Sumatriptan contraindications and the serotonin syndrome

OBJECTIVE: To determine the risk for serotonin syndrome associated with the concomitant use of sumatriptan and the currently contraindicated therapies, that is, the monoamine oxidase inhibitors (MAOIs), serotonin selective-reuptake inhibitors (SSRIs), and lithium. METHODOLOGY: A comprehensive search for reports of serotonin syndrome associated with sumatriptan use was conducted by using tertiary drug interaction literature, MEDLINE, EmBASE, Biological Abstracts, Current Contents, Reactions, ClinAlert, and the International Pharmaceutical Abstracts. In addition, related reports from the proprietary manufacturers, the Health Protection Branch of Health Canada, and the World Health Organization Collaborative Centre for International Drug Monitoring were also solicited. RESULTS: The concurrent use of sumatriptan with an SSRI or lithium has been reported to cause symptoms suggestive of serotonin syndrome in 16 and 2 cases, respectively. There were no reports involving MAOIs. In general, the reports indicated a mild-to-moderate, self-limited course with some features consistent with the serotonin syndrome. We found published reports of sumatriptan use without adverse events involving 148 patients receiving SSRIs, 31 patients taking MAOIs, and a small number using lithium. CONCLUSIONS: Clinical evidence supporting the strict contraindication of MAOIs, SSRIs and lithium was not identified. The balance of documented clinical experience pertaining to the use of sumatriptan concurrently with SSRIs or lithium suggests that most patients tolerate this combination without incident. Because there is little reliable experience with sumatriptan in combination with MAOIs, we suggest that sumatriptan should continue to be avoided in patients taking these agents until further data demonstrating safety become available.