Poisoning approach and drug overdoses

Poisoning in the ICU: initial approach and toxidromes, decontamination and enhanced elimination (AACT/EXTRIP), paracetamol, cardiotoxic overdoses (TCA, CCB, beta-blocker, digoxin), toxic alcohols, and an antidote reference with Indian availability notes.

6 topics

01
Initial approach and toxidromes
Resuscitate first, recognise the toxidrome, run the standard poisoning screen, and use the poisons information centre.
7 stepsAlgorithm1 dosesNew
02
Decontamination and enhanced elimination
When to use activated charcoal, gastric lavage and whole bowel irrigation, and when to dialyse (EXTRIP).
6 steps2 dosesNew
03
Paracetamol poisoning
Risk-assess with the nomogram, give acetylcysteine by the two-bag regimen, extend for massive ingestion, and know when to refer for transplant.
6 stepsAlgorithm2 dosesNew
04
Cardiotoxic overdoses: TCA, beta-blockers, CCB, digoxin
Sodium bicarbonate for sodium-channel blockade, calcium and high-dose insulin for CCB/beta-blocker shock, digoxin Fab, lipid and ECMO as rescue.
6 stepsAlgorithm6 dosesNew
05
Methanol and other toxic alcohols
Suspect methanol in hooch clusters, use osmolal and anion gaps, block alcohol dehydrogenase (fomepizole or ethanol), give folinic acid, correct acidosis and dialyse early.
6 stepsAlgorithm4 dosesNew
06
Antidote quick reference
Antidote, indication and adult dose for the agents an Indian ICU should be able to access.
6 steps4 dosesNew

Drugs in this module

Doses written for this module's context. The same drug may read differently in another module.

Naloxone

Opioid antagonist

Indications: Opioid toxicity with respiratory depression
Adult dose: 0.04-0.4 mg IV, repeat every 2-3 min to adequate breathing (up to 10 mg); infusion two-thirds of the effective reversal dose per hour.
Preparation (India): 0.4 mg/mL ampoules.
Cautions: Precipitated withdrawal and pulmonary oedema with large doses; shorter half-life than many opioids.

Activated charcoal

Adsorbent

Indications: Recent ingestion (usually < 1-2 h) of a toxic amount of an adsorbable drug, airway protected
Adult dose: Single dose 50 g (1 g/kg) orally/NG. Multiple-dose (carbamazepine, dapsone, phenobarbital, quinine, theophylline): 50 g, then 25 g every 4 h (or 12.5 g/h).
Cautions: Aspiration; contraindicated with unprotected airway, ileus/obstruction, corrosives, hydrocarbons. Does not bind alcohols, metals (iron, lithium), acids/alkalis.

N-acetylcysteine

Antidote (glutathione precursor)

Indications: Paracetamol poisoning above nomogram line or with liver injury
Adult dose: Two-bag regimen (ANZ): 200 mg/kg over 4 h, then 100 mg/kg over 16 h. Traditional 3-bag: 150 mg/kg over 1 h, 50 mg/kg over 4 h, 100 mg/kg over 16 h. Continue 100 mg/kg/16 h until criteria met.
Preparation (India): 200 mg/mL; Indian 2 g/10 mL ampoules; dilute in 5% dextrose or NS.
Cautions: Anaphylactoid reactions (fewer with 2-bag/12-h regimens): pause, antihistamine, restart slower.

Sodium bicarbonate 8.4%

Alkalinising agent

Indications: TCA/sodium-channel blocker cardiotoxicity (QRS > 100 ms); salicylate; methanol acidosis
Adult dose: Sodium-channel blockade: 1-2 mEq/kg (mmol/kg) IV bolus, repeat to QRS narrowing, target pH 7.45-7.55. Salicylate: 1-2 mEq/kg bolus then infusion to urine pH 7.5-8.
Preparation (India): 8.4% = 1 mEq/mL; 7.5% (0.9 mEq/mL) in many Indian hospitals.
Cautions: Hypokalaemia, hypernatraemia, volume overload.

Calcium chloride 10% / gluconate 10%

Electrolyte

Indications: CCB poisoning; hyperkalaemia; hypocalcaemia
Adult dose: CCB: calcium chloride 10% 10-20 mL (or gluconate 10% 30-60 mL) IV, repeat every 10-20 min or infusion (chloride 0.2-0.4 mL/kg/h); target ionised Ca up to 2× normal.
Cautions: Chloride via central line (tissue necrosis).

Insulin (high-dose insulin euglycaemic therapy)

Inotrope (metabolic)

Indications: CCB and beta-blocker poisoning with myocardial dysfunction
Adult dose: 1 units/kg IV bolus, then 1 units/kg/h, titrate every 10-15 min up to 10 units/kg/h; dextrose 25 g bolus if glucose < 250 mg/dL, then 0.5 g/kg/h; glucose every 15-30 min, potassium hourly.
Preparation (India): Concentrated infusion e.g. 500 units in 50 mL NS (10 units/mL) to limit volume.
Cautions: Hypoglycaemia (may persist for hours after stopping), hypokalaemia.

Glucagon

Inotrope/chronotrope (cAMP)

Indications: Beta-blocker poisoning (adjunct)
Adult dose: 3-10 mg (0.05-0.15 mg/kg) IV over 2-5 min, then 3-5 mg/h infusion.
Cautions: Vomiting (protect airway), hyperglycaemia; expensive and often unavailable in large quantities in India.

Lipid emulsion 20%

Lipid sink

Indications: Local anaesthetic systemic toxicity; refractory lipophilic drug cardiotoxicity (bupivacaine, some CCB, TCA) as rescue
Adult dose: 1.5 mL/kg bolus over 1 min, then 0.25 mL/kg/min (repeat bolus once or twice; max ~10-12 mL/kg).
Cautions: Interferes with lab tests, pancreatitis, ARDS; recommended for LAST; only rescue for other drugs.

Digoxin-specific antibody fragments (Fab)

Antidote

Indications: Digoxin toxicity with life-threatening arrhythmia, K > 6 mmol/L, end-organ dysfunction
Adult dose: Acute: 2-5 vials (40 mg each) titrated; empirical 10 vials for cardiac arrest. Chronic: 1-2 vials.

Fomepizole

Alcohol dehydrogenase inhibitor

Indications: Methanol or ethylene glycol poisoning
Adult dose: 15 mg/kg IV over 30 min, then 10 mg/kg q12h × 4 doses, then 15 mg/kg q12h; q4h during haemodialysis.

Ethanol (antidote)

Alcohol dehydrogenase competitive substrate

Indications: Methanol/ethylene glycol when fomepizole unavailable
Adult dose: Load 600-800 mg/kg (IV 10% ethanol ~8 mL/kg, or oral 40% spirit ~2 mL/kg diluted); maintenance 80-130 mg/kg/h (higher in drinkers and doubled on haemodialysis); target blood ethanol 100-150 mg/dL.
Cautions: CNS depression, hypoglycaemia, phlebitis; needs ethanol levels every 2-4 h.

Folinic acid (or folic acid)

Cofactor

Indications: Methanol poisoning (formate metabolism)
Adult dose: Folinic acid 1 mg/kg (max 50 mg) IV q4-6h (folic acid 50 mg IV q6h if unavailable).

Octreotide

Somatostatin analogue

Indications: Sulfonylurea-induced recurrent hypoglycaemia
Adult dose: 50 mcg SC/IV every 6 h (or 25-50 mcg/h infusion).

Methylene blue

Reducing agent

Indications: Methaemoglobinaemia (> 20-30% or symptomatic)
Adult dose: 1-2 mg/kg IV over 5 min; repeat after 1 h if needed.
Cautions: Contraindicated in G6PD deficiency; serotonin syndrome with SSRIs.

Hydroxocobalamin

Cyanide antidote

Indications: Cyanide poisoning (smoke inhalation, nitroprusside, cassava/amygdalin)
Adult dose: 5 g IV over 15 min (repeat 5 g if needed).

Pyridoxine

Vitamin B6

Indications: Isoniazid-induced seizures
Adult dose: 1 g per g of isoniazid ingested (unknown: 5 g IV over 5-15 min).

6 topics

Initial approach and toxidromes

Decontamination and enhanced elimination

Paracetamol poisoning

Cardiotoxic overdoses: TCA, beta-blockers, CCB, digoxin

Methanol and other toxic alcohols

Antidote quick reference

Drugs in this module

Module references (16)