ABSTRACT
The therapeutic efficacy of a drug is determined by the in vivo performance of the pharmaceu tical dosage form, which is in turn dependent on the quality and characteristics of the product. With a controlled release product a patient is typically exposed to specific plasma levels over an extended period of time (e.g., 12 or 24 h). There should be specific in vitro methods to assure the consistent in vivo performance from each batch of the same product. Among various in vitro procedures used to control the product quality, the drug release test is the single most useful method for this purpose, particularly when differences in the release rate can be correlated quantitatively with the in vivo differences in product performance, i.e., in vitro-in vivo correla tion (IVIVC). Over the last 10 years, there has been an increasing confidence in using in vitro dissolution as an indication of the in vivo bioavailability characteristics for the drug product based on IVIVC (1). As a result, an increasing number of IVIVC studies have been included in New Drug Application (NDA) submissions, particularly with controlled release dosage forms, and a guidance for industry on IVIVC was established by the FDA (1).
