A dissolution experiment evaluates the rate and extent that a compound forms a solution under carefully controlled conditions. The dissolution test in a USP drug product monograph helps evaluate the performance of a drug product (article) and indicates when the drug product performs in a substandard fashion. Although passing the test does not definitively demonstrate bioavailability of the sample or bioequivalence to other products, failure is a cause for concern. Typically, for oral drug products, USP monographs call for the use of dissolution testing with apparatus described in General Chapter <711> Dissolution.
A dissolution test in the monograph for an official article in the USP originates with a submission by an industry sponsor and represents criteria for a product that has been approved for the U.S. market. All proposed monograph dissolution tests for official articles are reviewed by the U.S. Food and Drug Administration (FDA) for conformance to marketing authorization commitments.
USP Apparatus 1 (basket) and 2 (paddle) were introduced in the 1970s for the purpose of providing a platform to evaluate the in vitro performance of dosage forms using standardized conditions. The dissolution test in a USP monograph solely provides conditions that facilitate discrimination among variations in critical quality attributes for the article. No claim has been made that the design of the apparatus is specifically linked to, or mimics, in vivo dissolution conditions of medium volume or agitation. However, since those early years, these apparatus and associated procedures have become widely used and accepted.
The Apparatus Suitability section in <711> describes the procedure and requirements for qualification of dissolution apparatus. Analytical instrument qualification/calibration is also required by FDA current Good Manufacturing Practices (cGMPs) and ISO/IEC 17025, an international standard specifying general requirements for the competence of testing and calibration laboratories. The USP Performance Verification Test (PVT) is used to determine the trueness and precision of the results in comparison with results from a broadly based international study. The test can also be diagnostic of errors in technique.
Within the context of regulatory approval, the USP dissolution test helps safeguard against the release of product that does not perform acceptably. In its more than 40-year history, the USP dissolution test has gained wide use and acceptance. The USP PVT helps users gain understanding of the contribution of their equipment to the variability of results. USP remains committed to sound science in the evaluation of drug product performance and is open to new approaches in this area.