Improving the solubility of nevirapine using A hydrotropy and mixed hydrotropy based solid dispersion approach

Nevirapine, an antiviral drug, is a potent reverse transcriptase inhibitor (NNRTI). It is used in combination with nucleoside analogues for treatment of HIV type-1 (HIV-1) infection and AIDS. Nevirapine is a BCS class II drug which shows dissolution rate limited absorption. The aim of the present research was to provide a fast dissolving solid dispersion of nevirapine. The solubility of nevirapine was initially determined individually in four hydrotropic agents - namely urea, lactose, citric acid and mannitol - at a concentration of 10, 20, 30 and 40% w/v solutions using purified water as a solvent. The highest solubility was obtained in the 40% citric acid solution. Then different combinations of 2 and 3 hydrotropic agents in different ratios were used to determine solubility, so that the total concentration of hydrotropic agents was always 40%. The highest solubility was obtained in a solution of lactose and citric acid at the optimum ratio of 15:25. This optimized combination was utilized in preparing solid dispersions by a common solvent technique using distilled water as a solvent. The solid dispersions were evaluated for XRD, DSC and FTIR to show no drug-hydrotrope interaction. It was concluded that the concept of mixed hydrotropic solid dispersion is a safe, novel and cost-effective technique for enhancing the bioavailability of poorly water-soluble drugs by dissolving the drug in a nonionized form. The enhancement in solubility of nevirapine using hydrotropy is a clear indication of its potential to be used in the future for other poorly water-soluble drugs in which low bioavailability is a major concern.