Metformin Ext-rel

  • Diabetes

Metformin Ext-rel Generic Name & Formulations

General Description

Metformin HCl 500mg, 750mg, 1000mg; ext-rel tabs.

Pharmacological Class


See Also

How Supplied

Contact supplier

Metformin Ext-rel Indications


Adjunct to diet and exercise in type 2 diabetes.

Metformin Ext-rel Dosage and Administration


Swallow whole. Take with evening meal. Individualize. ≥17yrs: initially 500mg once daily; may increase by 500mg increments at 1-week intervals; max 2g once daily or in 2 divided doses. If higher doses needed, switch to immediate-release form at max 2.55g/day in divided doses.


<17yrs: not established. Use immediate-release form.

Metformin Ext-rel Contraindications


Severe renal impairment (eGFR <30mL/min/1.73m2). Metabolic acidosis, diabetic ketoacidosis.

Metformin Ext-rel Boxed Warnings

Boxed Warning

Lactic acidosis.

Metformin Ext-rel Warnings/Precautions


Increased risk of metformin-associated lactic acidosis in renal or hepatic impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors), ≥65yrs of age, undergoing radiological contrast study, surgery and other procedures, hypoxic states, and excessive alcohol intake; discontinue if lactic acidosis occurs. Discontinue at time of, or prior to intravascular iodinated contrast imaging in patients with eGFR 30–60mL/min/1.73m2, history of hepatic impairment, alcoholism, heart failure, or will be given intra-arterial contrast; reevaluate eGFR 48hrs after procedure and restart therapy if renally stable. Suspend therapy if dehydration occurs or before surgery. Avoid if evidence of hepatic disease. Assess renal function prior to starting and periodically thereafter; more frequently in elderly or patients whose eGFR falls <45mL/min/1.73m2; see full labeling. Monitor hematology (esp. serum Vit. B12 in susceptible patients). Pregnancy. Nursing mothers.

Metformin Ext-rel Pharmacokinetics

See Literature

Metformin Ext-rel Interactions


Increased risk of lactic acidosis with topiramate, other carbonic anhydrase inhibitors (eg, zonisamide, acetazolamide, dichlorphenamide); monitor. Concomitant cationic drugs that interfere with renal tubular transport systems (eg, ranolazine, vandetanib, dolutegravir, cimetidine) may increase metformin levels; monitor. Avoid excessive alcohol intake (potentiates effects of metformin on lactate). Diuretics, steroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, sympathomimetics, calcium channel blockers, isoniazid, nicotinic acid, others may cause hyperglycemia. May need lower dose of concomitant insulin and/or insulin secretagogue (eg, sulfonylurea) to reduce risk of hypoglycemia.

Metformin Ext-rel Adverse Reactions

Adverse Reactions

Diarrhea, nausea, vomiting, flatulence, asthenia, indigestion, abdominal discomfort, headache; rare: lactic acidosis (may be fatal).

Metformin Ext-rel Clinical Trials

See Literature

Metformin Ext-rel Note


Formerly known under the brand name Glucophage, Glucophage XR.

Metformin Ext-rel Patient Counseling

See Literature