# Antidote

An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον (pharmakon antidoton), "(medicine) given as a remedy". An older term in English which is now rare is atterlothe, derived from "atter" ("poison" or "venom"). Antidotes for anticoagulants are sometimes referred to as reversal agents.
The antidotes for some particular toxins are manufactured by injecting the toxin into an animal in small doses and extracting the resulting antibodies from the host animals' blood. This results in an antivenom that can be used to counteract venom produced by certain species of snakes, spiders, and other venomous animals. Some animal venoms, especially those produced by arthropods (such as certain spiders, scorpions, and bees) are only potentially lethal when they provoke allergic reactions and induce anaphylactic shock; as such, there is no "antidote" for these venoms; however anaphylactic shock can be treated (e.g. with epinephrine).
Some other toxins have no known antidote. For example, the poison batrachotoxin – a highly poisonous steroidal alkaloid derived from various poison dart frogs, certain beetles, and birds – has no antidote, and as a result, is often fatal if it enters the human body in sufficient quantities.

## Mechanical approaches

Ingested poisons are frequently treated by the oral administration of activated charcoal, which adsorbs the poison and flushes it from the digestive tract, thereby removing a large part of the toxin. Poisons which are injected into the body (such as those from bites or stings from venomous animals) are usually treated by the use of a constriction band which limits the flow of lymph and/or blood to the area, thus slowing the circulation of the poison around the body. This should not be confused with the use of a tourniquet which cuts off blood flow completely – often leading to the loss of the limb.

## Techniques to identify antidotes

In early 2019, a group of researchers in Australia published the finding of a new box jellyfish venom antidote using CRISPR. The technology had been used to functionally inactivate genes in human cell lines and identify the peripheral membrane protein ATP2B1, a calcium transporting ATPase, as one host factor required for box jellyfish venom cytotoxicity.

## List of antidotes

| Agent | Indication |
| Activated charcoal with sorbitol | Used for many oral toxins |
| Theophylline or Caffeine | Adenosine receptor agonist poisoning |
| Antimuscarinic drugs (e.g. Atropine) | Organophosphate and carbamate insecticides, nerve agents, some poison mushrooms |
| Beta blocker | Theophylline |
| Calcium chloride | Calcium channel blocker toxicity, black widow spider bites |
| Calcium gluconate | Calcium channel blocker toxicity, hydrofluoric acid burns |
| Chelators such as EDTA, dimercaprol (BAL), penicillamine, and 2,3-dimercaptosuccinic acid (DMSA, succimer) | Heavy metal poisoning |
| Cyanide antidotes (hydroxocobalamin, amyl nitrite, sodium nitrite, or thiosulfate) | Cyanide poisoning |
| Cyproheptadine | Serotonin syndrome |
| Deferoxamine mesylate | Iron poisoning |
| Digoxin Immune Fab antibody (Digibind and Digifab) | Digoxin poisoning, Oleander ingestion |
| Diphenhydramine hydrochloride and benztropine mesylate | Extrapyramidal reactions associated with antipsychotics |
| 100% Ethanol or fomepizole | Ethylene glycol poisoning and methanol poisoning |
| Flumazenil | Benzodiazepine overdose |
| 100% oxygen or hyperbaric oxygen therapy (HBOT) | Carbon monoxide poisoning and cyanide poisoning |
| Idarucizumab | Reversal of dabigatran etexilate, an anticoagulant |
| Insulin + Glucagon | Beta blocker poisoning and calcium channel blocker poisoning |
| Leucovorin | Methotrexate, trimethoprim and pyrimethamine overdose |
| Intralipid | Local Anesthetic toxicity |
| Methylene blue | Treatment of conditions that cause methemoglobinemia |
| Naloxone hydrochloride | Opioid overdose |
| N-acetylcysteine | Paracetamol (acetaminophen) poisoning |
| Octreotide | Oral hypoglycemic agents |
| Pralidoxime chloride (2-PAM) | When given with Atropine: Organophosphate insecticides, nerve agents, some poison mushrooms |
| Protamine sulfate | Heparin poisoning |
| Prussian blue | Thallium poisoning |
| Physostigmine sulfate | Anticholinergic poisoning |
| Pyridoxine | Isoniazid poisoning, ethylene glycol, accidental hydrazine exposure (E.G from Gyromitra mushrooms) |
| Phytomenadione (vitamin K) and fresh frozen plasma | Warfarin overdose and some (but not all) rodenticides |
| Sodium bicarbonate | Aspirin, TCAs with a wide QRS |
| I.V Silibinin | Amatoxin ingestion |
| Succimer, chemical name Dimercaptosuccinic acid (DMSA) | Lead poisoning |