(metformin hydrochloride) Extended-release Tablets
Lactic acidosis is a rare, but serious, complication that can occur due to metformin accumulation. The risk increases with conditions such as sepsis, dehydration, excess alcohol intake, hepatic impairment, renal impairment, and acute congestive heart failure.
The onset of lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, increasing somnolence, and nonspecific abdominal distress.
Laboratory abnormalities include low pH, increased anion gap, and elevated blood lactate.
If acidosis is suspected, GLUMETZA (metformin hydrochloride extended-release tablets), should be discontinued and the patient hospitalized immediately. (See WARNINGS AND PRECAUTIONS)
GLUMETZA (metformin hydrochloride) extended-release tablet is an oral antihyperglycemic medication used in the management of type 2 diabetes. Metformin hydrochloride (N,N-dimethylimidodicarbonimidic diamide hydrochloride) is not chemically or pharmacologically related to any other classes of oral antihyperglycemic agents. The structural formula of metformin hydrochloride (metformin HCl) is as shown:
Metformin HCl is a white to off-white crystalline compound with a molecular formula of C4H11N5•HCl and a molecular weight of 165.63. Metformin HCl 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. GLUMETZA tablets are modified release dosage forms that contain 500 mg or 1000 mg of metformin HCl. Each 500 mg tablet contains coloring, hypromellose, magnesium stearate, microcrystalline cellulose and polyethylene oxide. Each 1000 mg tablet contains colloidal silicon dioxide, polyvinyl alcohol, crospovidone, glyceryl behenate, polyacrylate dispersion, hypromellose, talc, polyethylene glycol, eudragit, titanium dioxide, simethicone emulsion, polysorbate and coloring. GLUMETZA 500 mg and 1000 mg tablets are formulated to gradually release metformin to the upper gastrointestinal (GI) tract.
GLUMETZA is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
DOSAGE AND ADMINISTRATION
Adult Dosage And Administration
- The recommended starting dose of GLUMETZA 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 GLUMETZA once daily at the same total daily dose, up to 2,000 mg once daily.
- Swallow GLUMETZA whole and never crush, cut or chew.
- If a dose of GLUMETZA is missed, instruct patients not to take two doses the same day and to resume their usual dose of GLUMETZA with the next schedule dose.
Recommendations For Use In Renal Impairment
- Assess renal function prior to initiation of GLUMETZA and periodically thereafter.
- GLUMETZA is contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2.
- Initiation of GLUMETZA in patients with an eGFR between 30 to 45 mL/minute/1.73 m2 is not recommended.
- In patients taking GLUMETZA whose eGFR later falls below 45 mL/minute/1.73 m2, assess the benefit risk of continuing therapy.
- Discontinue GLUMETZA if the patient’s eGFR later falls below 30 mL/minute/1.73 m2 [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS].
Discontinuation For Iodinated Contrast Imaging Procedures
Discontinue GLUMETZA 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 m2; 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 GLUMETZA if renal function is stable [see WARNINGS AND PRECAUTIONS].
Dosage Forms And Strengths
GLUMETZA is available as:
- Extended-release tablets: 500 mg white, film-coated, oval-shaped tablets with “M500” on one side.
- Extended-release tablets: 1,000 mg white, film-coated, oval-shaped tablets with “M1000” on one side.
Storage And Handling
GLUMETZA is supplied as:
|500 mg||Bottles of 100||NDC 68012-004-50||white, film-coated, oval-shaped, extended-release tablets with “M500” on one side.|
|1,000 mg||Bottles of 90||NDC 68012-003-16||white, film-coated, oval-shaped, extended-release tablets with “M1000” on one side.|
Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].
Manufactured for: Salix Pharmaceuticals, a division of Valeant Pharmaceuticals North America LLC, Bridgewater, NJ 08807 USA. Revised: November 2018
The following adverse reactions are discussed in more detail in other sections of the labeling:
- Lactic Acidosis [see Boxed Warning and WARNINGS AND PRECAUTIONS]
- Vitamin B12 Deficiency [see WARNINGS AND PRECAUTIONS]
- Hypoglycemia [see WARNINGS AND PRECAUTIONS]
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 GLUMETZA 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 GLUMETZA or placebo. In total, 431 patients received GLUMETZA and glyburide and 144 patients received placebo and glyburide. Adverse reactions reported in greater than 5% of patients treated with GLUMETZA that were more common in the combined GLUMETZA and glyburide group than in the placebo and glyburide group are shown in Table 1. In 0.7% of patients treated with GLUMETZA and glyburide, diarrhea was responsible for discontinuation of study medication compared to no patients in the placebo and glyburide group.
Table 1: Adverse Reactions Reported by >5%* of Patients for the Combined GLUMETZA Groups Versus Placebo Group
|Adverse Reaction||GLUMETZA + Glyburide
|Placebo + Glyburide
|*Adverse reactions that were more common in the GLUMETZA-treated than in the placebo-treated patients.|
Vitamin B12 Concentrations
In clinical trials of 29-week duration with metformin HCl tablets, a decrease to subnormal levels of previously normal serum vitamin B12 levels was observed in approximately 7% of patients.
The following adverse reactions have been identified during post-approval use of GLUMETZA. 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 GLUMETZA.
Table 2: Clinically Significant Drug Interactions with GLUMETZA
|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 GLUMETZA may increase the risk for lactic acidosis.|
|Intervention:||Consider more frequent monitoring of these patients.|
|Examples:||Topiramate, zonisamide, acetazolamide or dichlorphenamide.|
|Drugs that Reduce GLUMETZA 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].|
|Intervention:||Consider the benefits and risks of concomitant use with GLUMETZA.|
|Examples:||Ranolazine, vandetanib, dolutegravir, and cimetidine.|
|Clinical Impact:||Alcohol is known to potentiate the effect of metformin on lactate metabolism.|
|Intervention:||Warn patients against excessive alcohol intake while receiving GLUMETZA.|
|Insulin Secretagogues or Insulin|
|Clinical Impact:||Coadministration of GLUMETZA 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 GLUMETZA, observe the patient closely for loss of blood glucose control. When such drugs are withdrawn from a patient receiving GLUMETZA, 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.|
Included as part of the "PRECAUTIONS" Section
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 GLUMETZA. In GLUMETZA-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 GLUMETZA 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.
- Before initiating GLUMETZA, obtain an estimated glomerular filtration rate (eGFR).
- GLUMETZA is contraindicated in patients with an eGFR less than 30 mL/minute/1.73 m2 [see CONTRAINDICATIONS].
- Initiation of GLUMETZA is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m2.
- Obtain an eGFR at least annually in all patients taking GLUMETZA. 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 GLUMETZA whose eGFR later falls below 45 mL/minute/1.73 m2, assess the benefit and risk of continuing therapy.
- Drug Interactions: The concomitant use of GLUMETZA with specific drugs may increase the risk of metforminassociated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance or increase metformin accumulation [see DRUG INTERACTIONS]. 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].
- Radiological Studies with Contrast: Administration of intravascular iodinated contrast agents in metformintreated patients has led to an acute decrease in renal function and the occurrence of lactic acidosis. Stop GLUMETZA 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 m2; 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 GLUMETZA 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. GLUMETZA 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 GLUMETZA.
- 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 GLUMETZA.
- 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 GLUMETZA in patients with clinical or laboratory evidence of hepatic disease.
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 and CLINICAL PHARMACOLOGY]:
Vitamin B12 Deficiency
In clinical trials of 29-week duration with metformin HCl tablets, a decrease to subnormal levels of previously normal serum vitamin B12 levels was observed in approximately 7% of patients. Such decrease, possibly due to interference with B12 absorption from the B12-intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin or vitamin B12 supplementation. Certain individuals (those with inadequate vitamin B12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B12 levels. Measure hematologic parameters on an annual basis and vitamin B12 at 2 to 3 year intervals in patients on GLUMETZA and manage any abnormalities [see ADVERSE REACTIONS].
Hypoglycemia With Concomitant Use With Insulin And Insulin Secretagogues
Insulin and insulin secretagogues (e.g., sulfonylurea) are known to cause hypoglycemia. GLUMETZA 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 GLUMETZA [see DRUG INTERACTIONS].
There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with GLUMETZA.
Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (PATIENT INFORMATION).
Explain the risks of lactic acidosis, its symptoms, and conditions that predispose to its development. Advise patients to discontinue GLUMETZA 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 GLUMETZA. Instruct patients to inform their doctor that they are taking GLUMETZA prior to any surgical or radiological procedure, as temporary discontinuation may be required [see WARNINGS AND PRECAUTIONS].
Inform patients that hypoglycemia may occur when GLUMETZA 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].
Vitamin B12 Deficiency
Inform patients about importance of regular hematological parameters while receiving GLUMETZA [see WARNINGS AND PRECAUTIONS].
Females Of Reproductive Age
Inform patients that GLUMETZA 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.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
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.
Use In Specific Populations
Limited data with GLUMETZA 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 6–10% in women with pregestational diabetes mellitus with an HbA1c >7 and has been reported to be as high as 20–25% 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 2–4% and 15–20%, respectively.
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.
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.
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.
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 GLUMETZA and any potential adverse effects on the breastfed child from GLUMETZA or from the underlying maternal condition.
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.
Females And Males Of Reproductive Potential
Discuss the potential for unintended pregnancy with premenopausal women as therapy with GLUMETZA may result in ovulation in some anovulatory women.
Safety and effectiveness of GLUMETZA in pediatric patients have not been established.
Clinical studies of GLUMETZA 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 and WARNINGS AND PRECAUTIONS]
Metformin is substantially excreted by the kidney, and the risk of metformin accumulation and lactic acidosis increases with the degree of renal impairment. GLUMETZA is contraindicated in severe renal impairment, patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2. [see DOSAGE AND ADMINISTRATION , CONTRAINDICATIONS , WARNINGS AND PRECAUTIONS , and CLINICAL PHARMACOLOGY]
Use of metformin in patients with hepatic impairment has been associated with some cases of lactic acidosis. GLUMETZA is not recommended in patients with hepatic impairment. [see WARNINGS AND PRECAUTIONS]
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] 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.
GLUMETZA is contraindicated in patients with:
Mechanism Of Action
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.
Following a single oral dose of 1,000 mg (2x500 mg tablets) GLUMETZA after a meal, the time to reach maximum plasma metformin concentration (Tmax) is achieved at approximately 7-8 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 Cmax, 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 24-48 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 Cmax and AUCs for the two formulations.
Single oral doses of GLUMETZA from 500 mg to 2,500 mg resulted in less than proportional increase in both AUC and Cmax.
Effect of food
Low-fat and high-fat meals increased the systemic exposure (as measured by AUC) from GLUMETZA tablets by about 38% and 73%, respectively, relative to fasting. Both meals prolonged metformin Tmax by approximately 3 hours but Cmax was not affected.
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.
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.
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.
Following a single-dose administration of GLUMETZA 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 2.36fold greater in subjects with moderate renal impairment as compared to healthy subjects. [see DOSAGE AND ADMINISTRATION , CONTRAINDICATIONS , and WARNINGS AND PRECAUTIONS]
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 Cmax 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 and WARNINGS AND PRECAUTIONS]
In the pharmacokinetic studies in healthy volunteers, there were no important differences between male and female subjects with respect to metformin AUC and t1/2. However, Cmax 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 Cmax are unlikely to be clinically important.
A trend towards 10% higher metformin Cmax 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).
There are no available pharmacokinetic data with GLUMETZA in pediatric patients.
Specific pharmacokinetic drug interaction studies with GLUMETZA have not been performed except for one with glyburide. However, such studies have been performed on metformin HCl tablets.
Table 3: Effect of Coadministered Drug on Plasma Metformin Systemic Exposure
|Coadministered Drug||Dose of Coadministered Drug1||Dose of Metformin HCl1||Geometric Mean Ratio (ratio with/ without coadministered drug)
|No dosing adjustments required for the following:|
|Glyburide||5 mg||500 mg4||0.983||0.993|
|Furosemide||40 mg||850 mg||1.093||1.223|
|Nifedipine||10 mg||850 mg||1.16||1.21|
|Propranolol||40 mg||850 mg||0.90||0.94|
|Ibuprofen||400 mg||850 mg||1.053||1.073|
|Cationic drugs that are eliminated by renal tubular secretion may increase the accumulation of metformin: [see WARNINGS AND PRECAUTIONS and DRUG INTERACTIONS].|
|Cimetidine||400 mg||850 mg||1.40||1.61|
|Carbonic anhydrase inhibitors may cause metabolic acidosis:
[see WARNINGS AND PRECAUTIONS and DRUG INTERACTIONS].
|Topiramate||100 mg5||500 mg5||1.255||1.17|
|1 All metformin HCl and coadministered drugs were given as single doses.
3 Ratio of arithmetic means
4 GLUMETZA (metformin HCl extended-release tablets) 500 mg
5 At steady state with topiramate 100 mg every 12 hours and metformin 500 mg every 12 hours; AUC=AUC0-12h
Table 4: Effect of Metformin on Coadministered Drug Systemic Exposure
|Coadministered Drug||Dose of Coadministered Drug1||Dose of Metformin HCl1||Geometric Mean Ratio (ratio with/ without coadministered drug)
|No dosing adjustments required for the following:|
|Glyburide||5 mg||500 mg4||0.783||0.633|
|Furosemide||40 mg||850 mg||0.873||0.693|
|Nifedipine||10 mg||850 mg||1.104||1.08|
|Propranolol||40 mg||850 mg||1.014||0.94|
|Ibuprofen||400 mg||850 mg||0.975||1.015|
|Cimetidine||400 mg||850 mg||0.954||1.01|
|1 All metformin HCl and coadministered drugs were given as single doses.
2 AUC=AUC0–inf unless otherwise noted
3 Ratio of arithmetic means, p-value of difference <0.05
4 AUC0-24 hr reported
5 Ratio of arithmetic means
In a multicenter, randomized, double-blind, active-controlled, dose-ranging, parallel group study conducted in patients type 2 diabetes mellitus, GLUMETZA 1,500 mg once daily, GLUMETZA 1,500 per day in divided doses (500 mg in the morning and 1,000 mg in the evening), and GLUMETZA 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 GLUMETZA 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.
Table 5: Mean Changes from Baseline in HbA1c and Fasting Plasma Glucose at Week 24 ComparingGLUMETZA versus Metformin HCl Tablets* in Patients with Type 2 Diabetes Mellitus
1,500 mg in Divided Doses
in Divided Doses
|HbA1c (%), N||169||175||159||170|
|Mean Change at Final Visit||-0.7||-0.7||-1.1||-0.7|
|Mean Difference from Metformin HCl Tablets* (98.4% CI)||0 (-0.3, 0.3)||0 (-0.3, 0.3)||-0.4 (-0,7, -0.1)||N/A|
|Fasting Plasma Glucose (mg/dL), N||175||179||170||172|
|Mean Change at Final Visit||-39||-32||-42||-32|
|Mean Difference from Metformin HCl Tablets* (95% CI)||-6 (-15, 2)||0 (-8, 9)||-10 (-19, -1)||N/A|
|*Immediate-release metformin HCl tablets|
Mean baseline body weight was 88.2 kg, 90.5 kg, 87.7 kg and 88.7 kg in the GLUMETZA 1,500 mg once daily, GLUMETZA 1,500 mg in divided doses, GLUMETZA 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 GLUMETZA 1,500 mg once daily, GLUMETZA 1,500 mg in divided doses, GLUMETZA 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); GLUMETZA 1,500 mg once a day + glyburide, GLUMETZA 2,000 mg once a day + glyburide, or GLUMETZA 1,000 mg twice a day + glyburide. A 3-week GLUMETZA 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.
Table 6: Mean Changes from Baseline in HbA1c and Fasting Plasma Glucose at Week 24 for the GLUMETZA + Glyburide Groups and Placebo+ Glyburide Treatment Group in Patients with Type 2 Diabetes Mellitus
|GLUMETZA + Glyburide*||Placebo + Glyburide*
|HbA1c (%), N||136||136||144||141|
|Mean Change at Final Visit||-0.7||-0.8||-0.7||-0.1|
|Mean Difference from Glyburide Alone (95% CI)||-0.8a
|Fasting Plasma Glucose (mg/dL), N||143||141||145||144|
|Mean Change at Final Visit||-14||-16||-9||16|
|Mean Difference from Glyburide Alone (95% CI)||-29.2a
*Glyburide was administered as 10 mg at breakfast and 5 mg at dinner.
a p-value for pairwise comparison <0.001
Mean baseline body weight was 89.4 kg, 103.7 kg, 102.9 kg and 95.6 kg in the GLUMETZA 1,500 mg once daily, GLUMETZA 1,500 mg in divided doses, GLUMETZA 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 GLUMETZA 1,500 mg once daily, GLUMETZA 1,500 mg in divided doses, GLUMETZA 2,000 mg once daily and metformin HCl tablets 1,500 mg in divided doses arms, respectively.
(metformin hydrochloride) extended-release tablets, for oral use
What is the most important information I should know about GLUMETZA?
GLUMETZA can cause serious side effects, including:
Lactic acidosis. Metformin hydrochloride, the medicine in GLUMETZA, can cause a rare, but serious side effect calledlactic acidosis (a buildup of lactic acid in the blood) that can cause death. Lactic acidosis is a medical emergency andmust be treated in the hospital.
Stop taking GLUMETZA 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 GLUMETZA 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 GLUMETZA before you have surgery or x-ray tests. Your doctor may need to stop GLUMETZA for a while if you have surgery or certain x-ray tests.
GLUMETZA can have other serious side effects. See “What are the possible side effects of GLUMETZA?”.
What is GLUMETZA?
- GLUMETZA is a prescription medicine that contains metformin hydrochloride. GLUMETZA is used with diet and exercise to help control high blood sugar (hyperglycemia) in adults with type 2 diabetes.
It is not known if GLUMETZA is safe and effective in children.
Do not take GLUMETZA if you:
- have severe kidney problems.
- are allergic to metformin hydrochloride or any of the ingredients in GLUMETZA. See the end of this Patient Information leaflet for a complete list of ingredients in GLUMETZA.
- have a condition called metabolic acidosis, including diabetic ketoacidosis (high levels of certain acids called “ketones” in your blood or urine).
Before taking GLUMETZA tell your doctor about all of your medical conditions, including if you:
- have a history or risk for diabetic ketoacidosis. See “Do not take GLUMETZA 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 GLUMETZA 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. GLUMETZA 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. GLUMETZA can pass into your breast milk. Talk with your doctor about the best way to feed your baby while you take GLUMETZA.
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.
GLUMETZA may affect the way other medicines work, and other medicines may affect how GLUMETZA works.
How should I take GLUMETZA?
- Take GLUMETZA exactly as your doctor tells you.
- GLUMETZA should be taken 1 time each day with your evening meal to help decrease an upset stomach.
- Swallow GLUMETZA 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 GLUMETZA tablets. This is normal and will not affect the way GLUMETZA 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 GLUMETZA.
- 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 GLUMETZA is 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 GLUMETZA?”.
- Check your blood sugar as your doctor tells you to.
- Stay on your prescribed diet and exercise program while taking GLUMETZA.
- If you miss a dose of GLUMETZA, take your next dose at the normal schedule. Do not take 2 doses of GLUMETZA on the same day.
- If you take too much GLUMETZA, call your doctor or go to the nearest hospital emergency room right away.
What should I avoid while taking GLUMETZA?
Do not drink a lot of alcoholic drinks while taking GLUMETZA. 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 GLUMETZA?
GLUMETZA can cause serious side effects, including:
- See “What is the most important information I should know about GLUMETZA?”.
- Low vitamin B12 (vitamin B12 deficiency). Using GLUMETZA may cause a decrease in the amount of vitamin B12 in your blood, especially if you have had low vitamin B12 levels before. Your doctor may do blood tests to check your vitamin B12 levels.
- Low blood sugar (hypoglycemia). Low blood sugar is a serious, but common, side effect of GLUMETZA. If you take GLUMETZA 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 GLUMETZA. Signs and symptoms of low blood sugar may include:
- fast heartbeat
- shaking or feeling jittery
The most common side effects of GLUMETZA include:
These are not all of the possible side effects of GLUMETZA.
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 GLUMETZA?
- Store GLUMETZA at room temperature between 68°F to 77°F (20°C to 25°C).
Keep GLUMETZA and all medicines out of the reach of children.
General information about the safe and effective use of GLUMETZA
Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use GLUMETZA for a condition for which it was not prescribed. Do not give GLUMETZA 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 GLUMETZA that is written for health professionals.
What are the ingredients in GLUMETZA?
Active Ingredient: metformin hydrochloride
Inactive Ingredient: 500 mg tablet: coloring, hypromellose, magnesium stearate, microcrystalline cellulose and polyethylene oxide.
1,000 mg tablet: colloidal silicon dioxide, polyvinyl alcohol, crospovidone, glyceryl behenate, polyacrylate dispersion, hypromellose, talc, polyethylene glycol, eudragit, titanium dioxide, simethicone emulsion, polysorbate and coloring.
This Patient Information has been approved by the U.S. Food and Drug Administration.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.