Serotonin Syndrome Induced by Fentanyl in a Child: Case Report. Robles LA. Clin Neuropharmacol 2015 Sept-Oct;38:206-8.
When many clinicians think of serotonin syndrome (SS), they consider the usual suspects:
- Selective Serotonin Uptake Inhibitors (SSRIs)
- Serotonin-Norepinephrine Reuptake Inhibitors
Aside from these common culprits, there are other commonly used drugs whose clear association with serotonin syndrome is less-often realized:
- Methylene blue
Since many ICU patients are treated with fentanyl and/or antiemetics such as ondansetron, and have other conditions that can cause altered mental status, the diagnosis is frequently not suspected initially, and causative pharmaceutical agents not discontinued.
This interesting report describes a 7-yead-old boy admitted to the intensive care unit after surgery for an intracerebral hemorrhage.Within 48 hours of admission, he developed the characteristic clinical triad of SS: altered mental status (consistent with his underlying condition,) inducible clonus and tremors, and autonomic instability (hyperthermia, hypertension, tachycardia.) Two days after surgery, clinicians considered the diagnosis of serotonin syndrome. They reviewed the patient’s medications and noted that fentanyl was the only drug he was receiving that was associated with SS. The fentanyl infusion was discontinued and “the patient showed a dramatic improvement” within 60 minutes.
Fentanyl seems to be a weak SSRI. The author argues somewhat persuasively that this patient’s clinical presentation meets the definition of SS according to Hunter’s Criteria. The case would have been stronger if instead of describing a “mild fever” an actual temperature had been provided. The authors claim that this is the first reported case of serotonin syndrome apparently caused by fentanyl alone.
The association of fentanyl with SS is one every clinicians should be aware of.