A Newly Discovered Racemic Compound of Pioglitazone Hydrochloride Is More Stable than the Commercial Conglomerate

A novel racemic compound of pioglitazone hydrochloride is discovered 17 years after the FDA approval of the conglomerate. The racemic compound shows a lower dissolution rate than the conglomerate in simulated gastric fluid at room temperature and is more thermodynamically stable as evidenced by solubility measurements. Slurry transformation of a mixture of the two forms converts fully to the racemic compound. This report highlights the necessity to thoroughly explore solid forms to access the most thermodynamically stable form of a pharmaceutical and contrasts the structural features of the two forms.