066 pharmacokinetic (PK) data and a population PK model for the pediatric chewable tablet and oral granules. Raltegravir PK parameters were calculated using noncompartmental analysis. A 2-compartment model was developed using data from P1066 and an adult study of the pediatric formulations. Interindividual variability was described by an exponential error model, and residual variability was captured by an additive/proportional error model. Twelve-hour concentrations (C_12h) were calculated from the model-derived elimination rate constant and 8-hour observed concentration. Simulated steady-state concentrations were analyzed by noncompartmental analysis. Target area under the curve (AUC_0-12h) and C_12h were achieved in each cohort. For the pediatric formulations, geometric mean AUC_0-12h values were 18.0-22.6-μM-hr across cohorts, and C_12h values were 71-130-nM, with lower coefficients of variation versus the film-coated tablet. A 2-compartment model with first-order absorption adequately described raltegravir plasma PK in pediatric and adult patients. Weight was a covariate on clearance and central volume and was incorporated using allometric scaling. Raltegravir chewable tablets and oral granules exhibited PK parameters consistent with those from prior adult studies and older children in P1066, as well as lower variability than the film-coated tablet.