Serotonin Syndrome

Serotonin syndrome, potentially life-threatening, results from excess serotonergic activity. Caused by drug interactions or self-poisoning, it exhibits altered mental state, hyperactivity, and neuromuscular issues. Treatment involves discontinuing agents, supportive care, benzodiazepines, serotonin antagonists, and sometimes paralysis and intubation.

2024-01-06 21:19:46 - Editor

Overview of Serotonin Syndrome:

Serotonin syndrome is a potentially life threatening condition associated with increased seretonergic activity in the central nervous system. It is frequently seen in the setting of advertent interactions between seretonergic agents and with intentional self poisoning. It usually manifests as a triad of altered mental status, autonomic hyperactivity, and neuromuscular abnormalities. It is occasionally lethal in 2% of patients. Seretonin drugs include amphetamine, tryptophan, oxitriptan, mertazipine, Selective serotonin reuptake inhibitors SSRI (citalopram, fluoxetine, escitalopram), monoamine oxidase inhibitor (MAOI) agents (isocarboxazid, phenelzine, selegiline), cocaine and ecstasy. Serotonin syndrome often resolves within 24 hours of discontinuing the seretonergic agent and initiating care but serotonin drugs, such as, SSRI and MAOI which have longer half lives may cause symptoms to persist and may contribute to the development of serotonin syndrome up to several weeks (1, 2, 3, 4)

Management of Serotonin Syndrome:

For management, mild cases only require discontinuation of inciting agents, supportive care and sedation with benzodiazepines. Moderately ill patients may additionally require aggressive treatment of autonomic instability and a serotonin antagonist agent. Hyperthermic patients (>41.1°C) are critically ill. They usually require paralysis and tracheal intubation. (5)

Supportive Care in Serotonin Syndrome:

Supportive care is the mainstay of therapy and includes oxygen administration, intravenous fluids and continuous cardiac monitoring. Sedation with benzodiazepines, such as diazepam (5 mgIV), or lorazepam (2-4mg IV) is important for controlling agitation.

Management of Autonomic Instability:

Autonomic instability management may be difficult since patients usually exhibit rapid and large changes in blood pressure and heart rate. Patients with severe hypertension and tachycardia should be treated with short acting agents, such as, esmolol (Bolus of 500- 1.000 mcg/ kg over 30 seconds, followed by 50 mcg/kg/ minute infusion) or nitroprusside ( 0.3-0.5 mcg/kg/minute; may be titrated by 0.5 mcg/kg/minute every few minutes to achieve the desired hemodynamic effect up to a maximum dose of 10 mcg/kg/minute for a maximum of 10 minutes). Hypotension in patients with serotonin syndrome should be treated with low doses of direct- acting sympathomimetic agents, such as phenylephrine (0.5 -6 mcg/kg/minute to be titrated to the desired blood pressure) or norepinephrine (8 -12 mcg/minute to be titrated to the desired response). (6, 7, 8)

Use of Antidotes in Serotonin Syndrome:

Antidote is achieved by Cyproheptadine which is a histamine- 1 receptor antagonist. An initial dose of 12 mg is recommended, followed by 2 mg every two hours until clinical response is seen. (9)

Control of Hyperthermia:

Control of hyperthermia is critical and can be achieved with cold water immersion, water ice therapy or cold thoracic and peritoneal lavage. No role for antipyretic agents, such as, acetaminophen. (10) Paralytic agents include etomidate (0.3 mg/kg IV) and succinylcholine (1.5 to 2 mg/kg IV). (11)

References

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