Serotonin Toxicity and Cytochrome p450 Poor Metaboliser Genotype Patient Case

Serotonin toxicity developed by patient with loss-of function Cytochrome P450 genetic polymorphisms' combination is described.Genotyping revealed CYP2D6, CYP2C19 and CYP1A2 non-functional polymorphisms previously associated with poor metaboliser phenotype. Inroduction CaseA 28year-old female patient was admitted to the emergency department (ED) for anxiety and agitation including increased sweating of palms and restless legs.She had been treated with antidepressants by her general practitioner (GP) for 2years.Her medication was switched 2months previously and threeweeks prior to presentation to ED, her GP increased the fluoxetine dose from fluoxetine 20mg/day, to 40mg daily.On admission, the patient was confused, irritable, restless and agitated.Her physical examination was significant for tachycardia (122 beats/minute), hypertension (systolic BP 147 mmHg) and agitation.Neurologic examination was positive for hyperreflexia and clonus.She denied thoughts of selfharm, was compliant with medications, alert and orientated.Her background included smoking 10-15 cigarettes per day, and she had a family history of anxiety (both her mother and brother); she had no known allergies.Routine laboratory investigations were normal except for hypokalaemia (K).Serotonin toxicity was suspected and fluoxetine was ceased.Cyproheptadine 4mg and diazepam 5mg were administered to reduce agitation and serotonergic symptoms.