Toxicology

• What is the main aim of the lecture on drug toxicity?

  To explain drug poisoning and toxicity
• What are the manifestations of toxicity that students should describe?

  Symptoms and effects of toxic substances
• How can the toxic potential of a drug be quantified?

  Using methods like carcinogenicity and mutagenicity
• What does pharmacology study?

  The effect of drugs on living systems
• What does toxicology study?

  The effect of poisons on living systems
• Name a chemical agent that causes toxicity.

  Paracetamol
• Who is known as the 'Grandfather of Toxicology'?

  Paracelsus
• What does the phrase "The dose makes the poison" imply?

  Higher doses can be toxic, lower doses safe
• What percentage of acute hospital admissions are due to ADRs?

  ~5%
• What are Type A ADRs characterized by?

  Common, dose-related, predictable effects
• What distinguishes Type B ADRs from Type A ADRs?

  Type B ADRs are unrelated to known pharmacology
• What is the acronym ADME stand for?

  Absorption, Distribution, Metabolism, Excretion
• How does absorption relate to toxicity?

  It predicts the concentration of toxin reaching injury
• What is the role of cytochrome P450 in metabolism?

  It facilitates Phase I oxidation and reduction
• What is detoxification in the context of metabolism?

  Rendering a compound less toxic
• What happens to toxins that are not excreted?

  They may be stored in bone or fat
• What are the four basic clinical syndromes of allergic responses?

  Types I, II, III, and IV hypersensitivity
• What triggers Type I hypersensitivity reactions?

  IgE-mediated mast cell degranulation
• What can Type II hypersensitivity reactions deplete?

  Red blood cells, neutrophils, and platelets
• What are the four major superfamilies of receptors?

  Ligand-gated, GPCRs, enzyme-linked, nuclear receptors
• What is the mechanism of action of Amanita phalloides?

  Inhibits RNA polymerase
• What does tetrodotoxin block?

  Sodium channels to block action potentials
• What are the sources and mechanisms of action of various toxins?

  • Plants:
  • Amanita phalloides: inhibits RNA polymerase
  • Digitalis lanata: Na+/K+ ATPase inhibitor
  • Bacteria:
  • Clostridium botulinum: inhibits synaptic protein
  • Cholera vibrio: activates Gαs proteins
• What are the effects of animal toxins on ion channels?

  • Kraits: a-bungarotoxin blocks nAChR
  • Green mamba: dendrotoxins block K+ channels
  • Funnel web spider: agatoxin blocks Ca2+ channels
  • Puffer fish: tetrodotoxin blocks Na+ channels
• What are the clinical implications of enzyme-mediated toxicology?

  • Enzyme inhibition can lead to toxicity
  • Toxicity can result from altered metabolic pathways
  • Understanding mechanisms aids in treatment strategies
• How do the symptoms described in the shopping mall scenario relate to toxicology?

  They indicate exposure to a toxic agent
• What is the significance of the symptoms like dim vision and constricted pupils?

  They are signs of potential poisoning
• What immediate action should be taken in a toxic exposure scenario?

  Cover nose and mouth, evacuate area
• What symptoms did the shoppers exhibit after the incident in the mall?

  Dim vision, runny nose, and seizures
• What immediate action did the narrator take upon noticing the symptoms?

  Covered nose and mouth, ran out
• What is the role of acetylcholinesterase (AChE) in the synapse?

  It breaks down acetylcholine (ACh)
• What are the key effects of enzyme-mediated toxicology?

  • Increased secretion (eyes watering, nose running)
  • Convulsions
  • Bradycardia
  • Hypotension
  • Bronchoconstriction
  • Respiratory depression
• How do oximes function in relation to acetylcholinesterase?

  They reactivate acetylcholinesterase
• What is the first line of defense against biological nerve gases?

  • Atropine: mAChR blocker
  • Pralidoxime: reactivates acetylcholinesterase
• What does cyanide inhibit in cellular respiration?

  Mitochondrial cytochrome c oxidase
• What is the effect of carbon monoxide on hemoglobin?

  It displaces oxygen, causing hypoxia
• What organs are particularly susceptible to toxin damage?

  • Liver
  • Kidney
• What is a prominent cause of hepatic poisoning?

  Paracetamol
• What is the treatment for paracetamol poisoning?

  Acetylcysteine
• What happens during paracetamol overdose?

  Enzyme saturation and glutathione depletion