DRUG OF THE DAY
metformin
Biguanide antihyperglycemic
Before opening the card, recall one use, one safety check and one counseling point.
Reveal the drug learning card
Names and formulations
- Metformin hydrochloride: immediate-release oral tablet
- Glumetza: extended-release oral tablet
Immediate-release and extended-release tablets differ in dosing and administration; ER tablets should be swallowed whole and may leave a soft shell in stool.
Common use
Improves glycemic control in type 2 diabetes alongside diet and exercise.
Mechanism of action
Reduces hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity.
Important adverse effects and monitoring
- Boxed warning: metformin-associated lactic acidosis is rare but serious; risk rises with severe kidney impairment, hypoxic states, liver impairment, and excessive alcohol use.
- Assess eGFR before initiation and periodically; initiation is not recommended at eGFR 30–45 mL/min/1.73 m² and use is contraindicated below 30.
- Monitor vitamin B12 periodically, especially with anemia, neuropathy, or long-term therapy.
Patient counseling
- Take with meals to reduce gastrointestinal effects; swallow ER tablets whole.
- Avoid excessive alcohol and tell the radiology team about metformin before iodinated-contrast procedures.
Interaction to recognize
With: carbonic anhydrase inhibitors such as topiramate
Why it matters: Can increase acidosis risk.
Practical response: Consider more frequent monitoring and reassess symptoms or kidney function when combined.
Check the original sources
- DailyMed — metformin immediate-release prescribing information
Sections: Boxed Warning; 1 Indications and Usage; 2 Dosage and Administration; 5 Warnings and Precautions; 7 Drug Interactions; 12.1 Mechanism of Action; 17 Patient Counseling Information. Source checked 2026-09-13.
- DailyMed — Glumetza (metformin ER) prescribing information
Sections: 2 Dosage and Administration; 5.2 Vitamin B12 Deficiency; 17 Patient Counseling Information. Source checked 2026-09-13.
Selected learning points; verify current labeling for the complete prescribing information.