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BACKGROUND
Methylene blue is used in medical practice for various reasons. Recent findings point to a potential interaction with serotonin reuptake inhibitors (SRIs) that could lead to serotonergic toxicity.


OBJECTIVE
To describe the risk of serotonergic toxicity associated with the interaction between methylene blue and SRIs.


METHODS
Relevant publications were searched systematically via MEDLINE (1946 to March 21, 2013) and Embase (1974 to 2013, week 11) with the following search terms: "methylene blue", "methylthioninium", "monoamine oxidase inhibitors", "serotonin reup-take inhibitors", and "serotonin syndrome". No restrictions were applied in relation to the indication for methylene blue or the language of publication. The reference lists of identified articles were also searched.


METHODS
Eighteen case reports and 2 case series were identified for inclusion. To date, no randomized controlled trials have been published.


RESULTS
The first case report indicating suspicion of an interaction between methylene blue and SRIs was published in 2003. Seventeen other case reports describing the same type of interaction have been published since then. The 2 case series provided data from about 325 parathyroidectomies in which methylene blue was used for staining. The 17 patients who experienced central nervous system toxicity were all taking SRIs in the preoperative period.


CONCLUSIONS
When administered in combination with SRIs, methylene blue may lead to serotonergic toxicity at doses as low as 0.7 mg/kg. Methylene blue would seem to have monoamine oxidase A inhibitory properties. Precautions should be taken to avoid this interaction. [Publisher's translation].
, B. Pharm, M. Sc., est pharmacienne ayant pour secteurs de pratique la médecine interne, la gériatrie ainsi que le Centre d'Information pharmacothérapeutique, Centre universitaire de santé McGill (CUSM), Montréal, Québec.
Annie
A
Charbonneau
methylene blue; methylthioninium; monoamine oxidase inhibitors; serotonin reuptake inhibitors; serotonin syndrome