Enhancement of Thiacetazone Solubility by Isoniazid in Aqueous Solutions

Abstract

The aqueous solubility of thiacetazone was enhanced in the presence of different concentrations of isoniazid. The nature of this solubilization was investigated by measuring some physicochemical properties of isoniazid in water. Slight surface activity and conductance were observed. Osmotic pressure and partition coefficient measurements indicated that isoniazid dimerizes in aqueous solutions and were used to obtain and verify the dimerization constant. There was no evidence of higher oligomer formation in concentrations lower than 1.0 M. This excluded the possibility of solubilization by aggregate formation. Citric and glutaric acids in the presence of isoniazid were found to increase thiacetazone solubility as a function of the acid concentration and structure.