Drug Groups

approved

Description

Chlorpropamide is an oral antihyperglycemic agent used for the treatment of non-insulin-dependent diabetes mellitus (NIDDM). It belongs to the sulfonylurea class of insulin secretagogues, which act by stimulating β cells of the pancreas to release insulin. Sulfonylureas increase both basal insulin secretion and meal-stimulated insulin release. Medications in this class differ in their dose, rate of absorption, duration of action, route of elimination and binding site on their target pancreatic β cell receptor. Sulfonylureas also increase peripheral glucose utilization, decrease hepatic gluconeogenesis and may increase the number and sensitivity of insulin receptors. Sulfonylureas are associated with weight gain, though less so than insulin. Due to their mechanism of action, sulfonylureas may cause hypoglycemia and require consistent food intake to decrease this risk. The risk of hypoglycemia is increased in elderly, debilitated and malnourished individuals. Chlorpropamide is not recommended for the treatment of NIDDM as it increases blood pressure and the risk of retinopathy (UKPDS-33). Up to 80% of the single oral dose of chlorpropramide is metabolized, likely in the liver; 80-90% of the dose is excreted in urine as unchanged drug and metabolites. Renal and hepatic dysfunction may increase the risk of hypoglycemia.

Indication

For treatment of NIDDM in conjunction with diet and exercise.

Pharmacology

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.

Toxicity

IPN-RAT LD₅₀ 580 mg/kg

Affected Organisms

Biotransformation

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.

Absorption

Readily absorbed from the GI tract. Peak plasma concentrations occur within 2-4 hours and the onset of action occurs within one hour. The maximal effect of chlorpropamide is seen 3-6 hours following oral administration.

Half Life

Approximately 36 hours with interindividual variation ranging from 25-60 hours. Duration of effect persists for at least 24 hours.

Protein Binding

Highly bound to plasma proteins.

Elimination

80-90% of a single oral dose is excreted in the urine as unchaged drug and metabolites within 96 hours.

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