Metformin ER

GLUCOPHAGE XR

Open Metformin ER in the interactive console ↗

What it isExtended-release biguanide (GLUCOPHAGE XR, 2000) that inhibits complex I and suppresses hepatic glucose production; type 2 diabetes.

Why this oneTaken once daily with the evening meal, slower delivery reduces GI peaks and can preserve therapy after immediate-release intolerance; ghost tablet in stool is expected.

What limits itRenal accumulation can precipitate lactic acidosis; monitor kidney function. GI symptoms and long-term B12 depletion still occur.

FDA-approved for

type 2 diabetes (2000)

FDA label

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BOXED WARNING Lactic acidosis: postmarketing metformin-associated lactic acidosis has caused death, hypothermia, hypotension, resistant bradyarrhythmias; risk rises with renal impairment, certain drugs, age ≥65, contrast, surgery, hypoxia, excess alcohol, hepatic impairment — discontinue and hemodialyze if suspected.

FDA dosing	Population	Start	Target	Max
Type 2 diabetes mellitus (adjunct to diet/exercise)	Adults	500 mg QD with evening meal	500–2000 mg/day	2000 mg QD (or 1000 mg BID)

Titration Increase in 500 mg increments at weekly intervals

Renal Contraindicated if eGFR <30 mL/min/1.73m²; initiation not recommended if eGFR 30–45; reassess risk/benefit if eGFR falls below 45; discontinue if below 30

Hepatic Avoid use in patients with hepatic impairment (risk of lactic acidosis)

Instructions

Swallow whole with evening meal; never crush, cut, or chew
Discontinue at time of or prior to iodinated contrast imaging in at-risk patients; re-evaluate eGFR after 48 h
May switch from IR metformin to same total daily dose once daily, up to 2000 mg

Contraindications

Severe renal impairment (eGFR below 30 mL/min/1.73 m²)
Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma

Cautions

Lactic acidosis (see Boxed Warning)
Vitamin B12 deficiency — monitor hematologic parameters annually, B12 every 2–3 years
Hypoglycemia when combined with insulin or insulin secretagogues — may need lower dose

Adverse reactions

Diarrhea
Nausea/vomiting
Flatulence
Asthenia
Indigestion
Abdominal discomfort
Headache

Pregnancy Limited data insufficient for risk; published data have not shown clear association with birth defects/miscarriage; poorly controlled diabetes carries maternal/fetal risk

Lactation Metformin present in human milk (infant dose ~0.11–1% maternal); insufficient data on effects; weigh benefits vs. risk

⚠ BOXED WARNING