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Metformin
From WikEM
Contents
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
- Pregnancy Rating: B
- Lactation risk: Probably safe
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
- CHF
- Elderly
- Alcohol abuse
- Hypoglycemia risk
Adverse Reactions
Serious
- Metformin-associated lactic acidosis
- Megaloblastic anemia
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
Authors
Colin Hoff, Claire, Ross Donaldson, Neil Young, Babak Missaghi, Daniel Ostermayer
