Metformin Hydrochloride Tablet, Film Coated, Extended Release
FDA Label NDC 50228-445

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 tablet and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended [see Warnings and Precautions (5.1)] .

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.

• 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.

• 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)] .

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)] .

Metformin hydrochloride extended-release tablets, USP 500 mg are white to off white, oval shape, film-coated tablet debossed with "445"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 "446"on one side and plain on the other side.

Metformin hydrochloride extended-release tablets is 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.

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 tablet is 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 is 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.

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 and manage any abnormalities [see Adverse Reactions (6.1)].

Insulin and insulin secretagogues (e.g., sulfonylurea) are known to cause hypoglycemia. Metformin hydrochloride 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)] .

There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with metformin hydrochloride extended-release tablets.

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)]

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.

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.

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.

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

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 3 and 1 times, respectively, a 2,000 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 pregestational diabetes mellitus with an HbA1c > 7 and has been reported to be as high as 20 to 25% in women with an 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 was not teratogenic or embyrolethal when administered to rats prior to pregnancy through the period of organogenesis at doses up to 900 mg/kg, or when administered to rabbits during the period of organogenesis at doses up to 90 mg/kg.

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.

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.

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

Clinical studies of metformin hydrochloride extended-release tablets did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. 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 Dosage and Administration (2.2) and Warnings and Precautions (5.1)].

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/minute/1.73 m ² [see Dosage and Administration (2.2), Contraindications (4), Warnings and Precautions (5.1), and Clinical Pharmacology (12.3)].

Use of metformin in patients with hepatic impairment has been associated with some cases of lactic acidosis. Metformin hydrochloride extended-release tablet is not recommended in patients with hepatic impairment [see Warnings and Precautions (5.1)].

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/minute under good hemodynamic conditions. Therefore, hemodialysis may be useful for removal of accumulated drug from patients in whom metformin overdosage is suspected.

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. The structural formula is as shown:

Structural-formula (Structural Formula)

Metformin hydrochloride is a white to off-white crystalline compound with a molecular formula of C ₄H ₁₁N ₅•HCl and a molecular weight of 165.63. Metformin hydrochloride is 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. Each tablet contains ammonio methacrylate copolymer, crospovidone, hypromellose, magnesium stearate, pregelatinized starch (maize), povidone, polyethylene glycol, silicon dioxide, talc, titanium dioxide and triethyl citrate.

Metformin hydrochloride extended-release tablets USP meets USP Dissolution Test 12.

Metformin is a biguanide that improves glucose tolerance in patients with type 2 diabetes, 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.

Absorption

Following a single oral dose of 1,000 mg (2x500 mg tablets) metformin hydrochloride extended-release tablets after a meal, the time to reach maximum plasma metformin concentration (T _max) is achieved at approximately 7 to 8 hours. In both single- and multiple-dose studies in healthy subjects, once daily 1,000 mg (2x500 mg tablets) dosing provides equivalent systemic exposure, as measured by area under the curve (AUC), and up to 35% higher C _max, of metformin relative to the immediate-release given as 500 mg twice daily. At usual clinical doses and dosing schedules of metformin, steady state plasma concentrations of metformin are reached within 24 to 48 hours and are generally <1 mcg/mL.

In a two-way, single-dose, crossover study in healthy volunteers, the 1,000 mg tablet was found to be similar to two 500 mg tablets under fed conditions based on equivalent C _max and AUCs for the two formulations.

Single oral doses of metformin hydrochloride extended-release tablets from 500 mg to 2,500 mg resulted in less than proportional increase in both AUC and C _max.

Effect of food: Low-fat and high-fat meals increased the systemic exposure (as measured by AUC) from metformin hydrochloride extended-release tablets by about 38% and 73%, respectively, relative to fasting. Both meals prolonged metformin T _max by approximately 3 hours but C _max was not affected.

Distribution

The apparent volume of distribution (V/F) of metformin following single oral doses of 850 mg metformin HCl 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 healthy 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.

Excretion

Renal clearance 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.

Special Populations

Renal Impairment

Following a single-dose administration of metformin hydrochloride extended-release tablets 500 mg in subjects with mild and moderate renal impairment, the oral and renal clearance of metformin were decreased by 33% and 50% and 16% and 53%, respectively. Metformin peak and systemic exposure was 27% and 61% greater, respectively in subjects with mild renal impairment and 74% and 2.36-fold greater in subjects with moderate renal impairment as compared to healthy subjects [see Dosage and Administration (2.2), Contraindications (4), and Warnings and Precautions (5.1)].

Hepatic Impairment

No pharmacokinetic studies of metformin hydrochloride extended-release tablets have been conducted in subjects 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 in healthy elderly subjects suggest that total plasma clearance of metformin is decreased by 35%, the half-life is prolonged by 64% and C _max is increased by 76%, compared to healthy young subjects. From these data, it appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function [see Dosage and Administration (2) and Warnings and Precautions (5.1)].

Gender

In the pharmacokinetic studies in healthy volunteers, there were no important differences between male and female subjects with respect to metformin AUC and t _1/2. However, C _max for metformin was 40% higher in female subjects as compared to males. In controlled clinical studies in patients with type 2 diabetes, the antihyperglycemic effect of metformin HCl tablets was comparable in males and females. The gender differences for C _max are unlikely to be clinically important.

Race

A trend towards 10% higher metformin C _max and AUC values for metformin are obtained in Asian subjects when compared to Caucasian, Hispanic and Black subjects. The differences between the Asian and Caucasian groups are unlikely to be clinically important. In controlled clinical studies of metformin HCl in patients with type 2 diabetes, the antihyperglycemic effect was comparable in whites (n=249), blacks (n=51) and Hispanics (n=24).

Pediatrics

There are no available pharmacokinetic data with metformin hydrochloride extended-release tablets in pediatric patients.

Drug Interactions

Specific pharmacokinetic drug interaction studies with metformin hydrochloride extended-release tablets have not been performed except for one with glyburide. However, such studies have been performed on metformin HCl tablets.

Long-term carcinogenicity studies have been performed in Sprague Dawley rats at doses of 150, 300, and 450 mg/kg/day in males and 150, 450, 900, and 1,200 mg/kg/day in females. These doses are approximately 2, 4, and 8 times in males, and 3, 7, 12, and 16 times in females of the maximum recommended human daily dose of 2,000 mg based on body surface area comparisons. No evidence of carcinogenicity with metformin was found in either male or female rats. A carcinogenicity study was also performed in Tg. AC transgenic mice at doses up to 2,000 mg applied dermally. No evidence of carcinogenicity was observed in male or female mice.

Genotoxicity assessments in the Ames test, gene mutation test (mouse lymphoma cells), chromosomal aberrations test (human lymphocytes) and in vivo mouse micronucleus tests were negative. Fertility of male or female rats was not affected by metformin when administered at doses up to 600 mg/kg/day, which is approximately 3 times the maximum recommended human daily dose based on body surface area comparisons.

In a multicenter, randomized, double-blind, active-controlled, dose-ranging, parallel group study conducted in patients type 2 diabetes mellitus, metformin hydrochloride extended-release tablets 1,500 mg once daily, metformin hydrochloride extended-release tablets 1,500 per day in divided doses (500 mg in the morning and 1,000 mg in the evening), and metformin hydrochloride extended-release tablets 2,000 mg once daily were compared to immediate-release metformin HCl tablets 1,500 mg per day in divided doses (500 mg in the morning and 1,000 mg in the evening). This study included patients (n=338) who were newly diagnosed with diabetes, patients treated only with diet and exercise, patients treated with a single antidiabetic medication (sulfonylureas, alpha-glucosidase inhibitors, thiazolidinediones, or meglitinides), and patients (n=368) receiving metformin HCl tablets up to 1,500 mg/day plus a sulfonylurea at a dose equal to or less than one-half the maximum dose. Patients who were enrolled on monotherapy or combination antidiabetic therapy underwent a 6-week washout. Patients randomized to metformin hydrochloride extended-release tablets began titration from 1,000 mg/day up to their assigned treatment dose over 3 weeks. Patients randomized to immediate-release metformin initiated 500 mg twice daily for 1 week followed by 500 mg with breakfast and 1,000 mg with dinner for the second week. The 3-week treatment period was followed by an additional 21-week period at the randomized dose.

The results are presented in Table 4.

Mean baseline body weight was 88.2 kg, 90.5 kg, 87.7 kg and 88.7 kg in the metformin hydrochloride extended-release tablets 1,500 mg once daily, metformin hydrochloride extended-release tablets 1,500 mg in divided doses, metformin hydrochloride extended-release tablets 2,000 mg once daily and metformin HCl tablets 1,500 mg in divided doses arms, respectively. Mean change in body weight from baseline to week 24 was -0.9 kg, -0.7 kg, -1.1 kg, and -0.9 kg in the metformin hydrochloride extended-release tablets 1,500 mg once daily, metformin hydrochloride extended-release tablets 1,500 mg in divided doses, metformin hydrochloride extended-release tablets 2,000 mg once daily and metformin HCl tablets 1,500 mg in divided doses arms, respectively.

A double-blind, randomized, placebo-controlled (glyburide add-on) multicenter study enrolled patients with type 2 diabetes mellitus who were newly diagnosed or treated with diet and exercise (n=144), or who were receiving monotherapy with metformin, sulfonylureas, alpha-glucosidase inhibitors, thiazolidinediones, or meglitinides, or treated with combination therapy consisting of metformin HCl/glyburide at doses up to 1,000 mg metformin + 10 mg glyburide per day (or equivalent doses of glipizide or glimepiride up to half the maximum therapeutic dose) (n=431). All patients were stabilized on glyburide for a 6-week run-in period, and then randomized to 1 of 4 treatments: placebo + glyburide (glyburide alone); metformin hydrochloride extended-release tablets 1,500 mg once a day + glyburide, metformin hydrochloride extended-release tablets 2,000 mg once a day + glyburide, or metformin hydrochloride extended-release tablets 1,000 mg twice a day + glyburide. A 3-week metformin hydrochloride extended-release tablets titration period was followed by a 21-week maintenance treatment period. Use of insulin and oral hypoglycemic agents other than the study drugs were prohibited. The results are presented in Table 5.

Mean baseline body weight was 89.4 kg, 103.7 kg, 102.9 kg and 95.6 kg in the metformin hydrochloride extended-release tablets 1,500 mg once daily, metformin hydrochloride extended-release tablets 1,500 mg in divided doses, metformin hydrochloride extended-release tablets 2,000 mg once daily and metformin HCl tablets 1,500 mg in divided doses arms, respectively. Mean change in body weight from baseline to week 24 was 0.3 kg, 0.1 kg, 0 kg, and 0.7 kg in the metformin hydrochloride extended-release tablets 1,500 mg once daily, metformin hydrochloride extended-release tablets 1,500 mg in divided doses, metformin hydrochloride extended-release tablets 2,000 mg once daily and metformin HCl tablets 1,500 mg in divided doses arms, respectively.

Metformin hydrochloride extended-release tablets are supplied as:

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].

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 tablet is 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. 09/19

PATIENT INFORMATION

Metformin Hydrochloride Extended-Release Tablets, USP

(met-FOR-min HYE-droe-KLOR-ide)

What is the most important information I should know about metformin hydrochloride extended-release tablets?

Metformin hydrochloride extended-release tablets can cause serious side effects, including:

Lactic acidosis. Metformin hydrochloride, the medicine in metformin hydrochloride extended-release tablets, can cause a rare, but serious side effect called lactic acidosis (a buildup of lactic acid in the blood) that can cause death. Lactic acidosis is a medical emergency and must be treated in the hospital.



Stop taking metformin hydrochloride extended-release tablets and call your doctor right away if you get any of the following symptoms of lactic acidosis:

• feel very weak and tired
• have unusual (not normal) muscle pain
• have trouble breathing
• have unexplained stomach or intestinal problems with nausea and vomiting, or diarrhea
• have unusual sleepiness or sleep longer than usual
• feel cold, especially in your arms and legs
• feel dizzy or lightheaded
• have a slow or irregular heartbeat

You have a higher chance of getting lactic acidosis if you:

• have severe kidney problems. See “ Do not take metformin hydrochloride extended-release tablets if you”
• have liver problems.
• drink a lot of alcohol (very often or short-term “binge” drinking).
• get dehydrated (lose a large amount of body fluids). This can happen if you are sick with a fever, vomiting, or diarrhea. Dehydration can also happen when you sweat a lot with activity or exercise and do not drink enough fluids.
• have certain x-ray tests with injectable dyes or contrast agents.
• have surgery or other procedure for which you need to restrict the amount of food and liquid you eat and drink.
• have congestive heart failure.
• have a heart attack, severe infection, or stroke.
• are 65 years of age or older.

Tell your doctor if you have any of the problems in the list above.

Tell your doctor that you are taking metformin hydrochloride extended-release tablets before you have surgery or x-ray tests. Your doctor may need to stop metformin hydrochloride extended-release tablets for a while if you have surgery or certain x-ray tests.



Metformin hydrochloride extended-release tablets can have other serious side effects. See “ What are the possible side effects of metformin hydrochloride extended-release tablets?”.

What is metformin hydrochloride extended-release tablet?

Metformin hydrochloride extended-release tablet is a prescription medicine that contains metformin hydrochloride.

Metformin hydrochloride extended-release tablet is used with diet and exercise to help control high blood sugar (hyperglycemia) in adults with type 2 diabetes.

It is not known if metformin hydrochloride extended-release tablet is safe and effective in children.

Do not take metformin hydrochloride extended-release tablets if you:

• have severe kidney problems.
• are allergic to metformin hydrochloride or any of the ingredients in metformin hydrochloride extended-release tablets. See the end of this Patient Information leaflet for a complete list of ingredients in metformin hydrochloride extended-release tablets.
• have a condition called metabolic acidosis, including diabetic ketoacidosis (high levels of certain acids called “ketones” in your blood or urine).

Before taking metformin hydrochloride extended-release tablets tell your doctor about all of your medical conditions, including if you:

• have a history or risk for diabetic ketoacidosis. See “ Do not take metformin hydrochloride extended-release tablets if you:”.
• have kidney problems.
• have liver problems.
• have heart problems, including congestive heart failure.
• are 65 years of age or older.
• drink alcohol very often, or drink a lot of alcohol in short-term “binge” drinking.
• are taking insulin or a sulfonylurea medicine.
• are pregnant or plan to become pregnant. It is not known if metformin hydrochloride extended-release tablets can harm your unborn baby. If you are pregnant, talk with your doctor about the best way to control your blood sugar while you are pregnant.
• are a woman who has not gone through menopause (premenopausal) who does not have periods regularly or at all. Metformin hydrochloride extended-release tablets can cause the release of an egg from an ovary in a woman (ovulation). This can increase your chance of getting pregnant.
• are breastfeeding or plan to breastfeed. Metformin hydrochloride extended-release tablets can pass into your breast milk. Talk with your doctor about the best way to feed your baby while you take metformin hydrochloride extended-release tablets.

Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements. Know the medicines you take. Keep a list of them to show your doctor and pharmacist. Talk to your doctor before you start any new medicine.



Metformin hydrochloride extended-release tablets may affect the way other medicines work, and other medicines may affect how metformin hydrochloride extended-release tablets works.

How should I take metformin hydrochloride extended-release tablets?

• Take metformin hydrochloride extended-release tablets exactly as your doctor tells you.
• Metformin hydrochloride extended-release tablets should be taken 1 time each day with your evening meal to help decrease an upset stomach.
• Swallow metformin hydrochloride extended-release tablets whole. Do not crush, cut, or chew the tablets.
• You may sometimes pass a soft mass in your stools (bowel movement) that looks like metformin hydrochloride extended-release tablets. This is normal and will not affect the way metformin hydrochloride extended-release tablets works.
• When your body is under some type of stress, such as fever, trauma (such as a car accident), infection, or surgery, the amount of diabetes medicine that you need may change. Tell your doctor right away if you have any of these problems.
• Your doctor should do blood tests to check how well your kidneys are working before and during your treatment with metformin hydrochloride extended-release tablets.
• Your doctor will check your diabetes with regular blood tests, including your blood sugar levels and your hemoglobin A1C.
• Low blood sugar (hypoglycemia) can happen more often when metformin hydrochloride extended-release tablets are taken with certain other diabetes medicines. Talk to your doctor about how to prevent, recognize, and manage low blood sugar. See " What are the possible side effects of metformin hydrochloride extended-release tablets?".
• Check your blood sugar as your doctor tells you to.
• Stay on your prescribed diet and exercise program while taking metformin hydrochloride extended-release tablets.
• If you miss a dose of metformin hydrochloride extended-release tablets, take your next dose at the normal schedule. Do not take 2 doses of metformin hydrochloride extended-release tablets on the same day.
• If you take too much metformin hydrochloride extended-release tablets, call your doctor or go to the nearest hospital emergency room right away.

What should I avoid while taking metformin hydrochloride extended-release tablets?

Do not drink a lot of alcoholic drinks while taking metformin hydrochloride extended-release tablets. This means you should not binge drink for short periods, and you should not drink a lot of alcohol on a regular basis. Alcohol can increase the chance of getting lactic acidosis.

What are the possible side effects of metformin hydrochloride extended-release tablets?

Metformin hydrochloride extended-release tablets can cause serious side effects, including:

• See “ What is the most important information I should know about metformin hydrochloride extended-release tablets?".
• Low vitamin B12 (vitamin B12 deficiency). Using metformin hydrochloride extended-release tablets may cause a decrease in the amount of vitamin B ₁₂ in your blood, especially if you have had low vitamin B ₁₂ levels before. Your doctor may do blood tests to check your vitamin B ₁₂ levels.
• Low blood sugar (hypoglycemia). Low blood sugar is a serious, but common, side effect of metformin hydrochloride extended-release tablets. If you take metformin hydrochloride extended-release tablets with another medicine that can cause low blood sugar, such as sulfonylureas or insulin, you have a higher risk of getting low blood sugar. The dose of your sulfonylurea medicine or insulin may need to be lowered while you take metformin hydrochloride extended-release tablets. Signs and symptoms of low blood sugar may include:
• headache
• drowsiness
• weakness
• irritability
• hunger
• fast heartbeat
• confusion
• shaking or feeling jittery
• dizziness
• sweating

The most common side effects of metformin hydrochloride extended-release tablets include:

• diarrhea
• nausea

These are not all of the possible side effects of metformin hydrochloride extended-release tablets.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store metformin hydrochloride extended-release tablets?

• Store metformin hydrochloride extended-release tablets at room temperature between 68°F to 77°F (20°C to 25°C).

Keep metformin hydrochloride extended-release tablets and all medicines out of the reach of children.

General information about the safe and effective use of metformin hydrochloride extended-release tablets

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use metformin hydrochloride extended-release tablets for a condition for which they were not prescribed. Do not give metformin hydrochloride extended-release tablets to other people, even if they have the same symptoms you have. It may harm them.

You can ask your pharmacist or doctor for information about Metformin Hydrochloride Extended-Release Tablets that is written for health professionals.

What are the ingredients in metformin hydrochloride extended-release tablets?

Active Ingredient: metformin hydrochloride, USP

Inactive Ingredient: Each tablet contains ammonio methacrylate copolymer, crospovidone, hypromellose, magnesium stearate, pregelatinized starch (maize), povidone, polyethylene glycol, silicon dioxide, talc, titanium dioxide and triethyl citrate.



Manufactured by:

ScieGen Pharmaceuticals Inc

Hauppauge, NY 11788

USA

For more information, call ScieGen at (855) 724-3436.

This Patient Information has been approved by the U.S. Food and Drug Administration.

Rev. 09/19

NDC 50228- 445-30
Metformin Hydrochloride
Extended-Release
Tablets, USP

500 mg

ONCE DAILY

30 Tablets Rx only

ScieGen
Pharmaceuticals Inc.

500mg Label (500mg 30s)

NDC 50228- 445-05
Metformin Hydrochloride
Extended-Release
Tablets, USP

500 mg

ONCE DAILY

500 Tablets Rx only

ScieGen
Pharmaceuticals Inc.

500mg Label (500mg 500s)

NDC 50228- 446-30
Metformin Hydrochloride
Extended-Release
Tablets, USP
1,000 mg

ONCE DAILY

30 Tablets Rx only

ScieGen
Pharmaceuticals Inc.

1000mg Label (1000mg 30s)

NDC 50228- 446-05
Metformin Hydrochloride
Extended-Release
Tablets, USP

1,000 mg

ONCE DAILY

500 Tablets Rx only

ScieGen
Pharmaceuticals Inc.

1000mg Label (1000mg 500s)