This is a biguanide

Indications: maturity-onset diabetes especially when this accompanies obesity (BMI > 25) and insulin resistance, Women with Polycystic ovary syndrome and a body mass index above 25 may be given metformin when other therapy has failed to produce results.

Cautions: congestive heart failure, hepatic and renal disease, acidosis, severe infections, gangrene, pregnancy; before or after surgery.

Contra-indications: renal impairment; ketoacidosis; withdraw if tissue hypoxia likely (e.g. sepsis, respiratory failure; recent mycardial infarction, hepatic impairment); use of iodine containing X-ray contrast media; pregnancy and breast feeding.

Side Effects: lactic acidosis in those with impaired liver or kidney function.

Gastrointestinal: diarrhea, cramps, nausea and vomiting.

Dose: Initially 500 mg with breakfast for 1 week followed by 500 mg with breakfast and evening meal for 1 week then 500 mg with breakfast, lunch and evening meal. Max 2 g daily in divided doses.

Polycystic ovary syndrome: Initially 500 mg with breakfast for 1 week followed by 500 mg with breakfast and evening meal for 1 week then 1.5 to 1.7 g daily in 2-3 divided doses.