Evaluation of the Toxic Effects of Clozapine in Zebra fish (Danio rerio) embryos with the Fish Embryo Toxicity Test

Clozapine (an atypical antipsychotic drug) is indicated in treatment-refractory schizophrenia. Antipsychotics have been reported to have cardiotoxic effects in humans.The zebra fish (Danio rerio) is a tropical cyprinid used in toxicological research. In the present study, the toxicity of clozapine was evaluated in zebra fish embryos with the aid of the fish embryo toxicity test (FET). The endpoints monitored included circulation, heart rate, pericardial oedema, tail extension, spinal deformation, hatching time, coagulation and death. Clozapine was tested at five different concentrations ranging from 1 µg/L to 10 mg/L. The toxic effects observed were a marked bradycardia at 10 mg/L and various abnormalities in the zebra fish embryos exposed to clozapine at 1 µg/L to 10 mg/L. Based on the results obtained in this study, clozapine is toxic to zebra fish embryos and its level in the aquatic environment should be closely monitored in order to forestall adverse effects on the reproductive capabilities and survival of aquatic organisms.