Acute metformin intoxication: diagnosis, management and prognosis

Background: Metformin intoxication can potentially originate a lactic acidosis of variable severity, but possibly fatal, diagnosis and prompt treatment of which are crucial. The difficulty in establishing a clear cause and effect relationship arises from the multitude of biologic actions exerted by metformin. Objective: Review of literature in order to compile the current knowledge regarding the diagnosis, management and prognosis of metformin associated lactic acidosis. Methods: Data were collected using PubMed database researching the terms “metformin” and “lactic acidosis”. After selection of 29 titles and abstracts, 25 fulltext articles were consulted. Results: The direct mechanism through which metformin induces lactic acidosis remains incompletely understood. Its anti-gluconeogenic actions and respiratory chain inhibition appear to play a key role. Prognosis depends mainly on the presence of comorbid conditions, rather than the degree of either metformin or lactate accumulation. And independent variable that seems to influence prognosis is prothrombin time at admission. Prolonged dialysis appears to be an adequate treatment. Conclusions: Prompt recognition and institution of both supportive treatment and renal replacement techniques are appropriate regarding the management of metformin associated lactic acidosis, being the most relevant aspects in improving the outcome of this condition.