Chitosan-functionalized nanostructured lipid carriers containing chloroaluminum phthalocyanine for photodynamic therapy of skin cancer.

The objective of this study was to obtain optimized nanostructured lipid carriers (NLC) functionalized with chitosan containing chloroaluminum phthalocyanine (ClAlPc) as a photosensitizer. Initially, the optimization of the preparation method of the NLC was performed, where the influence of different surfactants such as PVA and Tween 80, as well as different solid lipids such as stearic acid and Glycerol Monostearate (GM) was evaluated. The formulation containing GM and PVA (NLC10) was considered promising. Following, by the adsorption method (NLC10q), the formulation was functionalized with chitosan and characterized. NLC10 and NLC10q presented sizes of 131.5 and 231.5 nm, and ZP of -24.30 and + 19.96 mV, respectively. The encapsulation efficiency of NLC10q was 96 %, higher than NLC10 (79 %). The formulations were able to promote significant cutaneous retention of ClAlPc, after 2 h and 4 h of the study, and showed to be non-toxic to fibroblasts (biocompatible). PDT in BF16-F10 melanoma resulted in reduced cell viability to 70 % and 50 % for NLC10 and NLCq, respectively. In view of the results obtained, NLC showed to be promising in the treatment of skin cancer through PDT. NLC10q showed higher encapsulation efficiency and stability than NLC10, but, contrary to what was expected, it presented lower photodynamic efficiency.

Microemulsion systems to enhance the transdermal permeation of ivermectin in dogs: A preliminary in vitro study.

This study aims to evaluate the influence of the phase behavior of microemulsions in the transdermal administration ("spot-on") of ivermectin, an antiparasitic drug widely used in the treatment of endoparasites and ectoparasites in dogs. In this regard, pseudoternary phase diagrams composed of water (aqueous phase), isopropyl myristate (oil phase), tween 80 (surfactant) and labrasol (cosurfactant) were obtained in a different surfactant: cosurfactant (S:CS) ratios. S:CS in 1:3 ratio presented a larger region of microemulsion formation and three microemulsions were selected from it and characterized. Subsequently, in vitro permeation and retention studies were conducted using canine skin as membrane. SAXS, rheology and conductivity data were employed to confirm the phase behavior of the microemulsions (w/o, bicontinuous or o/w). The cutaneous permeation and retention tests showed that the w/o microemulsion, followed by bicontinuous microemulsion, resulted in a higher amount of drug permeated through canine skin, suggesting better transdermal permeation. On the other hand, o/w microemulsion resulted in a higher amount of drug accumulated into the skin, suggesting better topical activity. Thus, it can be concluded that phase behavior of microemulsions influenced the drug permeation in the canine skin differently from other animal models. Microemulsions, especially w/o and bicontinuous, can be promising vehicles regarding the transdermal delivery of ivermectin.

Third-Generation Transdermal Delivery Systems Containing Zidovudine: Effect of the Combination of Different Chemical Enhancers and a Microemulsion System.

This study aimed to examine the influence of the combination of chemical enhancers and a microemulsion on the transdermal permeation of zidovudine (AZT). Ethanol, 1,8-cineole, and geraniol were incorporated in a microemulsion. The droplet size, zeta potential, rheology, and SAXS analysis were performed. The permeation enhancer effect was evaluated using pig ear skin. Snake skin (Boa constrictor) treated with the formulations was also used as a stratum corneum model and studied by attenuated total reflectance-infrared spectroscopy. As a result, it was observed that the incorporation of the chemical enhancers promoted a decrease of the droplet size and some rheological modifications. The 1,8-cineole associated with the microemulsion significantly increased the permeated amount of AZT. Conversely, ethanol significantly increased the quantity of the drug retained in the skin. The probable mechanism for the cineole and ethanol effects was respectively: fluidization and increasing of the diffusion coefficient, and increasing of the partition coefficient. Surprising, geraniol + microemulsion drastically decreased both the permeated and the retained amount of AZT into the skin. Thus, the adequate association of microemulsion and chemical enhancers showed to be a crucial step to enable the topical or transdermal use of drugs.