Metformin

The mechanisms of action of metformin are unique compared to other classes of oral antihyperglycemic agents. Metformin lowers blood glucose levels by decreasing hepatic glucose production (gluconeogenesis), decreasing intestinal absorption of glucose, and increasing insulin sensitivity by increasing peripheral glucose uptake and utilization. Metformin is known to inhibit the respiratory chain in mitochondria, resulting in the antidiabetic effect. However, the exact mechanism of these processes has not been fully elucidated.

Pharmacokinetics

Metformin has an oral bioavailability of 50-60% under fasting conditions and is absorbed slowly. Maximum plasma concentration (Cmax) is reached within one to three hours after ingestion. Plasma protein binding is negligible. Metformin is excreted largely unchanged in the urine. The plasma half-life is approximately 17 hours.

Drug interactions

The H2 receptor antagonist cimetidine causes an increase in the plasma concentration of metformin.
Das Antibiotikum Cephalexin kann ebenfalls die Metforminkonzentration erhöhen.

Metformin interagiert auch mit anticholinergen Medikamenten. Anticholinergika reduzieren die Magenmotilität und verlängern so die Verweildauer der Medikamente im Magen-Darm-Trakt. Diese Beeinträchtigung kann dazu führen, dass mehr Metformin absorbiert wird, wodurch die Konzentration von Metformin im Plasma erhöht wird und das Risiko für unerwünschte Wirkungen steigt.