NEW Added to close a syllabus gap — "acute poisoning" is named under Intensive Care.

Acute poisoning

Antidotes, toxidromes, and the elimination techniques that actually work.

Antidotes

Poison	Antidote	Note
Paracetamol	N-acetylcysteine	Replenishes glutathione so NAPQI can be conjugated. Use the treatment nomogram; give regardless of level in staggered overdose
Opioids	Naloxone	Duration only 30–60 min — shorter than morphine, so re-narcotisation occurs; infusion often needed
Benzodiazepines	Flumazenil	Shorter acting than midazolam. Avoid in mixed overdose or epilepsy — precipitates seizures
Organophosphates	Atropine + pralidoxime	Atropine treats muscarinic effects only; pralidoxime reactivates the enzyme before "ageing"
Beta blockers	Glucagon	Bypasses the β receptor to raise cAMP. High-dose insulin-euglycaemia also used
Digoxin	Digoxin-specific Fab fragments	Correct electrolytes; avoid calcium
Cyanide	Hydroxocobalamin, dicobalt edetate, sodium thiosulphate	Suspect in fire victims with lactic acidosis and normal SpO₂
Methanol / ethylene glycol	Fomepizole or ethanol	Both compete for alcohol dehydrogenase. Raised osmolar AND anion gap
Methaemoglobinaemia	Methylene blue 1–2 mg/kg	Prilocaine, benzocaine, nitrates. SpO₂ stuck near 85%
Local anaesthetic	20% lipid emulsion	1.5 ml/kg bolus then 15 ml/kg/h
Iron	Desferrioxamine
Warfarin	Vitamin K + PCC

Toxidrome	Features	Causes
Cholinergic	SLUDGE — salivation, lacrimation, urination, defecation, GI upset, emesis. Plus bradycardia, bronchorrhoea, miosis, fasciculations	Organophosphates, anticholinesterase excess
Anticholinergic	"Mad as a hatter, dry as a bone, red as a beet, hot as a hare, blind as a bat" — dry, flushed, hyperthermic, mydriasis, delirium, retention	Tricyclics, atropine, antihistamines
Sympathomimetic	Agitation, tachycardia, hypertension, hyperthermia, mydriasis — but sweating, unlike anticholinergic	Cocaine, amphetamines
Opioid	Pinpoint pupils, respiratory depression, reduced consciousness	Opioids
Serotonin syndrome	Agitation, clonus and hyperreflexia (lower limbs > upper), hyperthermia	SSRIs with pethidine, tramadol, MAOIs, methylene blue

Anticholinergic vs sympathomimetic: the discriminator is the skin — anticholinergic is dry, sympathomimetic is sweaty.
Serotonin syndrome vs neuroleptic malignant syndrome: serotonin syndrome comes on within hours with clonus and hyperreflexia; NMS develops over days with lead-pipe rigidity and bradyreflexia.

Activated charcoal — within 1 hour, for most drugs. Does NOT bind: metals (iron, lithium), alcohols, acids and alkalis, hydrocarbons, cyanide.
Urinary alkalinisation — for salicylates and phenobarbital; traps the ionised drug in the tubule.
Haemodialysis works where the drug has low molecular weight, low protein binding, low Vd and water solubility: lithium, salicylate, methanol, ethylene glycol, metformin, theophylline, phenobarbital, valproate.
It works poorly for large-Vd drugs such as digoxin, tricyclics and benzodiazepines — most of the drug is in tissue, not plasma.
Lipid emulsion is used beyond local anaesthetic toxicity for other lipophilic drug overdoses in cardiac arrest.

Always confirm doses and current practice with your local toxicology service or TOXBASE before treating a real patient.