Recommended dose: For patients new to metformin, the usual starting oral dose of metformin is 500 mg once daily. If the patient does not have any gastrointestinal adverse reactions and needs to increase dose, an addition of 500 mg metformin may be given at 1-2 weeks intervals. The dosage of metformin should be individualized on the basis of effectiveness and tolerability and should not exceed the maximum recommended daily dose of 2000 mg metformin.
Adults: Metformin STELLA 500 mg: Initial: 1 tablet twice daily (given with the morning and evening meals). Dosage increases should be made in increments of one tablet daily, once every week, up to a maximum of 5 tablets/day. Doses of up to 4 tablets/day may be given twice daily. If a dose of 5 tablets/day is required, it may be better tolerated 3 times/day (with meals).
Metformin STELLA 850 mg: Initial: 1 tablet once daily (given with the morning meal). Dosage increases should be made in increments of one tablet every other week, given in divided doses, up to a maximum of 3 tablets/day.
The usual maintenance dose is 1 tablet twice daily (with the morning and evening meals). Some patients may be given 1 tablet x 3 times/day (with meals).
Children from 10 years of age and adolescents: Monotherapy and combination with insulin: The usual starting dose is one tablet once daily. After 10 to 15 days the dose should be adjusted on the basis of blood glucose measurements. The maximum recommended dose of metformin is 2 g daily, taken as 2 or 3 divided doses.
Elderly patients: The initial and maintenance dosing should be conservative, due to the potential for decreased renal function. Generally, elderly patients should not be titrated to the maximum dose of metformin.
Recommendation for use in patients with renal impairment: Assess renal function prior to initiation of metformin and periodically thereafter.
Metformin is contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2.
Initiation of metformin in patients with an eGFR between 30-45 mL/minute/1.73 m2 is not recommended.
In patients taking metformin whose eGFR later falls below 45 mL/minute/1.73 m2, assess the benefit and risk of continuing therapy.
Discontinue metformin if the patient's eGFR later falls below 30 mL/minute/1.73 m2 (see Contraindications, Precautions).
Patients with hepatic impairment: Because of the risk of lactic acidosis, which occurs rarely but may be fatal in approximately 50% of cases, metformin should not be used in patients with renal disease or dysfunction and should be avoided in those with clinical or laboratory evidence of hepatic disease.
Discontinuation for iodinated contrast imaging procedures: Discontinue metformin at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/minute/1.73 m2; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intraarterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart metformin if renal function is stable.
Administration: Metformin STELLA 500 mg/Metformin STELLA 850 mg is administered orally with or after meals.
Transfer from other antidiabetic agents: No transition period is generally necessary except when transferring from chlorpropamide. When transferring from chlorpropamide, care should be exercised during the first 2 weeks because of the prolonged retention of chlorpropamide in the body, leading to overlapping drug effects and possible hypoglycemia.
Concomitant metformin and oral sulfonylurea therapy: If patients have not responded to 4 weeks of the maximum dose of metformin monotherapy, consideration to a gradual addition of an oral sulfonylurea while continuing metformin at the maximum dose, even if prior primary or secondary failure to a sulfonylurea has occurred. In patients who do not respond to 1-3 months of concomitant therapy at the maximum dosage of each oral antidiabetic agent, oral antidiabetic therapy generally should be discontinued and insulin therapy instituted.