Human Skin Permeation of a Chloroaluminum Phthalocyanine Nanoemulsion for Optimization of Topical Cutaneous Leishmaniasis Formulations

Introduction: The nanoemulsions constitute excellent drug delivery systems for carrying and delivering active drugs. Chloroaluminum phthalocyanine (ClAlPc) in photodynamic therapy constitutes an interesting alternative in cutaneous leishmaniasis treatment. Objective: To de-termine the diffusion and retention of ClAlPc contained in a nanoemulsion (nano-ClAlPc) in human skin membranes for optimization of topical formulations. Materials and methods: Two formulations (ClAlPc-nano- and ClAlPc-solution) and vehicles without ClAlPc were prepared and physicochemical characterized. The permeation was tested in Franz-diffusion cells and the retention by the tape stripping method. ClAlPc concentration was determined fluorometrically (nM/cm2). Skin biopsies were analyzed by histologic technics. Results: The ClAlPc-nano average size, zeta potential and polydispersity index diluted in water was 132.9 nm, -19.23 and 0.14 and diluted in phosphate-buffer-saline was 25.33 nm, -13.69 and 0.139. ClAlPc maintains its stabil¬ity in each formulation. ClAlPc was unable to pass completely through the skin; it was retained in the different skin layers. A ClAlPc retention in stratum corneum and epidermis+dermis was observed with values of 44.17 nM and 8.48 nM after ClAlPc-nano treatment and 96.90 nM and 9.80 nM after ClAlPc-solution treatment. The ClAlPc-solution promoted greater retention in stratum corneum and both formulations showed similar ClAlPc-retention in epidermis+dermis. Histological changes as stratum corneum detachment and collagen-fragmentation were observed. Conclusion: ClAlPc was not able to cross completely the skin, it was retained in stratum corneum and epidermis+dermis Human permeation test using skin membranes without stratum corneum, and distribution assays in cutaneous leishmaniasis-infected animals, are suggested.