Toxicology/ Posions Flashcards
Most common route of exposure in poisonings
Ingestion
Most common route of occupational exposure
Inhalational
Difference between toxicology depends on
Dose
Name 5 antidote mechanisms
- Complex with poison
- Increase biotransformation to less toxic metabolite
- Increase excretion
- Block or compete for target receptors
- Bypass effect of poison
E.g. Of antidote that complexes with poison
- -NAC/ acetadote/ mucomyst: acetaminophen
- - Crofab: rattlesnakes, copperheads
E.g. of antidote increasing biotransformation to less toxic metabolite
Pyridoxine and thiamine: ethylene glycol
Folic acid: methanol
NAC/ acetadote/ mucomyst: acetaminophen
E.g. Of antidote that increases excretion
Normal saline: lithium toxicity
Urine alkalinization: salicylates
Hemodialysis
E.g. Of antidotes that competes for target receptors
Fomepizole: ethylene glycol or methanol
E.g. Of an antidote that bypasses effect of poison
Octreotide: sulfonlyurea
Bioactivation
May produce a more chemically active form of the xenobiotic
Name 6 mechanisms of toxicity
- receptor-ligand interactions
- perturbation of membrane function/permeability
- interference of ATP generation
- interaction with macromolecules
- alteration of Ca homeostasis
- generation of oxygen radicals/ oxidative stress
Paraquat
- herbicide
- SE: lung toxicity (pulmonary fibrosis)
- mechanism: yields hydroxyl radical
Parathione
- organophosphate insecticide
- mechanism: metabolized to paraoxon, which phosphorylates (and inactivates) acetylcholinesterase, causing increased Ach (cholinergic crisis)
- SLUDGEM (salivation, lacrimation, urination, defection, GI issues, emesis, miosis)
- antidotes: atropine (anti-muscarinic) and pralidoxone (ACHase activator)
Carbon monoxide
- Forms carboxyhemoglobin (Hg-Fe2+-CO), which inhibits O2 transport
- tx: O2 at high partial pressure to displace CO from HB (hyperbaric chamber)
Methemoglobinemia inducers
- due to exposure to NITRATES, abx, aromatic amines, local anesthetics, etc
- methemoglobin (Hb-Fe3+) –> dark blue color
- antidote: methylene blue (e- donor to reduce Fe3+ to Fe2+)
