(586a) Development and Evaluation of Nanostructured Formulations Containing 8-Methoxalen

Vitiligo is a disorder characterized by cutaneous depigmentation of the epidermis and predominantly affects the face area, causing serious emotional complications in patients.  The main topical treatment for vitiligo is based on a therapy with a psolaren such as 8-methoxalen (8-MOP) associated with ultraviolet a radiation (UVA).   However, this approach has presented some disadvantages, such as frequent local phototoxicity and slow response.  Nanostructured systems are able to promote controlled release and favor the folicular penetration, which cannot be achieved with conventional dosage forms.  Micelles can entrap drugs and thereby control the release of such molecules and promote skin retention of drugs.  Considering the advantages of nanoemulsified systems for the administration of poorly soluble drugs, to investigate the feasibility of introducing the 8-MOP in nanoemulsions may be an interesting approach for developing a topical formulation. 

In this work we will discuss the development and characterization of nanostructured formulations for prolonged release of (8-MOP).  The first step consisted in the selection of the oily phase for the preparation of nanoemulsion. The oil has been chosen after a study of the solubility of 8-MOP in several different oils.  Then, polymeric surfactants have been studied at different concentrations, for the preparation of nanoemulsions containing the oily phases preselected.  The nanoemulsions were prepared by the energy input of mechanical devices such as ultrassonicator.   All systems were characterized regarding the average droplet diameter and storage stability by dynamic light scattering using equipment Zetasizer Nano ZS (Malvern Instruments Ltd., UK).  The morphology of all formulations was accessed by Transmission Electron Microscopy.   The in vitrodrug release studies have been carried on a vertical diffusion system composed of a donor compartment and receptor compartment filled with a receptor solution.  Between both compartments, a semi-synthetic membrane composed by cellulose acetate was placed.   Samples were collected at regular time intervals and analyzed by HPLC to assess the amount of 8-MOP released.  The results indicate that the formulations developed in this study represent a promising approach for the topical treatment of located vitiligo.