Diarrhoea metformin

Oral formulations of metformin are rapidly and completely absorbed. The agent is poorly bound to plasma proteins its duration of action is determined exclusively by renal elimination. Higher concentrations of metformin than in most tissues are found in the intestinal mucosa, giving tise to common side effects (irritation, diarrhoea etc.). 

Biguanides. Metformin acts peripherally to increase glucose uptake by an unknown mechanism.. As it does not increase insulin release, it rarely cau-scs hypoglycaemia. Adverse effects include nausea, vomiting, diarrhoea and. very (Kcasionally, fatal lactic acidosis. 

Cimetidine 800 mg daily was found to reduce the renal clearance of metformin in 7 healthy subjects by 27% and increase the AUC by 50%. A 59-year-old woman with type 2 diabetes taking long-term metformin 500 mg three times daily developed severe metabolic acidosis with cardiovascular collapse and acute renal failure. Three months previously she had started orlistat 120 mg three times daily, which caused chronic diarrhoea. During the 4 days before hospital admission, she was prescribed cimetidine 400 mg twice daily for her abdominal pain. The metformin-assoeiated lactic acidosis was considered to have been precipitated by the orlistat , (p.498) and cimetidine. ... 

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