Exam aid · Drugs and therapeutics

Antidotes & Poisons

Poison → antidote, toxidromes and the poisonings most common in Pakistan.

Tables to memorise

Cover the right-hand column and test yourself before checking.

Poison	Antidote
Paracetamol	N-acetylcysteine
Opioids	Naloxone
Benzodiazepines	Flumazenil (rarely)
Organophosphates	Atropine + pralidoxime
Anticholinergics (datura)	Physostigmine
Digoxin	Digoxin-specific Fab
Warfarin / superwarfarins	Vitamin K (± PCC)
Heparin	Protamine sulphate
Dabigatran	Idarucizumab
Methanol / ethylene glycol	Fomepizole or ethanol + dialysis
Cyanide	Hydroxocobalamin; nitrites + thiosulphate
Carbon monoxide	100% oxygen (hyperbaric if severe)
Iron	Desferrioxamine
Lead	Succimer, Ca-EDTA, dimercaprol
β blockers	Glucagon
Calcium channel blockers	Calcium, high-dose insulin
Tricyclic antidepressants	Sodium bicarbonate
Isoniazid	Pyridoxine
Methaemoglobinaemia	Methylene blue
Local anaesthetic toxicity	20% lipid emulsion
Methotrexate	Folinic acid (leucovorin)
Sulfonylurea overdose	Glucose + octreotide
Thallium / radiocaesium	Prussian blue

Toxidrome	Signs
Opioid	Pinpoint pupils, respiratory depression, coma
Cholinergic	SLUDGE, miosis, bronchorrhoea, bradycardia
Anticholinergic	Hot, dry, flushed, dilated pupils, delirium, retention
Sympathomimetic	Hypertension, tachycardia, sweating, dilated pupils
Sedative-hypnotic	Sedation with near-normal vital signs
Serotonin syndrome	Clonus, hyperreflexia, hyperthermia, agitation

Activated charcoal does not bind iron, lithium, alcohols, acids, alkalis or hydrocarbons.
Never induce vomiting after corrosives or kerosene.
Aluminium phosphide ('wheat pills') has no specific antidote.
Pralidoxime works only before the enzyme 'ages'.
Methylene blue is contraindicated in G6PD deficiency.
Pakistan's 'big four' snakes: cobra, common krait, Russell's viper and saw-scaled viper.

Hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter: The anticholinergic toxidrome (datura, antihistamines, tricyclics).
SLUDGE: Salivation, Lacrimation, Urination, Defaecation, GI upset, Emesis: cholinergic excess.

Attempt MCQs on these topics while the sheet is fresh. Anything you get wrong goes to your incorrect list for the next round.