In vitro/in vivo correlations in biopharmaceutics: scientific and regulatory implications.

This paper explains the regulatory and scientific reasons for the regulatory authorities employing dissolution as a key variable for regulatory approval of batch to batch bioequivalence assurance, site of manufacture change, formulation changes, and batch size scale-up for immediate release dosage forms. It also explains the scientific and regulatory reasons why either an in vivo/in vitro correlation using USP's Level 'A', 'B' or 'C', or a newly proposed 'mapping' approach will be required for allowing such changes for controlled-release dosage forms.