toxi lab m3 pt 1

• antidotes


  Substances that can prevent, neutralize or counteract the action of poisons
• antidotes


  “Lifesavers” in the treatment of poisoning
• WHO: Appropriate use of antidotes and other agents may greatly enhance elimination and counteract the toxic actions of the poison.
• In certain circumstances, antidotes can:

  • Significantly reduce the medical resources needed for treatment and shorten the period of therapy

  • Reduces morbidity, mortality and health care costs
• Classification of Antidotes

  • Mechanical Antidote

  • Chemical Antidote

  • Physiological/Pharmacological Antidote
• mechanical antidote

  AKA: Physical Antidote
• Mechanical Antidote


  Prevent the absorption of poison into the body • Example: Activated Charcoal
• Activated Charcoal

  • MOA: Adsorbs the poison prior to intestinal absorption
• Chemical Antidote


  • Counteract the action of poison by coming in contact then forming harmless compounds

  • Example: Sodium Thiosulfate, Sodium Calcium Edentate
• Cyanide poisoning

  Mechanism of toxicity: Binds to cellular cytochrome oxidase
• Cyanide poisoning

  Clinical presentations:

  • Syncope

  • Seizure

  • Coma

  • Cardiovascular collapse
• Sodium Thiosulfate

  • Sulfur donor, promotes conversion of cyanide into thiocyanate by rhodanese
• Heavy Metal Poisoning


  Miniscule molecules of metals accumulate and attaches to cells
• Heavy Metal Poisoning

  Disrupts cellular functions
• Heavy Metal Poisoning

  Severe symptoms:

  • Arrhythmia

  • Anemia

  • Brain, Kidney and Liver damage

  • Miscarriage

  • Developing of cancer
• Lead

  source: Batteries, paint, gasoline
• Mercury

  source: Lightbulb, seafood
• Arsenic

  source:Herbicides, pesticides, fungicides
• Cadmium

  source: Cigarette smoke
• Thallium

  source: Rodenticides, fireworks
• Sodium Calcium Edentate

  • MOA: Chelates heavy metals
• Physiological Antidote

  • AKA: Pharmacological Antidote
• Physiological Antidote

  • Acts on tissues of the body and produces symptoms opposite to those caused by poisons
• Physiological Antidote

  Example:

  • Atropine and Pralidoxime for Organophosphate poisoning

  • NAC for Paracetamol poisoning

  • Naloxone for opioid poisoning
• Amanita Phalloides

  Toxin: α-amanitin

  • antidote: Benzylpenicillin

  • Silibinin
• Atropine

  antidote: Physostigmine
• Benzodiazepines

  Ex:

  • Alprazolam

  • Clonazepam

  • Diazepam

  • Lorazepam

  antidote: Flumazenil
• Beta-blockers

  Ex:

  • Metoprolol

  • Propranolol

  antidote:

  • Glucagon

  • Isoproterenol
• Carbon Monoxide

  Product: Carboxy hemoglobin (COHb)

  antidote:

  100% Oxygen

  • Hyperbaric oxygen therapy
• Carbon Tetrachloride

  Product: Freon

  antidote:

  • Acetylcysteine

  • Hyperbaric oxygen therapy
• Copper

  Disease: Wilson’s disease

  antidote:

  • Penicillamine
• Coumarin

  antidote:

  • Phytonadione

  • Vitamin K
• Cyanide

  antidote

  • Amyl nitrite

  • Sodium nitrite

  • 1% methylene blue
• Digoxin

  antidote: Digoxin Immune Fab

  (Digifab)
• Ethylene glycol

  antidote:

  • 4-Methylprazole (Fomepizole)

  • Ethanol

  • Digifab
• Heavy metals

  antidote:

  • EDTA – Lead

  • Dimecaprol (BAL) – Arsenic, Gold,

  Mercury, Lead

  • Penicillamine – Copper

  • Succimer (DMSA) – Lead, Arsenic,

  Mercury, Antimony
• Heparin

  antidote:

  • Protamine Sulfate

  • 1 mg PS: ~90 Units of Heparin
• Iron

  antidote: Deferoxamine
• Isoniazid

  antidote: Pyridoxine (1:1 ratio)
• Opiate

  Analgesics

  Example:

  • Codeine

  • Morphine

  • Heroin

  antidote:

  • Naloxone

  • Naltrexone