Published: 2 September 2015

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Reminder: Interactions Resulting in Serotonin Syndrome

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Prescriber Update 36(3): 35
September 2015

Healthcare professionals are reminded that the risk of developing serotonin syndrome is increased in patients taking more than one serotonergic medicine.

The Centre for Adverse Reactions Monitoring (CARM) has recently received two reports of patients taking regular fluoxetine who developed serotonin syndrome after tramadol was started. The symptoms improved after tramadol was stopped.

Although tramadol is an analgesic, it also has serotonergic effects and should be avoided in patients taking serotonin reuptake inhibitors.

Pharmacodynamic interactions include interactions that occur between medicines which have similar pharmacological effects or adverse effects¹. Serotonin syndrome is an example of a pharmacodynamic interaction where two or more medicines with serotonergic effects interact resulting in serotonin toxicity.

Further information on serotonin syndrome, including a summary table of serotonergic medicines, can be found in a previous edition of Prescriber Update².

Healthcare professionals are encouraged to report all suspicions of medicine interactions to CARM. Reports may be submitted on paper or electronically (https://nzphvc.otago.ac.nz/).

References

1. New Zealand Formulary. 2015. Drug interactions. NZF v37. URL: www.nzf.org.nz/nzf_9751 (accessed 14 July 2015).
2. Medsafe. 2010. Serotonin syndrome/toxicity — reminder. Prescriber Update 31(4): 30–31. URL: www.medsafe.govt.nz/profs/PUArticles/SerotoninSyndromeToxicityReminder.htm (accessed 14 July 2015).