Sulphonylureas are a class of oral medications commonly used to manage type 2 diabetes mellitus. They work by stimulating the pancreatic beta cells to produce more insulin, thereby lowering blood sugar levels. These drugs are particularly effective in patients who still retain some beta-cell function.
Examples of Sulphonylureas
- First-generation drugs:
- Tolbutamide
- Chlorpropamide
- Second-generation drugs (more commonly used today due to better potency and fewer side effects):
- Glipizide
- Glyburide (also called Glibenclamide)
- Glimepiride
Mechanism of Action
Sulphonylureas bind to specific receptors on the beta cells of the pancreas (the sulfonylurea receptor, SUR1). This interaction closes ATP-sensitive potassium channels, leading to depolarization of the cell membrane. The depolarization opens calcium channels, allowing calcium influx, which stimulates insulin release.
Indications
- Type 2 diabetes, especially in patients who are not achieving adequate control with diet and exercise alone.
Side Effects
- Hypoglycemia: The most significant risk, especially with long-acting agents or in patients with renal insufficiency.
- Weight gain: Often associated with increased insulin levels.
- GI disturbances: Such as nausea or heartburn.
- Rare adverse effects:
- Allergic skin reactions
- Bone marrow suppression
Contraindications
- Type 1 diabetes (as these patients lack functional beta cells)
- Severe liver or kidney impairment (due to metabolism and excretion issues)
- Sulfa allergy (though cross-reactivity is rare)