Metabolic acidosis metformin causing

Normally, the sum of the cations exceeds the sum of the anions by no more than 12-16 mEq/L (or 8-12 mEq/L if the formula used for estimating the anion gap omits the potassium level). A larger-than expected anion gap is caused by the presence of unmeasured anions (lactate, etc) accompanying metabolic acidosis. This may occur with numerous conditions, such as diabetic ketoacidosis, renal failure, or shock-induced lactic acidosis. Drugs that may induce an elevated anion gap metabolic acidosis (Table 58-1) include aspirin, metformin, methanol, ethylene glycol, isoniazid, and iron. 

ALCOHOL METFORMIN Enhanced effect of metformin and t risk of lactic acidosis. May cause a clisulfirain-like interaction Alcohol is known to potentiate the effect of metformin on lactate metabolism. It inhibits glucose production and release from many sources including the liver The onset of lactic acidosis is often subtle with symptoms of malaise, myalgia, respiratory distress and t non-specific abdominal distress. There may be hypothermia and resistant bradyarrhythmias... 

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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