True about sulfonylureas is -

Ans. is 'b' i.e., Most common side effect is hypoglycemiao Sulfonylureas are -1. First generation Tolbutamide, chlorpropamide.2. Second generation Glibenclamide (Glyburide), glipizide, gliclazide, glimpride.Sulfonylureas act byo Sulfonylurease provoke a brisk release of insulin from pancreas. They act on the so called "Sulfonylurea receptors" (SUR1) on pancreatic b-cell membrane - cause depolarization by reducing conductance of ATP sensitive K+ channels. This enhances influx of Ca+2 - degranulation. They do not cause hypoglycemia in pancreatectomized animals and type 1 diabetes (Presence of at least 30% of functional b-cells in essential for their action). A minor action reducing glucagon secretion by increasing insulin and somatostatin release has been demonstratedo Extrahepatic action# On chronic administration they sensitize the target cells (especially the liver) to the action of insulin.# On chronic administration their action on pancrease (to release insuline) declines due to down regulation of sulfonylurea receptors.# But glycemic control is maintained due to extrahepatic action.# Glimepiride exerts beneficial effects with regard to ischemic preconditioning.Sulfonyloreas cause following adverse effectso Hypoglycemia# This is commonest side effect.# More common in elderly, liver and kidney disease.# Chlorpropamide is a frequent culprit due to its long action due to its long action.# Tolbutamide carries lowest risk due to its low potency and short duration of action.# Lower incidence is also reported with glipizide, glibenclamide, glimepiride.o Hypersensitivity# Rashes, photosensitivity, purpura, transient leukopenia, rarely agranulocytosiso Adverse effects specific to particular drug# Cholorpropamide causes cholestasis, dilutional hyponatremia, intolerance to alcohol (disulfiram like reaction). Chlorpropamide causes dilutional hyponatremia by sensitising the kidney to ADH action.# Tolbutamide reduces iodine uptake by thyroid.o Sulfonylureas are not safe during pregnancy - change over to insulin. Sulfonylureas are secreted in milk - should not be given to nursing mothers. Gliclazide has an antiplatelet effect.