Tolbutamide and chlorpropamide were compared as to their intrinsic hypoglycemic action by statistical analysis of data obtained from 21 diabetic patients. The hypoglycemic agents, usually taken orally, were administered intravenously to avoid their possible differences in rate or completeness of gastrointestinal absorption. The blood specimens were drawn from the patients during three hours after administration of the drugs to assure comparison of their hypoglycemic effect at a time when the plasma concentrations would be similar. The specimens were analyzed for blood glucose and plasma levels of the two drugs. Each patient was tested once with each drug. The two drugs were found not to differ in their acute hypoglycemic potencies, and the need for a greater dosage of tolbutamide in long-term therapy is most likely explained by its more rapid rate of inactivation and excretion.
Craig JW, Miller M, Mills FD, Nickerson N. COMPARISON OF ACUTE HYPOGLYCEMIC POTENCIES OF TOLBUTAMIDE AND CHLORPROPAMIDE. JAMA. 1960;172(8):779-782. doi:10.1001/jama.1960.03020080009004