Ex vivo Skin Permeation Evaluation of An Innovative Transdermal Vehicle Using Nimesulide and Piroxicam as Model Drugs

Background: The transdermal dosage forms presented a limited usage for a long time, for it was believed that the stratum corneum, the outermost layer of epidermis, made it impracticable the permeation of medications through the skin. Studies exploring this area came up with strategies to overcome this barrier; for example, creating a transdermal vehicle to facilitate the drug absorption. Objective: This study aimed to evaluate a new transdermal vehicle through the comparison of its permeation profile and the profile of commercial products, using nimesulide and piroxicam, non steroidal anti-inflammatory drugs. Methods: Four different products were evaluated: nimesulide and piroxicam compounded with the new vehicle (emulsion) and commercial nimesulide and piroxicam gels. Ex vivo permeation experiments using Franz-type diffusion cell equipment were conducted, using human skin as membrane. For evaluation of permeated active pharmaceutical ingredients concentrations, we performed quantification from the receptor solution, stratum corneum and viable epidermis + dermis, through high-performance liquid chromatography analyses. Results: The new vehicle promoted increased permeation of active pharmaceutical ingredients through the viable epidermis and dermis, when compared to commercial products, but the stratum corrneum continued to keep the highest retention. Conclusion: The innovative vehicle was capable of enhancing the transdermal absorption of active pharmaceutical ingredients from the compounded formulations, thus, demonstrating the capability thereof to improve the permeability of active pharmaceutical ingredients by transdermal use. Keywords: Nimesulide, NSAIDS, permeation studies, piroxicam, stratum corneum, transdermal vehicle, viable epidermis.