Swelling-controlled release system for the vaginal delivery of miconazole.

Miconazole nitrate, a fungicidal, is effective for the local treatment of vaginitis. The objective of this project was to develop a swelling-controlled release delivery system for miconazole. An aqueous solution of 15% w/w poly(vinyl alcohol) was mixed with a specific amount of miconazole powder. The resultant mixture was cross-linked by freeze-thawing. The effect of the number of freeze-thawing cycles was studied at four levels. The effect of the presence of PEG was studied by mixing different concentrations of two different PEG. The swelling at the end of 48 h was significantly higher (32%) for the batch that underwent four cycles. The swelling within the first 15 min for the batches containing PEG1000 was approximately 9%. However, the swelling for the batches containing PEG1450, at much lower concentration, within the same period was between 10 and 19%. The drug release profiles up to 108 h were independent of the number of freeze-thawing cycles. The cumulative percent miconazole released, in the absence of PEG, (two, four, six, eight cycles) at the end of 108 h was between 30 and 35%. The drug release was lower for the batches containing PEG1000, irrespective of the concentrations, compared with the batches containing PEG1450. A comparison of the value of diffusional exponent (n) indicates the predominance of a Fickian diffusion mechanism of release from the hydrogels.