Vasopressor therapy in atypical antipsychotic overdose

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Abstract
Hypotension is a common presentation following an overdose of quetiapine. Adrenaline is often used as the vasopressor of choice for hypotension not responding to intravenous fluids. We present a case of quetiapine overdose with hypotension unresponsive to high-dose adrenaline. The patient was commenced on noradrenaline and made a full recovery. We highlight learning points about vasopressor therapy for atypical antipsychotic overdose. Quetiapine-induced hypotension is thought to be mediated by α1-receptor antagonism. Adrenaline is unlikely to improve blood pressure, as it is an agonist at both α- and β-receptors. Alpha-2- and β2-agonism can reduce sympathetic outflow and cause vasodilation, respectively, further exacerbating the hypotension. Noradrenaline is the preferred vasopressor of choice for hypotension caused by quetiapine overdose, as it has less affinity for α2- and β2-receptors, but maintains α1-receptor agonism. Drugs with a similar mechanism of inducing hypotension should also be treated with noradrenaline as the vasopressor of choice.