Serotonin Syndrome During Opioid Therapy – the Underdiagnosed Adverse Interaction and Its Implications for the Management of Chronic Pain

Abstract

The complexity of chronic pain demands interdisciplinary treatment approaches, however, complex analgesic regimens pose risks for potential adverse drug interactions. Effective management of chronic pain is further complicated by the presence of associated comorbidities, especially depression. As a result, is common for these patients to be prescribed opioid analgesics with antidepressant medications. The first ones may significantly affect serotonin kinetics in the presence of other serotoninergic agents, increasing intrasynaptic serotonin levels. Serotonin syndrome (SS) is a rare and potentially life-threatening iatrogenic complication of serotoninergic polypharmacy. It typically appears after initiation or dose escalation of the offending agent to a regimen that generally includes other serotoninergic agents (like antidepressants drugs and opioids) and all drugs that directly or indirectly increase central serotonin neurotransmission at postsynaptic 5-HT1A and 5-HT2A receptors can produce serotonin syndrome. Individual vulnerability appears to play a role in the development of this complication.

Aims

To report a clinical case of SS in a 62-yr-old woman with postmastectomy pain syndrome, resulting from the addition of duloxetine to a medication regimen of sertraline and fentanyl. The review of the literature serves as an overview of the epidemiology, pathophysiology, clinical features, differential diagnosis and prevention of SS.

Methods

Literature review and clinical case description.

Results and Conclusions

To our knowledge, few case-reports have been published including duloxetine as a precipitant agent of SS. Clinicians should be alert to this potential iatrogenic adverse interaction of serotoninergic antidepressants with commonly prescribed opioid analgesics in chronic pain patients.