Sulphonylureas Cimetidine

H2 RECEPTOR BLOCKERS SULPHONYLUREAS- GUMEPIRIDE t plasma concentrations of glimepride and t risk of hypoglycaemic episodes Cimetidine and ranitidine i renal elimination of glimepride and T intestinal absorption of glimepride. Cimetidine is also an inhibitor of CYP2D6 and CYP3A4 Consider alternative acid suppression, e.g. a proton pump inhibitor (not omeprazole), and monitor more closely... 

Hepatic enzyme inducers may enhance the metabolism of sulphonylureas that are metabolised in the liver (tolbutamide). Cimetidine, an inhibitor of drug metabolising enzymes, increases metformin plasma concentration and effect. 

On the whole cimetidine and ranitidine do not appear to significantly alter diabetic control with sulphonylureas, although cases of adverse effects have been seen when glibenclamide was given with ranitidine, and when gliclazide or glipizide were given with cimetidine. 

Where an interaction occurs it may be because the cimetidine inhibits the metabolism of the sulphonylurea by the liver, thereby increasing its effects. Cimetidine appears to inhibit the excretion of metformin by the kidneys, and this may have contributed to the case of metformin-assoeiated lactic acidosis described." ... 

Feely J, P en N. Enhanced sulphonylurea-induced hypoglycaemia with cimetidine. BrJ Clin Pharmacol (1983) 15,607P... 

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