Metformin

Increased risk of metformin-associated lactic acidosis in renal or hepatic impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors), ≥65yrs of age, undergoing radiological contrast study, surgery and other procedures, hypoxic states, and excessive alcohol intake; discontinue if lactic acidosis occurs. Discontinue at time of, or prior to intravascular iodinated contrast imaging in patients with eGFR 30–60mL/min/1.73m², history of hepatic impairment, alcoholism, heart failure, or will be given intra-arterial contrast; reevaluate eGFR 48hrs after procedure and restart therapy if renally stable. Suspend therapy if dehydration occurs or before surgery. Avoid if evidence of hepatic disease. Assess renal function prior to starting and periodically thereafter; more frequently in elderly or patients whose eGFR falls <45mL/min/1.73m²; see full labeling. Monitor hematology (esp. serum Vit. B₁₂ in susceptible patients). Pregnancy. Nursing mothers.