Metformin Hydrochloride

Clinical summary

Indications and usage 1 INDICATIONS AND USAGE Metformin hydrochloride tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. Metformin hydrochloride tablets are biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. ( 1 ) Dosage and administration 2 DOSAGE AND ADMINISTRATION Adult Dosage for metformin hydrochloride tablets: • Starting dose: 500 mg orally twice a day or 850 mg once a day, with meals ( 2.1 ) • Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks, up to a maximum dose of 2550 mg per day, given in divided doses ( 2.1 ) • Doses above 2000 mg may be better tolerated given 3 times a day with meals ( 2.1 ) Pediatric Dosage for metformin hydrochloride tablets: • Starting dose: 500 mg orally twice a day, with meals ( 2.2 ) • Increase dosage in increments of 500 mg weekly up to a maximum of 2000 mg per day, given in divided doses twice daily ( 2.2 ) Renal Impairment: • Prior to initiation, assess renal function with estimated glomerular filtration rate (eGFR) ( 2.3 ) o Do not use in patients with eGFR below 30 mL/minute/1.73 m 2 ( 2.3 ) o Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 ( 2.3 ) o Assess risk/benefit of continuing if eGFR falls below 45 mL/minute/1.73 m 2 ( 2.3 ) o Discontinue if eGFR falls below 30 mL/minute/1.73 m 2 ( 2.3 ) Discontinuation for Iodinated Contrast Imaging Procedures: • Metformin hydrochloride tablets may need to be discontinued at time of, or prior to, iodinated contrast imaging procedures ( 2.4 ) 2.1 Adult Dosage Metformin Hydrochloride Tablets The recommended starting dose of metformin hydrochloride tablets are 500 mg orally twice a day or 850 mg once a day, given with meals. Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks on the basis of glycemic control and tolerability, up to a maximum dose of 2550 mg per day, given in divided doses. Doses above 2000 mg may be better tolerated given 3 times a day with meals. 2.2 Pediatric Dosage for metformin hydrochloride tablets The recommended starting dose of metformin hydrochloride tablets for pediatric patients 10 years of age and older is 500 mg orally twice a day, given with meals. Increase dosage in increments of 500 mg weekly on the basis of glycemic control and tolerability, up to a maximum of 2000 mg per day, given in divided doses twice daily. 2.3 Recommendations for Use in Renal Impairment Assess renal function prior to initiation of metformin hydrochloride tablets and periodically thereafter. Metformin hydrochloride tablets are contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m 2 . Initiation of metformin hydrochloride tablets in patients with an eGFR between 30 to 45 mL/minute/1.73 m 2 is not recommended. In patients taking metformin hydrochloride tablets whose eGFR later falls below 45 mL/min/1.73 m 2 , assess the benefit risk of continuing therapy. Discontinue metformin hydrochloride tablets if the patient's eGFR later falls below 30 mL/minute/1.73 m 2 [ see Warnings and Precautions (5.1) ] . 2.4 Discontinuation for Iodinated Contrast Imaging Procedures Discontinue metformin hydrochloride tablets at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m 2 ; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart metformin hydrochloride tablets if renal function is stable. Warnings and cautions 5 WARNINGS AND PRECAUTION S • Lactic Acidosis: See boxed warning. ( 5.1 ) • Vitamin B 12 Deficiency: Metformin may lower vitamin B 12 levels. Measure hematological parameters annually and vitamin B12 at 2 to 3 year intervals and manage any abnormalities. ( 5.2 ) • Hypoglycemia with Concomitant Use with Insulin and Insulin Secretagogues: Increased risk of hypoglycemia when used in combination with insulin and/or an insulin secretagogue. Lower dose of insulin or insulin secretagogue may be required ( 5.3 ). 5.1 Lactic Acidosis There have been postmarketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin­ associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increased lactate: pyruvate ratio; metformin plasma levels were generally >5 mcg/m