Assessment of value and applications of in vitro testing of topical dermatological drug products

The FDA recently issued a guidance covering practices of scaleup and post a pproval changes with semisolids (SUPAC-SS).(17) This guidance outlines the steps that must be taken by a company to maintain certification of its semi solid dermatological products after quantitative changes have been made in their compositions and/or after changes have been made in the sourcing of t heir key ingredients, in their processing, in their batch sizes, and/or aft er their site of manufacture has been relocated. A key element within the g uidance is a release test to be used to determine if the diffusional releas e of a drug found in a formulation is the same after changes have been made to the formulation as it was prior to implementing the changes. The AAPS-F DA sponsored workshop was set up to explore this qualifying test. The state d aims of the workshop were: a) to illustrate the methodology and technique s of in vitro release testing, b) to show the sensitivity of in vitro relea se with respect to manufacturing variables and to variations in components and composition (of specific formulations), c) to recognize in vitro releas e testing as a useful procedure for SUPAC documentation, d) to highlight an d evaluate other applications of in vitro release testing, e) to explore th e degree to which in vitro release testing and bioavailability may be relat ed, and f) to evaluate the role of in vitro release testing of topical dosa ge forms as a tool to improve product quality.