Volume 184 - Issue 8
High rate of immediate systemic hypersensitivity reactions to tiger snake antivenom
Author: Jane Leong
Med J Aust 2006; 184 (8): 419-420. || doi: 10.5694/j.1326-5377.2006.tb00298.x
Published online: 17 April 2006
Published online: 17 April 2006
Comment: Thank you for the opportunity to comment on the letter by Isbister et al regarding hypersensitivity reactions to tiger snake antivenom.
CSL has been notified about the cases of hypersensitivity reactions to tiger snake antivenom in general, but has only received two individual case reports. We have been in contact with the study investigators and have requested more detailed information on the other patients so that we can further our investigations.
A thorough check of product manufacturing records revealed no deviations from approved specifications for tiger snake antivenom.
It is important to note Isbister et al have advised health professionals not to reduce or cease the use of tiger snake antivenom. We would like to draw physicians’ attention to the approved Product Information before use of the product. The tiger snake (and other antivenom) Product Information lists the possibility of both anaphylactic and anaphylactoid reactions. Hypersensitivity and skin reactions (including urticaria, rash, hypotension, bronchospasm, anaphylaxis and delayed serum sickness) are listed as common, and are more likely to occur in people who have had previous exposure to equine-based products.
In addition, the Product Information describes an anaphylactoid reaction which can occur because the antivenom has the ability to bind complement. The risk of this reaction can be minimised by adequate dilution of the antivenom (1 : 10 for adults and 1 : 5 in small children) before infusion. Further, the Product Information states that a syringe already loaded with 1 : 1000 adrenalin must be available during antivenom therapy.
CSL is continuing to monitor this situation closely and is awaiting further details on the patients from the reporting physicians. In the meantime, we encourage users of all antivenom products to report any untoward reaction to CSL so that these can be fully evaluated.