Sulfonylureas such as chlorpropamide bind to ATP-sensitive potassium channels on the pancreatic cell surface, reducing potassium conductance and causing depolarization of the membrane. Depolarization stimulates calcium ion influx through voltage-sensitive calcium channels, raising intracellular concentrations of calcium ions, which induces the secretion, or exocytosis, of insulin.
Chlorpropamide, a second-generation sulfonylurea antidiabetic agent, is used with diet to lower blood glucose levels in patients with diabetes mellitus type II. Chlorpropamide is twice as potent as the related second-generation agent glipizide.
Up to 80% of dose is metabolized likely through the liver to to 2-hydroxylchlorpropamide (2-OH CPA), p-chlorobenzenesulfonylurea (CBSU), 3-hydroxylchlorpropamide (3-OH CPA), and p-chlorobenzenesulfonamide (CBSA); CBSA may be produced by decomposition in urine. It is unknown whether chlorpropamide metabolites exert hypoglycemic effects.
IPN-RAT LD50 580 mg/kg