Metformine (metformin)

1 INDICATIONS AND USAGE Metformin hydrochloride extended-release 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 extended-release 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 )

2 DOSAGE AND ADMINISTRATION N/A Recommended Dosage in Adults and Pediatric Patients Aged 10 Years and Older: • Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew ( 2.2 ) • Starting dosage: 500 mg orally once daily with the evening meal ( 2.2 ) • Increase the dosage in increments of 500 mg weekly, up to a maximum dosage of 2,000 mg once daily with the evening meal ( 2.2 ) • Patients receiving metformin hydrochloride immediate-release tablets may be switched to metformin hydrochloride extended-release tablets once daily at the same total daily dosage, up to 2,000 mg once daily ( 2.3 ) Recommended Dosage in Patients with Renal Impairment: • Prior to initiation, assess renal function with estimated glomerular filtration rate (eGFR) ( 2.4 ) o Do not use in patients with eGFR below 30 mL/minute/1.73 m 2 ( 2.4 ) o Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 ( 2.4 ) o Assess risk/benefit of continuing if eGFR falls below 45 mL/minute/1.73 m 2 ( 2.4 ) o Discontinue if eGFR falls below 30 mL/minute/1.73 m 2 ( 2.4 ) Discontinuation for Iodinated Contrast Imaging Procedures: • Metformin hydrochloride extended-release tablets may need to be discontinued at time of, or prior to, iodinated contrast imaging procedures ( 2.5 ) 2.2 Recommended Dosage for Metformin Hydrochloride Extended-Release Tablets in Adults and Pediatric Patients Aged 10 Years and Older With Type 2 Diabetes Mellitus • Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew. • The recommended starting dosage of metformin hydrochloride extended-release is 500 mg orally once daily with the evening meal. • Increase the dosage in increments of 500 mg weekly on the basis of glycemic control and tolerability, up to a maximum of 2,000 mg once daily with the evening meal. • If glycemic control is not achieved with metformin hydrochloride extended-release tablets 2,000 mg once daily, consider a trial of metformin hydrochloride extended-release tablets 1,000 mg twice daily. • If a dose of metformin hydrochloride extended-release tablets is missed, instruct patients not to take two doses the same day and to resume their usual dose of metformin hydrochloride extended-release tablets with the next schedule dose. 2.3 Switching Between Metformin Hydrochloride Immediate-Release Tablets and Metformin Hydrochloride Extended-Release Tablets • Patients may switch between metformin hydrochloride immediate-release tablets and metformin hydrochloride extended-release tablets at the same total daily dosage. • Patients receiving metformin hydrochloride extended-release tablets who require dosages higher than 2,000 mg daily may switch to metformin hydrochloride immediate-release tablets and titrate to the maximum total daily dosage of 2,550 mg. 2.4 Recommended Dosage in Patients With Renal Impairment • Assess renal function prior to initiation of metformin hydrochloride extended-release tablets and periodically thereafter. • Metformin hydrochloride extended-release tablets are contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m 2 . • Initiation of metformin hydrochloride extended-release tablets in patients with an eGFR between 30 to 45 mL/minute/1.73 m 2 is not recommended. • In patients taking metformin hydrochloride extended-release tablets whose eGFR later falls below 45 mL/min/1.73 m 2 , assess the benefit risk of continuing therapy. • Discontinue metformin hydrochloride extended-release tablets if the patient’s eGFR later falls below 30 mL/minute/1.73 m 2 [see Warnings and Precautions (5.1) ]. 2.5 Discontinuation for Iodinated Contrast Imaging Procedures Discontinue metformin hydrochloride extended-release 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 extended-release tablets if renal function is stable.

5 WARNINGS AND PRECAUTIONS N/A • Lactic Acidosis: See boxed warning. ( 5.1 ) • Vitamin B 12 Deficiency : Metformin may lower vitamin B 12 levels. Measure hematological parameters annually and vitamin B 12 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/mL. Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk. If metformin-associated lactic acidosis is suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of metformin hydrochloride extended-release tablets. In metformin hydrochloride extended-release tablets treated patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct the acidosis and remove accumulated metformin (metformin hydrochloride is dialyzable with a clearance of up to 170 mL/min under good hemodynamic conditions). Hemodialysis has often resulted in reversal of symptoms and recovery. Educate patients and their families about the symptoms of lactic acidosis and, if these symptoms occur, instruct them to discontinue metformin hydrochloride extended-release tablets and report these symptoms to their healthcare provider. For each of the known and possible risk factors for metformin-associated lactic acidosis, recommendations to reduce the risk of and manage metformin-associated lactic acidosis are provided below: • Renal impairment — The postmarketing metformin-associated lactic acidosis cases primarily occurred in patients with significant renal impairment. The risk of metformin accumulation and metformin-associated lactic acidosis increases with the severity of renal impairment because metformin is substantially excreted by the kidney. Clinical recommendations based upon the patient’s renal function include [see Dosage and Administration (2.2) , Clinical Pharmacology (12.3) ]: o Before initiating metformin hydrochloride extended-release tablets, obtain an estimated glomerular filtration rate (eGFR). o Metformin hydrochloride extended-release tablets are contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2 [see Contraindications (4) ]. o Initiation of metformin hydrochloride extended-release tablets are not recommended in patients with eGFR between 30 to 45 mL/min/1.73 m 2 . o Obtain an eGFR at least annually in all patients taking metformin hydrochloride extended-release tablets. In patients at risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. o In patients taking metformin hydrochloride extended-release tablets whose eGFR falls below 45 mL/min/1.73 m 2 , assess the benefit and risk of continuing therapy. • Drug interactions — The concomitant use of metformin hydrochloride extended-release tablets with specific drugs may increase the risk of metformin-associated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance, or increase metformin accumulation. Consider more frequent monitoring of patients. • Age 65 or greater — The risk of metformin-associated lactic acidosis increases with the patient’s age because elderly patients have a greater likelihood of having hepatic, renal, or cardiac impairment than younger patients. Assess renal function more frequently in elderly patients. • Radiologic studies with contrast — Administration of intravascular iodinated contrast agents in metformin-treated patients has led to an acute decrease in renal function and the occurrence of lactic acidosis. Stop metformin hydrochloride extended-release 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 hepatic impairment, alcoholism or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure, and restart metformin hydrochloride extended-release tablets if renal function is stable. • Surgery and other procedures — Withholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension, and renal impairment. Metformin hydrochloride extended-release tablets should be temporarily discontinued while patients have restricted food and fluid intake. • Hypoxic states — Several of the postmarketing cases of metformin-associated lactic acidosis occurred in the setting of acute congestive heart failure (particularly when accompanied by hypoperfusion and hypoxemia). Cardiovascular collapse (shock), acute myocardial infarction, sepsis, and other conditions associated with hypoxemia have been associated with lactic acidosis and may cause prerenal azotemia. When such an event occurs, discontinue metformin hydrochloride extended-release tablets. • Excessive alcohol intake — Alcohol potentiates the effect of metformin on lactate metabolism. Patients should be warned against excessive alcohol intake while receiving metformin hydrochloride extended-release tablets. • Hepatic impairment — Patients with hepatic impairment have developed cases of metformin-associated lactic acidosis. This may be due to impaired lactate clearance resulting in higher lactate blood levels. Therefore, avoid use of metformin hydrochloride extended-released tablets in patients with clinical or laboratory evidence of hepatic disease. 5.2 Vitamin B 12 Deficiency In metformin hydrochloride tablets clinical trials of 29-week duration, a decrease to subnormal levels of previously normal serum vitamin B 12 levels was observed in approximately 7% of patients. Such decrease, possibly due to interference with B 12 absorption from the B 12 -intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin hydrochloride tablets or vitamin B 12 supplementation. Certain individuals (those with inadequate vitamin B 12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B 12 levels. Measure hematologic parameters on an annual basis and vitamin B 12 at 2 to 3 year intervals in patients on metformin hydrochloride extended-release tablets and manage any abnormalities [see Adverse Reactions (6.1) ]. 5.3 Hypoglycemia with Concomitant Use with Insulin and Insulin Secretagogues Insulin and insulin secretagogues (e.g., sulfonylurea) are known to cause hypoglycemia. Metformin hydrochloride extended-release tablets may increase the risk of hypoglycemia when combined with insulin and/or an insulin secretagogue. Therefore, a lower dose of insulin or insulin secretagogue may be required to minimize the risk of hypoglycemia when used in combination with metformin hydrochloride extended-release tablets [see Drug Interactions (7) ]. 5.4 Macrovascular Outcomes There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with metformin hydrochloride extended-release tablets.

6 ADVERSE REACTIONS The following adverse reactions are also discussed elsewhere in the labeling: • Lactic Acidosis [see Boxed Warning and Warnings and Precautions (5.1) ] • Vitamin B 12 Deficiency [see Warnings and Precautions (5.2) ] • Hypoglycemia [see Warnings and Precautions (5.3) ] For metformin hydrochloride extended-release tablets, the most common adverse reactions (>5%) are diarrhea, nausea/vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Granules Pharmaceuticals Inc. at 1-877-770-3183 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Studies Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Metformin Hydrochloride Extended-Release Tablets In placebo-controlled trials, in adults with type 2 diabetes mellitus, 781 patients were administered metformin hydrochloride extended-release tablets. Adverse reactions reported in greater than 5% of the metformin hydrochloride extended-release tablets patients, and that were more common in metformin hydrochloride extended-release tablets - than placebo-treated patients, are listed in Table 1. Table 1: Adverse Reactions from Clinical Trials of Metformin Hydrochloride Extended-Release Tablets Occurring >5% and More Common than Placebo in Adults with Type 2 Diabetes Mellitus Metformin Hydrochloride Extended-Release Tablets (n=781) Placebo (n=195) Diarrhea 10% 3% Nausea/Vomiting 7% 2% Diarrhea led to discontinuation of metformin hydrochloride extended-release tablets in 0.6% of patients. Additionally, the following adverse reactions were reported in ≥1% to ≤5% of metformin hydrochloride extended-release tablets patients and were more commonly reported with metformin hydrochloride extended-release tablets than placebo: abdominal pain, constipation, distention abdomen, dyspepsia/heartburn, flatulence, dizziness, headache, upper respiratory infection, taste disturbance. 6.2 Postmarketing Experience The following adverse reactions have been identified during post approval use of metformin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cholestatic, hepatocellular, and mixed hepatocellular liver injury have been reported with postmarketing use of metformin.