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an·ti·dote
/ˈan(t)iˌdōt/
An agent that negates the effect of a poison or toxin.


Poisons or toxins enter the body by intentional or accidental ingestion inhalation, swallowing, or absorption through the skin. There are a number of specific and non-specific antidotes available for poisonings such as overdoses of drugs or toxic chemicals: examples used in emergency medicine include naloxone for opiate overdose, DuoDote (atropine and pralidoxime chloride injection) for organophosphate poisoning, and activated charcoal for a variety of ingested poisons. In general, most of these antidotes are drugs or chemicals themselves (one exception is digoxin immune fab, which is derived from sheep).

On the other hand, Mother Nature’s poisons enter the body primarily without warning (unless you’re participating in a rattlesnake roundup), by injection of venom into the body such as snakes using fangs or scorpions using their stinger. Nature also supplies plenty of microscopic critters via infectious diseases that invade a body involuntarily through various routes—rabies via animal bites, measles through respiratory droplets, hepatitis A through ingestion of contaminated foods. “Antidotes” for venomous exposures include specific antivenoms, and immune globulins for infectious diseases—both categories made from natural sources. Just as not all drug or chemical poisonings have specific antidotes and primarily must be managed supportively (“Treat the patient, not the toxin”), similarly, not all venoms have available antivenoms to counteract their actions and exposures must be managed supportively. And most infectious diseases are not treated with immune globulin therapy; many can be prevented with vaccines or treated with antiinfectives such as antibiotics and antivirals.

It has been reported that <2% of toxins have an antidote, and some antidotes may have toxicities, so attention to the ABCs is the primary goal in managing acute poisonings. This article will focus on the limited number of preparations that are available to neutralize Nature’s assailants, the antivenoms and immune globulins.

Terminology

Poison - substances that cause harm to organisms when absorbed, inhaled, or ingested

Toxin - poisonous substance produced within living cells or organisms

Venom - a type of poison or toxin that is injected by a bite or sting

Antidote - prevents absorption of toxin, binding or neutralizing it, or inhibiting its conversion to toxic metabolites; pertains primarily to drugs/chemicals

Antitoxin - antibody that neutralizes a specific toxin; produced in animals by injecting the toxin or toxoid and using the serum containing the antibody to inject into victim

Antivenom - also called antivenin, an antiserum that contains antibodies against the poisons produced in the venom of certain spiders, snakes, and scorpions

Immune Globulin - preparations made from donated pooled human plasma that contain many types of antibodies, or that have high levels of a specific antibody (hyperimmune globulin); these infused antibodies provide immediate although temporary protection against an infectious agent or toxin. They are administered intramuscularly (IGIM), intravenously (IGIV), or subcutaneously (IGSC)

Antidotes for Venomous Assailants: Antivenoms

Antivenoms are produced by injecting a domestic animal such as horse or goat with the venom of a snake, spider, or scorpion; this method from the 1890s originated with the development of antitoxins for tetanus and diphtheria. The injected animal produces antibodies to the venom, then collected serum or plasma is purified into a pharmaceutical grade product. Antivenom does well at preventing the venom from wreaking havoc in the victim but works less well at reversing damage that has already been done, so antivenom treatment should be started as quickly as possible after the bite or sting. The first antivenoms were produced in 1926 against scorpions and in 1927 against North American rattlesnakes, followed globally over the next half a decade by agents for other snakes, spiders, fish, and jellyfish. Advances in purification techniques for some antivenoms have led to less risk of adverse effects, such as hypersensitivity, anaphylaxis, and serum sickness from the use of animal-derived products. Despite the new technologies, lack of economic interest in producing antivenoms led to the antivenom crisis which spurred the World Health Organization (WHO) to add snakebite envenoming to its list of Neglected Tropical Diseases in 2017.

Listed below are nature’s assailants for which antivenoms are available in the US as well as major clinical effects from an envenomation. All of these antivenoms are on the FDA’s Drug and Biologic Essential Medicines, Medical Countermeasures, and Critical Inputs list. For the WHO’s Essential Medicines List, it notes that antivenom immunoglobulins are to be defined locally and does not list them specifically. More about these lists can be found in a previous article in Wilderness Medicine Magazine.

Sources: https://www.reliasmedia.com/articles/148852-venomous-bites; https://www.fda.gov/vaccines-blood-biologics/approved-blood-products/immune-globulins

Antivenoms Available Outside the US

These antivenoms are for assailants that do not reside in the US.

-Banana spider (South America)
-Funnel web spiders (Australia)
-Indian red scorpion (India)
-Box jellyfish (Australia)
-Stonefish (Australia)
Infectious Assailants: Immune Globulins

The table below lists infectious diseases that may be encountered in a wilderness or travel setting for which an immune globulin or antitoxin exists. Some have vaccines available for pre- or postexposure prophylaxis. Inclusion in the FDA or WHO EML is noted in the last column. Note that some of these bacteria or viruses are listed as potential bioterrorism agents.


 

No Specific Antivenoms Available

These toxic venom-producing assailants are just waiting to pounce on you and deliver their best bite or sting, but there are no antivenoms available; treatment for envenomations are supportive. Better yet, avoiding getting bitten or stung!

- Hymenoptera (anaphylaxis risk) – bees, wasps, ants – avoid smelling like a flower
- Biting flies (blackflies cause river blindness in Africa) – use insecticide
- Brown recluse spiders, Hobo spiders, Tarantulas – watch where you go potty
- Cnidarians - jellyfish, hydras, corals, Portuguese man-of-war – stay out of the water and don’t touch
- Venomous lizards (eg, Gila monster) – leave it alone
- Venomous fish (eg, stingray, lionfish, stonefish, catfish) – don’t feed or catch the fish

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