CSL Antivenom Handbook

CSL Polyvalent Snake Antivenom

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Basic Information

Used for neutralising systemic envenoming by all dangerous Australian snakes. It is made from horse IgG. Each ampoule contains 1,000 units of neutralising capacity against brown snake venom, 3,000 units against tiger snake venom, 18,000 units against mulga snake venom, 6,000 units against death adder venom and 12,000 units against taipan venom. It is therefore equivalent in neutralising power, to giving the patient 1 ampoule of each of the five "monovalent" snake antivenoms. Average volume per ampoule is high, as expected, about 46-50mL.

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Information about the snakes covered by this antivenom

The species

CSL Polyvalent Snake Antivenom covers all dangerous Australian snakes. For details see the previous sections on "monovalent" snake antivenoms. There is some clinical experience suggesting that this antivenom may also be effective for the treatment of envenoming by the New Guinea small-eyed snake (Micropechis ikaheka).

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Distribution

See relevant specific snake antivenom pages. 

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Venom composition

 See relevant specific snake antivenom pages.

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Clinical effects

 See relevant specific snake antivenom pages.

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When to use this antivenom, how much to use and how to give it

As with most antivenoms, CSL Polyvalent Snake Antivenom should only be given if there is clear evidence of envenoming. See potential contraindications. It should be given intravenously, through a drip set. If possible, dilute antivenom up to 1 in 10, with an isotonic crystaloid solution (eg saline, Hartmans or dextrose). In general, each ampoule/ dose should be run over 15-30 minutes. Prior to commencing antivenom therapy, make sure everything is ready to treat anaphylaxis, should this occur. Specifically, have adrenaline ready to give. If there is an infusion pump available, have this set up to run through a side arm of the drip set, with a solution of dilute adrenaline (eg 6mg adrenaline in 100mL of saline or 5% dextrose, or equivalent dilution). Clearly mark this pump, so that it is not accidentally started.

The use of adrenaline as pre-treatment when using antivenoms is still being debated. The risk of anaphylaxis varies from antivenom to antivenom. People who have had previous exposure to equine derived products may be at greater risk. It is recommended that the Product Information be read before use and if necessary contact be made with a specialist in the field.

Because of its higher volume and cost, CSL Polyvalent Snake Antivenom should only be used if it is not possible to use a specific or "monovalent" snake antivenom. This will occur in several circumstances:

• The type of snake cannot be identified, because venom detection has failed or is not available, and the range of possible snakes would require mixing of 3 or more "monovalent" snake antivenoms.

• The patient is very severely envenomed, and waiting for venom detection results would cause unacceptable delay in starting antivenom treatment, and the range of possible snakes would require mixing of 3 or more "monovalent" snake antivenoms.

• CSL Polyvalent Snake Antivenom is the only antivenom available in the hospital able to cover the type of snake which caused the bite.

• Stocks of appropriate "monovalent" antivenom have all been used and the patient requires further antivenom before restocking supplies arrive. Never overlook polyvalent antivenom as a back up in this situation.

If the patient is not severely envenomed and it is possible to determine the type of snake involved, and appropriate "monovalent" antivenom is available, then do not use CSL Polyvalent Snake Antivenom as it is both higher volume (= higher risk of adverse reactions) and higher cost than the "monovalent" antivenom.

In some parts of Australia, the range of snake species is limited. If all likely species are covered by just 2 "monovalent" snake antivenoms, then it is better to give these as a mixture, rather than use polyvalent antivenom. Examples of this would be the greater metropolitan areas of Melbourne and Adelaide, where all naturally occurring snake species would be covered by just CSL Brown Snake Antivenom and CSL Tiger Snake Antivenom. Similarly, in Tasmania, only CSL Tiger Snake Antivenom would be required. The same applies to Kangaroo Island in SA. Detailing such options for every part of Australia is beyond the scope of this publication.

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What to do if there is an immediate untoward reaction to the antivenom go now

(This section is common to most antivenoms)

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What to do prior to discharge

Any patient who has received antivenom may develop serum sickness, from 4 to 14 days later. Before leaving hospital, they should be advised of the symptoms of serum sickness, such as rash, fever, joint aches and pains, malaise, and told to return immediately for review and probable commencement of oral steroid therapy, if this has not been given prophylactically. If there was major envenoming, organise follow up. This is usually not necessary for minor envenoming. It may be useful to give a 5 day course of oral steroids as prophylaxis for serum sickness (eg 30-50mg daily of prednisolone, for adults).

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