A pharmacokinetic method for designing prolonged-release formulations—Propoxyphene hydrochloride

Many prolonged-release preparations are designed so that a certain fraction is immediately available for absorption upon administration, while the remainder becomes available for absorption at an effectively constant rate. Recently, a number of prolonged-release propoxyphene hydrochloride formulations have been designed to dissolve in this manner in vitro.We employed a pharmacokinetic model, product dissolution data, and historical plasma concentration data to predict the plasma propoxyphene concentrations which might result from a particular mix and thus minimize the number of formulations requiring evaluation in subjects.