ATC Code A10BA02
Formula C4H11N5
Molar Mass (g·mol−1) 129,16
Physical State solid
Melting Point (°C) 218–220
PKS Value 12.4
CAS Number 657-24-9
PUB Number 4091
Drugbank ID DB00331
Solubility moderate in water / poor in ethanol


Metformin is the drug of choice for the treatment of type 2 diabetes, especially in overweight people, because its use is often associated with concomitant weight loss. It is also used in the treatment of polycystic ovary syndrome. Metformin is taken by mouth and requires a prescription. Metformin is often used in combination with other oral antidiabetic medications.



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.


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.


Side effects

Metformin is usually well tolerated.

Common adverse effects include diarrhea, nausea, and abdominal pain.

Toxicological Data

LD50 (rat, oral): 1 g/kg


  • Drugbank
  • PubChem
  • Aktories, Förstermann, Hofmann, Starke: Allgemeine und spezielle Pharmakologie und Toxikologie, Elsvier, 2017

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All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.

Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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