Serotonin syndrome

From Ganfyd

Thought to be due to an excess of 5-HT and most often quoted as a side effect of selective serotonin reuptake inhibitors. It is really a form of toxicity.

Aetiology

Toxic hyperserotonergic state from hyperstimulation of brain stem and spinal cord 5HT_1A and especially 5HT₂ receptors

Causes

• Overdose of drug with serotonin agonist properties
  • SSRI overdose has about 15% incidence serotonin syndrome.
  • Venlafaxine overdose has about 30% incidence serotonin syndrome.
• Drug interaction
  • Classic risk when monoamine oxidase inhibitors taken in combination with SSRIs, tricyclic antidepressants or venlafaxine
• Monotherapy in susceptible individuals

Clinical features

The so called Hunter criteria exist as differential diagnosis is not straightforward. Onset usually within 6 hours of the initial precipitating factor.

Hunter criteria Exposure to sertonic agent and: Spontaneous clonus Inducible or ocular clonus AND agitation or diaphoresis Tremor AND hyperreflexia Hypertonia AND hyperpyrexia > 38ºC AND ocular/inducible clonus

• agitation
• hyperpyrexia
• rigidity
• myoclonus - is fairly specfic
• coma
• death
• metabolic acidosis
• elevated creatine kinase
• elevated transaminases
• acute renal failure

Treatment

• Discontinuation of the causative serotonergic agent
• Supportive care

External link

• What is Serotonin syndrome UKMi