Serotonin syndrome caused by drug to drug interaction between escitalopram and dextromethorphan

Abstract

A 63-year-old woman with a history of long-standing depression, maintained on escitalopram, presented with altered mental status. Patient had recently been prescribed dextromethorphan-promethazine cough syrup 2 weeks prior for an upper respiratory tract infection. On admission, she was lethargic and obtunded and found to have inducible myoclonus on examination. The rest of her physical exam was unremarkable. Pertinent lab and imaging findings showed QTc prolongation on ECG, negative electroencephalogram and CT head findings, essentially normal blood tests and a negative toxicology screen. The patient was admitted to the step down unit for close observation; both escitalopram and the cough syrup were suspended and was supportively managed. Overnight the patient's mental status improved and the serial EcGs showed resolution of the prolonged QTc. Patient was discharged home without further complication.

Management of Pseudobulbar Affect With Fluoxetine and Dextromethorphan

“…It indicates the rarity and underrecognition of this adverse reaction. Although some limited evidence is available showing the occurrence of dysphagia as an adverse reaction to benzodiazepine use, 11 the response in our patient seems to be extrapyramidal and related to olanzapine.…”

“…Alternatively, bupropion may be the best choice in a patient with risk factors for serotonin syndrome, as dextromethorphan also binds to the serotonin reuptake transporter with high to moderate affinity 9 . Although the risk of serotonin syndrome is low, there are case studies where the combination of selective serotonin reuptake inhibitors and dextromethorphan has induced serotonin syndrome, 10,11 and the risk would be further elevated if the patient were on additional serotonergic agonist medications. Notably, the combination of dextromethorphan 45 mg and bupropion 105 mg is currently pending FDA approval for major depressive disorder, treatment resistant depression, and Alzheimer disease agitation.…”

Serotonin Syndrome and Dextromethorphan Toxicity Caused by Drug-Drug Interaction Between Fluoxetine and Bupropion-Dextromethorphan

“…Literature describes serotonin syndrome in the context of supratherapeutic DXM doses/ abuse, 4 and there is 1 report of appropriately consumed promethazine-DXM and escitalopram leading to presumed serotonin syndrome. 5 There were no results for a literature search conducted in September 2023 with keywords "Dextromethorphan," "Bupropion," "SSRI," and "Serotonin Syndrome" describing a presentation as described above.…”

Administration of Intravenous Lipid Emulsion for Dextromethorphan Poisoning with Serotonin Syndrome: A Case Report

“…Five fatal cases of DXM poisoning, two of which showed cerebral edema at autopsy, have been reported [ 5 ]. Although there have been some case reports of SS caused by DXM overdose or co-administration with antidepressants, there is currently no specific treatment for severe DXM poisoning, with symptomatic treatment being the primary approach [ 6 , 7 , 8 ]. Intravenous lipid emulsion (ILE) is reportedly effective against lipid-soluble drug poisoning [ 9 ], particularly in cases of local anesthetic systemic poisoning [ 10 ].…”