Application of Surface Active Agents to Pharmaceutical Preparations. I

Abstract

Drug preparations containing non-ionic surface active agents as a solubilizer is apt to become molded and the addition of an antifungal agents in such preparations at times do not exhibit the anticipated effect. This was assumed to be due to the fact that the solubilized antifungal agent is enveloped inside the micelle formed by the surface active agent. Using Tween 20 as the surface active agent and four kinds of p-hydroxybenzoic acid esters as the antifungal agent, solubility of the antifungal agent in the presence of surfactant and effect on Aspeyillus niger were tested and the relationship between the degree of hydrophilic or lipophilic properties of the antifungal agents and micelle formation of surfactants was considered. Addition of Tween 20 solution increases the solubility of the esters (Fig. 1) but the antifungal activity decreases (Fig. 2). Since the rate of decrease is different in each ester, antifungal activity of each ester differs in magnitude above a certain concentration of Tween 20. The ratio of solubility to antifungal concentration is approximately constant in each ester and this value is smaller in the esters with smaller number of carbon atoms (Fig. 3). It was thereby concluded that the antifungal agents easily soluble in aqueous phase outside the micelle possessed greater antifungal activity.