Comparison of Release Rates Derived from Cutaneous Versus Film-Forming Solution Containing Terbinafine: Approach Towards Qualification and Validation of In Vitro Parameters

Excipients play a very important role in the release pattern of an active pharmaceutical ingredient from topical semisolid dosages forms, and their physical and chemical properties can influence the release. The aim of this paper was to provide a validated, sensitive, and reproducible method to assess the in vitro release rate of an antifungal drug (Terbinafine) from controlled drug delivery systems (cutaneous and film-forming solution) and to prove product sameness. The samples obtained from in vitro testing were analyzed through a high performance liquid chromatographic (HPLC) system coupled with UV spectrometer at a wavelength of 283 nm. A Franz diffusion cell (FDC) system was used for the dissolution test. We recorded the drug release from the formulation for 6 hours. The release rate obtained from cutaneous and filmforming solutions were compared statistically to depict the sameness. The results met the relevant acceptance criteria (i.e., 90% confidence interval, falling within the limits of 75–133%) as defined in the scale-up and post-approval changes (SUPAC-SS) guidance. The obtained results confirm the competence of the IVRT method for the assessment of product sameness.