Population pharmacokinetics of sapropterin dihydrochloride, a synthetic preparation of naturally occurring phenylalanine hydroxylase cofactor tetrahydrobiopterin (BH4), were evaluated in pediatric phenylketonuria patients.

The best pharmacokinetic model was a one-compartment model with an absorption lag, first-order input, and linear elimination, with a factor describing endogenous BH4 levels. Body weight was the only covariate significantly affecting sapropterin pharmacokinetics.

The doses selected for pediatric patients provided similar exposure as in adults.