Brown Snake Antivenom

Brown Snake antivenom (equine IgG Fab) can be used to treat envenomation from the brown snakes in Australia, these include the eastern and western brown snake (gwardar), dugite and other Pseudonaja species

Indication:

• Clinical evidence of envenomation
• Laboratory evidence of complete or partial venom-induced consumptive coagulopathy (VICC)

Contraindication:

• No absolute
• Increased Risk of anaphylaxis in patients previously treated with antivenom or those who are suspected of equine sera allergy

Administration:

• Place the patient in a monitored area where anaphylaxis can be managed
• Administer 1 ampoule diluted in 500ml of 0.9% saline IV over 20 minutes (the dose is the same for adults and paediatrics – snakes don’t envenomate less because its a child)
• Antivenom maybe given as a rapid IV push if the patient is unstable or in cardiac arrest

Adverse drug reactions:

• Anaphylaxis: Cease antivenom infusion, treat as per anaphylaxis with oxygen, IV fluids and IM adrenaline. Recommence antivenom infusion when anaphylaxis has resolved. Rarely will ongoing administration of adrenaline be required to complete the antivenom infusion.
• Serum Sickness: A benign and self limiting complication occurs 5-10 days after antivenom, symptoms include fever, rash, arthralgia and myalgia. Oral steroids for 5 days may ameliorate symptoms (e.g. prednisolone 50mg/day in adults and 1mg/kg in children). All patients should be warned about this complication who receive antivenom.

Controversies:

• Reversal of VICC: Recent evidence would suggest that the antivenom does not hasten the recovery from VICC but may prevent or reverse other manifestations of envenoming
• The use of Fresh Frozen Plasma or Cryoprecipitate: When used after antivenom has been associated with a quicker recovery of VICC but not with earlier hospital discharge. The use of these products in envenomation has not been well defined and should be used at the recommendation of a toxicologist.

References

• Tox Library – Brown snakes
• Allen GE, Brown SCA, Buckley NA et al. Clinical effects and antivenom dosing in brown snake (Pseudonaja spp.) envenoming – Australian Snakebite Project (ASP – 14). PLoSONE 2012;7(12): e53188.
• Brown SGA, Caruso N, Borland M et al. Clotting factor replacement and recovery for snake venom-induced consumptive coagulopathy. Intensive Care Medicine 2009; 35(9):1532-1538
• Isbister GK, Buckley NA, Page CB et al. A randomised controlled trial of fresh frozen plasma for treating venom-induced consumption coagulopathy in cases of Australian snakebite (ASP-18). Journal of Thrombosis and Haemostats 2013; 11:1310-1318
• Isbister GK, Brown SG, MacDonald E et al. Current use of Australian snake antivenoms and frequency of immediate-type hypersensitivity reactions and anaphylaxis.  Medical Journal of Australia 2008; 188:473-476.
• Isbister GK, Duffull SB, Brown SGA. Failure of antivenom to improve recovery in Australian snakebite coagulopathy. Quarterly Journal of Medicine 2009; 102(8):563-568
• White J. A clinician’s guide to Australian venomous bites and stings: Incorporating the updated CSL antivenom handbook. Melbourne: CSL Ltd, 2012.