Toxicology

Antidote

TRAntidot
Also known as:Antidotal agent

A substance that counteracts the effects of a poison or drug overdose by preventing its absorption, binding or inactivating it, antagonising it at its site of action, enhancing its elimination or reversing its toxic effects.

In depth

Mechanisms include receptor antagonism (naloxone, flumazenil, atropine at muscarinic receptors); binding or neutralisation (digoxin-specific Fab fragments, idarucizumab for dabigatran, protamine for heparin, chelators such as deferoxamine); replenishing depleted substrates or cofactors (acetylcysteine restoring glutathione after paracetamol overdose, vitamin K for vitamin K antagonists); blocking toxic metabolism (fomepizole inhibiting alcohol dehydrogenase in toxic-alcohol poisoning); enzyme reactivation (pralidoxime); physiological antagonism (glucagon in beta-blocker toxicity); and reversal of a toxic effect (methylene blue for methaemoglobinaemia).

Few poisons have a specific antidote, and antidotes supplement rather than replace supportive care; safe use requires knowing the window of benefit, the antidote's duration of action relative to the toxin and its own adverse effects.

Clinical pearl

Flumazenil is generally avoided in undifferentiated overdose and in benzodiazepine-dependent patients because it can precipitate seizures, particularly when proconvulsant drugs such as tricyclic antidepressants have been co-ingested.

Example drugs

Naloxone Flumazenil Acetylcysteine Fomepizole Idarucizumab Deferoxamine
TRIn Turkish

Antidot

Bir zehrin ya da ilaç doz aşımının etkilerini; emilimini önleyerek, onu bağlayarak veya inaktive ederek, etki yerinde antagonize ederek, eliminasyonunu hızlandırarak ya da toksik etkilerini geri çevirerek ortadan kaldıran maddedir.

Mekanizmalar reseptör antagonizması (nalokson, flumazenil, muskarinik reseptörlerde atropin); bağlama veya nötralizasyon (digoksine özgü Fab fragmanları, dabigatran için idarusizumab, heparin için protamin, deferoksamin gibi şelatörler); tükenen substrat veya kofaktörlerin yerine konması (parasetamol doz aşımında glutatyonu yenileyen asetilsistein, K vitamini antagonistlerine karşı K vitamini); toksik metabolizmanın engellenmesi (toksik alkol zehirlenmesinde alkol dehidrogenaz inhibitörü fomepizol); enzim reaktivasyonu (pralidoksim); fizyolojik antagonizma (beta bloker toksisitesinde glukagon) ve toksik etkinin geri çevrilmesidir (metemoglobinemide metilen mavisi).

Özgül antidotu olan zehir azdır; antidotlar destek tedavisinin yerini almaz, onu tamamlar. Güvenli kullanım için yarar penceresi, antidotun etki süresinin toksik maddeninkine göre durumu ve kendi advers etkileri bilinmelidir.

Flumazenil, özellikle trisiklik antidepresanlar gibi prokonvülzan ilaçlar birlikte alındığında nöbet tetikleyebileceğinden, nedeni belirsiz doz aşımlarında ve benzodiazepin bağımlısı hastalarda genellikle kullanılmaz.

Diğer adları:Panzehir
Updated 24.09.2026 1 views Educational reference — verify against current sources before clinical use.

Read next

ToxidromeToksidrom

A constellation of signs and symptoms (vital signs, mental status, pupils, skin and bowel sounds) characteristic of poisoning by a particular class of agents, used to identify the likely cause at the bedside.

 Competitive AntagonismYarışmalı Antagonizma

Reversible antagonism in which the antagonist binds to the same site as the agonist, so the block can be overcome by raising the agonist concentration; the agonist curve shifts to the right in parallel without a fall in maximal response.

 Chemical AntagonismKimyasal Antagonizma

Inactivation of a drug by direct chemical combination with another substance to form an inactive complex, independently of receptors or physiological effects.

 Physiological AntagonismFizyolojik Antagonizma

Opposition between two drugs that act on different receptors or pathways to produce opposing physiological effects, so that each counteracts the other's action.

 Activated CharcoalAktif Kömür

A highly porous, finely powdered carbon adsorbent given orally or by nasogastric tube that binds many drugs and toxins in the gut lumen, limiting their systemic absorption and, with repeated doses, enhancing the elimination of some.

 Enhanced EliminationEliminasyonun Hızlandırılması

Measures that increase the removal of an already absorbed drug or toxin from the body beyond its intrinsic clearance, used in selected poisonings to shorten exposure and reduce toxicity.