Combined models for data from in vitro-in vivo correlation experiments.

A method is presented to describe the in vitro-in vivo correlation (IVIVC) of an extended release drug formulation. This extended release drug product is overencapsulated with immediate release material. The heterogeneity of the capsule is modelled using a combined model of an extended release and an immediate release pharmacokinetic profile. Whereas an IVIVC is conventionally performed using a two-stage procedure, the model uses a one-stage convolution-based method. The method is applied to a Galantamine controlled release formulation, an acetylcholinesterase inhibitor for the treatment of Alzheimer's disease. The average percentage prediction error indicated a good fit of the new model.