Surprise quiz: metformin overdose
December 18, 2012, 11:53 pm
Metformin-Associated Lactic Acidosis (MALA): Case Files of the Einstein Medical Center Medical Toxicology Fellowship. Kopec KT, Kowalski MJ. J Med Toxicol 2012 Dec 12 {Epub ahead of print]
No abstract available
This case-based review of metformin-associated metabolic acidosis (MALA) is concise and worth reading. The following is a surprise quiz based on some of the points made in the article. (Click on the question to reveal the answer.)
- decreased gluconeogenesis
- increased peripheral glucose uptake
- decreased fatty acid oxidation
- renal failure
- hepatic failure
- alcohol abuse
- history of lactic acidosis
- pregnancy
- cardiac or respiratory insufficiency
- Type A – caused by decreased perfusion, hypoxia, or increased lactate production
- Type B – caused by metabolic derangements (including metformin toxicity0
Metformin is primarily excreted unchanged in the urine.
- acute renal insufficiency (for instance, after administration of intravenous contrast)
- dehydration
- sepsis
- shock
- acidosis
- abdominal pain
- nausea
- vomiting
- fatigue
- myalgias
- altered mental status
- myocardial insufficiency
- removal of metformin
- correction of acid-base imbalance
Since metformin is water soluble, quickly distributes to the tissues, and has a large volume of distribution, it is most beneficial to institute HD early while the drug is still in the blood.
Dialyzing using a sodium bicarbonate buffer may help correct acid-base imbalance as well as increase metformin clearance.
A single abstract did not show benefit (J Clin Toxicol 2011;49:515). I would not expect this to be effective since metformin is highly water-soluble.
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