Antidote is a drug or agent that counteracts the effects of a
poison or over-dosage by another drug. Antidote neutralizes the harmful
effects of a poison.
The meaning of
Greek word "Antidotes" is “given against”. Following are some common
antidotes.
Acetylcysteine
Indication: Paracetamol, Carbon tetrachloride
Mode of Action: Protects against liver damage by enhancing
production of glutathione thereby increasing microcirculation and increasing
blood flow.
Activated
Charcoal
Indication: Most poisons
Mode of Action: Inhibits systemic absorption of toxin
through its high adsorptive capacity.
Amyl Nitrite
Indication: Cyanide
Mode of Action: Facilitates conversion of hemoglobin to
methemoglobin to inhibit cyanide’s affinity to cytochrome oxidase enzymes thereby
inhibiting its toxic effects.
Atropine
Indication: Organophosphates and carbamate poisoning
Mode of Action: Inhibits the action of acetylcholine at
the muscarinic sites to interrupt initial effects of organophosphate and
carbamate poisoning.
Benzylpenicillin
Indication: Amatoxin poisoning
Mode of Action: Protects the liver by inhibiting entry of
amatoxins into the hepatic cells.
Calcium
Gluconate
Indication: Hydrofluoric acid, calcium channel
blockers and oxalates
Mode of Action: Increases calcium concentration to
overcome calcium channel blockade in the cells and upkeep with depletion of
calcium concentration in the system.
Cholestyramine
Indication: Anti-coagulants
Mode of Action: Inhibits the absorption of anti-coagulants
in the system by forming non-adsorbable complex with bile acids in the
intestines.
Cyanokit
(Hydroxocobalamin)
Indication: Cyanide poisoning
Mode of Action: Binds with cyanide ions to facilitate excretion
into the urine.
Dicobalt
edetate
Indication: Cyanide toxicity
Mode of Action: Forms stable ion-complexes with cyanide to
facilitate its excretion in the urine.
Dimercaprol
Indication: Arsenic, gold and inorganic mercury
poisoning
Mode of Action: Binds with heavy metals to form
dimercaprol-metal complex which can be readily excreted in the urine.
Ethanol
Indication: Ethylene glycol and methanol poisoning
Mode of Action: Inhibits formation of toxic metabolites so
the toxic alcohol ingested can be excreted in the urine. It doesn’t directly
affect the presence of the toxic metabolites that have already formed so
hemodialysis is also recommended.
Flumazenil
Indication: Benzodiazepine overdose
Mode of Action: Acts on benzodiazepine receptors to block
central effects of benzodiazepine.
Glucagon
Indication: Beta blockers, calcium channel blockers
and hypoglycemic toxicity
Mode of Action: Increases myocardial contractility and
heart rate similar to beta-agonist effects. It also decreases vascular resistance
to improve cardiac output. Glucagon works on improving glucose levels by
activating hepatic glycogen.
Methionine
Indication: Paracetamol poisoning
Mode of Action: Protects against liver and renal toxicity
in cases of paracetamol poisoning. It acts as a precursor of glutathione to
replenish gluthione stores in the liver cells.
Naloxone
Indication: Opioid overdose
Mode of Action: A specific opioid antagonist that acts
directly at opioid receptors to inhibit its toxicity effects.
Penicillamine
Indication: Lead, copper and arsenic poisoning
Mode of Action: Binds with heavy metals to form stable
water-soluble complexes that can be excreted in the urine.
Phentolamine
Indication: Alpha-adrenergic poisoning, cocaine
toxicity
Mode of Action: Blocks alpha1 adrenoreceptors to inhibit
vasoconstriction and decrease peripheral resistance thereby reducing blood
pressure. For cocaine toxicity, it acts as an alpha-blocker to reduce
cocaine-induced coronary vasoconstriction thereby resolving cocaine-induced
myocardial ischemia.
Phytomenadione
(Vitamin K)
Indication: Anti-coagulant poisoning
Mode of Action: Interrupts anti-coagulant’s antagonistic
effects on vitamin-dependent coagulation factors thereby reducing
anti-coagulant poisoning effects.
Pralidoxime
Indication: Organophosphorous insecticides
Mode of Action: Restores acetylcholinesterase activity by
removing phosphate compounds in the phosphorylated acetylcholinesterase to
reestablish normal acetylcholinesterase activities.
Procyclidine
Indication: Induced dystonia caused by anti-psychotic
drugs and metoclopramide
Mode of Action: Elicits anti-muscarinic actions to relieve
parkinsonian symptoms caused by antipsychotic drugs and metoclopramide
Protamine
sulfate
Indication: Heparin poisoning
Mode of Action: Binds with heparin to neutralize
anti-coagulative effects in the bloodstream.
Prussian blue
Indication: Thallium poisoning
Mode of Action: Mobilizes intracellular thallium by
absorbing thallium into the insoluble crystal lattice of Prussian blue in the
gastrointestinal tract.
Silibinin
Indication: Amatoxin poisoning
Mode of Action: Protects the liver by blocking entry of
amatoxins into the hepatic cells.
Sodium Calcium
Edetate
Indication: Lead toxicity
Mode of Action: Binds with divalent and trivalent metals
like lead to form water soluble ring-compound to be readily excreted in the
urine.
Sodium nitrite
Indication: Cyanide/acrylonitrite
Mode of Action: Nitrites facilitate conversion of
hemoglobin to methemoglobin. Methemoglobin has higher binding affinity to
cyanide which further facilitates its excretion.
Sodium
thiosulphate
Indication: Cyanide/acrylonitrite
Mode of Action: Acts as a precursor for the enzyme
rhodanase which facilitates conversion of cyanide to non-toxic thiocyanate and
thereby promoting its excretion.
Starch
Indication: Iodine
Mode of Action: Converts iodine to iodide which is less
harmful.
