Week 9 - Toxicology Flashcards

Toxicology Overview

  • Definition: Toxicology is derived from two Greek words:
    • Toxicon: poisonous substance
    • Logos: study
    • It is the study of harmful effects of toxins and toxicants on living organisms and the environment.
  • Terminology:
    • Toxin: poison of natural origin
    • Toxicant: hazardous substance of chemical origin.

Key Areas of Toxicology

  • Nature:
    • Types, sources, and routes of entry of toxins.
  • Mechanism:
    • How poisons disrupt biological balances.
  • Detection:
    • Involves clinical assessments and testing methodologies.
  • Effects:
    • Cellular, organ/system, delayed effects, as well as psychological and behavioral changes.

Classification of Toxicology

  • Occupational Toxicology:
    • Focus on chemicals in the workplace, with historical regulations to protect workers.
  • Environmental Toxicology:
    • Studies chemicals as pollutants/contaminants in ecosystems.
  • Forensic Toxicology:
    • Explores medical and legal aspects of toxins and poisons.
  • Clinical Toxicology:
    • Investigates the clinical presentations and pathophysiological effects of intoxication.

Importance of Toxicology

  • Ensures workplace safety (Occupational Toxicology).
  • Manages environmental contamination effectively (Environmental Toxicology).
  • Identifies responsible parties in toxic incidents (Forensic Toxicology).
  • Promotes the safety and well-being of individuals (Clinical Toxicology).

Pharmacology Fundamentals

  • Pharmacokinetics:
    • Examines absorption, distribution, biotransformation, and excretion of drugs and chemicals.
  • Pharmacodynamics:
    • Deals with the biochemical and physiological impacts of chemicals on the body and their action mechanisms.

Laboratory Investigations

  • Sample Types:

    • Urine: Fast detection, standard methods, but short detection window.
    • Oral fluid: Quick collection, non-invasive but limited detection window.
    • Blood: Reliable for recent use but requires invasive collection.
    • Hair: Long detection window, stable but costly and may vary with hair characteristics.

  • Adulteration of Samples:

    • Biological methods (diluting with water).
    • Chemical methods (using acids or bleach).

  • Integrity Checks:

    • Measured parameters like pH, creatinine, specific gravity, etc., to ensure sample authenticity.

Clinical Toxicology Cases

  • Case 1: Ethylene glycol poisoning displayed with specific laboratory values indicating abnormal osmolality and gap.
  • Case 2: Carbon monoxide poisoning with significant carboxyhaemoglobin levels observed in a patient.
  • Case 3: Pregnant female with a history of drug use admitted for assessment.
  • Case 4: Lead poisoning demonstrated through acute symptoms and high lead concentration.

Analytical Techniques in Toxicology

  • Thin Layer Chromatography (TLC):
    • Initial screening method, requires expertise for accurate interpretation.
  • Immunoassay Methods:
    • Widely used screening tests prone to cross-reactivity, good precision but limited specificity.
  • Gas Chromatography (GC):
    • High specificity and sensitivity for various samples but requires extensive sample prep.
  • Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS):
    • Standard for confirmatory drug screening, capable of analyzing multiple compounds simultaneously.
  • Inductively Coupled Plasma Mass Spectrometry (ICP-MS):
    • Sensitive trace elements measurement, useful in forensic contexts.

Public Health Considerations

  • Importance of public and patient education in preventing and managing toxicity, highlighted by historical mass poisoning cases.
  • Use of platforms like WEDINOS for harm reduction and trend analysis of substance use.

Summary

  • Clinical toxicology is essential for diagnosing poisonings, often presenting at Emergency Departments with overlapping symptoms.
  • Collaboration with national poison information services can aid healthcare providers in managing acute toxicology cases effectively.