Copaiba oil enhances in vitro/in vivo cutaneous permeability and in vivo anti‐inflammatory effect of celecoxib.

Abstract: Objectives: The aim of this article was to use copaiba oil (C.O) to improve skin permeability and topical anti‐inflammatory activity of celecoxib (Cxb). Methods: Formulations containing C.O (1–50%) were associated with Cxb (2%). In vitro skin permeability studies were conducted using porcine ear skin. Histological analysis of the hairless mice skin samples after application of formulations was achieved with the routine haematoxylin/eosin technique. The anti‐inflammatory activity was assessed using the AA‐induced ear oedema mice model. Key findings: The formulation containing 25% C.O promoted the highest levels of in vitro Cxb permeation through pig ear skin, retention in the stratum corneum (SC) and epidermis/dermis of pig ear skin in vitro (~5‐fold) and hairless mice skin in vivo (~2.0‐fold), as compared with the control formulation. At 25%, C.O caused SC disorganization and increased cell infiltration and induced angiogenesis without clear signs of skin irritation. The formulation added to 25% C.O as adjuvant inhibited ear oedema and protein extravasation by 77.51 and 89.7%, respectively, and that it was, respectively, 2.0‐ and 3.4‐fold more efficient than the commercial diethylammonium diclofenac cream gel to suppress these inflammatory parameters. Conclusions: 25% C.O is a potential penetration enhancer for lipophilic drugs like Cxb that can improve cutaneous drug penetration and its anti‐inflammatory activity. [ABSTRACT FROM AUTHOR]