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ALIMENTARY TRACT AND METABOLISM › DRUGS USED IN DIABETES › BLOOD GLUCOSE LOWERING DRUGS, EXCL. INSULINS › Biguanides
metformin
A10BA02
Forms & Strengths
- Tablet, Immediate Release: 500 mg, 850 mg, 1000 mg
- Tablet, Extended Release: 500 mg, 750 mg, 1000 mg
- Oral Solution: 500 mg/5 mL
Adult Dosing
- Type 2 Diabetes Mellitus (Immediate Release): Initial 500 mg PO BID or 850 mg PO daily with meals; increase by 500 mg/day or 850 mg every 1-2 weeks; max 2550 mg/day in divided doses
- Type 2 Diabetes Mellitus (Extended Release): Initial 500 mg to 1000 mg PO daily with evening meal; increase by 500 mg weekly; max 2000 mg/day
Pediatric Dosing
- Type 2 Diabetes Mellitus (Children <10 years): Safety and efficacy not established
- Type 2 Diabetes Mellitus (Children ≥10 to 16 years, Immediate Release): Initial 500 mg PO BID with meals; increase in increments of 500 mg weekly; max 2000 mg/day in divided doses
Indications
- Management of type 2 diabetes mellitus to improve glycemic control in adults and pediatric patients aged 10 years and older
- Off-label: Prevention of type 2 diabetes in high-risk individuals
- Off-label: Treatment of insulin resistance in polycystic ovary syndrome (PCOS)
Mechanism of Action
- Decreases hepatic glucose production by inhibiting gluconeogenesis and glycogenolysis
- Decreases intestinal absorption of glucose
- Improves insulin sensitivity by increasing peripheral glucose uptake and utilization
Contraindications
- Severe renal impairment (eGFR <30 mL/min/1.73m2)
- Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma
- Known hypersensitivity to metformin hydrochloride
Adverse Reactions
- Diarrhea, nausea, vomiting, flatulence, abdominal discomfort (very common, dose-dependent)
- Lactic acidosis (rare, potentially fatal)
- Decreased vitamin B12 absorption and deficiency with long-term use
Drug Interactions
- Cationic drugs eliminated by renal tubular secretion (e.g., cimetidine, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, vancomycin) may increase metformin concentration
- Carbonic anhydrase inhibitors (e.g., topiramate, zonisamide, acetazolamide) increase risk of metabolic acidosis
- Intravascular iodinated contrast materials increase risk of acute kidney injury and associated lactic acidosis
Curated Content: Needs Vetting Before Put to Clinical Use