In some situations, concentration–time data may not be available to characterize the pharmacokinetics of a drug in children aged ≤ 2 years, especially in neonates and infants.

This study evaluated whether empirical models developed from children aged > 2 years to adults can be used to predict clearance in children aged ≤ 2 years.

The results indicated that only three of six empirical models (body weight-dependent sigmoidal Emax model, ADE, and semi-physiological model) were useful (prediction error ≤ 50%) for the prediction of drug clearance in children aged ≤ 2 years.

The study indicated that simple empirical models can provide more accurate results than complex models. Caution is needed when using these empirical models for extrapolation purposes.