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.
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)