Drugs

Question 1

Give an example of a repellent.

Answer 1

DEET

Question 2

When might you use a repellent? What is an example?

Answer 2

To try keep biting flies (e.g stable fly) off horse e.g citronella

Question 3

Give an example of a chlorinated hydrocarbon.

Answer 3

DDT, Lindane, Dieldrin

Question 4

Give an example of an OP and it’s use in animals.

Answer 4

Dichlorovos - used in flea collars

Tichlorphon - oral use for Gastrophilus spp.

Question 5

OPs persist for a long time in the environment, and may accumulate. True or false?

Answer 5

False

Question 6

How do OPs work?

Answer 6

Inhibit Acetylcholine esterase

Question 7

Which persists longer in the environment - carbamates or OPs?

Answer 7

Carbamates

Question 8

How do carbamates work?

Answer 8

Inhibit ACh-ester ase

Question 9

What is an example of a carbamate and its use in animals?

Answer 9

Carbaryl - powder or spray for flea control

Question 10

What is the mechanism of action for formamidines?

Answer 10

Inhibit monoamine oxidase

Question 11

What is an example of a formamidine and its use?

Answer 11

Amitraz - used in control of Rhiphicephalus australis

Question 12

Which persists for longer in the environment - carbamates or pyrethroids?

Answer 12

Carbamates - pyrethroids degenerate after 24h

Question 13

Why are synthetic pyrethroids more useful? What is one example and its use?

Answer 13

Longer half life.

E.g cypermethrin - backline treatment for lice in sheep

Question 14

What are the three Avermectins? What bigger drug family do they belong to?

Answer 14

Ivermectin
Abamectin
Selamectin

ML’s

Question 15

What is an example of a milbemycin?

Answer 15

Moxidectin

Question 16

What is an example of a neo-nicitinoid and its mechanism of action?

Answer 16

Imidacloprid - blocks nicotinic Acetylcholine receptors

Question 17

What class of chemical is Nitenpyram (capstar)?

Answer 17

A neo-nicitinoid

Question 18

What is the active ingredient in Frontline and what chemical class is it?

Answer 18

Fipronil - a neo-nicitinoid

Question 19

When might you use a growth regulator and what is one example?

Answer 19

Lufenuron - in a flea bomb

Question 20

What is the mechanism of action for benzimadazole?

Answer 20

Inhibit polymerisation of tubulin

Question 21

What generation and spectrum is thiabendazole?

Answer 21

Primary generation

Broad spectrum

Question 22

Give an example of a secondary benzimidazole. What is the important difference between this and primary BZs?

Answer 22

Oxibendazole

Longer half life

Question 23

Give an example of a tertiary benzimadazole and its use in animals

Answer 23

Fenbendazole

10x dose rate to kill migrating S. vulgaris larvae

5 daily doses to kill inhibited Ostertagia in cattle

Question 24

Explain the ‘depot’ effect of BZ drugs in ruminants

Answer 24

Drug’s metabolites (e.g sulphoxide, sulphone)also have antihelmintic activity
After being absorbed across rumen, are metabolised and re-deposited into rumen where they can be re-absorbed again. Drug can have antihelmintic activity from lumen or from blood, in its original form or as a metabolite.

Question 25

Are tertiary BZs effective against inhibited Cyathostominae in horses?

Answer 25

No

Question 26

Are tertiary BZs effective at killing inhibited Ancyclostoma larvae in dogs?

Answer 26

No

Question 27

Can you inject BZs?

Answer 27

No - insoluble

Question 28

What is an example of an imidazothiazole?

Answer 28

Levamisole

Question 29

How does levamisole work?

Answer 29

Agonist at cholinergic receptors to cause spastic paralysis

Question 30

What is levamisole used for? Is there anything it doesnt cover, or any contraindications?

Answer 30

Treatment of all GINs and lungworms. Ineffective against inhibited larvae and flatworms Widespread resistance among trichostrongyles of sheep Causes excitement in horses - not used

Question 31

Is levimasole ovicidal?

Answer 31

No

Question 32

Which has the wider safety margin - BZs or levimasole?

Answer 32

BZs. Levimasole safety index only 5

Question 33

What are two examples of tetrahydropyrimidines?

Answer 33

Morantel, pyrantel

Question 34

How does morantel work?

Answer 34

Depolarise motor end plates to cause spastic paralysis

Question 35

Give two important differences between morantel and levimasole.

Answer 35

Morantel - can use on horses (good against cestodes). | Levimasole - can use on lungworms (morantel ineffective)

Question 36

If a nematode becomes resistant to levamisole, it will also be resistant to ____ but not the other way around.

Answer 36

If a nematode becomes resistant to levamisole, it will also be resistant to morantel or pyrantel, but not the other way around.

Question 37

Which tetrahydropyrimidine is more commonly used in dogs and cats? Which parasites is it good for?

Answer 37

Pyrantel Hookworms and whipworms

Question 38

How do macrocyclic lactones work?

Answer 38

Bind to glutamate-gated chloride channels with high affinity > increase Cl- conductance across cell membrane to cause flaccid paralysis > paralysed pharyngeal pump = cant eat, paralysed somatic muscles = can't remain at predilection site

Question 39

What are the three modes of administration for MLs?

Answer 39

Oral, injectible, pour-on

Question 40

MLs are ___ safe and ____ potent than tetrahydropyrimidines.

Answer 40

MLs are more safe and more potent than tetrahydropyrimidines.

Question 41

``` What is an advantage of each - oral - subQ and - topical (pour on) administration of MLs? ```

Answer 41

Oral: High drug concentration at intestinal site so good efficacy against GINs SubQ: Flexible to modification with formula changes so can get extended activity Pour on: Skin forms depot of drug for persistent action

Question 42

Of the abomasal nematodes in sheep, which are mostly susceptible to MLs and which are resistant?

Answer 42

Haemonchus and Ostertagia are commonly resistant to MLs | Trichostrongylus usually susceptible

Question 43

What is an important use for MLs in cattle? What is one example of a resistant nematode in cattle?

Answer 43

MLs can kill inhibited Ostertagia Cooperia may be resistant

Question 44

Can you kill all inhibited cyathostomes in a horse using Moxidectin?

Answer 44

No - usually about 80% killed

Question 45

Give one example of a disadvantage of ML use.

Answer 45

Persists in dung so can kill arthropods (dung beetles) which means dung remains in environment longer

Question 46

True or false: Haemonchus is more resistant than Ostertagia or Trichostrongylus to OPs?

Answer 46

False - Haemonchus is more susceptible, higher doses needed for the other two

Question 47

Give an example of a heterocyclic compound and its use

Answer 47

Piperazine Hookworms in dogs and cats Oesophagostomum in pigs

Question 48

Give an example of a salicylanilide and its use in animals

Answer 48

Closantel Haemonchus contortus in sheep - best against blood feeders, can't penetrate cuticle

Question 49

How does closantel work?

Answer 49

Uncouples oxidative phosphorylation

Question 50

What is an example of an octadepsipeptide and which animal might it be used in

Answer 50

Emodepside - dogs and cats

Question 51

What class of drug is monepantel?

Answer 51

Amino-acetonitrile derivative

Question 52

How does mopantel work?

Answer 52

Binds to nematode-specific nicotinic ACh receptor to cause spastic paralysis

Question 53

How safe is mopantel? What dose do goats usually need compared to sheep?

Answer 53

Very safe - >30 safety index | Goats need double sheep dose

Question 54

Which would you use against a Dictyocaulus infection in sheep - Monepantel or derquantel?

Answer 54

derquantel. Monepantel ineffective against lungworms

Question 55

How does derquantel work?

Answer 55

Nicotinic antagonist causing flaccid paralysis

Question 56

What is the activity of derquantel like? Are there any species contraindications?

Answer 56

Not very effective against Ostertagia, oesophagostamum or chabertia. Medium spectrum - used in sheep in combination with abamectin. TOXIC to horses

Question 57

What are two acceptable protocols for killing of encysted Cythastominae larvae in horses?

Answer 57

Fenbndazole at 10mg/kg/day for 5 days Moxidectin @ 0.4mg/kg

Question 58

What is an acceptable protocol for treating a bitch for Ancyclostoma spp. encysted larvae, such that her puppies have the best possible protection from transmammary transmission?

Answer 58

fenbendazole at 50mg/kg/day from 3 weeks prepartum to 2-15 days post partum