Caution when used in patients with CHF especially in those with unstable or acute heart failure. Risk of lactic acid accumulation increases with the degree of renal impairment. May need to discontinue treatment in patients with stress-related states e.g. fever, trauma, infection or surgery. Metformin should be temporarily discontinued for 48 hr in patients undergoing radiologic studies involving intravascular admin of iodinated contrast materials. Elderly. Monitor renal function regularly. Because of possibility of hypoglycemia in combination therapy with a sulphonylurea or insulin, diabetic control should be monitored by blood sugar readings.
The usual starting dose is 500 mg twice daily or 850 mg once a day, given with meals. Dosage increase should be made in increments of 500 mg weekly or 850 mg every 2 weeks up to a total of 2000 mg per day, given in divided doses.
Patients can be titrated from 500 mg twice a day to 850 mg twice a day after 2 weeks. For these patients requiring additional glycaemic control, metformin may be given to a maximum daily dose of 2550 mg per day.
Doses above 2000 mg may be better tolerated when given three times a day with meals. The usual starting dose of Metformin HCl extended – release tablet is 500 mg once daily with the evening meal. Dosage increase may be made up to a max. of 2000 mg once daily with the evening meal.
Polycystic ovary syndrome Initial: 500 mg/day in the morning for 1 wk, then 500 mg twice daily for 1 wk, then 1.5-1.7 g/day in 2-3 divided doses.