Adaptation of USP types II and IV controlled release assays for sparingly soluble compounds by direct eluent HPLC analysis.

Measurement of drug release of a sparingly soluble drug by conventional methods proceeds very slowly without the aid of surfactants. Two preliminary automated methods were developed that increase sensitivity and accelerate such studies by working at very small reservoir volumes. All high pressure liquid chromatography (HPLC) equipment components were commercially available. Results are presented for the drug release of a single pellet of the sparingly soluble drug Eliprodil in two types of drug release experiments using (1) a stirred cell and (2) a flow-through method. Release rates measured from each method were comparable.