Formulation and evaluation of clotrimazole from pluronic F127 gels

Thermally re v e r s i b l e g e l s of poly(oxyethylene)-poly(oxypropylene)- poly(oxyethylene)-triblock copolymer, pluronic F127 (PF127), were evaluated as a vehicle for topical administration of clotrimazole as a model of a broad spectrum antifungal agent against superficial fungal infections. The solubility of clotrimazole was significantly increased as a linear function of pluronic F127 concentration at four temperatures. Clotrimazole was highly trapped by the micelles as indicated by a large partition coefficient. The micellar solubilization was a spontaneous (ΔG < 0) and exothermic (ΔH < 0) process which resulted in a less orderly state (ΔS > 0). Different additives were used to enhance drug release from preparations including propylene glycol, polyethylene glycol 400, glycerin, and dimethyl sulfoxide at concentrations of 5 and 10% and polysorbate 80 at concentrations of 1 and 2%. Different formulae were characterized in terms of drug content, pH and particle size measurement, spreadability, rheological properties, drug release, diffusion, and permeation. The formulae showing the best drug release were selected to study the effect of storage on various parameters over a period of 6 months and for microbiological evaluation. The best release enhancers were propylene glycol and polyethylene glycol 400 at a concentration of 10% and polysorbate 80 at a concentration of 2% and the formulae containing it were stable and proved to be effective in inhibition. Furthermore they were tested microbiologically against three fungi as well as yeast. The antimicrobial activities of the tested preparations were compared with the pure drug at the same concentrations and also tested for their antifungal activity. It was found to be effective against Aspergillus niger, A. flaves, Candida albicans, and Sacharomyces cerevisiae with inhibition zones of 39, 39, 35, and 32 mm, respectively.