metformins

Metformin is a biguanide oral antihyperglycemic used as the first-line pharmacologic therapy for many adults with type 2 diabetes. It is also prescribed for polycystic ovary syndrome (PCOS) and, in certain guidelines, for prediabetes or gestational diabetes. It is available in immediate-release and extended-release forms.

Mechanism: Metformin lowers hepatic glucose production, improves insulin sensitivity, and reduces intestinal glucose absorption. It does not stimulate pancreatic insulin release, so it has a relatively low risk of hypoglycemia when used alone. The exact mechanism is not fully understood and may involve changes in cellular energy status.

Administration and dosing: Treatment typically begins at a low dose with meals to minimize gastrointestinal side effects. Dosing is adjusted based on efficacy and tolerability, with formulation-specific maximum daily doses. Dose may require modification in patients with reduced kidney function. It is usually withheld before and after contrast imaging procedures.

Pharmacokinetics and safety: Metformin is excreted unchanged by the kidneys and is not metabolized by the liver. Common adverse effects include gastrointestinal symptoms such as nausea, diarrhea, and abdominal discomfort. Long-term use can be associated with vitamin B12 deficiency. Lactic acidosis is a rare but serious complication, primarily in patients with significant renal impairment or other risk factors.

History and brand names: Metformin was developed in the mid-20th century and introduced for medical use in the 1990s. Brand names include Glucophage, Riomet, Fortamet, and Glumetza.