antidote

An antidote is a medical substance that counteracts a poison. Antidotes may neutralize toxins, block their effects on biological targets, or accelerate their detoxification and elimination from the body. They are most effective when given promptly and are part of broader medical care, which includes observation and supportive therapies. Not all poisons have antidotes, and some antidotes can cause adverse effects if misused.

Antidotes work by several mechanisms: chemical antagonism or neutralization that binds or deactivates the toxin; pharmacological antagonism that blocks the toxin’s interactions at receptors or enzymes; and agents that reverse or bypass toxin-induced dysfunction, such as restoring enzyme activity. Chelating agents bind metals, facilitating renal excretion; antibody-based antidotes use specific binding to neutralize toxins; and adsorbents or dialysis methods remove substances from circulation.

Common examples include naloxone for opioid overdose; flumazenil for benzodiazepine overdose (used with caution); atropine and pralidoxime for organophosphate poisoning; vitamin K for warfarin overdose; protamine sulfate for heparin overdose; N-acetylcysteine for acetaminophen poisoning; digoxin-specific antibody fragments for digoxin toxicity; deferoxamine for iron poisoning; edetate disodium calcium for lead poisoning; and dimercaprol or succimer for certain heavy metals.

Antidotes are not substitutes for general care; patient monitoring, supportive care, and management of complications are essential. The efficacy and safety of antidotes depend on the poison, dose, timing, and individual factors. The term antidote comes from Latin antidotum, meaning “given against.”