It is generally understood that positive symptoms of schizophrenia arise from a dysregulated striatal dopamine pathway, leading to hyperstimulation of D 2 receptors. Many antipsychotic agents work by blocking D 2 receptors as antagonists similarly, cis(Z)-flupentixol, the active stereoisomer, is an antagonist at D 2 receptors. However, there is now evidence that antipsychotic agents can work by blocking other dopamine receptor subtypes, such as D 1, D 3, or D 4 receptors. One study showed that cis(Z)-flupentixol is an antagonist at both dopamine D 1 and D 2 receptors with equal affinities, and binds to D3 and D4 receptors with lower affinities. Antidepressant effects of flupentixol are understood to be mediated by antagonism at 5-HT 2A receptors, which are commonly downregulated following repeated antidepressant treatment. Flupentixol also binds to 5-HT 2C receptors. The oral LD 50 is 423 mg/kg in mice and 791 mg/kg in rats. The intravenous LD 50 is 37 mg/kg in rats.įlupentixol overdose is characterized by sedation, frequently preceded by extreme agitation, excitement, confusion, somnolence, coma, convulsions, and hyperthermia or hypothermia. Extrapyramidal symptoms or respiratory and circulatory collapse may be observed. ECG changes, QT prolongation, Torsades de Pointes, cardiac arrest and ventricular arrhythmias have been reported from the combined use of drugs known to affect the heart with large doses of flupentixol. In case of overdose, symptomatic treatment should be initiated with airway management. In case of severe hypotension, epinephrine should not be used: instead, intravenous vasopressor drugs, such as levarterenol, can be used. Antiparkinsonian medication should be administered only if extrapyramidal symptoms develop. Gastric lavage should be initiated in the case of flupentixol tablet overdose. Further injections of flupentixol should be discontinued in case of an intramuscularly-administered drug overdose until the patient shows signs of relapse, in which the dosage can subsequently be decreased.
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