Desenvolvimento de gel de Minoxidil para uso tópico

Abstract

Minoxidil was discovered in 1965 due to its vasodilator mechanism of action and thus very effective at treating the most severe and resistant hypertension, although its adverse effect of inducing hypertrichosis turned it useful for treating alopecia. Nowadays, minoxidil is available on the market, at high prices, in both gel and lotion formulations, produced especially by compounding pharmacies, to treat beard alopecia. In order to lower the costs of preparing the 5% gel formulation of minoxidil, the main objective of this paper was to evaluate the chemical and physical stability of this product under different temperature and packaging conditions. This study elaborated calibration curves for minoxidil, evaluated the forced decay under acidic, alkaline and oxidizing conditions, accompanying the evolution of the process by TLC and spectrophotometry analysis. The rheological behavior of several gel-basis formulations as well as their capacity of being spread were determined and the polymer and solvent effects were quantified by factorial experiment. The final samples of the product were analyzed regarding their viscosity, capability of being spread and minoxidil concentration. The evaluation of the decay results and the calibration curves showed that minoxidil degraded more easily by oxidative reactions. As of the factorial experiment, an expressive interaction between the ethanol and the polymer was observed, which increased the formulations’ viscosity and, therefore, influenced on the reduction of their capability of being spread. The formulation composition reached the ideal cosmetic expectation for topical use, which are good capacity of being spread and enough viscosity to allow the extrusion of the material from its packaging. This study showed the formulation should be packed in aluminum tubes and at room temperature.