ORGANOPHOSPHATES Flashcards

1
Q

ORGANOPHOSPHATES

A

High lipophilicity
Sensitive to alkaline pH
STORAGE! (moisture → 300-2000x)

Pharmacokinetics
Good absorption (oral 35% > dermal 2-14%)
LD50 po vs LD50 dermal (200-800 vs 2000 mg/kg) Excellent distribution (special barriers, BBB)
Metabolism (partial activation) diazinon (t1/2 hours) → diazoxon (t1/2 days)
Excretion (80% urine metabolites, 20% feces)
long t1/2 + biological accumulation!
cat: increased sensitivity

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2
Q

ORGANOPHOSPHATES

Mechanism of action and side effects

A

Contact poisons Irreversible inhibition of AChE!
• Muscarinic ACh receptors
SLUDGE (salivation, lacrimation, urination, diarrhea, GI pain, emesis)
• Nicotinic ACh receptors
muscle tremors, spasms
• Central nervous system
seizures, coma, death

Antidote:
Competitive antagonism
SLUDGE <=> Atropine (0.2-0.5 mg/kg iv, sc)
Enzyme reactivation (pralidoxime, obidoxime)

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3
Q

ORGANOPHOSPHATES Application

A

Broad spectrum in most species (diazinon)
fleas, ticks, lice, mites, myiasis mostly for dipping cats are very sensitive!
Varroosis of honeybees (coumaphos)
vaporizers and fumigant strips

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4
Q

CARBAMATES

A

Agent: propoxur (Bolfo®, Kiltix®)
Toxicity: much safer (↔atropine)
Pharmacokinetics: less lipophilic, oral vs dermal Fleas, ticks
Collars, aerosol sprays, shampoos

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5
Q

Substances

A

Diazinon (=dimpylate)
Coumaphos
Phoxim
Fenthion

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