Solid lipid nanoparticles as delivery systems for percutaneous administration of capsaicin

Capsaicin, the primary pungent principle in hot peppers, is finding increasing use as a topical therapy for a variety of cutaneous disorders that involve pain and inflammation. Although topical capsaicin has shown therapeutic potential, the utility of capsaicin appears to be limited at present primarily by its irritant properties and secondarily by less than optimal therapeutic response, perhaps resulting from insufficient drug delivery. Solid lipid nanoparticles (SLN), due to the safety of the component materials and the controlled release abilities, possess a great potential for topical administration of drugs and active substances. Main advantages associated with SLN compared with other colloidal system are high biocompatibility, good physical stability, possibility of controlled release of drug and active substances, easy large scale production and cheap raw materials. Therefore, the aim of the present work was to evaluate the efficacy of SLN as delivery system for percutaneous administration of capsaicin. Capsaicin loaded SLN were prepared, using solvent injection technique, and characterized by means of photo correlation spectroscopy (PCS), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). Percutaneous absorption has been studied, in vitro, using excised human skin membranes (i.e., SCE) mounted in Franz type cells. From the results obtained, capsaicin loaded SLN showed a mean diameter of 240 nm and a high encapsulation efficiency (97%). In vitro percutaneous absorption study, demonstrated that the particles were able to reduce drug penetration increasing, simultaneously, the permeation and the accumulation in the horny layer.