Development of oral controlled release preparations, a PVA swelling controlled release system (SCRS). II. In vitro and in vivo evaluation

A novel controlled release system, the PVA swelling controlled release syst em, was evaluated in vitro and in vivo using emedastine difumarate as a mod el drug. In the in vitro drug release study, the release profile of this sy stem had almost zero-order kinetics. The effect of dissolution test conditi ons, which were paddle rotation speed, mechanical stress, and pH of the dis solution medium, on the release rate was very small. In an in vivo human bi oavailability study of two formulations with a different release rate, the absorption rate was dependent on the release rate, and both formulations sh owed constant plasma levels of the drug for long periods. The variations of plasma concentration on the simulation of repetitive administration of the formulations at 24-h intervals were almost equal to the experimental value for the twice daily controlled release capsule currently on the market. It is concluded that the PVA swelling controlled release system is feasible f or a long-acting preparation as a once-daily treatment. (C) 2000 Elsevier S cience B.V. All rights reserved.