GLUMET Metformin Hydrochloride 1g Tablet 1's

Indications/Uses

Glumet 500 mg & 1 g/Glumet-XR: Adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus.
Metformin may be used as monotherapy or in combination with other oral antidiabetic agents or with insulin.
Glumet 850 mg: Metformin hydrochloride (Glumet) is a biguanide hypoglycemic agent used in the treatment of Non-Insulin-Dependent Diabetes Mellitus. It is given to patients who are no longer responding to sulfonylureas, either alone or in combination with sulfonylurea.

Dosage/Direction for Use

Glumet 500 mg & 1 g/Glumet-XR: General Dosing Recommendations: There is usually no fixed dosage regimen with any antidiabetic agent for the management of hyperglycemia in patients with diabetes mellitus. Dosage of metformin HCl tablets must be individualized based on both effectiveness and tolerance while not exceeding the maximum recommended daily doses.
During treatment initiation and dose titration, fasting plasma glucose should be used to determine the therapeutic response to metformin HCl tablet and identify the minimum effective dose. Thereafter, glycosylated hemoglobin (HbA_1c) should be measured at intervals of approximately three months. The therapeutic goal should be to decrease both fasting plasma glucose and glycosylated hemoglobin levels to normal or near normal by using the lowest effective dose of metformin when used as monotherapy or in combination with other oral antidiabetic agents or insulin.
Monitoring of glycemic control through frequent measurements of fasting blood glucose and periodic testing of HbA_1c will detect primary failure (i.e., inadequate lowering of blood glucose at the maximum recommended dose of medication), and secondary failure (i.e., loss of adequate blood glucose lowering response after an initial period of effectiveness).
It is recommended that metformin HCl be administered with meals to ensure optimum delivery of metformin to the systemic circulation and minimize gastric intolerance. Administration of metformin in the fed state has been shown to significantly increase the systemic delivery of metformin compared to the fasted state. (See Table 3.)

Recommended Oral Dose of Immediate-Release Metformin Tablet in Children 10 to 16 years Old with Type 2 Diabetes Mellitus: Usual starting dose: 500 mg twice a day, given with meals.
Dosage may be increased by 500 mg weekly up to a maximum of 2,000 mg daily given in divided doses.
The efficacy and safety of extended-release metformin in pediatric patients have not been established.
Transfer from Metformin HCl Immediate-Release Tablet to Metformin HCl Extended-Release Tablet: In patients already treated with metformin HCl immediate-release tablet, the starting dose of metformin HCl extended-release tablet should be equivalent to the daily dose of metformin HCl immediate-release tablet. Switching to metformin HCl extended-release is not recommended in patients treated with metformin HCl immediate-release at doses above 2,000 mg daily. If glycemic control is still not achieved with metformin HCl extended-release tablets 2,000 mg daily, patients may be switched to metformin HCl immediate-release up to a maximum dose of 3,000 mg daily.
Transfer from Other Antidiabetic Therapy: No transition period is generally necessary when transferring patients from standard oral hypoglycemic agents other than chlorpropamide. When transferring patients from chlorpropamide, exercise caution during the first two weeks because overlapping drug effects and hypoglycemia may occur due to prolonged retention of chlorpropamide in the body.
Concomitant Metformin and Oral Sulfonylurea Therapy: Gradual addition of an oral sulfonylurea while continuing maximum dose metformin therapy may be considered in patients who have not responded to four weeks of maximum dose metformin therapy.
Consider alternative therapies such as insulin (with or without metformin) if response to 1 to 3 months maximum dose of sulfonylurea and metformin combination therapy remains unsatisfactory.
Concomitant Metformin and Insulin Therapy: The current insulin dose should be continued upon initiation of metformin therapy.
Initial Oral Dose of Metformin HCl Tablet: 500 mg once a day.
Metformin dose may be increased by 500 mg after approximately one week and by 500 mg every week thereafter until adequate glycemic control is achieved.
Maximum Recommended Daily Dose with Insulin: 2,500 mg.
It is recommended that the insulin dose be reduced by 10 to 25% when fasting plasma glucose concentrations decrease to less than 120 mg/dL. Individualize further dose adjustments based on patient response in patients receiving metformin with insulin.
Or, as prescribed by a physician.
Glumet 850 mg: Adult: The usual starting dose is 500 mg or 850 mg twice or thrice daily given by mouth, with or after meals. The maximum recommended dose is 3 g daily, taken as 3 divided doses.
Children and adolescents: 1 g tablet can be used in children from 10 years of age and adolescents. Unless otherwise prescribed, the usual starting dose is one tablet of 500 mg or 850 mg once daily, given by mouth, during or after meals. The maximum recommended dose is 2 g daily, taken as 2 or 3 divided doses.
Or, as prescribed by a physician.

Overdosage

Glumet 500 mg & 1 g/Glumet-XR: There were no cases of overdose reported in clinical studies. Symptoms of metformin overdose include extensions of the common adverse effects (e.g., epigastric discomfort, nausea, vomiting, diarrhea, drowsiness, weakness, dizziness, malaise, and headache). Should these symptoms occur, lactic acidosis should be excluded. Metformin therapy should be discontinued and proper supportive therapy should be instituted.
Metformin ingestion of up to 50 g has been reported. Hypoglycemia was reported in 10% of cases, but no causal relationship with metformin has been established. Lactic acidosis has been reported in approximately 32% of metformin overdose cases. 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.
Glumet 850 mg: Overdosage may lead to lactic acidosis. In such cases, medical emergency is required and must be treated in a hospital. The most effective way to remove lactate and metformin in the blood is hemodialysis.

Administration

Should be taken with food. Glumet-XR Swallow whole, do not chew/crush.

Contraindications

Glumet 500 mg & 1 g/Glumet-XR: Hypersensitivity to metformin HCl or to any ingredient in the product.
Unstable and/or type 1 (insulin-dependent) diabetes mellitus.
History of lactic acidosis irrespective of precipitating factors.
Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Treat diabetic ketoacidosis with insulin.
Severe renal impairment (eGFR <30mL/min/1.73 m²).
Acute conditions with the potential to alter renal function such as: Dehydration due to persistent or severe diarrhea, recurrent vomiting; Severe infection; Diagnostic examinations (e.g., intravenous urography, angiography) that would involve the use of iodinated contrast agents/media.
Acute or chronic disease which may cause tissue hypoxia such as: Cardiac or respiratory failure; Recent myocardial infarction; Shock.
Acute or chronic alcoholism.
Severe liver disease.
Pregnancy or breastfeeding.
Glumet 850 mg: Metformin hydrochloride (Glumet) should not be used in Insulin-Dependent Diabetes Mellitus. Use in Non-Insulin-Dependent Diabetes Mellitus is contraindicated in patients with ketoacidosis and in those with severe infection, stress, trauma, and other severe conditions where it is unlikely to control hyperglycemia. It should not be given in severe impairment of renal or hepatic function because of an increased risk of hypoglycemia.
It should not be given to pregnant or lactating women since it is excreted in breast milk.
It should not be used in patients with heart failure, recent myocardial infarction, dehydration, acute or chronic alcoholism or any other condition likely to predispose to lactic acidosis.

Warnings

Glumet 500 mg & 1 g/Glumet-XR: Lactic acidosis is a rare, but serious (high mortality in the absence of prompt treatment), metabolic complication that can occur due to metformin accumulation. Reported cases of lactic acidosis in patients on metformin have occurred primarily in diabetic patients with significant renal failure. The incidence of lactic acidosis can be reduced by also assessing other associated risk factors such as poorly controlled diabetes, ketosis, prolonged fasting, excessive alcohol intake, hepatic insufficiency, and any condition associated with hypoxia.
Lactic acidosis is characterized by elevated blood lactate levels (>5 mmol/L), reduced blood pH, electrolyte disturbance with an increased anion gap, and an increased lactate/pyruvate ratio. When metformin is implicated as the cause of lactic acidosis, metformin plasma levels >5 mcg/mL are generally found.
Lactic acidosis is usually accompanied by nonspecific symptoms such as acidotic dyspnea, vomiting, abdominal pain with muscle cramps, and/or a general feeling of malaise with severe fatigue. Hypothermia followed by coma, hypotension, and resistant bradyarrhythmias may be seen with marked acidosis. Instruct patients to immediately alert their physicians if these symptoms occur. Serum electrolytes, ketones, blood glucose, and if indicated, blood pH, lactate levels, and even blood metformin levels may be useful.
Lactic acidosis is a medical emergency that must be treated in a hospital setting. In a patient with lactic acidosis who is taking metformin, the drug should be discontinued immediately and general supportive measures promptly instituted. Because metformin HCl is dialyzable, prompt hemodialysis is recommended to correct the acidosis and remove the accumulated metformin. Such management often results in prompt reversal of symptoms and recovery.
Do not use metformin in patients with congestive heart failure receiving drugs such as digoxin and furosemide because of the risk of hypoperfusion and hypoxemia which may lead to lactic acidosis.
Glumet 850 mg: Lactic acidosis is a rare, but serious (high mortality in the absence of prompt treatment), metabolic complication that occurs due to accumulation of metformin during treatment.
The risk of lactic acidosis must be considered in the event of non-specific signs such as muscle cramps with digestive disorders as abdominal pain and severe asthenia. Lactic acidosis is characterized by acidotic dyspnea, abdominal pain and hypothermia followed by coma. Diagnostic laboratory findings are decreased blood pH, plasma lactate levels above 5 mmol/L, and an increased anion gap and lactate/pyruvate ratio. If metabolic acidosis is suspected, metformin should be discontinued and the patient should be hospitalized immediately.

Special Precautions

Glumet 500 mg & 1 g/Glumet-XR: Monitoring of Renal Function: Impaired renal function would increase the risk of metformin accumulation and lactic acidosis. Renal function should be assessed and verified as normal before initiation of metformin therapy. Estimated glomerular filtration rate (eGFR) should be determined at least annually in all patients taking metformin. In patients at increased risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently.
Initiating metformin HCl therapy in patients with eGFR between 30 to 45 mL/min/1.73 m² is not recommended. In patients taking metformin whose eGFR later falls below 45 mL/min/1.73 m², the benefits and risks of continuing treatment should be assessed. Discontinue metformin if the patient's eGFR later falls below 30 mL/min/1.73 m².
Medications which may affect renal function or result in significant hemodynamic change or interfere with the disposition of metformin (i.e., cationic drugs) should be used with caution since these drugs are eliminated by renal tubular secretion.
Macrovascular Outcomes: Macrovascular risk reduction with the use of metformin or any antidiabetic drug has not been established in clinical studies.
Radiologic Studies: Administration of parenteral iodinated contrast agents has led to an acute decrease in renal function and the occurrence of lactic acidosis in patients receiving metformin. Discontinue metformin at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m², 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, and restart metformin if renal function is stable.
Hypoxic States: Cardiovascular collapse (shock) from whatever cause, acute congestive heart failure, acute myocardial infarction and other conditions characterized by hypoxemia have been associated with lactic acidosis and may also cause prerenal azotemia. Promptly discontinue metformin when such events occur in patients on metformin HCl therapy.
Surgical Procedures: Temporarily discontinue metformin use in patients undergoing surgery associated with restricted food or fluid intake. Metformin therapy may be reinstituted when the patient's oral intake has resumed and renal function has been found normal.
Impaired Hepatic Function: Metformin HCl should generally be avoided in patients with clinical or laboratory evidence of hepatic disease since impaired hepatic function has been associated with lactic acidosis.
Alcohol: Combined use of alcohol and metformin may increase the risk of hypoglycemia and lactic acidosis since alcohol decreases lactate clearance and hepatic gluconeogenesis, and may increase insulin secretion. Excessive alcohol intake on an acute or chronic basis should be avoided in patients receiving metformin.
Vitamin B₁₂ Levels: Evaluate hematologic parameters prior to initiation of metformin therapy and at least annually since decreases in serum vitamin B₁₂ have been associated with metformin use.
Hypoglycemia: Hypoglycemia does not occur in patients receiving metformin alone under usual circumstances of use, but could occur when caloric intake is deficient, when strenuous exercise is not compensated by caloric supplementation, or during concomitant use with other glucose-lowering agents (such as sulfonylureas and insulin) or ethanol.
Elderly, debilitated or malnourished patients, and those with adrenal or pituitary insufficiency or alcohol intoxication are particularly susceptible to hypoglycemia. It may be difficult to recognize hypoglycemic states in the elderly, and in people who are taking beta-adrenergic blocking drugs.
Maintaining Adequate Glycemic Control during Periods of Stress: Temporary discontinuation of metformin and administration of insulin may be necessary in periods of stress such as fever, trauma, infection, or surgery to maintain adequate glucose control. Metformin may be reinstituted after the acute episode is resolved.
Effects on Ability to Drive and Use Machines: Patients should be warned about driving a vehicle or operating machinery under conditions where risk of hypoglycemia is present.
Use in Children: The use of metformin HCl immediate-release tablet has been established in pediatric patients 10 to 16 years old with type 2 diabetes.
The safety and efficacy of metformin HCl extended-release tablet have not been established in these patients.
Use in Elderly: Aging is associated with reduced renal function and metformin is known to be substantially excreted in the kidney. The risk of serious adverse reactions to metformin is greater in patients with reduced/impaired renal function especially in the elderly. Care should be taken in dose selection and should be based on careful and regular monitoring of renal function. Generally, dose of elderly patients should not be titrated to the maximum dose. Metformin treatment should not be initiated in patients ≥80 years old unless creatinine clearance demonstrates that renal function is not reduced.

Use In Pregnancy & Lactation

Glumet 500 mg & 1 g/Glumet-XR: Pregnancy: Pregnancy Category B. Oral hypoglycemic agents (including metformin) are not recommended during pregnancy. Maintaining blood glucose levels as close to normal as possible is necessary during pregnancy since abnormal blood glucose levels are associated with a higher incidence of congenital abnormalities. Insulin is recommended during pregnancy.
Lactation: Metformin is excreted into human milk and should therefore not be used by breastfeeding mothers. The importance of metformin HCl to the mother should be considered when deciding whether to discontinue breastfeeding or discontinue metformin because the potential for hypoglycemia in breastfeeding infants may exist. Consider insulin therapy for adequate glycemic control if metformin HCl is discontinued.
Glumet 850 mg: Metformin hydrochloride (Glumet) should not be given to pregnant or lactating women since it is excreted in breast milk.

Adverse Reactions

Glumet 500 mg & 1 g/Glumet-XR: Metformin may provoke or augment lactic acidosis particularly if it is present in high concentrations in the blood. Some of the symptoms of lactic acidosis may mimic certain adverse effects of metformin. Physicians should instruct their patients to recognize the onset of symptoms of lactic acidosis to avoid this adverse reaction.
The most frequent adverse effects reported with metformin include nausea, vomiting, diarrhea, abdominal pain and loss of appetite. These adverse effects occur during initiation of treatment and resolve spontaneously in most cases.
Blood and lymphatic system disorders: Decrease in serum vitamin B₁₂, megaloblastic anemia (rare); serum folic acid concentrations do not appear to decrease substantially in patients receiving metformin.
Metabolism and nutrition disorders: Hyperglycemia, hypoglycemia (may occur when metformin is given concomitantly with sulfonylureas and/or alcohol), lactic acidosis, weight decreased.
Nervous system disorders: Agitation, dizziness, headache, lightheadedness.
Cardiac disorders: Chest discomfort, palpitations.
Vascular disorders: Flushing, hypertension.
Respiratory, thoracic and mediastinal disorders: Dyspnea, flu syndrome, pneumonitis with vasculitis, rhinitis, upper respiratory infection.
Gastrointestinal disorders: Abdominal discomfort (e.g., bloating, abdominal cramps), abdominal distention, abnormal stools/loose stools, anorexia, constipation, dry mouth, dyspepsia/heartburn, epigastric discomfort, flatulence, gastric disorder, gastric ulcer, gastrointestinal disorder, indigestion, taste disturbance specifically metallic taste in the mouth.
Hepatobiliary disorders: Abnormal liver function tests, autoimmune hepatitis, cholestasis, hepatic injury, hepatitis.
Skin and subcutaneous tissue disorders: Erythema, nail disorder, pruritus, rash, skin lesion, urticaria.
Musculoskeletal and connective tissue disorders: Asthenia, chills, musculoskeletal pain, myalgia.
Renal and urinary disorders: Urinary tract infection.
General disorders and administration site conditions: Fatigue, increased sweating.
Glumet 850 mg: The following adverse reactions may occur under treatment with metformin. Frequencies are defined as follows: very common: ≥1/10; common: ≥1/100, <1/10; uncommon: ≥1/1,000, <1/100; rare: ≥1/10,000, <1/1,000; very rare: <1/10,000.
Gastrointestinal disorders: Very common: nausea, vomiting, diarrhea, abdominal pain and anorexia.
Nervous system disorders: Common: taste disturbance.
Metabolism and nutrition disorders: Very rare: lactic acidosis (see Warnings), impaired absorption of various substances including vitamin B₁₂.
Skin and subcutaneous tissue disorders: Very rare: erythema, pruritus, urticarial.
Hepatobiliary disorders: Very rare: liver function test abnormalities, hepatitis.

Drug Interactions

Glumet 500 mg & 1 g/Glumet-XR: Cationic Drugs: Cationic drugs such as amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, and vancomycin that are eliminated by renal tubular secretion, theoretically may cause an increase in metformin peak plasma concentrations, whole blood concentrations and whole blood AUC by competing with metformin for common renal tubular transport systems. Concomitant administration of metformin and cimetidine has been observed to result in reduced urinary metformin excretion and increased plasma metformin concentrations.
Other Antidiabetic Agents: Hypoglycemia may occur when metformin is used concomitantly with other antidiabetic agents such as sulfonylureas, meglitinides, glitazones, or insulin.
Diuretics: Thiazide diuretics may exacerbate diabetes mellitus and may result in increased requirements of oral antidiabetic agents, metformin included. Temporary loss of diabetic control or secondary failure to the antidiabetic agent may also occur. Potassium-sparing diuretics, which are less diabetogenic, may be considered as a substitute.
Furosemide may increase metformin plasma and blood concentrations and blood AUC without significantly affecting metformin renal clearance.
Nifedipine: Nifedipine increases the absorption, C_max and AUC of metformin, and increases metformin excretion in the urine. Metformin has minimal effects on nifedipine pharmacokinetics.
β-Adrenergic Blocking Agents: β-adrenergic blocking agents (e.g., propranolol, nadolol) may impair glucose tolerance and mask the true frequency or severity of hypoglycemia, block hypoglycemia-induced tachycardia but not hypoglycemic sweating, delay the rate of recovery of blood glucose concentration following drug-induced hypoglycemia, and impair peripheral circulation. Use these drugs with caution in patients with type 2 diabetes.
Protein-Bound Drugs: Interaction of metformin and highly protein-bound drugs (e.g., salicylates, sulfonamides, chloramphenicol, probenecid) is unlikely because metformin is negligibly bound to plasma proteins.
Angiotensin-Converting Enzyme (ACE) Inhibitors: ACE inhibitors (e.g., captopril, enalapril) may reduce fasting blood glucose concentrations. These drugs have also been associated with unexplained hypoglycemia in diabetic patients. Caution should be exercised when administering metformin together with ACE inhibitors to prevent severe hypoglycemia.
Alcohol: There is an increased risk of hypoglycemia and lactic acidosis when alcohol and metformin are used concomitantly since alcohol decreases lactate clearance and hepatic gluconeogenesis, and may increase insulin secretion. Acute or chronic intake of alcohol should be avoided in patients receiving metformin therapy.
Clomifene: Ovulatory response may be increased when clomifene and metformin are used concomitantly in premenopausal patients with polycystic ovary syndrome.
Anticoagulants: Metformin may affect the pharmacokinetic properties of coumarin anticoagulants when administered concomitantly. An increase in prothrombin time may occur upon cessation of metformin therapy, with an increased risk of hemorrhage. Patients receiving phenprocoumon or other vitamin K anticoagulants should be carefully monitored.
Iodinated Contrast Media: Intravascular administration of iodinated contrast media may lead to renal failure, resulting in metformin accumulation with the risk of lactic acidosis. Metformin should be discontinued prior to, or at the time of the procedure, and withheld for 48 hours afterwards. Metformin may be reinstituted only after renal function has been re-evaluated and found to be normal.
Glyburide: Concomitant administration of metformin and glyburide produced no changes in metformin pharmacokinetics and pharmacodynamics. Decreases in C_max, blood AUC of glyburide were observed, but were highly variable. The clinical significance of this finding was unclear.
Others: Drugs that may cause hyperglycemia and may exacerbate loss of glycemic control in patients with diabetes include thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid. Close monitoring of glycemic control and metformin dose adjustments are recommended when such drugs are administered or withdrawn in patients.
The pharmacokinetics of metformin and propranolol, and metformin and ibuprofen were not affected when coadministered in single-dose interaction studies in healthy volunteers.
Glumet 850 mg: Dosage of metformin hydrochloride (Glumet) may be lowered in patients receiving metformin hydrochloride and cimetidine to reduce the risk of lactic acidosis. Diuretics may increase the risk of lactic acidosis due to their potential to decrease renal function. Avoid consumption of alcohol and alcohol-containing medications, as it may cause increased risk of lactic acidosis.

Storage

Store at temperatures not exceeding 30°C.

Action

Pharmacology: Pharmacodynamics: Glumet 500 mg & 1 g/Glumet-XR: Metformin is a biguanide antidiabetic agent that reduces both basal and postprandial plasma glucose concentrations in patients with type 2 diabetes mellitus by improving both peripheral and hepatic sensitivity to insulin. It does not stimulate insulin secretion and therefore does not produce hypoglycemia when used alone. Fasting insulin levels and day-long insulin response remain the same or may even decrease with metformin therapy.
Metformin may act via three mechanisms: It reduces hepatic glucose production by inhibiting gluconeogenesis and glycogenolysis; increases insulin sensitivity in the skeletal muscles and adipocytes, improving peripheral glucose uptake and utilization; delays intestinal glucose absorption.
Metformin stimulates intracellular glycogen synthesis by acting on glycogen synthase. It also increases the transport capacity of all types of membrane glucose transporters.
Metformin has demonstrated modest favorable effects on lipid metabolism in patients with type 2 diabetes. It lowers total cholesterol, mean fasting serum triglycerides and low density lipoprotein cholesterol levels; it has no adverse effects on other lipid levels.
Glumet 850 mg: Metformin is a biguanide hypoglycemic agent lowering both basal and postprandial plasma glucose. It does not stimulate insulin secretion and as a result does not produce hypoglycemia.
Pharmacokinetics: Glumet 500 mg & 1 g/Glumet-XR: Metformin HCl immediate-release (Glumet) 1 g tablet and extended-release (Glumet-XR) 500 mg tablet were shown to be bioequivalent to the reference product (innovator) in adults under fasting conditions. The following are important pharmacokinetic parameters of metformin in adult volunteers who received immediate-release metformin HCl (Glumet) 1 g tablet (as a single oral dose) and extended-release metformin HCl (Glumet-XR) 500 mg tablet (two 500-mg tablets given once a day for three days) under fasting conditions: See Table 1 and 2.

Metformin HCl is slowly and incompletely absorbed from the gastrointestinal tract after oral administration. The absolute bioavailability of metformin HCl tablet under fasting conditions is approximately 50 to 60% with metformin HCl doses of 500 mg to 1,500 mg. Single doses of metformin HCl 500 mg to 1,500 mg show lack of dose proportionality with increasing doses which is due to decreased absorption rather than altered elimination.
Metformin HCl extended-release tablet is intended for once-a-day dosing. Once-a-day dosing is possible through control of metformin release rate and prolonging absorption in the upper gastrointestinal tract.
Metformin distributes rapidly to peripheral body tissues and fluids. It also appears to distribute slowly into erythrocytes and into a deep tissue compartment. Metformin is negligibly bound to plasma proteins. Steady-state plasma concentrations of metformin are generally <1 mcg/mL and are reached within 24 to 48 hours at usual clinical doses and dosing schedules.
Renal elimination of metformin is via glomerular filtration and secretion by the proximal convoluted tubules as unchanged drug. The principal plasma elimination half-life of metformin is about 6.2 hours with 90% of the total dose being cleared within 24 hours in patients with normal renal function. In the blood, the elimination half-life is about 17.6 hours.
Special Populations: Renal Insufficiency: The plasma and blood half-life of metformin is prolonged and the renal clearance decreased in proportion to the decrease in creatinine clearance in patients with decreased renal function (based on measured creatinine levels).
Geriatrics: The limited pharmacokinetic data of metformin in healthy elderly subjects suggest that total plasma clearance of metformin is decreased, half-life is prolonged, and C_max is increased, compared to healthy young subjects. It appears that the change in metformin pharmacokinetics with aging is primarily related to a change in renal function.
Pediatrics: After oral administration of a single metformin HCl 500 mg tablet with food, C_max and AUC differed less than 5% between pediatric type 2 diabetic patients (12 to 16 years old) compared with healthy adults (20 to 45 years old), all with normal renal function.
The safety and efficacy of metformin HCl extended-release tablet has not been established in pediatric patients. Pharmacokinetic studies have not been conducted in these patients.
Glumet 850 mg: Metformin hydrochloride (Glumet) is slowly and incompletely absorbed from the gastrointestinal tract. A single 500-mg dose is reported to have a bioavailability of 50-60% (may be reduced in the presence of food). Plasma protein binding is negligible. It is excreted as unchanged drug in the urine. Plasma elimination half-life is reported to range from about 2 to 6 hours after oral administration.

MedsGo Class

Antidiabetic Agents