metformin
Adjunctive therapy • Brands: Glucophage, Glucophage XR, Fortamet, Glumetza
Last reviewed: 2025-12-30
General information
- Primary label indications include: Type 2 diabetes mellitus; adjunct to diet and exercise for glycemic control (label).
- Class: Adjunctive therapy
- Common US brands: Glucophage, Glucophage XR, Fortamet, Glumetza
- Therapeutic drug monitoring not routinely recommended.
- Last reviewed: 2025-12-30
Dosing & forms
- Forms/strengths: —
- Frequency: —
- Food: —
- Typical range: —
Mechanism (brief)
Biguanide antihyperglycemic that reduces hepatic glucose production and improves insulin sensitivity; does not typically cause hypoglycemia as monotherapy. In psychiatry it is commonly used off label to help mitigate antipsychotic-associated weight gain and metabolic risk.
Metabolism & Half‑life
- Metabolism: Not metabolized; eliminated by renal filtration and active tubular secretion (label).
- Half‑life: Single-dose mean 6.2 h
Therapeutic Drug Monitoring (TDM)
Recommended: No
Monitoring highlights
- —
Sources
- Metformin hydrochloride tablets prescribing information — DailyMed (2025)
- Lifestyle Intervention and Metformin for Treatment of Antipsychotic-Induced Weight Gain — JAMA (2008)
- A systematic review of metformin to limit weight gain with atypical antipsychotics — Journal of Clinical Pharmacy and Therapeutics (2011)
- Efficacy of Metformin and Topiramate in Prevention and Treatment of Second-Generation Antipsychotic–Induced Weight Gain — The Annals of Pharmacotherapy (2010)
- AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology — Pharmacopsychiatry (2018)