Metformin Hydrochloride

Boxed Warning 6/2026 Warnings and Precautions, Lactic Acidosis ( 5.1 ) 6/2026

1 INDICATIONS AND 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 )

2 DOSAGE AND 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 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. 2.2 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 tablet is 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) ] .

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. …

3 DOSAGE FORMS AND STRENGTHS Metformin Hydrochloride Extended-Release Tablets, USP are available containing 500 mg or 1000 mg of metformin hydrochloride, USP. • The 500 mg tablets are pink, film-coated, round, unscored tablets imprinted with M over MN2 in black ink on one side of the tablet and blank on the other side. • The 1000 mg tablets are pink, film-coated, round, unscored tablets imprinted with M over MN1 in black ink on one side of the tablet and blank on the other side. Extended-Release Tablets: 500 mg and 1000 mg ( 3 )

4 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 )

6 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 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 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% Adverse reactions that were more common in the metformin hydrochloride extended-release tablets-treated than in the placebo-treated patients. 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% 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.

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 tab …

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 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 )

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 hydrochloride and coadministered drugs were given as single doses Dose of Metformin Hydrochloride 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) .] To …

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 HbA 1C >7 and has been reported to be as high as 20 to 25% in women with a HbA 1C >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 …

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.

11 DESCRIPTION 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 USP is a white crystalline powder with a molecular formula of C 4 H 11 N 5 •HCl and a molecular weight of 165.63. Metformin hydrochloride, USP is freely soluble in water and is practically insoluble in acetone, ether, and chloroform. 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, USP are modified release dosage forms that contain 500 mg or 1000 mg of metformin HCl. Each 500 mg tablet containsAmmonio Methacrylate Copolymer Type A, Coloring (Hypromellose, FD&C Blue#2/Indigo Carmine, Titanium Dioxide, Triethyl Citrate), Glyceryl dibehenate, Hydroxypropyl cellulose, Hypromellose, Magnesium Stearate, Methacralic Acid and Methyl Methacrylate Coplymer (1:1), Microcrystalline cellulose, Povidone, Talc, Triethyl citrate. Each 1000 mg tablet contains Ammonio Methacrylate Copolymer Type A, Glyceryl behenate, Hydroxypropyl cellulose, Hypromellose, Magnesium Stearate ,Methacralic Acid and Methyl Methacrylate Coplymer (1:1), Microcrystalline cellulose, Povidone, Talc, Triethyl citrate. FDA approved dissolution test specifications differ from USP. strc

10 OVERDOSAGE Overdose of metformin hydrochloride 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.

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied Metformin hydrochloride extended-release tablets, USP as are supplied as modified capsule-shaped, film-coated extended-release tablets containing 500 mg or 1,000 mg of metformin hydrochloride. NDC 51407-058-60: 500 mg extended-release, white to off-white, film coated, modified capsule-shaped tablets debossed with “NF5” on one side: bottles of 60. NDC 51407-059-60: 1,000 mg extended-release, white to off-white, film coated, modified capsule-shaped tablets debossed with “NF0” on one side: bottles of 60. 16.2 Storage Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature] excursions permitted to 15° to 30°C (59° to 86°F). Avoid excessive heat and humidity. Keep tightly closed (protect from moisture). Protect from light. Dispense in a tight, light-resistant container as defined in the USP.

16.1 How Supplied Metformin hydrochloride extended-release tablets, USP as are supplied as modified capsule-shaped, film-coated extended-release tablets containing 500 mg or 1,000 mg of metformin hydrochloride. NDC 51407-058-60: 500 mg extended-release, white to off-white, film coated, modified capsule-shaped tablets debossed with “NF5” on one side: bottles of 60. NDC 51407-059-60: 1,000 mg extended-release, white to off-white, film coated, modified capsule-shaped tablets debossed with “NF0” on one side: bottles of 60.