Dextromethorphan-induced serotonin syndrome.
BACKGROUND
The ability of dextromethorphan to potentiate serotonin levels and lead to serotonin syndrome is well known but few case reports are published. The lack of published cases suggests therapeutic doses of these drugs are not enough to cause serotonin syndrome. We present two cases of serotonin syndrome associated with supra-therapeutic doses of dextromethorphan and therapeutic levels of a selective serotonin reuptake inhibitors (SSRI).


METHODS
In case one, serum drug levels from admission revealed a dextromethorphan level of 950 ng/mL (normal < 5), escitalopram of 23 ng/mL (normal < 200), chlorpheniramine of 430 ng/mL (normal < 20) and undetectable levels of aripiprazole and benztropine. In case two, serum drug levels from admission revealed a dextromethorphan level of 2820 ng/mL, sertraline of 12.5 ng/mL (normal < 200), and caffeine of 1.4 microg/mL (normal < or = 9 microg/mL).


CONCLUSIONS
To our knowledge, these are the first cases to use serum levels of dextromethorphan and a SSRI to confirm dextromethorphan-induced serotonin syndrome.


CONCLUSIONS
Our cases suggest supra-therapeutic dextromethorphan doses with a therapeutic amount of a SSRI are required for serotonin syndrome. More work is needed to answer this question more completely.
Schwartz
Anna R
AR
University of Pittsburgh, Division of Medical Toxicology, UPMC Presbyterian, Pittsburgh, Pennsylvania 15213, USA.
Pizon
Anthony F
AF
Brooks
Daniel E
DE
D000996:Antitussive Agents / Q000009:adverse effects* / Q000097:blood; D002648:Child; D015283:Citalopram / Q000009:adverse effects; D003915:Dextromethorphan / Q000009:adverse effects* / Q000097:blood; D004347:Drug Interactions; D006801:Humans; D008297:Male; D020230:Serotonin Syndrome / Q000097:blood / Q000139:chemically induced* / Q000628:therapy; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects* / Q000097:blood; D020280:Sertraline / Q000009:adverse effects; D016896:Treatment Outcome; D055815:Young Adult
D000996:Antitussive Agents; D015283:Citalopram; D003915:Dextromethorphan; D017367:Selective Serotonin Reuptake Inhibitors; D020280:Sertraline