The invention provides enantiopure deuterium-enriched pioglitazone, pharmaceutical compositions, and methods of treating neurological disorders, cancer, respiratory disorders, metabolic disorders, and other disorders using enantiopure deuterium-enriched pioglitazone. A preferred aspect of the invention provides methods of treating Alzheimer's disease, non-small cell lung cancer, hepatocellular carcinoma, and chronic obstructive pulmonary disease using enantiopure deuterium-enriched pioglitazone.