METFORMIN HYDROCHLORIDE

Metformin hydrochloride tablets, USP contain the antihyperglycemic agent metformin, which is a biguanide, in the form of monohydrochloride. The chemical name of metformin hydrochloride is N,N- dimethylimidodicarbonimidic diamide hydrochloride. The structural formula is as shown below: Metformin hydrochloride, USP is a white to off-white crystalline compound with a molecular formula of C 4 H 11 N 5 • HCl and a molecular weight of 165.63. Metformin hydrochloride is freely soluble in water, slightly soluble in alcohol, practically insoluble in acetone and in methylene chloride. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68. Metformin hydrochloride tablets, USP contain 500 mg, 850 mg, or 1000 mg of metformin hydrochloride. Each tablet contains the inactive ingredients povidone (K-30), Povidone (K-90), pregelatinized starch, and magnesium stearate. In addition, the coating for the tablet contains artificial blackberry flavor, hypromellose, macrogol and titanium dioxide. structural formula

INDICATIONS & USAGE Metformin hydrochloride tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. Metformin hydrochloride tablets are biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. ( 1 )

DOSAGE & ADMINISTRATION Adult Dosage for metformin hydrochloride tablets: • Starting dose: 500 mg orally twice a day or 850 mg once a day, with meals ( 2.1 ) • Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks, up to a maximum dose of 2550 mg per day, given in divided doses ( 2.1 ) • Doses above 2000 mg may be better tolerated given 3 times a day with meals ( 2.1 ) Pediatric Dosage for metformin hydrochloride tablets: • Starting dose: 500 mg orally twice a day, with meals ( 2.2 ) • Increase dosage in increments of 500 mg weekly up to a maximum of 2000 mg per day, given in divided doses twice daily ( 2.2 ) Renal Impairment: • Prior to initiation, assess renal function with estimated glomerular filtration rate (eGFR) ( 2.3 ) • Do not use in patients with eGFR below 30 mL/minute/1.73 m 2 ( 2.3 ) • Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m 2 ( 2.3 ) • Assess risk/benefit of continuing if eGFR falls below 45 mL/minute/1.73 m 2 ( 2.3 ) • Discontinue if eGFR falls below 30 mL/minute/1.73 m 2 ( 2.3 ) 2.1 Adult Dosage Metformin Hydrochloride Tablets • The recommended starting dose of metformin hydrochloride tablets are 500 mg orally twice a day or 850 mg once a day, given with meals. • Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks on the basis of glycemic control and tolerability, up to a maximum dose of 2550 mg per day, given in divided doses. • Doses above 2000 mg may be better tolerated given 3 times a day with meals. 2.2 Pediatric Dosage for metformin hydrochloride tablets • The recommended starting dose of metformin hydrochloride tablets for pediatric patients 10 years of age and older is 500 mg orally twice a day, given with meals. • Increase dosage in increments of 500 mg weekly on the basis of glycemic control and tolerability, up to a maximum of 2000 mg per day, given in divided doses twice daily. 2.3 Recommendations for Use in Renal Impairment • Assess renal function prior to initiation of metformin hydrochloride tablets and periodically thereafter. • Metformin hydrochloride tablets are contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m 2 . • Initiation of metformin hydrochloride tablets in patients with an eGFR between 30 to 45 mL/minute/1.73 m 2 is not recommended. • In patients taking metformin hydrochloride tablets whose eGFR later falls below 45 mL/min/1.73 m 2 , assess the benefit risk of continuing therapy. • Discontinue metformin hydrochloride tablets if the patient’s eGFR later falls below 30 mL/minute/1.73 m 2 [ see Warnings and Precautions (5.1) ] . 2.4 Discontinuation for Iodinated Contrast Imaging Procedures Discontinue metformin hydrochloride tablets at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m 2 ; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart metformin hydrochloride tablets if renal function is stable.

Metformin hydrochloride 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 )

The following adverse reactions are also discussed elsewhere in the labeling: • Lactic Acidosis [ see Boxed Warning and Warnings and Precautions (5.1) ]. • Vitamin B12 Deficiency [ see Warnings and Precautions (5.2) ]. • Hypoglycemia [ see Warnings and Precautions (5.3) For metformin hydrochloride tablets, the most common adverse reactions (>5.0%) 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 Tablets In a U.S. clinical trial of metformin hydrochloride tablets in patients with type 2 diabetes mellitus, a total of 141 patients received metformin hydrochloride tablets up to 2550 mg per day. Adverse reactions reported in greater than 5% of metformin hydrochloride tablets treated patients and that were more common than in placebo-treated patients, are listed in Table 1. Table 1: Adverse Reactions from a Clinical Trial of Metformin Hydrochloride TabletsOccurring >5% and More Common than Placebo in Patients with Type 2 Diabetes Mellitus Metformin Hydrochloride Tablets (n=141) Placebo (n=145) Diarrhea 53% 12% Nausea/Vomiting 26% 8% Flatulence 12% 6% Asthenia 9% 6% Indigestion 7% 4% Abdominal Discomfort 6% 5% Headache 6% 5% Diarrhea led to discontinuation of metformin hydrochloride tablets in 6% of patients. Additionally, the following adverse reactions were reported in ≥1 % to ≤5% of metformin hydrochloride tablets treated patients and were more commonly reported with metformin hydrochloride tablets than placebo: abnormal stools, hypoglycemia, myalgia, lightheaded, dyspnea, nail disorder, rash, sweating increased, taste disorder, chest discomfort, chills, flu syndrome, flushing, palpitation. 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. Pediatric Patients In clinical trials with metformin hydrochloride tablets in pediatric patients with type 2 diabetes mellitus, the profile of adverse reactions was similar to that observed in adults. 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.

Table 3 presents clinically significant drug interactions with metformin hydrochloride tablets. Table 3: Clinically Significant Drug Interactions with Metformin Hydrochloride 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 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 tablet 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 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 tablets. Insulin Secretagogues or Insulin Clinical Impact: Coadministration of metformin hydrochloride 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 tablets, observe the patient closely for loss of blood glucose control. When such drugs are withdrawn from a patient receiving metformin hydrochloride 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 )