Resumo

RICO, CI et al. Skin permeation and biodistribution of chloroaluminum phthalocyanine (ClAlPc) nanoemulsion applied topically in Wistar rats. Rev. argent. dermatol. [online]. 2013, vol.94, n.2. ISSN 1851-300X.

A successful formulation contained aluminum phthalocyanine chloride (ClAlPc) able for cutaneous leishmaniasis (CL) ensures the skin permeation and retention of the compound in dermis, a place where macrophages infected with Leishmania are located. The aim of this study was to determine the ClAlPcex vivo permeation and retention in Wistar rat skin and its distribution in animals with healthy skin and surgically damaged skin. Two formulations were prepared: nanoemulsion (ClAlPc-nano) and solution (ClAlPc-solution). The diffusion was determined using Franz diffusion cells with Wistar rat skin as membrane after 12 and 24 hours of testing. Retention in stratum corneum (SC) and epidermis plus dermis (E+D) was determined by the tape stripping method and organic solvent extraction. The distribution was performed after the topical application of formulations analyzing the CLAlPc concentration in the skin layers and organs by fluorometry. The results were expressed as nM/mg of tissue of ClAlPc. Simultaneously, skin biopsies were taken in order to determine their histological characteristics. ClAlPc formulations were effective in maintaining compound solubility and spectroscopic characteristics. ClAlPc was unable to pass completely through the skin; its skin retention was related with the used formulation, time of assays and type of skin layer. After 12 and 24 hours, the SC retention induced by ClAlPc-nano treatment was 99.73 and 79.40nM and by ClAlPc-solution was 66.73 and 57.01nM. In E+D the retention induced by ClAlPc-nano was 40.94 and 62.49nM and by ClAlPc-solution was 81.92 and 50.28nM. In SC, ClAlPc-nano showed greater retention after 12 and 24 hours, while in E+D, ClAlPc-solution was greater retained at 12 hours and ClAlPc-nano at 24 hours. After the permeation assays, detachment and reduction in epithelial layers were observed in skin membranes. In Wistar rats, ClAlPc-nano placed on healthy skin retained the compound in E+D and SC with values of 33.18nM and 6.43nM and placed on damaged skin retained in E+D in SC with values of 17.08nM and 0.99nM respectively; no organs distribution occur, except in lung where values of 0.82nM in animals with healthy skin and 1.92nM in animals with damaged skin were observed. ClAlPc-solution induced retention of 31.86 in SC and 202,40nM in E+D placed on healthy skin and 5.93 in SC and 63.83nM E+D placed on damaged skin; concentrations in lung with values of 2,36nM after application in animals with healthy skin and 20,33nM in animals with damaged skin were observed. In addition, ClAlPc-solution promoted, after application on damaged skin, distribution of ClAlPc to other organs with values between 1.58 and 5.80nM. In animals without skin injury, normal histologic skin anatomy were observed after treatment. In contrast, epithelial regeneration, detachment of keratin, loss of cellular differentiation, cellular infiltration and neovascularization were observed in animals with skin injury. The efficacy of the formulation to penetrate the SC and be retained in the viable skin layers was demonstrated. The in vivo ClAlPc-biodistribution was related on its concentration and skin state. A nanoemulsion contained ClAlPc, represents a good system of drug delivery because induce both the SC penetration and E+D retention, without systemic organ distribution even when presented tissue repair and regeneration. A ClAlPc-nano prepared in this work constitutes a good formulation for the topical application of ClAlPc in LC treatment.

Palavras-chave : Nanoemulsion; Choroaluminum phthalocyanine; Franz diffusion cells; Skin permeation; Biodistribution; Cutaneous leishmaniasis.