## Mechanism of Action Comparison **Key Point:** Both sulfonylureas and meglitinides are insulin secretagogues that bind to the SUR1 (sulfonylurea receptor 1) subunit of ATP-sensitive potassium channels on pancreatic β-cells, but their kinetics and duration differ fundamentally. ### Sulfonylureas - Bind tightly and persistently to SUR1 - Cause **sustained, long-lasting** insulin secretion - Glucose-independent action (risk of hypoglycemia even during fasting) - Examples: glibenclamide, glipizide, gliclazide ### Meglitinides - Bind rapidly and reversibly to SUR1 - Cause **rapid onset, short-duration** insulin secretion (mimics physiologic postprandial response) - Glucose-dependent action (lower fasting hypoglycemia risk) - Examples: repaglinide, nateglinide | Feature | Sulfonylureas | Meglitinides | |---------|---------------|---------------| | **Binding** | Tight, sustained | Rapid, reversible | | **Insulin release** | Sustained | Rapid & short-lived | | **Glucose-dependent** | No | Yes | | **Fasting hypoglycemia** | Common | Rare | | **Meal-related action** | Weak | Strong | | **Duration** | 12–24 hrs | 1–4 hrs | **Clinical Pearl:** Meglitinides are preferred in elderly patients and those with erratic meal patterns because their short duration and glucose-dependent action minimize fasting hypoglycemia risk. **High-Yield:** The reversible, rapid binding of meglitinides to SUR1 is the key discriminator — it explains why they cause fewer hypoglycemic episodes despite the same molecular target. [cite:KD Tripathi 8e Ch 32]
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