INTRODUCTION

This chapter provides information on performance tests to assess drug release from finished ophthalmic products. These tests are applicable to products that have an extended-release mechanism (beyond 1 day); the dissolution/drug release rate is rate limiting for absorption and is expected to provide a controlled therapeutic response. Examples of such products include intraocular matrix-type and polymer-based bioerodible implants, non-bioerodible intraocular matrix and reservoir implants, intraocular injectable suspensions/colloidal systems, intraocular in situ–forming depots and gels, punctal plug-based delivery systems, non-biodegradable drug release devices (e.g., drug-coated stents, drug-coated contact lenses), biodegradable and non-degradable ocular inserts/bioadhesives (for cul-de-sac or conjunctival-sac applications), and other such dosage forms. For products having a localized and immediate response when applied to the eye (e.g., topically applied dosage forms, including dispersed systems, having very short residence time for absorption), a dissolution/drug release test may have no practical value.