The effects of antivenom and verapamil on the haemodynamic actions of Chironex fleckeri (box jellyfish) venom.

The efficacy of antivenom and verapamil against Chironex fleckeri (box jellyfish) venom was investigated in monitored mechanically ventilated piglets. Chironex fleckeri tentacle extract alone, a mixture of tentacle extract with antivenom, and verapamil before tentacle extract were administered intravenously to groups of animals. Tentacle extract caused severe systemic hypotension, cardiac dysrrhythmias, pulmonary hypertension, haemolysis and hyperkalaemia. These effects were prevented by pre-incubation of tentacle extract with antivenom. Verapamil did not prevent any effect of venom, exacerbated cardiovascular collapse and increased mortality. We conclude that antivenom neutralizes the cardiovascular, haemolytic and hyperkalaemic effects of box jellyfish venom. Verapamil does not prevent any of these effects and is contra-indicated for treatment of envenomation.