Used for neutralising systemic envenoming by members of the Australian taipan snake group. It is made from horse IgG. Each ampoule contains 12,000 units of neutralising capacity against the target venoms. Average volume per ampoule is 43-50mL. The immunising venom is from the common taipan.
The taipans are, at least in theory, amongst the most deadly snakes in the world, combining very potent venom, large amounts of venom and long fangs with accurate strike. The common taipan may exceed 2.5m in length and is found in mixed habitats. It often has a pale head with olive to brown body and is a swift moving snake.
The inland taipan (=western taipan; small scaled snake; fierce snake) has a more restricted natural distribution, but is also a large snake, sometimes exceeding 2.5m. Colour is variable, some specimens having a shiny black sheen to the head at some times of the year.
|Common taipan Oxyuranus scutellatus|
Inland taipan Oxyuranus microlepidotus
The common taipan is found across the top of Australia and part way down the east coast, and may enter urban areas. The inland taipan is restricted to arid areas, mostly black soil plains country in part of central inland Australia, including some of the Lake Eyre drainage basin. It is only rarely encountered, but is possibly common within its range, where it may spend much of the time beneath the surface, in the deep cracks in the soil.
Because of their reputation, both taipans are much sought after by reptile collectors, and a considerable number of these snakes are kept alive in both public and private collections in capital cities and some rural towns, thus bites may present well outside of the natural range for these snakes.
Taipan venom is amongst the most potent of all snake venoms. Inland taipan venom is the most toxic snake venom known. Both species of taipans have similar venom components, including both pre and post-synaptic neurotoxins, powerful procoagulants, myolysins, and clinically, kidney damage may occur, though this may be secondary. The common taipan may have fangs >1cm in length, capable of penetrating a leather boot! This, coupled with the large quantity of venom produced, has helped fuel the fearsome reputation of these snakes.
Prior to the development by CSL of specific taipan antivenom in 1956, taipan bite was nearly always fatal. There were only two reported survivors of taipan bite in the years before 1956. Nearly all taipan bites are likely to result in life threatening envenoming, with the exception of bites by juveniles in captivity, where current experience suggests that the rate of major bites may be lower.
There is often pain and swelling at the bite site, though this is not always so and a trivial looking bite site does not imply a trivial bite. There may be rapid development of major systemic envenoming, including headache, nausea/vomiting, collapse, convulsions (especially in children), paralysis, defibrination coagulopathy, myolysis and kidney damage. The paralysis may be severe, with major respiratory paralysis developing within 2 to 6 hours of the bite in some cases. The coagulopathy is often profound, with complete defibrination within an hour of the bite and a potential for major haemorrhage, including cerebral haemorrhage. The myolysis, if present, is often not as severe as seen with some tiger snake and mulga snake bites. The kidney damage is by no means a constant feature of taipan bite but does occur sometimes, possibly as a secondary phenomenon. There is one case of renal cortical necrosis following taipan bite.
As with most antivenoms, CSL Taipan 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.
Given the high potential for severe envenoming with taipan bites, antivenom therapy should be considered as soon as there is any suggestion of systemic envenoming, such as headache, nausea/vomiting, abdominal pain, or clinical evidence of paralysis (eg ptosis), coagulopathy (eg bleeding from the bite or gums), or myolysis (eg muscle pain or myoglobinuria). Initial dose in even a mild case should be 1 vial of CSL Taipan Antivenom. If there is severe defibrination, then start with at least 3 vials of antivenom and be prepared to give more, up to 5 to 8 in total (only rarely would more be needed). In areas of Australia where the taipan is only found as captive specimens, which includes most capital cities, then CSL Taipan Antivenom may not be readily available.
In this circumstance, CSL Polyvalent Snake Antivenom is a very good alternative. It is only slightly higher in volume and price than the taipan specific antivenom. Bites by inland taipans should be handled in the same way as for the common taipan.
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 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).