Bioequivalence of Topical Clotrimazole Formulations: An Improved Tape Stripping Method

Natalie Rae Parfitt1, Michael Frederick Skinner2, Charles Bon3, Isadore Kanfer4

1Division of Pharmaceutics Faculty of Pharmacy Rhodes University Grahamstown
2Director Biopharmaceutics Research Institute Rhodes University Grahamstown
3Biostudy Solutions LLC Wilmington
4Faculty of Pharmacy, Rhodes University, Grahamstown

Abstract


Purpose: Investigations were carried out to assess the use of tape stripping (TS) for the determination of bioequivalence of topical products containing 1% clotrimazole. Methods: The study design involved the establishment of an appropriate application time, which was determined by conducting a dose duration study. Subsequently, two bioequivalence studies were conducted: i) using the brand (Canesten Topical - 1% clotrimazole cream) as both the test and the reference product and ii) comparing Canesten cream with a gel product containing the same concentration of clotrimazole (1%). Each tape strip was individually analyzed for clotrimazole content using an HPLC method and Transepidermal Water Loss (TEWL) measurements were used to normalize the stratum corneum thicknesses between subjects. Results: The results of the TS investigations showed that, if the study is sufficiently powered, tape stripping may be used to determine bioequivalence according to the conventional bioequivalence limits of 0.8–1.25, as well as detect formulation differences between different clotrimazole products. Conclusions: The data from this study provided compelling evidence that tape stripping has the necessary attributes and potential to be used as a tool for the bioequivalence assessment of topical clotrimazole and/or other topical formulations, thereby circumventing the need to undertake expensive and time-consuming clinical trials for such products.

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J Pharm Pharm Sci, 14 (3): 347-357, 2011

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