methods for treatment of poisoned or overdosed

What are the two main goals when treating a poisoned or overdosed patient?

Prevent further absorption of the toxin and enhance elimination of the toxin.

What is the single most important factor affecting GI decontamination effectiveness?

Time since ingestion (most effective within 30–60 minutes).

What is emesis used for in poisoning?

To expel swallowed drug/poison from the GI tract by vomiting to prevent absorption.

What drug was historically used to induce emesis?

Syrup of ipecac.

Why is syrup of ipecac no longer recommended or available in Canada?

Due to safety concerns (cardiotoxicity, aspiration, GI rupture) and lack of benefit.

List contraindications to emesis.

Drowsiness, unconsciousness, coma, seizures, loss of gag reflex, corrosives, caustics, petroleum distillates

What is gastric lavage?

Administration and evacuation of small volumes of fluid via orogastric tube to remove stomach contents.

When is gastric lavage indicated?

Massive or life-threatening overdose when toxin remains in stomach and charcoal is ineffective.

When is gastric lavage most effective?

Recently ingested liquid toxins.

When is gastric lavage NOT effective?

Sustained-release or enteric-coated tablets and undissolved solids.

List contraindications to gastric lavage.

Coma, seizures, corrosives, caustics, petroleum distillates, sustained-release products.

Name major complications of gastric lavage.

Aspiration, esophageal or gastric perforation, bleeding, arrhythmias, hypoxia.

What is activated charcoal?

A non-specific adsorbent that binds drugs/poisons in the GI tract.

Why is activated charcoal considered the most useful treatment for oral overdoses?

It prevents absorption and enhances elimination for most acute oral poisonings.

What is the usual charcoal-to-drug ratio

10:1 (charcoal : drug/poison).

How does activated charcoal bind toxins?

Through ion-ion, hydrogen bonding, dipole, and Van der Waals forces.

What factors increase adsorption to charcoal?

Lipid solubility, non-ionized state, presence of gastric contents

Which substances are NOT adsorbed by activated charcoal?

Alcohols, metals (iron, lithium), heavy metals, electrolytes, boric acid, cyanide, ethylene glycol.

List contraindications to activated charcoal.

Unconsciousness without airway protection, corrosives, hydrocarbons, bowel obstruction, GI bleeding.

What are complications of activated charcoal?

Vomiting, aspiration pneumonitis, constipation, bowel obstruction, charcoal emphysema.

When should activated charcoal be given for best effect?

Within 1–2 hours of ingestion (up to 6 hours in select cases).

What is MDAC also called?

Charcoal intestinal dialysis.

What is the purpose of MDAC?

Prevent reabsorption and enhance elimination via enterohepatic recirculation.

Name drug classes where MDAC is useful.

Anticonvulsants, TCAs, beta-blockers, salicylates, NSAIDs, sedatives, cardiac glycosides.

Adult MDAC dosing?

50 g loading dose, then 12.5 g every 1–4 hours for 24 hours

What solution is used for whole-bowel irrigation?

PEG-balanced electrolyte solution (e.g., GoLYTELY®).

Key indications for WBI?

Iron, lithium, potassium ingestion; sustained-release drugs; body packers.

Major contraindications to WBI?

Coma, ileus, bowel obstruction, GI bleeding, uncooperative patient.

Main complications of WBI?

Diarrhea, vomiting, electrolyte imbalance, aspiration.

Purpose of cathartics in poisoning?

Speed GI transit and eliminate drug or charcoal-drug complexes.

Why are saline cathartics avoided in elderly and renal patients?

Risk of electrolyte disturbances and renal dysfunction.

What is dilution therapy?

Giving water or milk shortly after ingestion to reduce mucosal injury.

When is dilution contraindicated?

Coma or convulsions.

What pharmacokinetic properties favor extracorporeal removal?

Low volume of distribution, low protein binding, small molecular weight.

What is ion trapping?

Altering urine pH to trap ionized drug and enhance renal excretion

Why is ionized diuresis rarely used?

Limited benefit and high risk of electrolyte and acid-base disturbances.

Which extracorporeal treatment is most effective overall?

Hemodialysis

Which extracorporeal method is best for hemodynamically unstable patients?

Hemofiltration (CVVH).

Which treatment is best for lipid-soluble, high-MW toxins?

Hemoperfusion.

Why is peritoneal dialysis rarely used now?

Slow and only ~10–15% as effective as hemodialysis.

What is intralipid therapy used for?

Severe toxicity from lipid-soluble drugs (e.g., local anesthetics, TCAs, CCBs)

Proposed mechanism of lipid rescue therapy?

A: Lipid shuttle that redistributes drug away from vital organs.