Serotonin Syndrome Precipitated by Amantadine in a Patient With Persistent Post Concussive Symptoms - A Case Report.
Dmitry Esterov, Billie A Schultz, Kari L Bottemiller and 1 others
PMID 37744194WHAT IT FOUND
A 22-year-old with persistent post-concussive symptoms developed serotonin syndrome 10 days after starting amantadine while taking duloxetine, bupropion, gabapentin, and receiving botulinum toxin.
Symptoms resolved after stopping amantadine and bupropion and lowering duloxetine. This is one case, not proof amantadine caused it.
Key findings
01The patient met Hunter Criteria for serotonin syndrome with tremor, bilateral ankle clonus, inducible upper extremity clonus, ocular clonus, and tachycardia while taking duloxetine 40 mg twice daily, bupropion 450 mg daily, gabapentin 300 mg three times daily, and amantadine 100 mg twice daily.
02The patient was admitted to the intensive care unit and treated with cyproheptadine 12 mg initially, then 2 mg every 2 hours to a total of 24 mg, plus lorazepam 1 mg; serotonin syndrome symptoms resolved within 24 hours.
03After amantadine and bupropion were discontinued and duloxetine was restarted at 40 mg daily, the patient reported improvement in dizziness and memory, though headache and fatigue persisted.
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What it does not show
This is a single case report, so it describes one person, not a pattern, and cannot establish that amantadine caused serotonin syndrome in other patients. The patient was taking multiple medications that could affect serotonin or interact, including duloxetine, bupropion, gabapentin, and amantadine, and the authors state the precise mechanism of amantadine's role was unclear. Symptoms improved after stopping medications, but natural recovery after mild traumatic brain injury and ongoing botulinum toxin injections could also have contributed. The report does not test a rehabilitation intervention, dose, or outcome in a comparison group.
The easy way to misread this
Do not conclude that amantadine alone caused serotonin syndrome in patients with post-concussive symptoms. This is one case, and the patient was also taking duloxetine, bupropion, and gabapentin while receiving botulinum toxin; the authors state the precise mechanism of amantadine's role was unclear, so the contribution of any single component cannot be separated.