This equine IgG Fab is used in the treatment of envenoming by the Australian redback spider (Latrodectus hasselti). It may also be useful in the treatment of envenoming due to Steatoda sp. and Latrodectus sp. elsewhere in the world.
Handy tips
- Redback antivenom may be used as a diagnostic (and therapeutic) tool in patients who present with clinical features of envenoming, but no history of bite.
Pitfalls
- Withholding antivenom from the envenomed child or pregnant woman due to concerns about the potential adverse reactions. Children receive the same doses of antivenom as adults, but dilution may need to be adjusted to a suitable volume
- Administration of antivenom to a non-envenomed patient.
Controversies
- Both the relative efficacy of intravenous versus intramuscular route of administration and the efficacy of redback antivenom itself are currently being questioned. Antivenom is measurable in serum following intravenous but not intramuscular administration. However, a randomised controlled trial comparing intravenous with intramuscular antivenom failed to demonstrate any difference in pain scores at two hours. This raises the possibility that antivenom by any route may not provide benefit over placebo. A placebo-controlled randomised controlled trial of antivenom is underway.
References
- Isbister GK, Brown SGA, Miller M et al. A randomised controlled trial of intramuscular versus intravenous antivenom for lactrodectism – the RAVE study. Quarterly Journal of Medicine 2008; 101:557-565.
- Isbister GK, O’Leary MA, Miller M et al. A comparison of serum antivenom concentrations after intravenous and intramuscular administration of redback (widow) spider antivenom. British Journal of Clinical Pharmacology 2008; 65:138-143.
- Isbister GK. Safety of i.v. administration of redback spider antivenom. Internal Medicine Journal 2007; 37:820-822.
- White J. CSL Antivenom Handbook 2001. CSL Ltd Parkville Melbourne Victoria
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