GLUCOPHAGE XR 1000/MG PR TAB 30/TAB

Indications

Approved Uses

Type 2 diabetes mellitus in adults, as an adjunct to diet and exercise (monotherapy or in combination with other antidiabetic agents).

Dosage & Administration

Dosing by Condition

Type 2 diabetes mellitus (adults, XR): start 500 mg once daily with the evening meal (some patients may start 1000 mg once daily if already tolerating metformin); increase by 500 mg weekly (or every 1-2 weeks) based on glycemic control/tolerability; usual max 2000 mg/day (some XR products allow up to 2500 mg/day depending on label).

Initial Dose

1000 mg once daily with the evening meal.

Maintenance Dose

1000mg to 2000mg once daily.

Maximum Dose

Extended-release metformin: maximum 2000 mg/day.

Children's Dosage

Extended-release form is not approved for use in children. Immediate-release form: For children 10-16 years, initial dose is 500mg twice daily, with a maximum dose of 2000mg per day.

Dose Adjustment Notes

Titrate gradually to minimize GI adverse effects; assess renal function before initiation and periodically-do not use if eGFR <30 mL/min/1.73 m², and if eGFR 30-45 mL/min/1.73 m² avoid initiation and reassess risk/benefit if already on therapy; temporarily withhold around iodinated contrast in at-risk patients and for major surgery/acute illness causing hypoxia or dehydration.

How to Take

Swallow the extended-release tablet whole with the evening meal (or immediately after); do not crush, chew, or split; the tablet shell may appear in stool (normal).

Side Effects

Common Side Effects

Diarrhea, nausea, vomiting, flatulence, abdominal discomfort, indigestion, loss of appetite, metallic taste.

Side Effect Frequency

Very common (>10%): Diarrhea, nausea, vomiting, flatulence, abdominal discomfort. Common (1-10%): Metallic taste, indigestion, vitamin B12 deficiency with prolonged use. Rare (<0.1%): Lactic acidosis.

Safety & Warnings

Contraindications

Contraindicated in: severe renal impairment (eGFR <30 mL/min/1.73 m²), acute or chronic metabolic acidosis (including DKA), and hypersensitivity to metformin.

Warnings & Precautions

Warnings/precautions: lactic acidosis risk (stop if suspected); assess renal function before start and periodically; temporarily withhold for iodinated contrast in at-risk patients and around major surgery/acute illness causing hypoxia/dehydration/sepsis; monitor for vitamin B12 deficiency with long-term use; do not crush/chew XR tablets.

Age Restriction

Not recommended/approved for pediatric use (<18 years) for this 1000 mg extended-release product; pediatric approval applies to immediate-release metformin for ages ≥10 years.

Drug Interactions

Drug Interactions

Key interactions: iodinated contrast media (temporary hold to reduce lactic acidosis risk), alcohol (↑ lactic acidosis risk), carbonic anhydrase inhibitors (e.g., topiramate/acetazolamide; ↑ acidosis risk), cationic drugs affecting renal tubular secretion (e.g., cimetidine; may ↑ metformin exposure), and drugs that raise glucose (e.g., corticosteroids/diuretics); hypoglycemia risk increases when combined with insulin/secretagogues.

Interaction Severity

MAJOR: Iodinated contrast media in patients with risk factors for renal impairment/AKI (withhold metformin per guidance); excessive alcohol intake (increases lactic acidosis risk). MODERATE: Carbonic anhydrase inhibitors (e.g., topiramate, acetazolamide) (increase metabolic acidosis risk), cationic drugs that reduce renal tubular secretion (e.g., cimetidine, trimethoprim) (increase metformin exposure), and drugs that can worsen renal function (e.g., diuretics/NSAIDs) (increase accumulation risk).

Food Interaction

Take with food; for XR, take with the evening meal.

Alcohol Interaction

Avoid

Special Populations

Pregnancy

Consult Doctor

Children

Extended-release form is not approved for use in children. Immediate-release form: For children 10-16 years, initial dose is 500mg twice daily, with a maximum dose of 2000mg per day.

Elderly

Start at lower dose and titrate cautiously; monitor renal function more frequently (every 3-6 months); avoid use in patients ≥80 years unless renal function is confirmed to be normal; increased risk of lactic acidosis

Kidney Impairment

eGFR ≥60: no adjustment; eGFR 45-59: continue/monitor; eGFR 30-44: do not initiate-if already on, assess risk/benefit, consider dose reduction and closer monitoring; eGFR <30: contraindicated.

Liver Impairment

Avoid use in hepatic impairment (no dose-adjustment strategy; generally not recommended due to lactic acidosis risk).

Storage & Patient Advice

Stopping the Medicine

Can be stopped without tapering, but should not be discontinued without prescriber input because glycemic control may worsen.

Overdose

Overdose primarily causes lactic acidosis (nonspecific symptoms such as malaise/myalgias/respiratory distress/abdominal pain, hypothermia, hypotension, bradyarrhythmias); stop drug, urgent hospital evaluation, supportive care, and hemodialysis can remove metformin and correct acidosis.

Patient Counseling

Take once daily with the evening meal; swallow whole (do not crush/chew/split); you may see the tablet shell in stool (normal); limit/avoid excessive alcohol; maintain hydration and follow diet/exercise; inform providers before iodinated-contrast imaging or major surgery/acute illness; seek urgent care for symptoms suggestive of lactic acidosis (e.g., severe weakness, muscle pain, trouble breathing, abdominal pain, marked drowsiness).

Monitoring Requirements

Monitor glycemic control (HbA1c about every 3 months until stable then every 3-6 months); renal function (eGFR) at baseline and at least annually (more often if elderly or at risk); vitamin B12 periodically (e.g., every 1-2 years or if anemia/neuropathy); monitor for GI intolerance and signs of lactic acidosis in high-risk situations.

Pharmacology

Mechanism of Action

Decreases hepatic glucose production (gluconeogenesis), decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake/utilization (AMPK-mediated effects contribute).

Onset of Action

Initial glucose-lowering effect within 24-48 hours; maximal effect may take 1-2 weeks.

Duration of Effect

Approximately 24 hours (extended-release formulation).

Half-Life

Plasma elimination half-life ~6.2 hours; whole-blood half-life ~17.6 hours (reflecting erythrocyte distribution).

Bioavailability

Immediate-release metformin oral bioavailability is ~50-60% under fasting conditions; XR has slower absorption and food can affect the absorption rate/extent depending on formulation.

Metabolism

Not metabolized; excreted unchanged in urine.

Excretion

Eliminated renally, excreted largely unchanged in urine via glomerular filtration and active tubular secretion (major route).

Protein Binding

Negligible (essentially not bound to plasma proteins).

Product Information

Available Dosage Forms

Metformin is available as immediate-release tablets, extended-release/prolonged-release tablets, and oral solution (availability varies by market).

Composition per Dose

Each extended-release tablet: 1000 mg metformin hydrochloride

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Diabetes Type

Type 2

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