A.29 Drugs Against Ectoparasites Flashcards
Organophosphate Drugs to know
Diazinon
Coumaphos
Carbamates drugs to know
Propoxur
Pyrethroids drugs to know
Permethrin
Deltamethrin
Flumethrin
Formamidine drugs to know
Amitraz
Types of ectoparasiticides
Adulticides (contact poison or systemic agents)
Insect growth regulators
Repellents
Absorption of ectoparasiticides
Slow, but good absorption
Distribution of ectoparasiticides
Broad goes through BBB
Mechanism of action of ectoparasiticides
GluCl channels (hyperpolarisation and depolarisation)
Acts on Ach receptor
Duration of action of : collars, spot on, sprays
4-8 months
4-12 weeks
Days
PK of organophosphates
A: good
D: excellent
M: met by liver (partial activation , increase of toxicity)
E: urine & faeces
Organophosphate after being metabolised by liver
Diazoxone (much more toxic and longer half life)
Mode of action of organophosphate
Contact poison
IRREVERSIBLE inhibition of Ach E
Diazinon spectrum:
Fleas, ticks, lice, mites, myiasis
Coumaphos spectrum
Varroosis of honey bees
Side effects of organophosphate
SLUDGE, bradycardia, bronchoconstriction
Muscle tremor
Seizures, coma
Antidote for organophosphate overdose
Atropine
Pralidoxine (Ach E réactivation)
Dose of atropine in case of organophosphate overdose
0.2-0.5 mg/kg (1/4 given IV, 3/4 given SC)
For which species are organophosphates very toxic
Cats
Carbamates mode of actions
reversible inhibition of Ach E
Antidote in case of Propoxur overdose
Atropine
Spectrum of propoxur
Fleas & ticks
1st generation pyrethroids
tetramethrin
which generation of pyrethroids is safest
2
2nd generation pyrethroids
Permethrin
deltamethrin
flumethrin (varoosis of honey bees)
pyrethroid mode of action
repellent & contact poison
opens Na channels
called “knock down effect”
spectrum of pyrethroids
good: ticks, flies & mosquitoes
poor: fleas & mange mites
toxicity of pyrethroid
Fish
cats spot on can be toxic
Side effects of pyrethroids
tremors, excitation, MYDRIASIS
local irritation & allergy
antidote for pyrethroids overdose
none
intralipid: prevents drug to reach CNS
Amitraz mode of action
MAO - inhibitors (no neurotransmitter uptake)
alpha 2 agonists
spectrum of Amitraz
8 legged parasites
toxicity of Amitraz
narrow TI
not to be given to horses, chihuahuas and cats
side effects of amitraz
sedation
bradycardia
hypothermia
emesis
hyperglycemia
antidote for amitraz overdose
Atipamezole
which gene mutation can be dangerous whilst giving ectoparasiticides
ABCB1 & MD8 mostly in collies
P-glucoprot. cannot pump out drugs from CNS
