Tolbutamide (Orinase), when effective in maintaining euglycemia, may be the drug of choice in the adult, stable, ketoacidosis-resistant form of diabetes mellitus. Its toxicity is low, hypoglycemic reactions are minimal, and its beta-cytotropic action makes it sound physiologically. Because tolbutamide fails to achieve or to maintain the desired blood glucose levels in a substantial segment of this group of patients, the need exists for other oral regimens capable of treating effectively the stable diabetic patient who is hyporesponsive to tolbutamide.
The use of the other two currently available oral antihyperglycemic drugs, chlorpropamide (Diabinese) and phenformin hydrochloride (DBI), may control satisfactorily a minority of these patients. Chlorpropamide is a longer acting and more potent sulfonylurea than tolbutamide. Although a small percentage of tolbutamide hyporesponders can be regulated with chlorpropamide, its use entails a small but definite risk of hepatic, dermatologic, or hematologic toxicity, as well as of severe hypoglycemic reactions. In