Metformin Hydrochloride

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) ] Common adverse reactions are diarrhea, nausea/vomiting, abdominal pain, constipation, abdomen distention, dyspepsia/heartburn, flatulence, dizziness, headache, upper respiratory infection, taste disturbance. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact ScieGen Pharmaceuticals, Inc. at 1-855-724-3436 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 placebo-controlled trials, 781 patients were administered metformin HCl extended-release tablets. Adverse reactions reported in greater than 5% of the patients treated with metformin HCl extended-release tablets and that were more common than in placebo-treated patients are listed in Table 1. Table 1: Adverse Reactions from Clinical Trials of Metformin HCl Extended-Release Tablets Occurring >5% and More Common than Placebo in Patients with Type 2 Diabetes Mellitus Adverse Reaction Metformin HCl Extended-Release Tablets (n=781) Placebo (n=195) Diarrhea 10% 3% Nausea/Vomiting 7% 2% Diarrhea led to the discontinuation of metformin HCl extended-release tablets in 0.6% of patients. Additionally, the following adverse reactions were reported in 1.0% to 5.0% of patients treated with metformin HCl extended-release tablets and were more commonly reported than in placebo-treated patients: abdominal pain, constipation, abdomen distention, dyspepsia/heartburn, flatulence, dizziness, headache, upper respiratory infection, taste disturbance. 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. 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.

4 CONTRAINDICATIONS Metformin hydrochloride extended-release tablets are contraindicated in patients with: Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) [see Warnings and Precautions (5.1) ] . Hypersensitivity to metformin. Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Severe renal impairment (eGFR below 30 mL/min/1.73 m 2 ) ( 4 , 5.1 ) Hypersensitivity to metformin ( 4 ) Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. ( 4 )

11 DESCRIPTION Metformin hydrochloride extended-release tablets, USP contain the biguanide antihyperglycemic agent, metformin, in the form of monohydrochloride salt. The chemical name of metformin hydrochloride is N, N-dimethylimidodicarbonimidic diamide hydrochloride with a molecular formula of C 4 H 11 N 5 •HCl and a molecular weight of 165.63. Its structural formula is: Metformin hydrochloride is a white to off-white crystalline powder that freely soluble in water, slightly soluble in alcohol and is practically insoluble in acetone and methylene chloride. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68. Metformin hydrochloride extended-release tablets contain 500 mg or 1,000 mg of metformin hydrochloride, USP which is equivalent to 389.93 mg or 779.86 mg metformin, respectively. In addition to the active ingredient metformin HCl, each tablet contains ammonio methacrylate copolymer, hypromellose, magnesium stearate, pregelatinized starch (maize), polyethylene glycol, polyvinylpyrrolidone, silicon dioxide, talc, titanium dioxide and triethyl citrate. Metformin hydrochloride extended-release tablets USP meets USP Dissolution Test 12. Formula

2 DOSAGE AND ADMINISTRATION Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew ( 2.1 ) Starting dose: 500 mg orally once daily with the evening meal ( 2.1 ) Increase the dose in increments of 500 mg weekly, 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 ) 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 ( 2.2 ) Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 ( 2.2 ) Assess risk/benefit of continuing if eGFR falls below 45 mL/minute/1.73 m 2 ( 2.2) Discontinue if eGFR falls below 30 mL/minute/1.73 m 2 ( 2.2 ) 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 Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew. 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 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. 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. 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/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 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/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.

1 INDICATIONS AND USAGE Metformin hydrochloride extended-release tablet is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. Metformin hydrochloride extended-release tablet is a biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. ( 1 )

10 OVERDOSAGE Overdose of metformin HCl has occurred, including ingestion of amounts greater than 50 grams. Hypoglycemia was reported in approximately 10% of cases, but no causal association with metformin has been established. Lactic acidosis has been reported in approximately 32% of metformin overdose cases [ see Warnings and Precautions (5.1) ]. Metformin is dialyzable with a clearance of up to 170 mL/min under good hemodynamic conditions. Therefore, hemodialysis may be useful for removal of accumulated drug from patients in whom metformin overdosage is suspected.

7 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 )

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with type 2 diabetes mellitus, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease. 12.3 Pharmacokinetics Absorption In a multiple-dose crossover study, 23 patients with type 2 diabetes mellitus were administered either metformin hydrochloride extended-release tablets 2,000 mg once a day (after dinner) or metformin HCl tablets 1,000 mg twice a day (after breakfast and after dinner). After 4 weeks of treatment, steady-state pharmacokinetic parameters, area under the concentration-time curve (AUC), time to peak plasma concentration (T max ), and maximum concentration (C max ) were evaluated. The appearance of metformin in plasma from metformin hydrochloride extended-release tablets is slower and more prolonged compared to metformin HCl tablets. Results are presented in Table 3 . Table 3 Metformin Hydrochloride Extended-Release Tablets vs. Metformin HCl Tablets Steady-State Pharmacokinetic Parameters at 4 Weeks Pharmacokinetic Parameters (mean ± SD) Metformin hydrochloride extended-release tablets 2,000 mg (administered q.d. after dinner) Metformin HCl tablets Immediate-release metformin HCl tablets 2,000 mg (1,000 mg b.i.d.) AUC 0 to 24 hr (ng•hr/mL) 26,811 ± 7055 27,371 ± 5,781 T max (hr) 6 (3 to 10) 3 (1 to 8) C max (ng/mL) 2849 ± 797 1820 ± 370 In four single-dose studies and one multiple-dose study, the bioavailability of metformin hydrochloride extended-release tablets 2,000 mg given once daily, in the evening, under fed conditions [as measured by AUC] was similar to the same total daily dose administered as metformin HCl tablets 1,000 mg given twice daily. The geometric mean ratios (metformin hydrochloride extended-release tablets / metformin HCL tablets) of AUC 0 to 24 hr , AUC 0 to 72 hr , and AUC 0 to inf for these five studies ranged from 0.96 to 1.08. In a single-dose, four-period replicate crossover design study, comparing two 500 mg metformin hydrochloride extended-release tablets to one 1,000 mg metformin hydrochloride extended-release tablet administered in the evening with food to 29 healthy male subjects, two 500 mg metformin hydrochloride extended-release tablets were found to be equivalent to one 1,000 mg metformin hydrochloride extended-release tablet. In a study carried out with metformin hydrochloride extended-release tablets, there was a dose-associated increase in metformin exposure over 24 hours following oral administration of 1,000, 1,500, 2,000, and 2,500 mg. In three studies with metformin hydrochloride extended-release tablets using different treatment regimens (2,000 mg after dinner; 1,000 mg after breakfast and after dinner; and 2,500 mg after dinner), the pharmacokinetics of metformin as measured by AUC appeared linear following multiple-dose administration. Effect of food: The extent of metformin absorption (as measured by AUC) from metformin hydrochloride extended-release tablets increased by approximately 60% when given with food. When metformin hydrochloride extended-release tablets was administered with food, C max was increased by approximately 30% and T max was more prolonged compared with the fasting state (6.1 versus 4.0 hours). Distribution The apparent volume of distribution (V/F) of metformin following single oral doses of metformin HCl tablets 850 mg averaged 654 ± 358 L. Metformin is negligibly bound to plasma proteins. Metformin partitions into erythrocytes, most likely as a function of time. Metabolism Intravenous single-dose studies in normal subjects demonstrate that metformin is excreted unchanged in the urine and does not undergo hepatic metabolism (no metabolites have been identified in humans) nor biliary excretion. Elimination Renal clearance (see Table 4 ) is approximately 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution. Specific Populations Renal Impairment: In patients with decreased renal function the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased (see Table 4 ) [ See Dosage and Administration (2.2) , Contraindications (4) , and Warnings and Precautions (5.1) and Use in Specific Populations (8.6) ]. Hepatic Impairment No pharmacokinetic studies of metformin have been conducted in patients with hepatic impairment [ See Warnings and Precautions (5.1) and Use in Specific Populations (8.7) ] . Geriatrics Limited data from controlled pharmacokinetic studies of metformin HCl tablets in healthy elderly subjects suggest that total plasma clearance of metformin is decreased, the half-life is prolonged, and C max is increased, compared to healthy young subjects. It appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function (see Table 4 ). [ See Warnings and Precautions (5.1) and Use in Specific Populations (8.5) ]. Table 4: Select Mean (±S.D.) Metformin Pharmacokinetic Parameters Following Single or Multiple Oral Doses of Metformin HCl Tablets a All doses given fasting except the first 18 doses of the multiple dose studies b Peak plasma concentration c Time to peak plasma concentration d Combined results (average means) of five studies: mean age 32 years (range 23 to 59 years) e Kinetic study done following dose 19, given fasting f Elderly subjects, mean age 71 years (range 65 to 81 years) g CLcr = creatinine clearance normalized to body surface area of 1.73 m 2 Subject Groups: Metformin HCl dose a (number of subjects) C max b (mcg/mL) T max c (hr) Renal Clearance (mL/min) Healthy, nondiabetic adults: 500 mg single dose (24) 850 mg single dose (74) d 850 mg three times daily for 19 doses e (9) 1.03 (±0.33) 1.60 (±0.38) 2.01 (±0.42) 2.75 (±0.81) 2.64 (±0.82) 1.79 (±0.94) 600 (±132) 552 (±139) 642 (±173) Adults with type 2 diabetes mellitus: 850 mg single dose (23) 850 mg three times daily for 19 doses e (9) 1.48 (±0.5) 1.90 (±0.62) 3.32 (±1.08) 2.01 (±1.22) 491 (±138) 550 (±160) Elderly f , healthy nondiabetic adults: 850 mg single dose (12) 2.45 (±0.70) 2.71 (±1.05) 412 (±98) Renal-impaired adults: 850 mg single dose Mild (CLcr g 61 to 90 mL/min) (5) Moderate (CL cr 31 to 60 mL/min) (4) Severe (CL cr 10 to 30 mL/min) (6) 1.86 (±0.52) 4.12 (±1.83) 3.93 (±0.92) 3.20 (±0.45) 3.75 (±0.50) 4.01 (±1.10) 384 (±122) 108 (±57) 130 (±90) Pediatrics: There are no available pharmacokinetic data with metformin hydrochloride extended-release tablets in pediatric patients. Gender: Metformin pharmacokinetic parameters did not differ significantly between normal subjects and patients with type 2 diabetes mellitus when analyzed according to gender (males=19, females=16). Race: No studies of metformin pharmacokinetic parameters according to race have been performed. Drug Interactions In Vivo Assessment of Drug Interactions: Table 5: Effect of Coadministered Drug on Plasma Metformin Systemic Exposure Coadministered Drug Dose of Coadministered Drug All metformin HCl and coadministered drugs were given as single doses Dose of Metformin HCl Geometric Mean Ratio (ratio with/without coadministered drug) No Effect=1.00 AUC AUC=AUC inf C max No dosing adjustments required for the following: Glyburide 5 mg 850 mg metformin 0.91 Ratio of arithmetic means 0.93 Furosemide 40 mg 850 mg metformin 1.09 1.22 Nifedipine 10 mg 850 mg metformin 1.16 1.21 Propranolol 40 mg 850 mg metformin 0.90 0.94 Ibuprofen 400 mg 850 mg metformin 1.05 1.07 Cationic drugs eliminated by renal tubular secretion may reduce metformin elimination [see Warnings and Precautions (5.1) and Drug Interactions (7) .] Cimetidine 400 mg 850 mg metformin 1.40 1.61 Carbonic anhydrase inhibitors may cause metabolic acidosis [ see Warnings and Precautions (5.1) and Drug Interactions (7) .] Topiramate 100 mg At steady state with topiramate 100 mg every 12 hours and metformin 500 mg every 12 hours; AUC=AUC 0-12h 500 mg metformin 1.25 1.17 Table 6: Effect of Metformin on Coadministered Drug Systemic Exposure Coadministered Drug Dose of Coadministered Drug All metformin HCl and coadministered drugs were given as single doses Dose of Metformin HCl Geometric Mean Ratio (ratio with/without coadministered drug) No Effect=1.00 AUC AUC=AUC inf unless otherwise noted C max No dosing adjustments required for the following: Glyburide 5 mg 850 mg glyburide 0.78 Ratio of arithmetic means, p-value of difference <0.05 0.63 Furosemide 40 mg 850 mg furosemide 0.87 0.69 Nifedipine 10 mg 850 mg nifedipine 1.10 AUC 0-24hr reported 1.08 Propranolol 40 mg 850 mg propranolol 1.01 1.02 Ibuprofen 400 mg 850 mg ibuprofen 0.97 Ratio of arithmetic means 1.01 Cimetidine 400 mg 850 mg cimetidine 0.95 1.01

12.1 Mechanism of Action Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with type 2 diabetes mellitus, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease.

12.3 Pharmacokinetics Absorption In a multiple-dose crossover study, 23 patients with type 2 diabetes mellitus were administered either metformin hydrochloride extended-release tablets 2,000 mg once a day (after dinner) or metformin HCl tablets 1,000 mg twice a day (after breakfast and after dinner). After 4 weeks of treatment, steady-state pharmacokinetic parameters, area under the concentration-time curve (AUC), time to peak plasma concentration (T max ), and maximum concentration (C max ) were evaluated. The appearance of metformin in plasma from metformin hydrochloride extended-release tablets is slower and more prolonged compared to metformin HCl tablets. Results are presented in Table 3 . Table 3 Metformin Hydrochloride Extended-Release Tablets vs. Metformin HCl Tablets Steady-State Pharmacokinetic Parameters at 4 Weeks Pharmacokinetic Parameters (mean ± SD) Metformin hydrochloride extended-release tablets 2,000 mg (administered q.d. after dinner) Metformin HCl tablets Immediate-release metformin HCl tablets 2,000 mg (1,000 mg b.i.d.) AUC 0 to 24 hr (ng•hr/mL) 26,811 ± 7055 27,371 ± 5,781 T max (hr) 6 (3 to 10) 3 (1 to 8) C max (ng/mL) 2849 ± 797 1820 ± 370 In four single-dose studies and one multiple-dose study, the bioavailability of metformin hydrochloride extended-release tablets 2,000 mg given once daily, in the evening, under fed conditions [as measured by AUC] was similar to the same total daily dose administered as metformin HCl tablets 1,000 mg given twice daily. The geometric mean ratios (metformin hydrochloride extended-release tablets / metformin HCL tablets) of AUC 0 to 24 hr , AUC 0 to 72 hr , and AUC 0 to inf for these five studies ranged from 0.96 to 1.08. In a single-dose, four-period replicate crossover design study, comparing two 500 mg metformin hydrochloride extended-release tablets to one 1,000 mg metformin hydrochloride extended-release tablet administered in the evening with food to 29 healthy male subjects, two 500 mg metformin hydrochloride extended-release tablets were found to be equivalent to one 1,000 mg metformin hydrochloride extended-release tablet. In a study carried out with metformin hydrochloride extended-release tablets, there was a dose-associated increase in metformin exposure over 24 hours following oral administration of 1,000, 1,500, 2,000, and 2,500 mg. In three studies with metformin hydrochloride extended-release tablets using different treatment regimens (2,000 mg after dinner; 1,000 mg after breakfast and after dinner; and 2,500 mg after dinner), the pharmacokinetics of metformin as measured by AUC appeared linear following multiple-dose administration. Effect of food: The extent of metformin absorption (as measured by AUC) from metformin hydrochloride extended-release tablets increased by approximately 60% when given with food. When metformin hydrochloride extended-release tablets was administered with food, C max was increased by approximately 30% and T max was more prolonged compared with the fasting state (6.1 versus 4.0 hours). Distribution The apparent volume of distribution (V/F) of metformin following single oral doses of metformin HCl tablets 850 mg averaged 654 ± 358 L. Metformin is negligibly bound to plasma proteins. Metformin partitions into erythrocytes, most likely as a function of time. Metabolism Intravenous single-dose studies in normal subjects demonstrate that metformin is excreted unchanged in the urine and does not undergo hepatic metabolism (no metabolites have been identified in humans) nor biliary excretion. Elimination Renal clearance (see Table 4 ) is approximately 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution. Specific Populations Renal Impairment: In patients with decreased renal function the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased (see Table 4 ) [ See Dosage and Administration (2.2) , Contraindications (4) , and Warnings and Precautions (5.1) and Use in Specific Populations (8.6) ]. Hepatic Impairment No pharmacokinetic studies of metformin have been conducted in patients with hepatic impairment [ See Warnings and Precautions (5.1) and Use in Specific Populations (8.7) ] . Geriatrics Limited data from controlled pharmacokinetic studies of metformin HCl tablets in healthy elderly subjects suggest that total plasma clearance of metformin is decreased, the half-life is prolonged, and C max is increased, compared to healthy young subjects. It appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function (see Table 4 ). [ See Warnings and Precautions (5.1) and Use in Specific Populations (8.5) ]. Table 4: Select Mean (±S.D.) Metformin Pharmacokinetic Parameters Following Single or Multiple Oral Doses of Metformin HCl Tablets a All doses given fasting except the first 18 doses of the multiple dose studies b Peak plasma concentration c Time to peak plasma concentration d Combined results (average means) of five studies: mean age 32 years (range 23 to 59 years) e Kinetic study done following dose 19, given fasting f Elderly subjects, mean age 71 years (range 65 to 81 years) g CLcr = creatinine clearance normalized to body surface area of 1.73 m 2 Subject Groups: Metformin HCl dose a (number of subjects) C max b (mcg/mL) T max c (hr) Renal Clearance (mL/min) Healthy, nondiabetic adults: 500 mg single dose (24) 850 mg single dose (74) d 850 mg three times daily for 19 doses e (9) 1.03 (±0.33) 1.60 (±0.38) 2.01 (±0.42) 2.75 (±0.81) 2.64 (±0.82) 1.79 (±0.94) 600 (±132) 552 (±139) 642 (±173) Adults with type 2 diabetes mellitus: 850 mg single dose (23) 850 mg three times daily for 19 doses e (9) 1.48 (±0.5) 1.90 (±0.62) 3.32 (±1.08) 2.01 (±1.22) 491 (±138) 550 (±160) Elderly f , healthy nondiabetic adults: 850 mg single dose (12) 2.45 (±0.70) 2.71 (±1.05) 412 (±98) Renal-impaired adults: 850 mg single dose Mild (CLcr g 61 to 90 mL/min) (5) Moderate (CL cr 31 to 60 mL/min) (4) Severe (CL cr 10 to 30 mL/min) (6) 1.86 (±0.52) 4.12 (±1.83) 3.93 (±0.92) 3.20 (±0.45) 3.75 (±0.50) 4.01 (±1.10) 384 (±122) 108 (±57) 130 (±90) Pediatrics: There are no available pharmacokinetic data with metformin hydrochloride extended-release tablets in pediatric patients. Gender: Metformin pharmacokinetic parameters did not differ significantly between normal subjects and patients with type 2 diabetes mellitus when analyzed according to gender (males=19, females=16). Race: No studies of metformin pharmacokinetic parameters according to race have been performed. Drug Interactions In Vivo Assessment of Drug Interactions: Table 5: Effect of Coadministered Drug on Plasma Metformin Systemic Exposure Coadministered Drug Dose of Coadministered Drug All metformin HCl and coadministered drugs were given as single doses Dose of Metformin HCl Geometric Mean Ratio (ratio with/without coadministered drug) No Effect=1.00 AUC AUC=AUC inf C max No dosing adjustments required for the following: Glyburide 5 mg 850 mg metformin 0.91 Ratio of arithmetic means 0.93 Furosemide 40 mg 850 mg metformin 1.09 1.22 Nifedipine 10 mg 850 mg metformin 1.16 1.21 Propranolol 40 mg 850 mg metformin 0.90 0.94 Ibuprofen 400 mg 850 mg metformin 1.05 1.07 Cationic drugs eliminated by renal tubular secretion may reduce metformin elimination [see Warnings and Precautions (5.1) and Drug Interactions (7) .] Cimetidine 400 mg 850 mg metformin 1.40 1.61 Carbonic anhydrase inhibitors may cause metabolic acidosis [ see Warnings and Precautions (5.1) and Drug Interactions (7) .] Topiramate 100 mg At steady state with topiramate 100 mg every 12 hours and metformin 500 mg every 12 hours; AUC=AUC 0-12h 500 mg metformin 1.25 1.17 Table 6: Effect of Metformin on Coadministered Drug Systemic Exposure Coadministered Drug Dose of Coadministered Drug All metformin HCl and coadministered drugs were given as single doses Dose of Metformin HCl Geometric Mean Ratio (ratio with/without coadministered drug) No Effect=1.00 AUC AUC=AUC inf unless otherwise noted C max No dosing adjustments required for the following: Glyburide 5 mg 850 mg glyburide 0.78 Ratio of arithmetic means, p-value of difference <0.05 0.63 Furosemide 40 mg 850 mg furosemide 0.87 0.69 Nifedipine 10 mg 850 mg nifedipine 1.10 AUC 0-24hr reported 1.08 Propranolol 40 mg 850 mg propranolol 1.01 1.02 Ibuprofen 400 mg 850 mg ibuprofen 0.97 Ratio of arithmetic means 1.01 Cimetidine 400 mg 850 mg cimetidine 0.95 1.01

20220321

2

3 DOSAGE FORMS AND STRENGTHS Metformin hydrochloride extended-release tablets, USP 500 mg are white to off white, oval shape, film-coated tablet debossed with "503" on one side and plain on the other side. Metformin hydrochloride extended-release tablets, USP 1000 mg are white to off white, oval shape, film-coated tablets debossed with "504" on one side and plain on the other side. Extended-Release Tablets: 500 mg and 1,000 mg ( 3 )

Metformin Hydrochloride Metformin Hydrochloride Extended-Release Tablets AMMONIO METHACRYLATE COPOLYMER TYPE A HYPROMELLOSE, UNSPECIFIED MAGNESIUM STEARATE STARCH, CORN POLYETHYLENE GLYCOL, UNSPECIFIED COPOVIDONE K25-31 SILICON DIOXIDE TALC TITANIUM DIOXIDE TRIETHYL CITRATE METFORMIN HYDROCHLORIDE METFORMIN White to off white 503 Metformin Hydrochloride Metformin Hydrochloride Extended-Release Tablets AMMONIO METHACRYLATE COPOLYMER TYPE A HYPROMELLOSE, UNSPECIFIED MAGNESIUM STEARATE STARCH, CORN POLYETHYLENE GLYCOL, UNSPECIFIED COPOVIDONE K25-31 SILICON DIOXIDE TALC TITANIUM DIOXIDE TRIETHYL CITRATE METFORMIN HYDROCHLORIDE METFORMIN White to off white 504

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term carcinogenicity studies have been performed in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1,500 mg/kg/day, respectively. These doses are both approximately 3 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons. No evidence of carcinogenicity with metformin was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day. There was no evidence of a mutagenic potential of metforminin the following in vitro tests: Ames test (S. typhimurium), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vivo mouse micronucleus test were also negative. Fertility of male or female rats was unaffected by metformin when administered at doses as high as 600 mg/kg/day, which is approximately 2 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons.

13 NONCLINICAL TOXICOLOGY 13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term carcinogenicity studies have been performed in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1,500 mg/kg/day, respectively. These doses are both approximately 3 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons. No evidence of carcinogenicity with metformin was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day. There was no evidence of a mutagenic potential of metforminin the following in vitro tests: Ames test (S. typhimurium), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vivo mouse micronucleus test were also negative. Fertility of male or female rats was unaffected by metformin when administered at doses as high as 600 mg/kg/day, which is approximately 2 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons.

ANDA214629

Metformin Hydrochloride

Metformin Hydrochloride Extended-Release Tablets

50228-504

HUMAN PRESCRIPTION DRUG

ORAL

PACKAGE LABEL.PRINCIPAL DISPLAY PANEL NDC 50228-503-30 Metformin Hydrochloride Extended-Release Tablets, USP 500 mg 30 Tablets Rx Only ScieGen Pharmaceuticals Inc. NDC 50228-503-60 Metformin Hydrochloride Extended-Release Tablets, USP 500 mg 60 Tablets Rx Only ScieGen Pharmaceuticals Inc. NDC 50228-503-05 Metformin Hydrochloride Extended-Release Tablets, USP 500 mg 500 Tablets Rx Only ScieGen Pharmaceuticals Inc. NDC 50228-504-30 Metformin Hydrochloride Extended-Release Tablets, USP 1,000 mg 30 Tablets Rx Only ScieGen Pharmaceuticals Inc. NDC 50228-504-60 Metformin Hydrochloride Extended-Release Tablets, USP 1,000 mg 60 Tablets Rx Only ScieGen Pharmaceuticals Inc. NDC 50228-504-05 Metformin Hydrochloride Extended-Release Tablets, USP 1,000 mg 500 Tablets Rx Only ScieGen Pharmaceuticals Inc. Container Label 500mg-60s Container Label Container Label 1000mg-60s Container Label

17 PATIENT COUNSELING INFORMATION Advise the patient to read the FDA-approved patient labeling ( Patient Information ). Lactic Acidosis: Explain the risks of lactic acidosis, its symptoms, and conditions that predispose to its development. Advise patients to discontinue metformin hydrochloride extended-release tablets immediately and to promptly notify their healthcare provider if unexplained hyperventilation, myalgias, malaise, unusual somnolence or other nonspecific symptoms occur. Counsel patients against excessive alcohol intake and inform patients about importance of regular testing of renal function while receiving metformin hydrochloride extended-release tablets. Instruct patients to inform their doctor that they are taking metformin hydrochloride extended-release tablets prior to any surgical or radiological procedure, as temporary discontinuation may be required [ see Warnings and Precautions (5.1) ]. Hypoglycemia: Inform patients that hypoglycemia may occur when metformin hydrochloride extended-release tablets are coadministered with oral sulfonylureas and insulin. Explain to patients receiving concomitant therapy the risks of hypoglycemia, its symptoms and treatment, and conditions that predispose to its development [ see Warnings and Precautions (5.3) ]. Vitamin B 12 Deficiency: Inform patients about importance of regular hematological parameters while receiving metformin hydrochloride extended-release tablets [see Warnings and Precautions (5.2) ] . Females of Reproductive Age: Inform females that treatment with metformin hydrochloride extended-release tablets may result in ovulation in some premenopausal anovulatory women which may lead to unintended pregnancy [see Use in Specific Populations (8.3) ]. Administration Information: Inform patients that metformin hydrochloride extended-release tablets must be swallowed whole and not crushed, cut, or chewed, and that the inactive ingredients may occasionally be eliminated in the feces as a soft mass that may resemble the original tablet. Manufactured by: ScieGen Pharmaceuticals Inc Hauppauge, NY 11788 USA Rev. 8/2021

14 CLINICAL STUDIES A 24-week, double-blind, placebo-controlled study of metformin HCl extended-release tablets, taken once daily with the evening meal, was conducted in patients with type 2 diabetes mellitus who had failed to achieve glycemic control with diet and exercise. Patients entering the study had a mean baseline HbA 1c of 8.0% and a mean baseline FPG of 176 mg/dL. The treatment dose was increased to 1,500 mg once daily if at Week 12 HbA 1c was ≥7.0% but <8.0% (patients with HbA 1c ≥8.0% were discontinued from the study). At the final visit (24-week), mean HbA 1c had increased 0.2% from baseline in placebo patients and decreased 0.6% with metformin HCl extended-release tablets. A 16-week, double-blind, placebo-controlled, dose-response study of metformin HCl extended-release tablets, taken once daily with the evening meal or twice daily with meals, was conducted in patients with type 2 diabetes mellitus who had failed to achieve glycemic control with diet and exercise. The results are shown in Table 7. Table 7: Mean Changes from Baseline* in HbA1c and Fasting Plasma Glucose at Week 16 Comparing Metformin HCl Extended-Release Tablets vs Placebo in Patients with Type 2 Diabetes Mellitus a All comparisons versus Placebo Metformin HCl Extended-Release Tablets Placebo 500 mg Once Daily 1,000 mg Once Daily 1,500 mg Once Daily 2,000 mg Once Daily 1,000 mg Twice Daily Hemoglobin A1c (%) Baseline Change at FINAL VISIT p-value a (n=115) 8.2 –0.4 <0.001 (n=115) 8.4 –0.6 <0.001 (n=111) 8.3 –0.9 <0.001 (n=125) 8.4 –0.8 <0.001 (n=112) 8.4 –1.1 <0.001 (n=111) 8.4 0.1 – FPG (mg/dL) Baseline Change at FINAL VISIT p-value a (n=126) 182.7 –15.2 <0.001 (n=118) 183.7 –19.3 <0.001 (n=120) 178.9 –28.5 <0.001 (n=132) 181.0 –29.9 <0.001 (n=122) 181.6 –33.6 <0.001 (n=113) 179.6 7.6 – Mean baseline body weight was 193 lbs, 192 lbs, 188 lbs, 196 lbs, 193 lbs and 194 lbs in the metformin HCl extended-release tablets 500 mg, 1,000 mg, 1,500 mg, and 2,000 mg once daily, 1,000 mg twice daily and placebo arms, respectively. Mean change in body weight from baseline to week 16 was -1.3 lbs, -1.3 lbs, -0.7 lbs, -1.5 lbs, -2.2 lbs and 1.8 lbs, respectively. A 24-week, double-blind, randomized study of metformin HCl extended-release tablets, taken once daily with the evening meal, and metformin HCl tablets, taken twice daily (with breakfast and evening meal), was conducted in patients with type 2 diabetes mellitus who had been treated with metformin HCl tablets 500 mg twice daily for at least 8 weeks prior to study entry. The results are shown in Table 8. Table 8: Mean Changes from Baseline* in HbA1c and Fasting Plasma Glucose at Week 24 Comparing Metformin HCl Extended-Release vs Metformin HCl in Patients with Type 2 Diabetes Mellitus †a n=68 Metformin HCl 500 mg Twice Daily Metformin HCl Extended-Release 1,000 mg Once Daily 1,500 mg Once Daily Hemoglobin A1c (%) Baseline Change at FINAL VISIT (95% CI) (n=67) 7.06 0.14 a (–0.04, 0.31) (n=72) 6.99 0.27 (0.11, 0.43) (n=66) 7.02 0.13 (–0.02, 0.28) FPG (mg/dL) Baseline Change at FINAL VISIT (95% CI) (n=69) 127.2 14.0 (7.0, 21.0) (n=72) 131.0 11.5 (4.4, 18.6) (n=70) 131.4 7.6 (1.0, 14.2) Mean baseline body weight was 210 lbs, 203 lbs and 193 lbs in the metformin HCl tablets 500 mg twice daily, and metformin HCl extended-release tablets 1,000 mg and 1,500 mg once daily arms, respectively. Mean change in body weight from baseline to week 24 was 0.9 lbs, 1.1 lbs and 0.9 lbs, respectively.

8.5 Geriatric Use Controlled clinical studies of metformin hydrochloride extended-release tablets did not include sufficient numbers of elderly patients to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy and the higher risk of lactic acidosis. Assess renal function more frequently in elderly patients [ see Warnings and Precautions (5.1) ].

8.4 Pediatric Use Safety and effectiveness of metformin hydrochloride extended-release tablets in pediatric patients have not been established.

8.1 Pregnancy Risk Summary Limited data with metformin hydrochloride extended-release tablets in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. Published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk [ see Data ]. There are risks to the mother and fetus associated with poorly controlled diabetes mellitus in pregnancy [ see Clinical Considerations ]. No adverse developmental effects were observed when metformin was administered to pregnant Sprague Dawley rats and rabbits during the period of organogenesis at doses up to 2- and 5- times, respectively, a 2550 mg clinical dose, based on body surface area [ see Data ]. The estimated background risk of major birth defects is 6 to 10% in women with pre-gestational diabetes mellitus with an HbA1C >7 and has been reported to be as high as 20 to 25% in women with a HbA1C >10. The estimated background risk of miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Clinical Considerations Disease-associated maternal and/or embryo/fetal risk Poorly-controlled diabetes mellitus in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, stillbirth and delivery complications. Poorly controlled diabetes mellitus increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity. Data Human Data Published data from post-marketing studies have not reported a clear association with metformin and major birth defects, miscarriage, or adverse maternal or fetal outcomes when metformin was used during pregnancy. However, these studies cannot definitely establish the absence of any metformin-associated risk because of methodological limitations, including small sample size and inconsistent comparator groups. Animal Data Metformin HCl did not adversely affect development outcomes when administered to pregnant rats and rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 5 times a 2550 mg clinical dose based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin.

8 USE IN SPECIFIC POPULATIONS Females and Males of Reproductive Potential: Advise premenopausal females of the potential for an unintended pregnancy. ( 8.3 ) Geriatric Use: Assess renal function more frequently. ( 8.5 ) Hepatic Impairment: Avoid use in patients with hepatic impairment. ( 8.7 ) 8.1 Pregnancy Risk Summary Limited data with metformin hydrochloride extended-release tablets in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. Published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk [ see Data ]. There are risks to the mother and fetus associated with poorly controlled diabetes mellitus in pregnancy [ see Clinical Considerations ]. No adverse developmental effects were observed when metformin was administered to pregnant Sprague Dawley rats and rabbits during the period of organogenesis at doses up to 2- and 5- times, respectively, a 2550 mg clinical dose, based on body surface area [ see Data ]. The estimated background risk of major birth defects is 6 to 10% in women with pre-gestational diabetes mellitus with an HbA1C >7 and has been reported to be as high as 20 to 25% in women with a HbA1C >10. The estimated background risk of miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Clinical Considerations Disease-associated maternal and/or embryo/fetal risk Poorly-controlled diabetes mellitus in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, stillbirth and delivery complications. Poorly controlled diabetes mellitus increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity. Data Human Data Published data from post-marketing studies have not reported a clear association with metformin and major birth defects, miscarriage, or adverse maternal or fetal outcomes when metformin was used during pregnancy. However, these studies cannot definitely establish the absence of any metformin-associated risk because of methodological limitations, including small sample size and inconsistent comparator groups. Animal Data Metformin HCl did not adversely affect development outcomes when administered to pregnant rats and rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 5 times a 2550 mg clinical dose based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin. 8.2 Lactation Risk Summary Limited published studies report that metformin is present in human milk [ see Data ]. However, there is insufficient information to determine the effects of metformin on the breastfed infant and no available information on the effects of metformin on milk production. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for metformin hydrochloride extended-release tablets and any potential adverse effects on the breastfed child from metformin hydrochloride extended-release tablets or from the underlying maternal condition. Data Published clinical lactation studies report that metformin is present in human milk which resulted in infant doses approximately 0.11% to 1% of the maternal weight-adjusted dosage and a milk/plasma ratio ranging between 0.13 and 1. However, the studies were not designed to definitely establish the risk of use of metformin during lactation because of small sample size and limited adverse event data collected in infants. 8.3 Females and Males of Reproductive Potential Discuss the potential for unintended pregnancy with premenopausal women as therapy with metformin hydrochloride extended-release tablets may result in ovulation in some anovulatory women. 8.4 Pediatric Use Safety and effectiveness of metformin hydrochloride extended-release tablets in pediatric patients have not been established. 8.5 Geriatric Use Controlled clinical studies of metformin hydrochloride extended-release tablets did not include sufficient numbers of elderly patients to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy and the higher risk of lactic acidosis. Assess renal function more frequently in elderly patients [ see Warnings and Precautions (5.1) ]. 8.6 Renal Impairment Metformin is substantially excreted by the kidney, and the risk of metformin accumulation and lactic acidosis increases with the degree of renal impairment. Metformin hydrochloride extended-release tablets are contraindicated in severe renal impairment, patients with an estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m 2 [ see Dosage and Administration (2.2) , Contraindications (4) , Warnings and Precautions (5.1) , and Clinical Pharmacology (12.3) ]. 8.7 Hepatic Impairment Use of metformin in patients with hepatic impairment has been associated with some cases of lactic acidosis. Metformin hydrochloride extended-release tablets are not recommended in patients with hepatic impairment [ see Warnings and Precautions (5.1) ].

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied Metformin hydrochloride extended-release tablets are supplied as: 500 mg Bottles of 30 NDC 50228-503-30 White to off white, oval shape, film-coated tablet debossed with "503" on one side and plain on the other side. Bottles of 60 NDC 50228-503-60 Bottles of 500 NDC 50228-503-05 1,000 mg Bottles of 30 NDC 50228-504-30 White to off white, oval shape, film-coated tablets debossed with "504" on one side and plain on the other side. Bottles of 60 NDC 50228-504-60 Bottles of 500 NDC 50228-504-05 16.2 Storage Store at 20°C to 25°C (68°F to 77°F) [See USP Controlled Room Temperature] excursions permitted to 15°C to 30°C (59°F to 86°F). Avoid excessive heat and humidity. Keep tightly closed (protect from moisture). Protect from light.

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 [ see Dosage and Administration (2.2) , Contraindications (4) , Warnings and Precautions (5.1) ] . If metformin-associated lactic acidosis is suspected, immediately discontinue metformin hydrochloride extended-release tablet 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 tablet and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended. ( 5.1 )