Ectoparaciticides

Question 1

What drugs affect acetylcholine?

Answer 1

Organophosphates

carbamates

Question 2

What drugs affect axonal sodium channels?

Answer 2

Pyrethroids

Question 3

What drugs affect the octopamine system?

Answer 3

Amidines

Question 4

What drugs affect the chloride channels?

Answer 4

Avermectins, fipronil, isoxazolines

Question 5

What drug acts on insect growth regulators - juvenile hormones?

Answer 5

Methoprene

Question 6

What drug acts on insect growth regulators - chitin synthesis inhibitors?

Answer 6

Benzoyl urea derivatives

Question 7

What are 4 modes of application of ectoparasiticides?

Answer 7

Systemic treatment of the host
Topical application
Dips
Bands, collars and tags

Question 8

How do organophosphates kill ectoparasites?

Answer 8

Irreversibly inhibits acetylcholinesterase

Causes flaccid paralysis

Question 9

How do carbamates kill ectoparasites?

Answer 9

Reversibly inhibits acetylcholinesterase

Causes flaccid paralysis

Question 10

How are organophosphates administered?

Answer 10

All routes - absorbed systemically by host

Question 11

How are carbamates administered?

Answer 11

Topically

Question 12

How does Imidacloprid (neonicotinoid) kill ectoparasites?

Answer 12

Partial agonist at nicotinic ACh receptors in
insect CNS
Causes depolarising block and flaccid paralysis

Question 13

How is Imidacloprid administered?

Answer 13

Spot on

Question 14

How do pyrethroids kill ectoparasites?

Answer 14

Opens sodium channel

Causes prolonged depolarising afterpotential

Question 15

How are pyrethroids selectively toxic?

Answer 15

Temperature dependence - insects colder
Metabolic rate - insects slower
Body size - small less chance to metabolise

Question 16

How are pyrethroids administered?

Answer 16

Topically

Question 17

How do amidines kill ectoparasites?

Answer 17

Agonists of the octopamine receptor

Question 18

What is octopamine?

Answer 18

Invertebrate equivalent of noradrenaline neurotransmitter

Question 19

What is the consequence of amidines on parasites?

Answer 19

CNS hyperexcitability

Death

Question 20

How are amidines administered?

Answer 20

Topically

Question 21

What do pyrethroids always end in?

Answer 21

-thrin

Question 22

How does fipronil kill ectoparasites?

Answer 22

Antagonist of GABA receptors

Causes hyperexcitation in the CNS, convulsions and death

Question 23

How is fipronil administered?

Answer 23

Spray or spot on

Stored in sebaceous glands for 3 months

Question 24

What is a side effect of fipronil?

Answer 24

Hypersalivation if licked

Question 25

How do avermectins kill ectoparasites?

Answer 25

Activate the GABA receptor which inhibits neurotransmission

Question 26

How are avermectins administered?

Answer 26

Systemically by injection or orally

Question 27

What are avermectins used to treat?

Answer 27

``` Arthropod ectoparasites Fleas Mites Lice Nematodes ```

Question 28

What is a new ectoparasiticide that can help with resistance? How?

Answer 28

Isoxazolines | Acts at a different binding site to the other GABA antagonists

Question 29

How does methoprene and pyriproxyfen affect ectoparasites?

Answer 29

Prevent metamorphosis by mimicing insect juvenile hormone

Question 30

How do benzoyl ureas affect ectoparasites?

Answer 30

Inhibit the enzymes than synthesise chitin | Affects the development of the fleas offspring

Question 31

How are benzoyl ureas administered?

Answer 31

Orally