Metformin

Administration

  • Type: Diabetes medication
  • Dosage Forms: 500, 850, 1000; ER 500, 750, 1000
  • Routes of Administration: PO
  • Common Trade Names: Fortamet, Glucophage, Glumetza, Riomet

Adult Dosing

Diabetes Mellitus type 2

  • Take with meals
  • Hold 48 hours for iodinated contrast
Immediate Release
  • 850-1000mg PO bid
  • Start 500mg BID or 850mg QD
  • Increase 500mg qwk or 850mg q2wk
  • Max 2550mg/day
Extended Release
  • 1000-2000mg PO QD
  • Start 500mg QD
    • Increase 500mg qwk
  • Alt dosing; 1000mg bid
    • Add 500mg immediate release for inadequate response
  • Do not crush or chew

Polycystic Ovarian Syndrome

  • Take with meals
  • Hold for iodinated contrast
Immediate Release
  • 500mg tid
  • Alt dosing; 850-1000mg bid
  • Increase as needed
  • Max 2550mg/day
Extended Release
  • 1500-2000mg QD
  • Do not crush or chew
  • Max 2000mg/day

Pediatric Dosing

  • Take with meals
  • Hold for iodinated contrast
  • Children aged 10-18 years of age

Diabetes Mellitus type 2

  • 500-1000mg bid
  • Start 500mg QD
  • Increase 500mg/day every 1-2 weeks
  • Max 2000mg/day

Special Populations

Renal Dosing

  • Adult: Contraindicated Cr>1.4 in females and Cr>1.5 in med
  • Pediatric: Contraindicated Cr>1.4 in females and Cr>1.5 in med

Hepatic Dosing

  • Adult: Avoid with hepatic impairment
  • Pediatric: Avoid with hepatic impairment

Contraindications

  • Allergy to class/drug
  • Creatinine >1.4 female or >1.5 male
  • Metabolic acidosis
  • DKA
  • Lactic acidosis
  • Iodinated contrast
  • Hypoxemia
  • Dehydration
  • Sepsis
  • Surgery
  • Hepatic impairment
Caution

Adverse Reactions

Serious

Common

  • Diarrhea
  • nausea and vomiting
  • Flatulence
  • Indigestion
  • Abdominal discomfort
  • Anorexia
  • Headache
  • Rash
  • Ovulation reduction

Pharmacology

  • Half-life: 6 hours in plasma and 17 hours in blood
  • Metabolism: CYP450
  • Excretion: Urine

Mechanism of Action

  • Decreases hepatic glucose production and intestinal absorption
  • Increases insulin sensitivity

Comments

See Also

References

Epocrates