Novel extended in vitro-in vivo correlation model for the development of extended-release formulations for baclofen: From formulation composition to in vivo pharmacokinetics

In vitro-in vivo correlation (IVIVC), a predictive mathematical model between the in vitro dissolution and the in vivo pharmacokinetics has been utilized for the development of new extended release (ER) formulations. The aim of the present study was to extend the IVIVC approach, which correlates among the formulation composition, the in vitro dissolution, and the plasma drug concentration, to predict plasma drug concentrations from a given composition of the formulation, and vice versa, using baclofen as a model drug. Baclofen ER tablets with different dissolution rates were prepared by varying the composition of hydroxypropyl methylcellulose (HPMC). First, the HPMC compositions and the corresponding in vitro dissolutions parameters were correlated, and then the in vitro dissolution parameters were correlated with the in vivo dissolution parameters extracted from the pharmacokinetic profiles of the baclofen ER formulations via population pharmacokinetic modeling. The final extended IVIVC model linked the composition of the formulation, the in vitro dissolution, and the in vivo plasma concentration profile and was successfully applied for the prediction of in vivo pharmacokinetics from the amount of HPMC in baclofen ER formulations. The present approach holds great promise for designing optimal compositions of ER formulations to present desired plasma concentration profile.