The effects of ascorbic acid and tartaric acid on pioglitazone hydrochloride solubility

Application of two coformers, l-tartaric acid (TA) and ascorbic acid (AA) was evaluated on the solubility of pioglitazone hydrochloride (PGZ.HCl). Solid dispersions were prepared using the solvent evaporation method. Drug solubility was evaluated in bio-relevant media and the results were compared to the physical mixtures (PM) of the drug + coformer, and the pure drug. Physicochemical characterisation of the developed products was characterised using Fourier transformation-infrared spectroscopy (FT-IR), Differential scanning calorimeter (DSC), and X-ray powder diffractometry (XPRD). Physical mixtures of PGZ-AA (PM) were able to enhance drug solubility to the same extent as the solvent evaporation method (PGZ-AA). This indicates that the preparation process has little effect on drug solubility. Up to 7-fold enhancement was observed for drug solubility in distilled water and buffer pH 1.2. Physical mixtures seem more feasible method to significantly enhance drug solubility without the need to use toxic solvents and time-consuming evaporation methods.