Can acute overdose of metformin lead to lactic acidosis?
BACKGROUND
Metformin-associated lactic acidosis (MALA) is well described in patients taking therapeutic metformin who develop renal failure or other serious comorbid conditions. Metformin-associated lactic acidosis from acute overdose has also been described in case series but is debated by some clinicians, arguing that metformin overdose does not cause lactic acidosis. Our aim was to perform a multicenter poison control database review to determine if MALA can occur in mono-overdose patients with no comorbid conditions.


METHODS
This was a retrospective chart review of the Illinois and Washington Poison Centers between the 2001-2006 and 1999-2006 periods, respectively. Metformin overdoses that were referred to health care facilities were categorized into mono-overdose with or with out MALA and polypharmacy overdose with or without MALA.


RESULTS
The overall prevalence of MALA was 14 (3.5%) of 398 cases referred to a health care facility. Metformin-associated lactic acidosis occurred in 9.1% of mono-overdose and in 0.7% of polypharmacy overdose patients referred to health care facilities and was 16% for intentional mono-overdoses. There was one death of 132 mono-overdoses referred to health care facilities.


CONCLUSIONS
Apparent metformin mono-overdose is associated with MALA. Dosages that place patients at risk for MALA will require additional study.
Wills
Brandon K
BK
Department of Emergency Medicine, Madigan Army Medical Center, Tacoma, WA 98431, USA. bkwills@gmail.com
Bryant
Sean M
SM
Buckley
Peter
P
Seo
Ben
B
D000140:Acidosis, Lactic / Q000139:chemically induced*; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D062787:Drug Overdose; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000506:poisoning*; D007022:Hypotension / Q000139:chemically induced; D007087:Illinois / Q000453:epidemiology; D007773:Lactates / Q000097:blood; D008297:Male; D008687:Metformin / Q000506:poisoning*; D008875:Middle Aged; D011039:Poison Control Centers / Q000706:statistics & numerical data; D019338:Polypharmacy; D012189:Retrospective Studies; D014861:Washington / Q000453:epidemiology; D055815:Young Adult
D007004:Hypoglycemic Agents; D007773:Lactates; D008687:Metformin