Antivenom

For the Marvel Comics character, see Anti-Venom (comics).
Milking a snake for the production of antivenom.

Antivenom (or antivenin or antivenene) is a biological product used in the treatment of venomous bites or stings. Antivenom is created by milking venom from a relevant snake, spider, insect, or fish. The venom is then diluted and injected into a horse, sheep, rabbit, or goat. The subject animal will undergo an immune response to the venom, producing antibodies against the venom's active molecules which can then be harvested from the animal's blood and used to treat envenomation. Internationally, antivenoms must conform to the standards of pharmacopoeia and the World Health Organization (WHO).[1]

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.[2]

Medical uses

The principle of antivenom is based on that of vaccines, developed by Edward Jenner; however, instead of inducing immunity in the patient directly, it is induced in a host animal and the hyperimmunized serum is transfused into the patient.

Antivenoms can be classified into monovalent (when they are effective against a single species' venom) or polyvalent (when they are effective against a range of species, or several different species at the same time). The first antivenom for snakes (called an anti-ophidic serum) was developed by Albert Calmette, a French scientist of the Pasteur Institute working at its Indochine branch in 1895, against the Indian Cobra (Naja naja). In 1901, Vital Brazil, working at the Instituto Butantan in São Paulo, Brazil, developed the first monovalent and polyvalent antivenoms for Central and South American Crotalus and Bothrops genera, as well as for certain species of venomous spiders, scorpions, and frogs.

Antivenoms for therapeutic use are often preserved as freeze-dried ampoules, but some are available only in liquid form and must be kept refrigerated. They are not immediately inactivated by heat, however, so a minor gap in the cold chain is not disastrous. The majority of antivenoms (including all snake antivenoms) are administered intravenously; however, stonefish and redback spider antivenoms are given intramuscularly. The intramuscular route has been questioned in some situations as not uniformly effective.[3]

Antivenoms bind to and neutralize the venom, halting further damage, but do not reverse damage already done. Thus, they should be administered as soon as possible after the venom has been injected, but are of some benefit as long as venom is present in the body. Since the advent of antivenoms, some bites which were previously invariably fatal have become only rarely fatal provided that the antivenom is administered soon enough.

Antivenoms are purified by several processes but will still contain other serum proteins that can act as antigens. Some individuals may react to the antivenom with an immediate hypersensitivity reaction (anaphylaxis) or a delayed hypersensitivity (serum sickness) reaction and antivenom should, therefore, be used with caution. Although rare, severe hypersensitivity reactions including anaphylaxis to antivenin are possible.[4] Despite this caution, antivenom is typically the sole effective treatment for a life-threatening condition, and once the precautions for managing these reactions are in place, an anaphylactoid reaction is not grounds to refuse to give antivenom if otherwise indicated. Although it is a popular myth that a person allergic to horses "cannot" be given antivenom, the side effects are manageable, and antivenom should be given as rapidly as the side effects can be managed.[5]

In the U.S. the only approved antivenom for pit viper (rattlesnake, copperhead and water moccasin) snakebite is based on a purified product made in sheep known as CroFab.[6] It was approved by the FDA in October, 2000. U.S. coral snake antivenom is no longer manufactured, and remaining stocks of in-date antivenom for coral snakebite expired in the Fall of 2009, leaving the U.S. without a coral snake antivenom. Efforts are being made to obtain approval for a coral snake antivenom produced in Mexico which would work against U.S. coral snakebite, but such approval remains speculative. In the absence of antivenom, all coral snakebite should be treated in a hospital by elective endotracheal intubation and mechanical ventilation until the effects of coral snake neurotoxins abate. It is important to remember that respiratory paralysis in coral snakebite can occur suddenly, often up to 12 or more hours after the bite, so intubation and ventilation should be employed in anticipation of respiratory failure and not after it occurs, when it may be too late.

As an alternative when conventional antivenom is not available, hospitals sometimes use an intravenous version of the antiparalytic drug neostigmine to delay the effects of neurotoxic envenomation through snakebite.[7] Some promising research results have also been reported for administering the drug nasally as a "universal antivenom" for neurotoxic snakebite treatment.[8]

Natural and acquired immunity

Although individuals can vary in their physiopathological response and sensitivity to animal venoms, there is no natural immunity to them in humans. Some ophiophagic animals are immune to the venoms produced by some species of venomous snakes, by the presence of antihemorrhagic and antineurotoxic factors in their blood.

It is quite possible to immunize a person directly with small and graded doses of venom rather than an animal. According to Greek history, King Mithridates did this in order to protect himself against attempts of poisoning, therefore this procedure is often called mithridatization. However, unlike a vaccination against disease which must only produce a latent immunity that can be roused in case of infection, to neutralize a sudden and large dose of venom requires maintaining a high level of circulating antibody (a hyperimmunized state), through repeated venom injections (typically every 21 days). The long-term health effects of this process have not been studied. Further, cytotoxic venom components can cause pain and scarring at the immunization site. Finally, the resistance is specific to the particular venom used; maintaining resistance to a variety of venoms requires multiple monthly venom injections. Thus, there is no practical purpose or favorable cost/benefit ratio for this, except for people like zoo handlers, researchers, and circus artists who deal closely with venomous animals. Mithridatization has been tried with success in Australia and Brazil and total immunity has been achieved even to multiple bites of extremely venomous cobras and pit vipers.

Because neurotoxic venoms must travel farther in the body to do harm and are produced in smaller quantities, it is easier to develop resistance to them than directly cytotoxic venoms (such as those of most vipers) that are injected in large quantity and do damage immediately upon injection.

Availability of antivenoms

Antivenoms have been developed for the venoms associated with the following animals:[9]

Spiders

Antivenom Species Country
Funnel web spider antivenom Sydney funnel-web spider Australia
Soro antiaracnidico Brazilian wandering spider Brazil
Soro antiloxoscelico Recluse spider Brazil
Suero antiloxoscelico Chilean recluse Chile
Aracmyn All species of Loxosceles and Latrodectus Mexico
Redback spider antivenom Redback spider Australia
Black widow antivenom Black widow spider United States
SAIMR Spider antivenom Button spider South Africa
Anti Latrodectus antivenom Black Widow spider Argentina

Acarids

Antivenom Species Country
Tick antivenom Paralysis tick Australia

Insects

Antivenom Species Country
zoro antilonomico Lonomia obliqua caterpillar Brazil

Scorpions

Antivenom Species Country
Alacramyn Centruroides limpidus, C. noxius, C. suffusus Mexico
Suero Antialacran Centruroides limpidus, C. noxius, C. suffusus Mexico
Tunisian polyvalent antivenom All Iranian scorpions Tunisia
Anti-Scorpion Venom Serum I.P.(AScVS) Indian red scorpion India
Anti-scorpionique Androctonus spp., Buthus spp. Algeria
Scorpion antivenom Black scorpion, Buthus occitanus Morocco
Soro antiscorpionico Tityus spp. Brazil
SAIMR scorpion antivenin Parabuthus spp. South Africa
Purified prevalent Anti-Scorpion Serum(equine) Leiurus spp.& Androctonus scorpions Egypt
INOSCORPI MENA (Middle East and North Africa) Androctonus australis Hector, Androctonus mauritanicus, Androctonus australis garzoni, Buthus occitanus mardochei, Buthus occitanus occitanus, Leiurus quinquestriatus quinquestriatus, Leiurus quinquestriatus hebreus" and related species. Spain

Marine animals

Antivenom Species Country
CSL box jellyfish antivenom Box jellyfish Australia
CSL stonefish antivenom Stonefish Australia

Snakes

Antivenom Species Country
Polyvalent snake antivenom South American Rattlesnake Crotalus durissus and fer-de-lance Bothrops asper Mexico (Instituto Bioclon)
Polyvalent snake antivenom South American Rattlesnake Crotalus durissus and fer-de-lance Bothrops asper South America
INOSERP MENA Bitis arietans, Cerastes cerastes, Naja haje, Macrovipera lebetina obtusa, Vipera palestinae, Naja pallida, Naja nigricollis, Walterinnesia aegyptia, Echis leucogaster, Macrovipera deserti, Cerastes vipera, Cerastes gasperettii, Echis coloratus, Echis pyrramidum, Echis khosatzkii, Echis sochureki, Echis megalocephalus, Echis omanensis, Echis carinatus sochureki; Macrovipera lebetina transmediterranea, Macrovipera lebetina turanica, Macrovipera mauritanica, Naja nubiae, Pseudocerastes persicus fieldi, Pseudocerastes persicus persicus, Vipera bornmuelleri, Vipera latastei, Vipera raddei kurdistanica Spain
INOSERP Pan-Africa (Sub-Sahara) Naja nigricollis, Dendroaspis polylepis, Echis ocellatus, Bitis arietans, Echis leucogaster, Echis pyramidum, Echis coloratus, Bitis gabonica, Bitis gabonica rhinoceros, Dendroaspis viridis, Dendroaspis angusticeps, Dendroaspis jamesoni, Naja haje, Naja pallida, Naja melanoleuca Spain
Polyvalent snake antivenom Saw-scaled Viper Echis carinatus, Russell's Viper Daboia russelli, Spectacled Cobra Naja naja, Common Krait Bungarus caeruleus India
Death adder antivenom Death adder Australia
Taipan antivenom Taipan Australia
Black snake antivenom Pseudechis spp. Australia
Tiger snake antivenom Australian copperheads, Tiger snakes, Pseudechis spp., Rough scaled snake Australia
Brown snake antivenom Brown snakes Australia
Polyvalent snake antivenom Many Australian snakes Australia
Sea snake antivenom Sea snakes Australia
Vipera tab Vipera spp. UK
Polyvalent crotalid antivenin (CroFab—Crotalidae Polyvalent Immune Fab (Ovine)) North American pit vipers (all rattlesnakes, copperheads, and cottonmouths) North America
Soro antibotropicocrotalico Pit vipers and rattlesnakes Brazil
Antielapidico Coral snakes Brazil
SAIMR polyvalent antivenom Mambas, Cobras, Rinkhalses, Puff adders (Unsuitable small adders: B. worthingtoni, B. atropos, B. caudalis, B. cornuta, B. heraldica, B. inornata, B. peringueyi, B. schneideri, B. xeropaga) South Africa[10]
SAIMR echis antivenom Saw-scaled vipers South Africa
SAIMR Boomslang antivenom Boomslang South Africa
Panamerican serum Coral snakes Costa Rica
Anticoral Coral snakes Costa Rica
Anti-mipartitus antivenom Coral snakes Costa Rica
Anticoral monovalent Coral snakes Costa Rica
Antimicrurus Coral snakes Argentina
Coralmyn Coral snakes Mexico
Anti-micruricoscorales Coral snakes Colombia

Terminology

The name "antivenin" comes from the French word venin, meaning venom, which in turn was derived from Latin venenum, meaning poison.

Historically, the term antivenin was predominant around the world, its first published use being in 1895.[11] In 1981, the World Health Organization decided that the preferred terminology in the English language would be venom and antivenom rather than venin and antivenin or venen and antivenene.[12]

Antivenom sources

The following groups assist in locating antivenoms:

References

  1. ↑ Theakston RD, Warrell DA, Griffiths E (April 2003). "Report of a WHO workshop on the standardization and control of antivenoms". Toxicon 41 (5): 541–57. doi:10.1016/S0041-0101(02)00393-8. PMID 12676433.
  2. ↑ "19th WHO Model List of Essential Medicines (April 2015)" (PDF). WHO. April 2015. Retrieved May 10, 2015.
  3. ↑ Isbister GK. (2002). "Failure of intramuscular antivenom in Redback spider envenoming". Emerg Med (Fremantle) 14 (4): 436–9. doi:10.1046/j.1442-2026.2002.00356.x. PMID 12534488.
  4. ↑ Bhoite RR, Bhoite GR, Bagdure DN, Bawaskar HS (2015). "Anaphylaxis to scorpion antivenin and its management following envenomation by Indian red scorpion, Mesobuthus tamulus". Indian Journal of Critical Care Medicine 19 (9): 547–549. doi:10.4103/0972-5229.164807.
  5. ↑ See, for example, the Antivenom Precautions paragraph of the Medication section of James Forster, MD, MS (2006-03-14). "Snake Envenomations, Sea". eMedicine Emergency Medicine (environmental). Archived from the original on 26 June 2006. Retrieved 2006-06-25.
  6. ↑ http://www.savagelabs.com/Products/CroFab/Home/crofab_frame.htm Link to PDF for full prescribing information, retrieved 11/11/12
  7. ↑ Franklin, Deborah, "Potential Treatment For Snakebites Leads To A Paralyzing Test", NPR.org, July 31, 2013.
  8. ↑ "Universal antidote for snakebite: Experimental trial represents promising step", California Academy of Sciences via Science Daily, May 28, 2014.
  9. ↑ "Appendix: Antivenom Tables". Clinical Toxicology 41 (3): 317–27. 2003. doi:10.1081/CLT-120021117.
  10. ↑ Spawls, S; Branch B (1995). The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press. p. 192. ISBN 0-88359-029-8.
  11. ↑ "Antivenin". Merriam-Webster Dictionary.
  12. ↑ World Health Organization (1981). Progress in the characterization of venoms and standardization of antivenoms. Geneva: WHO Offset Publications. p. 5. ISBN 92-4-170058-0.

External links

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