Meforex500 mg

Meforex 500 mg is indicated for the management of type 2 diabetes mellitus (T2DM), particularly in overweight and obese patients when dietary management and regular physical exercise alone do not result in adequate glycemic control. It is the most widely prescribed oral antidiabetic drug globally and is recommended as first-line pharmacotherapy for type 2 diabetes by the American Diabetes Association (ADA), the European Association for the Study of Diabetes (EASD), and the International Diabetes Federation (IDF).

In Adults

Metformin may be used as:

• Monotherapy — as first-line treatment when lifestyle interventions (diet and exercise) fail to achieve adequate blood glucose control, particularly in overweight patients where it provides the additional benefit of weight neutrality or modest weight reduction
• Combination therapy with other oral antidiabetic agents — including sulfonylureas (e.g., glipizide, gliclazide), DPP-4 inhibitors (e.g., sitagliptin, vildagliptin, linagliptin), SGLT-2 inhibitors (e.g., empagliflozin, dapagliflozin), thiazolidinediones (e.g., pioglitazone), GLP-1 receptor agonists, and others — when monotherapy fails to achieve target HbA1c
• Combination therapy with insulin — Metformin combined with insulin reduces the required insulin dose and limits weight gain associated with insulin therapy

In overweight type 2 diabetic adult patients treated with Metformin as first-line therapy after dietary failure, a significant reduction in diabetic complications — including macrovascular events (myocardial infarction, stroke) — has been demonstrated in the landmark UK Prospective Diabetes Study (UKPDS). This cardiovascular benefit adds to the glycemic indications.

In Children from 10 Years of Age and Adolescents

Metformin may be used in children aged 10 years and older and adolescents as:

• Monotherapy — as initial treatment of type 2 diabetes in pediatric patients when dietary and lifestyle modifications are insufficient
• Combination therapy with insulin — when insulin alone does not achieve adequate glycemic control

The extended-release formulation of Metformin has not been studied in children; only immediate-release tablets should be used in the pediatric population.

Off-Label and Emerging Indications

• Polycystic Ovary Syndrome (PCOS) — widely used off-label to improve insulin sensitivity, restore ovulatory cycles, and reduce androgen levels in women with PCOS, particularly those with insulin resistance
• Pre-diabetes and Metabolic Syndrome — recommended by ADA guidelines for high-risk pre-diabetic patients (particularly those with BMI >35 kg/m², age <60 years, or women with prior gestational diabetes) to delay or prevent onset of type 2 diabetes
• Gestational Diabetes Mellitus (GDM) — used in some countries as an alternative or adjunct to insulin under specialist supervision

Biguanides / Oral Antidiabetic Agents

Meforex 500 mg is a biguanide-class oral antihyperglycemic agent and the most prescribed antidiabetic drug worldwide. Its pharmacological profile is distinct from all other antidiabetic drug classes — it lowers blood glucose through insulin-sensitizing mechanisms rather than by increasing insulin secretion, meaning it does not cause hypoglycemia when used as monotherapy.

Mechanism of Action

Metformin lowers both fasting (basal) and postprandial plasma glucose through three primary complementary mechanisms:

1. Reduction of Hepatic Glucose Production (Primary Action)

The dominant mechanism of Metformin action is the inhibition of hepatic gluconeogenesis (the synthesis of new glucose from non-glucose precursors such as lactate, amino acids, and glycerol). Metformin achieves this primarily by:

• Inhibiting mitochondrial complex I of the electron transport chain in hepatocytes, which reduces hepatic ATP production and raises the AMP:ATP ratio
• This activates AMP-activated protein kinase (AMPK) — a key cellular energy-sensing enzyme — and inhibits fructose-1,6-bisphosphatase (a rate-limiting gluconeogenesis enzyme), together suppressing hepatic glucose output
• The result is a significant reduction in fasting plasma glucose, with typical HbA1c lowering of 1–2%

2. Improvement of Peripheral Insulin Sensitivity

Metformin improves insulin sensitivity in peripheral tissues — primarily skeletal muscle — by:

• Activating AMPK, which stimulates GLUT4 glucose transporter translocation to the cell surface, increasing glucose uptake into muscle cells
• Enhancing post-receptor insulin signaling pathways
• This effect is particularly important for reducing postprandial blood glucose levels

3. Reduction of Intestinal Glucose Absorption

Metformin reduces the rate of gastrointestinal glucose absorption, contributing to lower postprandial blood glucose peaks. This mechanism also stimulates intestinal GLP-1 secretion, which may partially explain Metformin's modest additional benefits on satiety and weight.

Key Pharmacological Distinctions

• No insulin secretagogue activity — Metformin does not stimulate insulin release from pancreatic beta cells, which is why it does not cause hypoglycemia when used as monotherapy
• Weight neutral or modest weight reduction — unlike sulfonylureas and insulin, Metformin does not cause weight gain; it typically reduces weight by 1–3 kg, making it particularly suitable for overweight and obese patients
• Cardioprotective effects — beyond glycemic control, Metformin has been shown to reduce LDL cholesterol, improve endothelial function, reduce platelet aggregation, and lower cardiovascular mortality in type 2 diabetic patients

Pharmacokinetics

• Absorption: Metformin is absorbed primarily from the small intestine. Oral bioavailability is approximately 50–60% of an oral dose. Absorption is relatively slow — peak plasma concentrations (C_max) are reached in approximately 2 to 3 hours for immediate-release tablets. Food reduces and delays absorption — taking with meals is recommended to improve GI tolerability while having minimal effect on overall glycemic efficacy.
• Distribution: Metformin does not bind to plasma proteins. It has a large volume of distribution and is distributed throughout body fluids and accumulates in intestinal cells, salivary glands, and red blood cells. Tissue concentrations (particularly in the gut, liver, and muscle) substantially exceed plasma concentrations.
• Metabolism: Metformin is not metabolized in humans — it is excreted unchanged. This is a major pharmacokinetic advantage: no hepatic drug interactions through CYP enzyme pathways, and no active or toxic metabolites.
• Half-life: Plasma half-life is approximately 4 to 8 hours. The blood half-life (red blood cell residence) is approximately 17.6 hours — explaining why the drug accumulates in red blood cells.
• Elimination: Excreted entirely unchanged by the kidney, primarily via active renal tubular secretion (by organic cation transporters OCT1, OCT2, MATE1, and MATE2). Approximately 90% of absorbed Metformin is eliminated renally within 24 hours. This complete renal dependence for elimination is critical — renal impairment leads to Metformin accumulation and increased lactic acidosis risk.

Immediate-Release (IR) Tablets

• Always take Metformin IR tablets with or immediately after meals. Taking with food significantly reduces the incidence of gastrointestinal side effects (nausea, diarrhea, abdominal discomfort) — the main barrier to Metformin adherence.
• Swallow tablets whole with a full glass of water.
• For twice-daily dosing, take one dose with the morning meal and one with the evening meal.
• For three-times-daily dosing, take with breakfast, lunch, and dinner — evenly spaced throughout the day.
• If a dose is missed, take it with the next meal. Never double a dose to make up for a missed one.
• Start low and titrate slowly — beginning with the lowest dose and gradually increasing it over weeks is the most effective strategy for minimizing GI side effects.

Extended-Release (XR/ER/SR) Tablets

• Swallow extended-release tablets whole — do not crush, break, or chew. Disrupting the tablet matrix releases the full dose immediately, eliminating the controlled-release benefit and dramatically worsening GI tolerability.
• Take XR tablets once daily with the evening meal for optimal absorption and tolerability (evening administration with dinner improves bioavailability of XR formulations).
• Patients may notice an inactive tablet "ghost" in the stool — this is the insoluble tablet matrix and does not indicate that the drug was not absorbed.
• If once-daily 2000 mg XR is not tolerated, split the dose to 1000 mg twice daily with morning and evening meals.

Optimizing Tolerability

• Titrate slowly: Increase the dose gradually (every 1–2 weeks) rather than all at once. Most GI side effects are transient and resolve within the first 2–4 weeks of a new dose level.
• Take consistently with the same meal every day to maintain consistent drug levels.
• Consider switching from IR to XR formulation if GI side effects persist — the extended-release formulation has significantly better GI tolerability while maintaining equivalent glycemic efficacy.
• Adequate hydration is important, particularly in hot weather or during illness — dehydration increases the risk of Metformin accumulation and lactic acidosis.

Iodinated Contrast Media (Critical Interaction)

This is the most clinically critical interaction involving Metformin. Iodinated contrast agents (used for CT scans, angiography, and IV urography) can cause acute kidney injury in susceptible patients. If renal function is acutely reduced in a patient taking Metformin, the drug accumulates to toxic levels, dramatically increasing the risk of lactic acidosis. Metformin must be withheld on the day of contrast administration and for 48 hours after, and only restarted after renal function is confirmed to remain stable. This applies to all iodinated contrast procedures, not just intravenous urography.

Cationic Drugs (Competition for Renal Tubular Secretion)

Since Metformin is eliminated primarily via renal tubular secretion (through organic cation transporters OCT2, MATE1, and MATE2), drugs that are also secreted by these renal tubular transport systems may compete with Metformin for secretion — potentially increasing Metformin plasma levels and accumulation risk. These include:

• Amiloride
• Digoxin
• Morphine
• Procainamide
• Quinidine and Quinine
• Triamterene
• Trimethoprim
• Vancomycin

Monitor for signs of Metformin accumulation (GI symptoms, lactic acidosis) when initiating these drugs concurrently.

Furosemide (Loop Diuretics)

No clinically significant chronic interaction data are available between Metformin and furosemide. However, furosemide and other loop diuretics can cause volume depletion and reduced renal perfusion, which may reduce Metformin elimination and increase accumulation risk. Monitor renal function when initiating diuretic therapy in patients on Metformin.

Nifedipine (Calcium Channel Blocker)

Nifedipine has been shown to enhance the gastrointestinal absorption of Metformin — increasing its C_max by approximately 20% and AUC by approximately 9% — likely through enhanced gastrointestinal blood flow improving intestinal drug uptake. Metformin has minimal effects on nifedipine pharmacokinetics. This interaction is generally not clinically significant but should be noted in patients in whom Metformin levels may already be elevated.

Cimetidine

Cimetidine has been reported to inhibit renal tubular secretion of Metformin, resulting in a modest increase in Metformin plasma concentration. Metformin had no effect on cimetidine pharmacokinetics. A dose reduction of Metformin should be considered during concurrent cimetidine therapy, particularly in patients at risk for accumulation.

Hyperglycemia-Inducing Drugs — Loss of Glycemic Control

Certain drugs cause elevated blood glucose and may lead to loss of glycemic control in patients taking Metformin. These include:

• Thiazide and other diuretics
• Corticosteroids (glucocorticoids)
• Phenothiazines (antipsychotics)
• Thyroid hormones
• Estrogens and combined oral contraceptives
• Phenytoin (anticonvulsant)
• Nicotinic acid (niacin)
• Sympathomimetics (e.g., epinephrine, decongestants)
• Calcium channel blocking drugs
• Isoniazid (anti-tuberculosis)

Blood glucose should be monitored more frequently when these drugs are initiated or discontinued in patients on Metformin. Dose adjustment of Metformin may be required.

Insulin and Insulin Secretagogues (Increased Hypoglycemia Risk)

When Metformin is used in combination with insulin or sulfonylureas (insulin secretagogues), the risk of hypoglycemia increases. Metformin itself does not cause hypoglycemia as monotherapy, but the combination creates an additive blood glucose-lowering effect. Blood glucose should be carefully monitored during combination therapy, and insulin or sulfonylurea doses may need to be reduced. Initiation of insulin + Metformin combination should ideally be performed under supervised inpatient or close outpatient conditions.

Alcohol

Alcohol potentiates the risk of lactic acidosis with Metformin by: (1) increasing hepatic lactate production through inhibition of hepatic gluconeogenesis, and (2) potentially causing dehydration and reduced renal perfusion. Patients taking Metformin should be counseled to avoid excessive alcohol consumption, particularly binge drinking.

Anticoagulants (Warfarin)

An interaction between Metformin and anticoagulants is theoretically possible. Dosage of anticoagulants (e.g., warfarin) may need adjustment during Metformin therapy. INR monitoring is recommended when initiating, changing, or discontinuing Metformin in patients on warfarin.

The following adverse effects are classified by frequency using standard pharmacovigilance terminology. Gastrointestinal effects are by far the most common and are the primary reason for early Metformin discontinuation, though they are largely manageable with proper dosing strategies.

Very Common (Affecting More than 1 in 10 Patients)

Gastrointestinal Disorders

• Nausea and vomiting
• Diarrhea and loose stools
• Abdominal pain and cramping
• Loss of appetite (anorexia)
• Metallic taste or taste disturbance
• Flatulence and bloating

Important clinical note: These GI effects occur most frequently at the initiation of therapy or after dose increases, and resolve spontaneously in most patients within 2–4 weeks of continued treatment. Taking Metformin with meals and starting with a low dose with slow titration significantly reduces their incidence and severity. Switching to the extended-release formulation also substantially improves GI tolerability.

Common (Affecting 1 in 100 to 1 in 10 Patients)

Nervous System Disorders

• Taste disturbance (dysgeusia) — a metallic taste in the mouth; usually transient

Rare (Affecting 1 in 10,000 to 1 in 1,000 Patients)

Hepatobiliary Disorders

• Isolated elevation of liver function test values or hepatitis — usually reversible upon Metformin discontinuation

Skin and Subcutaneous Tissue Disorders

• Skin reactions — erythema (redness), pruritus (itching), urticaria (hives)

Very Rare (Affecting Fewer than 1 in 10,000 Patients) — but Clinically Most Serious

Lactic Acidosis — Life-Threatening Emergency

Lactic acidosis is the most serious adverse effect of Metformin, with a mortality rate of approximately 50% when it occurs. However, it is extremely rare when Metformin is used appropriately within licensed indications and contraindications are respected. Risk is substantially increased in:

• Renal impairment (impaired Metformin clearance)
• Hepatic impairment (impaired lactate clearance)
• Tissue hypoxia (cardiac failure, respiratory failure, severe infection)
• Excessive alcohol intake
• High doses of Metformin

Symptoms of lactic acidosis include:

• Severe nausea, vomiting, and abdominal pain
• Muscle pain and weakness (myalgias)
• Difficulty breathing and respiratory distress
• Severe general malaise, fatigue, and drowsiness
• Hypothermia
• Hypotension and bradyarrhythmia

Lactic acidosis is a medical emergency — if suspected, stop Metformin immediately and seek emergency hospital care.

Metabolic and Nutritional Disorders

Vitamin B12 Deficiency (Important Long-Term Risk)

Long-term Metformin use — particularly at higher doses — causes a significant reduction in vitamin B12 absorption from the ileum (by interfering with intrinsic factor-mediated ileal absorption). This results in a gradual decline in serum B12 levels, which may eventually lead to:

• Megaloblastic anemia — macrocytic anemia with hypersegmented neutrophils
• Peripheral neuropathy — numbness, tingling, and burning of the feet and hands (which may mimic or worsen diabetic neuropathy)
• Subacute combined degeneration of the spinal cord (in severe untreated cases)

Regular monitoring of serum B12 levels (annually) and routine supplementation with vitamin B12 (particularly in patients on long-term high-dose Metformin, or those with dietary deficiency) is recommended. This is especially important in patients presenting with peripheral neuropathy or anemia that is worsening despite adequate glycemic control.

Frequency Not Known (From Post-Marketing Surveillance)

• Hemolytic anemia (blood and lymphatic system disorder) — rare, immune-mediated
• Encephalopathy (nervous system) — very rare; reported in cases of Metformin toxicity

Pregnancy

Uncontrolled diabetes during pregnancy — whether gestational or pre-existing type 2 diabetes — is associated with a significantly increased risk of congenital malformations, macrosomia (large baby), perinatal mortality, preeclampsia, and neonatal hypoglycemia. Maintaining blood glucose levels as close to normal as possible throughout pregnancy is essential to minimize these risks.

Insulin remains the recommended antidiabetic treatment during pregnancy. When a patient plans to become pregnant or discovers she is pregnant, it is recommended that Metformin be discontinued and insulin therapy be initiated or continued, as it provides more precise blood glucose control and has a longer established safety record in pregnancy.

That said, a substantial and growing body of observational data (including systematic reviews and meta-analyses from multiple countries) has not demonstrated clear evidence of teratogenicity or increased risk of major congenital abnormalities from Metformin use in the first trimester. International guidelines are evolving on this topic — Metformin is increasingly used in gestational diabetes management in many countries under specialist supervision. However, the official position remains that Metformin should not be routinely used during pregnancy unless specifically recommended by a specialist, and insulin is the preferred pharmacotherapy for established gestational or pre-existing diabetes in pregnancy.

Lactation (Breastfeeding)

Metformin is excreted into human breast milk. The relative infant dose (RID) is low — estimated at approximately 0.28–0.65% of the weight-adjusted maternal dose — and no adverse effects have been observed in breastfed newborns or infants in published observational studies. However, because only limited clinical data are available on long-term effects of Metformin exposure in nursing infants, breastfeeding is currently not recommended during Metformin treatment as a general precautionary measure.

The decision on whether to discontinue breastfeeding or to withhold Metformin should be made on a case-by-case basis, taking into account the significant benefits of breastfeeding for both mother and infant (including reduced maternal risk of re-developing type 2 diabetes post-partum), and the potential — though low — risk of adverse effects on the infant. This decision should be made in consultation with the treating physician.

Lactic Acidosis — Critical Warning

The most serious potential complication of Metformin therapy is lactic acidosis — a rare but life-threatening buildup of lactic acid in the blood. Metformin inhibits hepatic lactate metabolism (through complex I inhibition), and in conditions where lactate accumulates or Metformin clearance is reduced, plasma Metformin and lactate levels can reach dangerous concentrations. The risk is directly proportional to the degree of renal impairment, age, and presence of tissue hypoxia. To minimize this risk:

• Carefully follow all contraindications and discontinue Metformin in any high-risk clinical situation
• Monitor renal function regularly throughout therapy
• Educate patients about symptoms of lactic acidosis — patients should seek immediate medical attention for unexplained muscle pain, difficulty breathing, abdominal pain, fatigue, or cold feeling

Renal Function Monitoring

Since Metformin is substantially excreted by the kidney, the risk of Metformin accumulation and lactic acidosis increases with the degree of renal functional impairment. Regular monitoring of renal function (serum creatinine, eGFR) is essential throughout Metformin therapy:

• At least annually in patients with normal renal function
• At least 2 to 4 times per year in elderly patients and those with creatinine clearance at the lower limit of normal
• More frequently in any patient receiving drugs that may affect renal function (NSAIDs, ACE inhibitors, ARBs, contrast agents, aminoglycosides)

Metformin is contraindicated when eGFR is <30 mL/min/1.73 m², and should be used with caution and dose reassessment when eGFR falls below 45 mL/min/1.73 m².

Surgical Procedures and Contrast Media

Metformin should be temporarily discontinued 2–3 days before any major surgical procedure and all clinical investigations involving intravenous iodinated contrast media (CT with contrast, angiography, IV urography). These procedures can cause acute, transient deterioration in renal function. Metformin should only be restarted after renal function has been confirmed normal following the procedure.

Vitamin B12 Monitoring

Metformin reduces intestinal absorption of vitamin B12 by interfering with intrinsic factor-mediated uptake in the ileum. Patients on continuous Metformin therapy should have annual estimation of serum vitamin B12 levels. Patients who develop peripheral neuropathy, megaloblastic anemia, or unexplained neurological symptoms while on Metformin should be evaluated for B12 deficiency. Routine vitamin B12 supplementation should be considered for patients on long-term Metformin, particularly those with dietary risk factors for B12 deficiency (vegetarians, vegans, elderly).

Hypoglycemia Risk in Combination Therapy

As monotherapy, Metformin does not cause hypoglycemia. However, when combined with insulin or sulfonylureas, the risk of hypoglycemia increases significantly. Blood glucose should be monitored carefully. Patients should be educated on recognizing and managing hypoglycemia. Initiation of insulin + Metformin combination therapy should ideally be conducted in a supervised setting until the correct dosing ratio is established.

Dehydration, Infections, and Acute Illness

Metformin is not recommended in conditions that may cause dehydration — including severe vomiting, diarrhea, or reduced fluid intake — or in patients with serious acute infections or trauma. These conditions impair renal perfusion, reduce Metformin elimination, and increase lactic acid production. Metformin should be temporarily withheld during any acute febrile illness or gastrointestinal illness causing dehydration, and restarted only when the patient has fully recovered, is eating and drinking normally, and renal function has been confirmed stable.

Alcohol Warning

Patients should be warned to avoid excessive alcohol consumption during Metformin therapy. Alcohol increases the risk of lactic acidosis by augmenting hepatic lactate production and may cause episodes of hypoglycemia in poorly nourished patients on combination antidiabetic therapy.

Reduced Renal Clearance with Cimetidine

Reduced renal clearance of Metformin has been reported during cimetidine therapy (due to competition for renal tubular secretion). A dose reduction of Metformin should be considered during concurrent cimetidine treatment.

Metformin overdose has a distinct clinical profile compared to most other antidiabetic drugs:

Hypoglycemia

Hypoglycemia does not occur with Metformin overdose alone, even at very high doses. In a reported case, hypoglycemia was not observed with Metformin ingestion of up to 85 grams. This is because Metformin does not stimulate insulin secretion — its glucose-lowering mechanism is insulin-independent.

Lactic Acidosis — The Primary Overdose Complication

The major risk with Metformin overdose (or accumulation in the context of renal failure) is lactic acidosis. This is a medical emergency with a mortality rate of approximately 50% and must be treated in hospital. Lactic acidosis has occurred with Metformin doses as low as those that did not cause hypoglycemia. Features include:

• Severe nausea, vomiting, and abdominal pain
• Muscle aches, cramps, and weakness
• Extreme fatigue and malaise
• Difficulty breathing (compensatory hyperventilation/Kussmaul breathing)
• Confusion and altered consciousness
• Hypotension and cardiovascular collapse
• Hypothermia
• Laboratory findings: elevated serum lactate (>5 mmol/L), metabolic acidosis with wide anion gap, elevated Metformin plasma levels

Treatment of Overdose and Lactic Acidosis

• Immediate hospital admission — lactic acidosis is a life-threatening emergency requiring intensive care
• Discontinue Metformin immediately
• Hemodialysis is the most effective treatment — Metformin is dialyzable and hemodialysis rapidly removes both Metformin and lactate from the blood. Emergency hemodialysis should be instituted as soon as possible in confirmed cases of Metformin-associated lactic acidosis
• Supportive care — correct hemodynamic instability, maintain oxygenation, correct electrolyte disturbances
• IV sodium bicarbonate may be considered for severe metabolic acidosis (pH <7.1)
• Activated charcoal may be considered in very recent acute oral overdose (within 1 hour) if the patient is alert and can protect the airway

In the event of suspected Metformin overdose or signs of lactic acidosis, contact emergency services or a poison control center immediately.

• Store all Meforex 500 mg formulations below 30°C, in a cool, dry place protected from direct light and moisture.
• Keep all formulations out of the reach of children.
• Do not use any formulation after the expiry date printed on the packaging or label.
• Store in original blister packs or bottles to protect from humidity — exposure to moisture can degrade the tablet.
• Extended-release tablets: Store under the same conditions as immediate-release tablets; keep in original packaging. The intact matrix tablet should not be stored once the packaging is damaged.
• Do not store in a bathroom medicine cabinet or near a kitchen sink where moisture exposure is common.
• Do not freeze any Metformin formulation.
• Metformin tablets do not require refrigeration under normal storage conditions.

Elderly Patients (Age ≥65 Years)

Metformin is commonly used in elderly patients with type 2 diabetes. However, due to the high prevalence of age-related decline in renal function — which is often subclinical and asymptomatic in the elderly — Metformin dosage should be carefully adjusted based on renal function assessment rather than age alone. Key considerations:

• Obtain baseline eGFR before initiating Metformin in any elderly patient
• Re-evaluate renal function at least 2–4 times per year in elderly patients
• Use the lowest effective dose
• Be alert for situations that may acutely impair renal function in elderly patients (dehydration, intercurrent illness, concurrent nephrotoxic drugs)
• Exercise particular caution when starting antihypertensive therapy (ACE inhibitors, ARBs, diuretics) or NSAIDs concurrently in elderly patients on Metformin

Pediatric Population (Children Aged 10–17 Years)

The diagnosis of type 2 diabetes mellitus should be definitively confirmed (including distinguishing from type 1 diabetes) before initiating Metformin in children. Relevant considerations:

• Metformin IR tablets are approved for children aged 10 years and over; Metformin XR has not been studied in children
• No effect of Metformin on growth and puberty was detected during controlled clinical studies of one-year duration — but no long-term data are available on these endpoints. Careful follow-up of growth and pubertal development is recommended in prepubescent children on Metformin.
• Maximum daily dose in children is 2000 mg — equivalent to adult maximum

Children Aged 10–12 Years — Additional Caution

Particular caution is recommended when prescribing Metformin to children aged between 10 and 12 years, as clinical experience in this specific age group is limited. Type 2 diabetes is significantly less common in this younger pediatric group, and the possibility of alternative diagnoses (including latent autoimmune diabetes of the young, LADY, or MODY) should be carefully excluded before initiating Metformin.

Patients with Renal Impairment

Renal function is the single most important determinant of Metformin safety. The complete guidance is in the Dosage section. Key principles:

• Measure eGFR before initiating and regularly thereafter throughout treatment
• Contraindicated in eGFR <30 mL/min/1.73 m²
• Use with caution and reduce dose when eGFR is 30–45 mL/min/1.73 m²
• Extra caution in clinical situations where renal function may acutely deteriorate (see Precautions)
• Hemodialysis can effectively remove Metformin in cases of toxic accumulation

Patients with Hepatic Impairment

The liver plays a crucial role in lactate clearance through hepatic gluconeogenesis. Patients with significant hepatic impairment have reduced capacity to clear lactate, substantially increasing the risk of lactic acidosis during Metformin therapy. Metformin should not be used in patients with hepatic impairment — including those with cirrhosis, significant hepatitis, or other active liver disease. Liver function tests should be assessed before initiating Metformin in patients with suspected liver disease.