When Commonwealth Serum Laboratories (CSL) developed the first Australian snake antivenom (Tiger Snake Antivenom) in the 1930′s, the recommended dose was 1 vial. Over time the recommended dose increased to 4 vials and there are many case reports of much higher doses being administered. This trend has not been specific to Tiger Snake Antivenom with multiple doses recommended as the starting point for all venomous snakes in recent decades.
Geoff Isbister and colleagues have finally published their work around the dose of Tiger Snake Antivenom required to neutralise venom in vivo and this promises to change the landscape yet again on the treatment of snake envenoming in Australia.
The administration of antivenom is not without risk. The foreign protein load in a single vial of equine generated antivenom represents a significant risk for allergic reaction. This anaphylaxis risk is obviously increased when multiple vials are administered and the morbidity associated with serum sickness which occurs when multiple vials are administered cannot be ignored.
Isbister and his fellow researchers have argued for some time that large doses of antivenom are not required to fully bind all venom in vivo and that once venom is bound, additional doses of antivenom do not provide any further clinical value. Their recent publication in the Medical Journal of Australia (MJA) is further evidence to support this argument.
The recently revised 2012 edition of the Toxicology and Wilderness Therapeutic Guidelines has adopted these recommendations.
A single dose of antivenom is the appropriate dose for all Australian snake envenomings requiring treatment.
Simple is good. Thanks Geoff!