drugs for ectoparasite control

Question 1

What is the mode of action of neurotoxins?

Answer 1

Act of CNS synapses, axons or neuromuscular junctions => spastic or flaccid paralysis

Question 2

Which life stage do neurotoxins target?

Answer 2

all adulticidal
some are ovicidal/larvicidal

Question 3

what extra safety mechanisms need to be considered when using neurotoxins?

Answer 3

Insects and mammals have many neurotransmitters in common – better safety profile if drugs act on non-mammalian mechanisms

Question 4

Give examples of different types of neurotoxins

Answer 4

Nicotinic Ach receptor stimulant (neonicatinoids)
GABA inhibitors
(Phenylpyrrazoles
Cl channel stimulants
(Macrocyclic lactones)
Cholinesterase inhibitor
(Organophophates)
GABA + Cl channel inhibitors
(Isoxazolines)
Na channel stimulants
(Pyrethroids)

Question 5

Give an example of nicotinic acetylcholine (Ach) receptor stimulants (neonicatinoids)

Answer 5

imidacloprid
- licensed for fleas in small animals and chewing lice (dogs)
- not absorbed systemically
- topical applicaiton, washes off easily

Question 6

Give an example of a cholinesterase inhibitor (organophosphate)

Answer 6

diazinon (dimpylate)
- sheep dip vs wide range of ectoparasites

Question 7

Give an example of a GABA inhibitor (phenylprazoles)

Answer 7

Fibronil
- active against fleas and ticks and chewing lice (dogs)
- topical application, washes off
- not absorbed systemically
- toxic to rabbits

Question 8

Give an example of a GABA and chloride channel inhibitors (Isoxazolines)

Answer 8

Fluralaner, sarolaner, afoxolaner
- fleas and ticks and mites
- rapid onset
- absorbed systemically
- unaffected by bathing
- contraindicated in patients with seizures

Question 9

give an example of chloride channel stimulators (macrocyclic lactones)

Answer 9

Avermectins (ivermectin, dopramectin, moxidectin etc.) - toxic to chelonians, avoid in dogs/cats
Milbemycins (wormer)
- absorbed systemically
- does not wash off
- ecto and endo parasites
- risk of neurotoxicity (esp. collies/herding breeds)

Question 10

Give an example of a sodium channel stimulant (pyrethroids)

Answer 10

permethrin, cypermethrin, deltamethrin, flumethrin
- adulticide vs fleas, flies, lice, keds, ticks and some mites
- also repellant
- toxic to cats and aquatic life

Question 11

What stage of life cycle do insect growth regulators act on?

Answer 11

interrupt juvenile stage (no adulticidal properties)
- very slow to act
- often used in conjunction with rapid acting adulticide

Question 12

What are the different modes of actions of insect growth regulators?

Answer 12

Juvenile hormone analogues
Chitin synthesis inhibitors
Triazine derivatives

Question 13

Give examples of juvenile hormone analogues

Answer 13

S-methoprene Pyriproxyfen
Fenoxycarb
- environmental flea sprays most commonly

Question 14

Give examples of chitin synthesis inhibitors

Answer 14

lufenuron
- all cats and dogs in house must be treated

Question 15

Give examples of triazine derivatives

Answer 15

Cyromazine
Dicyclanil
- prevention of cutaneous myiasis

Question 16

Give examples of repellant drugs

Answer 16

Pyrethrins/pyrethroids
- sandflies, midges (sweet itch), ticks

Question 17

Give examples of synergistic ectoparasite drugs

Answer 17

Piperonyl butoxide
- inhibits insect detoxification pathways => increase available concentration of insecticide

Question 18

Describe the use of lime sulphur dips as an ectoparasite control

Answer 18

Traditional pesticide, fungicidal, bactericidal
- smelly, stains and must not be ingested

Question 19

Give examples of dessicants

Answer 19

Sodium polyborate
- used in environment

Question 20

Give examples of mechanical agents for ectoparasite control

Answer 20

Diatomaceous earth
- sharp particles that damage exoskeleton
- used in environment