Physicochemical and Structural (Q3) Characterization of Topical Drug Products

This guidance is intended to assist applicants who are submitting abbreviated new drug applications (ANDAs) for liquid-based and/or other semisolid products applied to the skin, including integumentary and mucosal (e.g., vaginal) membranes, which are hereinafter called topical products.

Because of the complex route of delivery associated with these products, which are typically locally acting, and the potential complexity of certain formulations, topical products (other than topical solutions) are classified as complex products.

This guidance provides recommendations for physicochemical and structural (collectively, Q3) characterizations that can be used

(1) to identify the dosage form of a proposed generic (test) topical product and

(2) to describe properties of the drug product that may be critical to its performance (to support a demonstration of bioequivalence (BE).

When comparing the Q3 attributes of two topical products (e.g., to support a demonstration of BE), we generally advise that applicants conduct a comparative Q3 characterization of their proposed generic product against the reference standard, which ordinarily is the reference listed drug (RLD).

It is beyond the scope of this guidance to discuss specific reference standards for topical products or to enumerate the specific tests and comparative product characterizations that are recommended for each such product.

FDA recommends that applicants consult this guidance in conjunction with any relevant product-specific guidances (PSGs) and in conjunction with any other relevant guidances for industry when considering the design and conduct of Q3 characterization tests that may be appropriate to support a demonstration that a proposed generic topical product and its reference standard are of the same dosage form and are bioequivalent.

FDA also recommends that applicants routinely refer to FDA’s guidance web pages because additional guidances may become available that could assist in the development of a generic topical product.