Thermal Stimuli-Responsive Topical Platform Based on Copaiba Oil-Resin: Design and Performance Upon Ex-Vivo Human Skin

Cutaneous leishmaniasis (CL) is a neglected endemic disease that causes significant damage to the skin and upper respiratory mucosa. Topical treatments are a promising alternative, but the low permeation of the drugs is a huge medical challenge. Herein, a chemometric design approach leads to an innovative thermal stimuli-responsive emulsion-filled gel (SR-EFG) as a proposed medical therapeutic. Several combinations of the Pluronic (R) F127, Carbopol C934P (R), and high Copaifera reticulata Ducke oil-resin levels allowed the obtention of optimized delivery systems. The SR-EFG were mechanic and rheologically robust and had interfacial layer properties that allowed physicochemical stability. Human skin and SR-EFG contact proved bioadhesive effect and marked ability for SR-EFG to act as a permeation enhancer. The oil-resin-carried micelles reached deep layers of the human skin and had droplet size-dependent permeation properties. The validation of the medicinal ensured the composition stability by two years. The antiproliferative activity for Leishmania amazonensis and Leishmania infantum promastigotes ensured the drug's effectiveness, with IC50 (50% parasite inhibitory concentration) values equivalent to the effect of the non-formulated oil-resin. These characteristics consolidated the SR-EFG as a promising and innovative phytotherapeutic treatment proposal for CL and wound healing. (C) 2022 Elsevier B.V. All rights reserved.