Sulphonylureas potentiation

Q85 Enalapril may precipitate a hypoglycaemic attack in a diabetic patient. Enalapril may potentiate the effect of sulphonylureas. 

II.f.2.2. Sulphonylureas. These drugs stimulate pancreatic /3-cell insulin secretion, reduce serum glucagon levels, potentiate insulin action on target tissues, and improve /3-cell function. The sulphonylureas differ in their potency, extent of hepatic metabolism, hypoglycaemic activity of their metabolites, renal excretion, peak and duration of action, side effects and costs. 

Non-selective p-receptor blockers potentiate hypo-glycaemia of insulin and sulphonylureas. 

Renal and hepatic disease. A biguanide should not be used in patients with either condition as the risk of lactic acidosis is too great. Sulphonylureas are potentiated in these diseases and a drug with a short t) (i.e. not glibenclamide) should be used in low dose. 

Chlorpropamide (but not other sulphonylureas) and carbamazepine are effective in partial pituitary diabetes insipidus, i.e. some natural hormone production remains, because they act on the kidney potentiating the effect of vasopressin on the renal tubule. H5q oglycaemia may occur with chlorpropamide. 

Chlorpropamide and tolbutamide are excreted in breast milk. Data on other sulphonylureas are not available. Because of the potential for hypoglycaemia in nursing infants, it has to be decided whether to discontinue nursing or to discontinue the drug. 

This is chemically 2-acetamido-(p-chloro-phenyl)-(m-trifluoromethylphenoxy)acetate it is thus closely related to clofibrate. Rot-tiers and Van Egmond(15 ) conducted a 48-week double-blind comparison between halofenate and clofibrate, but used only 1 g daily of the former and 2 g daily of the latter. Under these conditions, halofenate had less effect than did clofibrate on triglycerides, and virtually none on cholesterol levels, and one is bound to wonder whether it was not administered in too low a dose. This would explain why halofenate produced no side effects except in one patient who withdrew from the study because of gastric intolerance. The properties of halofenate are probably very similar to those of clofibrate, and its ability to potentiate the effects of anticoagulants and sulphonylureas (see above) has apparently been demonstrated (12 =). 

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