1 Flashcards
Classification according to toxicity
Extremely toxic
Highly toxic
Moderately toxic
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Factors affecting GI absorption of toxins
- lipophilicity
- feed (e.g. DDT - very lipophilic and food can increase their absorption)
- pH (e.g. urea - acidified rumen will decrease absorption because ammonium will be in ionised form, and iOS are in general absorbed worse)
- gut microbiom (e.g. nitrate-nitrite - bacteria will convert)
- circulation enterohepatica (theobromine) - to block activated charcoal is used
Absorption through respiratory tract
- very big absorption surface !
- reactions with water can occur, especially in case of gas poisoning, acid formation !
Absorption through skin
- very lipophilic substances can be absorbed
- e.g. organophosphates, DDT
First pass effect
Liver!
Hepatoprotectos e.g.: …
How blood proteins affect toxicity?
If substance has high protein binding but patient has decreased blood proteins, drug will be in free from that will increase toxicity
Physics-chemical accumulation of different metals
- lead -> bones
- fluoride -> bone, teeth
- copper -> liver
- arsenic -> hair, bone
- selenium -> horn
- Cl- CH -> fat
Biological accumulation
E.g. organophosphates inhibit irreversibly AChE
Accumulation of effect (=> BIOLOGICAL)
Phase 1 and phase 2 reaction of metabolism
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What substance is antioxidant and also liver protector?
N-acetyl-cystein
Substances affecting metabolism (CYP450)
- induction: e.g. phenobarbital
- inhibition: e.g. tiamulin
Factors influencing excretion
URINE:
- urinary pH
- hydration
- pre-existing renal disease
LIVER:
- larger molecules
- enterohepatic circulation
LUNGS:
- gases, volatile poisons
- special scent ! (Cyanide -> bitter almond, phosphorus -> garlic)
What can poison act on?
- Soluble enzymes (e.g. carbamates, organophosphates)
- Receptor (agonist: e.g. ivermectin, antagonist: e.g. atropine)
- Damaging the cell membrane (cell destruction: detergents, alcohols; oxidation of membrane lipids and proteins: e.g. para quart, Cu ions)
- Damaging electron transport (e.g. cyanide)
Emergency measures
- Anticonvulsant (e.g. BZD, pentobarbital, levetiracetam, propofol, isoflurane)
- Respiratory maintenance:
- analeptics: doxapram (carefully because GABA antagonist -> risk of convulsions)
- bronchodilators: salbutamole, terbutaline, aminophyllin - Electrolyte ad fluid therapy (crystalloids, e.g. ringer lactate (liver !)
Elimination of poison in GI tract
- emetics (contraindicated: in horses, rabbits, unconsciousness, lung deems, seizures, late pregnancy, corrosive substance); e.g. apomorphine and …)
- adsorbents (ACTIVATED CHARCOAL - asap)
- neutralising, preventing transformation (diluted vinegar, cold water)
- enhancing elimination by increasing GFR (glucose, mannitol)
