Solubility Enhancement of Rifabutin by Co-solvency Approach

Abstract

Rifabutin is wide spectrum antimicrobial agent, effective in the treatment of infection caused by M. tuberculosis, M. avium and M. Leprae and also used in the treatment of multidrug resistant TB. Rifabutin is very poorly water soluble drug (0.19mg/ml) with high permeability. For enhancement of solubility of a hydrophobic drug has a significant role in the development of a liquid dosages form. The main purpose of this study was to improve the solubility of Rifabutin by co solvency method. Different blends were prepared by usinf different solvents and surfactants in different proportions have been used to enhance the solubility of Rifabutin like water, phosphate buffer, ethanol, propylene glycol and PEG 400, Tween 80 and Brij 35. In thisit was found that the blend 90% PEG and 10% co solvents (ethanol and propylene glycol) give highest solubility and among the surfactant systems, Tween 80 had shown enhanced solubility of Rifabutin. Solubility of rifabutin was determined by preparing saturated solutions of rifabutin in pure solvents and in mixture of co solvents with or without surfactants. It observed that the blend of 90% PEG and 10% ethanol and propylene glycol had shown the better improvement of solubility when compared with the other solvents and co solvents as it caused a noteworthy enhancement in solubility of Rifabutin that was 1.6803 mg/ml.The above observations lead to propose that the addition of small amount of polar solvent enhances the solubility of drug.Thus, the study generated an important array of data to compare the effect of these cosolvents on the aqueous solubility of rifabutin.