Generic development of topical dermatologic products: formulation development, process development, and testing of topical dermatologic products.

This review presents considerations which can be employed during the development of a semi-solid topical generic product. This includes a discussion on the implementation of quality by design concepts during development to ensure the generic drug product has similar desired quality attributes to the reference-listed drug (RLD) and ensure batch to batch consistency through commercial production. This encompasses the concept of reverse-engineering to copy the RLD as a strategy during product development to ensure qualitative (Q1) and quantitative (Q2) formulation similarity, as well as similarity in formulation microstructure (Q3). The concept of utilizing in vitro skin permeation studies as a tool to justify formulation differences between the test generic product and the RLD to ensure a successful pharmacodynamic or clinical endpoint bioequivalence study is discussed. The review concludes with a discussion on drug product evaluation and quality tests as well as in vivo bioequivalence studies.