Snake antivenom

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Snake antivenom
Clinical data
Other namesSnake antivenin, snake antivenene, snake venom antiserum, antivenom immunoglobulin
Identifiers
ChemSpider
  • none

Snake antivenom is a medication made up of antibodies used to treat snake bites by venomous snakes.[1] It is a type of antivenom.

It is a biological product that typically consists of venom neutralizing antibodies derived from a host animal, such as a horse or sheep. The host animal is hyperimmunized to one or more snake venoms, a process which creates an immunological response that produces large numbers of neutralizing antibodies against various components (toxins) of the venom.[2] The antibodies are then collected from the host animal, and further processed into snake antivenom for the treatment of envenomation.

It is on the World Health Organization's List of Essential Medicines.[3]

Production[edit]

Antivenoms are typically produced using a donor animal, such as a horse or sheep. The donor animal is hyperimmunized with non-lethal doses of one or more venoms to produce a neutralizing antibody response. Then, at certain intervals, the blood from the donor animal is collected and neutralizing antibodies are purified from the blood to produce an antivenom.[4]

Regulations[edit]

Classification[edit]

Monovalent vs. polyvalent[edit]

Snake antivenom can be classified by which antigens (venoms) were used in the production process. If the hyperimmunizing venom is obtained from a single species, then it is considered a monovalent antivenom. If the antivenom contains neutralizing antibodies raised against two or more species of snakes, then the composition is considered polyvalent.

Antibody composition[edit]

Compositions of the antivenom can be classified as whole IgG, or fragments of IgG. Whole antibody products consist of the entire antibody molecule, often immunoglobulin G (IgG), whereas antibody fragments are derived by digesting the whole IgG into Fab (monomeric binding) or F(ab')2 (dimeric binding). The fragment antigen binding, or Fab, is the selective antigen binding region. An antibody, such as IgG, can be digested by papain to produce three fragments: two Fab fragments and one Fc fragment. An antibody can also be digested by pepsin to produce two fragments: a F(ab')2 fragment and a pFc' fragment. The fragment antigen-binding (Fab fragment) is a region on an antibody that binds to antigens, such as venoms. The molecular size of Fab is approximately 50kDa, making it smaller than F(ab')2 which is approximately 110kDa. These size differences greatly affect the tissue distribution and rates of elimination.

Cross neutralization properties[edit]

Antivenoms may also have some cross protection against a variety of venoms from snakes within the same family or genera. For instance, Antivipmyn (Instituto Bioclon) is made from the venoms of Crotalus durissus and Bothrops asper. Antivipmyn has been shown to cross neutralize the venoms from all North American pit vipers.[5] Cross neutralization affords antivenom manufacturers the ability to hyperimmunize with fewer venom types to produce geographically suitable antivenoms.

Availability[edit]

Snake antivenom is complicated for manufacturers to produce.[6] When weighed against profitability (especially for sale in poorer regions), the result is that many snake antivenoms, world-wide, are very expensive. Availability, from region to region, also varies.[7]

Antivenom shortage for New World coral snake[edit]

As of 2012, the relative rarity of coral snake bites, combined with the high costs of producing and maintaining an antivenom supply, means that antivenom (also called "antivenin") production in the United States has ceased. According to Pfizer, the owner of the company that used to make the antivenom Coralmyn, it would take between $5–$10 million for researching a new synthetic antivenom.[citation needed][clarification needed] The cost was too high in comparison to the small number of cases presented each year. The existing American coral snake antivenom stock technically expired in 2008, but the U.S. Food and Drug Administration has extended the expiration date every year through to at least 30 April 2017.[8][9]

Foreign pharmaceutical manufacturers have produced other coral snake antivenoms, but the costs of licensing them in the United States have stalled availability.[10] Instituto Bioclon is developing a coral snake antivenom.[11] In 2013, Pfizer was reportedly working on a new batch of antivenom but had not announced when it would become available.[9] As of 2016, the Venom Immunochemistry, Pharmacology and Emergency Response (VIPER) institute of the University of Arizona College of Medicine was enrolling participants in a clinical trial of INA2013, a "novel antivenom," according to the Florida Poison Information Center.[12][13]

Families of venomous snakes[edit]

Over 600 species are known to be venomous—about a quarter of all snake species. The following table lists some major species.

Family Description
Atractaspididae (atractaspidids) Burrowing asps, mole vipers, stiletto snakes.
Colubridae (colubrids) Most are harmless, but others have toxic saliva and at least five species, including the boomslang (Dispholidus typus), have caused human fatalities.
Elapidae (elapids) Sea snakes, Taipans, Brown snakes, Coral snakes, Kraits, King Cobra, Mambas, Cobras.
Viperidae (viperids) True vipers and pit vipers, including rattlesnakes and copperheads and cottonmouths.

Types[edit]

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
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
EchiTabG Echis 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[14]
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
West, Central and Eastern Sub-Saharan Africa polyvalent (EchiTAb-plus-ICP) Carpet vipers (E. ocellatus), Puff adders (B. arietans), Black-necked spitting cobras (N. nigricollis) Costa Rica
Antimicrurus Coral snakes Argentina
Coralmyn Coral snakes Mexico
Anti-micruricoscorales Coral snakes Colombia

References[edit]

  1. ^ Stuart MC, Kouimtzi M, Hill SR, eds. (2009). WHO Model Formulary 2008. World Health Organization. p. X. hdl:10665/44053. ISBN 9789241547659.
  2. ^ de la Rosa G, Olvera F, Archundia IG, Lomonte B, Alagón A, Corzo G (August 2019). "Horse immunization with short-chain consensus α-neurotoxin generates antibodies against broad spectrum of elapid venomous species". Nature Communications. 10 (1): 3642. Bibcode:2019NatCo..10.3642D. doi:10.1038/s41467-019-11639-2. PMC 6692343. PMID 31409779.
  3. ^ World Health Organization model list of essential medicines (21st list 2019 ed.). Geneva: World Health Organization. 2019. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  4. ^ WHO Expert Committee on Biological Standardization (2017). "Annex 5; Guidelines for the production, control and regulation of snake antivenom immunoglobulins;Replacement of Annex 2 of WHO Technical Report Series, No. 964" (PDF). WHO Expert Committee on Biological Standardization, sixty-seventh report. Geneva, Switzerland: World Health Organization (WHO). pp. 197–388. hdl:10665/255657. ISBN 978-92-4-069645-7. ISSN 0512-3054. WHO technical report series;1004. License: CC BY-NC-SA 3.0 IGO.
  5. ^ Sánchez EE, Galán JA, Perez JC, Rodríguez-Acosta A, Chase PB, Pérez JC (March 2003). "The efficacy of two antivenoms against the venom of North American snakes". Toxicon. 41 (3): 357–65. doi:10.1016/s0041-0101(02)00330-6. PMID 12565759.
  6. ^ Lewis, Danny (11 September 2015). "Why A Single Vial Of Antivenom Can Cost $14,000". Smithsonian. Retrieved 9 January 2017.
  7. ^ "Antivenom Supply for Snake bites". www.pharmaceutical-technology.com. 24 April 2019.
  8. ^ "Safety & Availability (Biologics) > Expiration Date Extension for North American Coral Snake Antivenin (Micrurus fulvius) (Equine Origin) Lot 4030026 Through October 31, 2014". Food and Drug Administration. Retrieved 19 March 2016.
  9. ^ a b Breen, David (12 October 2013). "Risk from coral-snake bites grows as antivenin dwindles". Orlando Sentinel. Retrieved 25 May 2014.
  10. ^ "Antivenom Shortages – Cost of Antivenom Production Creates Shortages". Popular Mechanics. 2010-05-10. Retrieved 2010-11-16.
  11. ^ "Our Products – Coralmyn". Bioclon.com.mx. Archived from the original on 13 October 2010. Retrieved 2010-11-16.
  12. ^ "Coral Snake Antivenom - Poison Center Tampa". Poison Center Tampa. Retrieved 19 March 2016.
  13. ^ "Emergency Treatment of Coral Snake Envenomation With Antivenom - Full Text View - ClinicalTrials.gov". National Institutes of Health. Retrieved 19 March 2016.
  14. ^ Spawls S, Branch B (1995). The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press. p. 192. ISBN 0-88359-029-8.

Further reading[edit]