Chlorpropamide is an antidiabetic drug, belonging to the sulfonylurea class of organic compounds. It is used to treat diabetes mellitus type 2. It is a long-acting first-generation sulfonylurea.
Mechanism of action
Like other sulfonylureas, chlorpropamide acts to increase the secretion of insulin, so it is only effective in patients who have some pancreaticbeta cell function. It can cause relatively long episodes of hypoglycemia; this is one reason why shorter-acting sulfonylureas such as gliclazide or tolbutamide are used instead. The risk of hypoglycemia makes this drug a poor choice for the elderly and patients with mild to moderate hepatic and renal impairment. Chlorpropamide is also used in partial central diabetes insipidus.[1]
Pharmacokinetics
Maximal plasma concentrations are reached 3 to 5 hours after quick and nearly complete (>90%) resorption from the gut. plasmahalf life is 36 hours; the drug is effective for about 24 hours, longer than other sulfonylureas. A stable plasma level is only reached after three days of continuous application. 90% of the drug are bound to plasma proteins; at least two albumin binding sites exist. More than 99% of chlorpropamide are excreted unchanged via the kidneys. It is first filtrated in the glomeruli, then reabsorbed, and finally secreted into the tubular lumen.[1]
Chlorpropamide and other sulfonylureas encourage weight gain, so they are generally not favored for use in very obese patients. Metformin (Glucophage) is considered a better drug for these patients. Sulfonylureas should be used with caution or generally avoided in patients with hepatic and renal impairment, patients with porphyria, patients who are breastfeeding, patients with ketoacidosis, and elderly patients.[1][2]
Chlorpropamide is a white crystalline powder with no characteristic taste or smell. It exhibits polymorphism. Its acid dissociation constant pKa is 5.0 at 20 °C.[1]