According to World health organization Antidote is therapeutic substance which is used to counteract to the toxic substances or toxic action of a specific xenobiotic. These are interact with an ingested toxic substances to deactivate and remove from body. In another words antidotes counteract the undesirable effects of ingested toxins or toxic substances, accumulated toxic dose or over dose of active drug.
Antidotes act by different methods;
- By neutralizing the poison or it’s toxic effect pharmacologically which means antagonistic action against poison.
- By converting them chemically to non-toxic or less toxic form
- By adsorbing or absorbing and facilitate elimination from the site of action
An ideal antidote is specific for a particular poison because one antidote is not suitable for all poisons. When administered(taken) antidote it has to reach the site where the poison has accumulated and exerting it’s toxic effect. antidote extract the toxic material from the bound state.The resulting complex between the toxic substance and antidote should be easily and fastly removed from the site and reach the eliminating. mostly kidneys involve in elimination process. when person take toxic substance first step is removal of toxic substance as much as by physically from the alimentary canal. If it is still present in the stomach second step is removal of toxic substance by inducing vomiting or by gastric lavage. In case toxic substance absorbed from body system some other methods are used.
Classification of Antidotes
Antidotes are classified based on their mechanism of action, Three types
These are counteract with toxic substance by bringing about physiological changes in the body
Example: sodium nitrite converts haemoglobin to methaemoglobin which binds to cyanide and inactivates it.
Chemical antidotes act by changing the chemical nature of poison or toxic substance.
Example:Sodium thiosulphate converts cyanide to thiocyanate, Thiocyanate is non-toxic form.
Mechanical antidotes act by inhibiting the absorption of poison or toxin in the body.
Some examples of Inorganic Antidotes
General examples of antidotes for different toxic substances
Toxic agents Antidotes
Cyanide Tydroxycobalamin, sodium thiosulfate
Hydrofluoric acid Calcium Gluconate
Beta Blockers Glucagon
Magnesium Sulfate Calcium Gluconate
Heparin Protamine Sulfate
Opiates Narcotic analgesics
Anticoagulants Vitamin K
Aspirin Sodium bicarbonate
When an accidental poisoning occurs, first line drug preferred is an Antidote. As these are highly specific against specific poisons, it shows high efficacy. Antidotes neutralize the poison either by adsorption and makes it non-toxic or eliminates the poison from the body. Be cautious and stay safe while dealing with toxic agents.