Drug Facts
Composition & Profile
Identifiers & Packaging
16 HOW SUPPLIED/STORAGE AND HANDLING Metformin Hydrochloride Extended-Release Tablets, USP are supplied as: 500 mg Bottles of 100 NDC 68462-520-01 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 500 mg Bottles of 500 NDC 68462-520-05 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 500 mg Bottles of 1,000 NDC 68462-520-10 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 1,000 mg Bottles of 90 NDC 68462-521-90 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side 1,000 mg Bottles of 100 NDC 68462-521-01 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side 1,000 mg Bottles of 500 NDC 68462-521-05 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature].; Principle Panel Display–500 mg NDC 68462-520-01 Metformin Hydrochloride Extended Release Tablets 500 mg Bottle Label 100 Tablets LBL500mg100; Principle Panel Display–1000 mg NDC 68462-521-90 Metformin Hydrochloride Extended Release Tablets 1000 mg Bottle Label 90 Tablets LBL1000mg90
- 16 HOW SUPPLIED/STORAGE AND HANDLING Metformin Hydrochloride Extended-Release Tablets, USP are supplied as: 500 mg Bottles of 100 NDC 68462-520-01 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 500 mg Bottles of 500 NDC 68462-520-05 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 500 mg Bottles of 1,000 NDC 68462-520-10 white to off-white, oval shaped, coated tablets, imprinted with ‘G520’ on one side and plain on the other side 1,000 mg Bottles of 90 NDC 68462-521-90 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side 1,000 mg Bottles of 100 NDC 68462-521-01 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side 1,000 mg Bottles of 500 NDC 68462-521-05 white to off-white, oval shaped, coated tablets, imprinted with ‘G521’ on one side and plain on the other side Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature].
- Principle Panel Display–500 mg NDC 68462-520-01 Metformin Hydrochloride Extended Release Tablets 500 mg Bottle Label 100 Tablets LBL500mg100
- Principle Panel Display–1000 mg NDC 68462-521-90 Metformin Hydrochloride Extended Release Tablets 1000 mg Bottle Label 90 Tablets LBL1000mg90
Overview
Metformin Hydrochloride Extended-Release Tablets, USP contains the biguanide antihyperglycemic agent metformin in the form of monohydrochloride salt. The chemical name of metformin hydrochloride is N,N-dimethylimidodicarbonimidic diamide hydrochloride. The structural formula is as shown: Metformin hydrochloride is a white crystalline powder with a molecular formula of C 4 H 11 N 5 •HCl and a molecular weight of 165.62 g/mol. Metformin hydrochloride is freely soluble in water, slightly soluble in alcohol, practically insoluble in acetone and in methylene chloride. The pKa of metformin is 2.8 and 11.5 at 32°C. The pH of a 5% aqueous solution of metformin hydrochloride is 6 to 7. Metformin Hydrochloride Extended-Release Tablets, USP contain 500 mg or 1,000 mg of metformin hydrochloride, which is equivalent to 389.93 mg or 779.86 mg metformin, respectively. Each 500 mg and 1,000 mg tablet contains ammonio methacrylate copolymer dispersion type A, ammonio methacrylate copolymer dispersion type B, hypromellose, magnesium stearate, povidone K 30, talc, titanium dioxide, and triethyl citrate. The tablets are imprinted using a water-soluble black ink which contains shellac, black iron oxide, propylene glycol and ammonium hydroxide. Meets USP Dissolution Test 12. structure.jpg
Indications & Usage
Metformin hydrochloride extended-release tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. Metformin hydrochloride extended-release tablets are a biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. ( 1 )
Dosage & Administration
• Starting dose: 500 mg orally once daily with the evening meal ( 2.1 ) • Increase the dose in increments of 500 mg every 1 to 2 weeks, up to a maximum of 2,000 mg once daily with the evening meal. ( 2.1 ) • Patients receiving metformin hydrochloride (HCl) tablets may be switched to metformin hydrochloride extended-release tablets once daily at the same total daily dose, up to 2,000 mg once daily. ( 2.1 ) • Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew. ( 2.1 ) Renal Impairment: • Prior to initiation, assess renal function with estimated glomerular filtration rate (eGFR). ( 2.2 ) • Do not use in patients with eGFR below 30 mL/minute/1.73 m 2 . • Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 . • Assess risk/benefit of continuing metformin hydrochloride extended-release tablets if eGFR falls below 45 mL/minute/1.73 m 2 . • Discontinue if eGFR falls below 30 mL/minute/1.73 m 2 . 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. ( 2.3 ) 2.1 Adult Dosage and Administration • The recommended starting dose of metformin hydrochloride extended-release tablets is 500 mg orally once daily with the evening meal. • Increase the dose in increments of 500 mg every 1 to 2 weeks on the basis of glycemic control and tolerability, up to a maximum of 2,000 mg once daily with the evening meal. • Patients receiving metformin hydrochloride (HCl) may be switched to metformin hydrochloride extended-release tablets once daily at the same total daily dose, up to 2,000 mg once daily. • Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew. • If a dose of metformin hydrochloride extended-release tablet 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. 2.2 Recommendations for Use in 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/minute/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 Contraindications ( 4 ) and Warnings and Precautions ( 5.1 )] . 2.3 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/minute/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 [see Warnings and Precautions ( 5.1 )] .
Warnings & Precautions
• Lactic Acidosis: See boxed warning. ( 5.1 ) • Vitamin B 12 Deficiency: Metformin may lower vitamin B 12 levels. Monitor 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, hypothermia, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin-associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/Liter), 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 HCl is dialyzable, with a clearance of up to 170 mL/minute 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 ) and Clinical Pharmacology ( 12.3 )]: • Before initiating metformin hydrochloride extended-release tablets, obtain an estimated glomerular filtration rate (eGFR). • Metformin hydrochloride extended-release tablets are contraindicated in patients with an eGFR less than 30 mL/minute/1.73 m 2 [see Contraindications ( 4 )] . • Initiation of metformin hydrochloride extended-release tablets are not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 . • Obtain an eGFR at least annually in all patients taking metformin hydrochloride extended-release tablets. In patients at increased risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. • In patients taking metformin hydrochloride extended-release tablets whose eGFR later falls below 45 mL/minute/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 [see Drug Interactions ( 7 )]. Therefore, 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 [see Use in Specific Populations ( 8.5 )]. • Radiological 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/minute/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 also cause prerenal azotemia. When such events occur, discontinue metformin hydrochloride extended-release tablets. • Excessive Alcohol Intake: Alcohol potentiates the effect of metformin on lactate metabolism, and this may increase the risk of metformin-associated lactic acidosis. Warn patients 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-release tablets in patients with clinical or laboratory evidence of hepatic disease. 5.2 Vitamin B 12 Deficiency In clinical trials of 29-week duration with metformin HCl tablets, 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 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.
Boxed Warning
LACTIC ACIDOSIS Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin-associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin-associated lactic acidosis was characterized by elevated blood lactate levels (>5 mmol/Liter), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate/pyruvate ratio, and metformin plasma levels generally >5 mcg/mL [see Warnings and Precautions ( 5.1 )] . Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (e.g., carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment. Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided in the full prescribing information [see Dosage and Administration ( 2.2 ), Contraindications ( 4 ), Warnings and Precautions ( 5.1 ), and Drug Interactions ( 7 )] . If metformin-associated lactic acidosis is suspected, immediately discontinue metformin hydrochloride extended-release tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended [see Warnings and Precautions ( 5.1 )]. WARNING: LACTIC ACIDOSIS See full prescribing information for complete boxed warning. • Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL. ( 5.1 ) • Risk factors include renal impairment, concomitant use of certain drugs, age ≥65 years old, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided in the Full Prescribing Information. ( 5.1 ) • If lactic acidosis is suspected, discontinue metformin hydrochloride extended-release tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended. ( 5.1 )
Contraindications
Metformin hydrochloride extended-release tablets are contraindicated in patients with: • Severe renal impairment (eGFR below 30 mL/minute/1.73 m 2 ) [see Warnings and Precautions ( 5.1 )] . • Known hypersensitivity to metformin. • Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. • Severe renal impairment: (eGFR below 30 mL/minute/1.73 m 2 ) ( 4 , 5.1 ) • Known hypersensitivity to metformin ( 4 ) • Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma ( 4 )
Adverse Reactions
The following adverse reactions are discussed in more detail in other sections of 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 )] Adverse reactions occurring >5% in metformin hydrochloride extended-release tablets clinical trials: hypoglycemia, diarrhea, and nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Glenmark Pharmaceuticals, Inc., USA at 1 (888) 721-7115 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials 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. In clinical trials conducted in the U.S., over 1,000 patients with type 2 diabetes mellitus have been treated with metformin hydrochloride extended-release tablets 1,500 to 2,000 mg/day in active-controlled and placebo-controlled studies with the 500 mg dosage form. In the add-on to sulfonylurea study, patients receiving background glyburide therapy were randomized to receive add-on treatment of either one of three different regimens of metformin hydrochloride extended-release tablets or placebo. In total, 431 patients received metformin hydrochloride extended-release tablets and glyburide and 144 patients received placebo and glyburide. Adverse reactions reported in greater than 5% of patients treated with metformin hydrochloride extended-release tablets that were more common in the combined metformin hydrochloride extended-release tablets and glyburide group than in the placebo and glyburide group are shown in Table 1. In 0.7% of patients treated with metformin hydrochloride extended-release tablets and glyburide, diarrhea was responsible for discontinuation of study medication compared to no patients in the placebo and glyburide group. Table 1: Adverse Reactions Reported by >5% * of Patients for the Combined Metformin Hydrochloride Extended-Release Tablets Groups Versus Placebo Group Adverse Reaction Metformin Hydrochloride Extended-Release Tablets + Glyburide (n = 431) Placebo + Glyburide (n=144) Hypoglycemia 14% 5% Diarrhea 13% 6% Nausea 7% 4% * Adverse reactions that were more common in the metformin hydrochloride extended-release tablets -treated than in the placebo-treated patients. Laboratory Tests Vitamin B 12 Concentrations In clinical trials of 29-week duration with metformin HCl tablets, a decrease to subnormal levels of previously normal serum vitamin B 12 levels was observed in approximately 7% of patients. 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of metformin hydrochloride extended-release tablets. 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.
Drug Interactions
Table 2 presents clinically significant drug interactions with metformin hydrochloride extended-release tablets. Table 2: Clinically Significant Drug Interactions with Metformin Hydrochloride Extended-Release Tablets Carbonic Anhydrase Inhibitors Clinical Impact: Carbonic anhydrase inhibitors frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of these drugs with metformin hydrochloride extended-release tablets may increase the risk for lactic acidosis. Intervention: Consider more frequent monitoring of these patients. Examples: Topiramate, zonisamide, acetazolamide or dichlorphenamide. Drugs that Reduce Metformin Hydrochloride Extended-Release Tablets Clearance Clinical Impact: Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2] / multidrug and toxin extrusion [MATE] inhibitors) could increase systemic exposure to metformin and may increase the risk for lactic acidosis [see Clinical Pharmacology ( 12.3 )]. Intervention: Consider the benefits and risks of concomitant use with metformin hydrochloride extended-release tablets. Examples: Ranolazine, vandetanib, dolutegravir, and cimetidine. Alcohol Clinical Impact: Alcohol is known to potentiate the effect of metformin on lactate metabolism. Intervention: Warn patients against excessive alcohol intake while receiving metformin hydrochloride extended-release tablets. Insulin Secretagogues or Insulin Clinical Impact: Coadministration of metformin hydrochloride extended-release tablets with an insulin secretagogue (e.g., sulfonylurea) or insulin may increase the risk of hypoglycemia. Intervention: Patients receiving an insulin secretagogue or insulin may require lower doses of the insulin secretagogue or insulin. Drugs Affecting Glycemic Control Clinical Impact: Certain drugs tend to produce hyperglycemia and may lead to loss of glycemic control. Intervention: When such drugs are administered to a patient receiving metformin hydrochloride extended-release tablets, observe the patient closely for loss of blood glucose control. When such drugs are withdrawn from a patient receiving metformin hydrochloride extended-release tablets, observe the patient closely for hypoglycemia. Examples: Thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blockers, and isoniazid. • Carbonic anhydrase inhibitors may increase risk of lactic acidosis. Consider more frequent monitoring. ( 7 ) • Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin. Consider the benefits and risks of concomitant use. ( 7 ) • Alcohol can potentiate the effect of metformin on lactate metabolism. Warn patients against excessive alcohol intake. ( 7 )
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