The Role of Clindamycin Phosphate Associated with Adapalene in Three Semisolid Formulations Developed for Topical Acne Treatment
Despite the fact that in mild-to moderate acne vulgaris the standard first-line therapy is the topical treatment with fixed combinations of antimicrobial agents and retinoids, the skin type and the skin barrier function should be taken into account when formulating a topical product. The aim of this study was the comparison of three new semisolid formulations developed for topical application by evaluation of their rheological behavior, as well as the evaluation of in vitro percutaneous diffusion through human epidermis membrane of the pharmaceutical ingredients. Clindamycin phosphate and adapalene were incorporated in three different topical bases, an HPLC method for the determination of their content in the new formulations being developed and validated. A higher concentration of drugs was released from the two gel systems (hydroxypropylmethylcellulose 2.5% -F1 and hydroxyethylcellulose 3% -F2) than from the oil-in-water cream (F3) at pH 7.4, whereas at pH 5.5 the drugs were released in higher amounts from the formulation F3. Following the rheological behavoir associated with the penetrability through the human epidermis membrane, our study results suggest that F1 and F2 could be appropriate in treating acne lesions in patients with oily skin and unaffected skin barrier function. In contrast, the oil-in-water cream (F3), due to its possible emolient effect and its higher penetrability at pH 5.5 than gel vehicles, may be indicated for patients with dry and sensitive skin associated with an altered skin barrier.