Glibenclamide¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Sulfonylureas such as glibenclamide likely bind to ATP-sensitive potassium-channel receptors 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. Metformin¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Metformin's pharmacologic mechanisms of action are different from other classes of oral antihyperglycemic agents. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
Pharmacology
Glibenclamide¿¡ ´ëÇÑ Pharmacology Á¤º¸ Glibenclamide (INN), also known as glyburide (USAN), a second-generation sulfonylurea antidiabetic agent, appears to lower the blood glucose acutely by stimulating the release of insulin from the pancreas, an effect dependent upon functioning beta cells in the pancreatic islets. With chronic administration in Type II diabetic patients, the blood glucose lowering effect persists despite a gradual decline in the insulin secretory response to the drug. Extrapancreatic effects may be involved in the mechanism of action of oral sulfonyl-urea hypoglycemic drugs. The combination of glibenclamide and metformin may have a synergistic effect, since both agents act to improve glucose tolerance by different but complementary mechanisms. In addition to its blood glucose lowering actions, glibenclamide produces a mild diuresis by enhancement of renal free water clearance. Glibenclamide is twice as potent as the related second-generation agent glipizide. Metformin¿¡ ´ëÇÑ Pharmacology Á¤º¸ Metformin is an antihyperglycemic agent, which improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose. Metformin is not chemically or pharmacologically related to any other classes of oral antihyperglycemic agents. Unlike sulfonylureas, metformin does not produce hypoglycemia in either patients with type 2 diabetes or normal subjects and does not cause hyperinsulinemia. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and daylong plasma insulin response may actually decrease.
Protein Binding
Glibenclamide¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Extensively bound to serum proteins Metformin¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Metformin is negligibly bound to plasma proteins.
Half-life
Metformin¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 6.2 hours
Absorption
Glibenclamide¿¡ ´ëÇÑ Absorption Á¤º¸ Significant absorption within 1 hour and peak plasma levels are reached within 4 hours. Metformin¿¡ ´ëÇÑ Absorption Á¤º¸ Absorbed over 6 hours, bioavailability is 50 to 60% under fasting conditions. Food delays absorption.
Glibenclamide¿¡ ´ëÇÑ Biotransformation Á¤º¸ Primarily hepatic (mainly cytochrome P450 3A4). The major metabolite is the 4-trans-hydroxy derivative. A second metabolite, the 3-cis-hydroxy derivative, also occurs. These metabolites contribute no significant hypoglycemic action in humans as they are only weakly active. Metformin¿¡ ´ëÇÑ Biotransformation Á¤º¸ Metformin is not metabolized.
Toxicity
Glibenclamide¿¡ ´ëÇÑ Toxicity Á¤º¸ Oral rat LD50: > 20,000 mg/kg. Oral mouse LD50: 3250 mg/kg. Metformin¿¡ ´ëÇÑ Toxicity Á¤º¸ Acute oral toxicity (LD50): 350 mg/kg [Rabbit]. It would be expected that adverse reactions of a more intense character including epigastric discomfort, nausea, and vomiting followed by diarrhea, drowsiness, weakness, dizziness, malaise and headache might be seen.
Drug Interactions
Glibenclamide¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Acebutolol The beta-blocker decreases the symptoms of hypoglycemiaAtenolol The beta-blocker decreases the symptoms of hypoglycemiaBevantolol The beta-blocker decreases the symptoms of hypoglycemiaBetaxolol The beta-blocker decreases the symptoms of hypoglycemiaBisoprolol The beta-blocker decreases the symptoms of hypoglycemiaCarteolol The beta-blocker decreases the symptoms of hypoglycemiaCarvedilol The beta-blocker decreases the symptoms of hypoglycemiaEsmolol The beta-blocker decreases the symptoms of hypoglycemiaLabetalol The beta-blocker decreases the symptoms of hypoglycemiaMetoprolol The beta-blocker decreases the symptoms of hypoglycemiaNadolol The beta-blocker decreases the symptoms of hypoglycemiaOxprenolol The beta-blocker decreases the symptoms of hypoglycemiaPenbutolol The beta-blocker decreases the symptoms of hypoglycemiaPindolol The beta-blocker decreases the symptoms of hypoglycemiaPractolol The beta-blocker decreases the symptoms of hypoglycemiaPropranolol The beta-blocker decreases the symptoms of hypoglycemiaSotalol The beta-blocker decreases the symptoms of hypoglycemiaTimolol The beta-blocker decreases the symptoms of hypoglycemiaTrisalicylate-choline The salicylate increases the effect of sulfonylureaSalsalate The salicylate increases the effect of sulfonylureaSalicylate-magnesium The salicylate increases the effect of sulfonylureaSalicylate-sodium The salicylate increases the effect of sulfonylureaBismuth Subsalicylate The salicylate increases the effect of sulfonylureaAspirin The salicylate increases the effect of sulfonylureaBosentan Increased risk of hepatic toxicityDicumarol The agent increases the effect of sulfonylureaChloramphenicol The agent increases the effect of sulfonylureaClofibrate The agent increases the effect of sulfonylureaCyclosporine The sulfonylurea increases the effect of cyclosporineDiazoxide Diazoxide/sulfonylurea: antagonism of actionGlucosamine Possible hyperglycemiaIsocarboxazid The MAO inhibitor increases the effect of the hypoglycemic agentPhenelzine The MAO inhibitor increases the effect of the hypoglycemic agentPhenylbutazone Phenylbutazone increases the effect of the hypoglycemic agentRepaglinide Similar mode of action - questionable associationRifampin Rifampin decreases the effect of sulfonylureaTranylcypromine The MAO inhibitor increases the effect of the hypoglycemic agent Metformin¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Cimetidine Cimetidine increases the effect of metforminGlucosamine Possible hyperglycemia
Glibenclamide¿¡ ´ëÇÑ Description Á¤º¸ An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide. [PubChem] Metformin¿¡ ´ëÇÑ Description Á¤º¸ A biguanide hypoglycemic agent used in the treatment of non-insulin-dependent diabetes mellitus not responding to dietary modification. Metformin improves glycemic control by improving insulin sensitivity and decreasing intestinal absorption of glucose. (From Martindale, The Extra Pharmacopoeia, 30th ed, p289)