Controlled Drug Release from Polymeric Devices I: Technique for Rapid in vitro Release Studies

Abstract

A simple system was developed which allows the rapid and reproducible quantification of parameters influencing the release of drug by solid polymeric devices. The apparatus utilizes only 150ml of elution medium and maintains “sink” conditions with water-miscible (nonaqueous) cosolvent combinations. Consant diffusin layer thickness is controlled by constant stirring and fixed temperature conditions. Factors influencing the rate of release of ethynodiol diacetate, a synthetic progestin, from solid silicone polymer vaginal devices were evaluated. The cumulative amount of drug released was proportional to the square root of time. The drug diffusivity was calculated and found in excellent agreement with previously reported data for similar compounds in silicone matrixes. The presence of a matrix-controlled process was confirmed by the independence of the steady-state diffusion rate on drug solubility in the eluant.