Anthelmintics – factors influencing use in companion animals

Question 1

Resistance

Answer 1

The ability of an organism to survive a particular treatment which would normally be effective

Question 2

Interval

Answer 2

Timed to maximise impact based on knowledge of lifecycle and persistence of the drug

Question 3

Targeted

Answer 3

Based on known facts

Question 4

Strategic

Answer 4

Based on known facts and known risks

Question 5

Main drug classes for anthelmintics and examples

Answer 5

Benzimidazoles
Macrocyclic lactones
Tetrahydropyrimidine
Praziquantel
Cyclooctadepsipeptides

Question 6

Examples of Benzimidazoles

Answer 6

fenbendazole (febantel), mebendazole

Question 7

Examples of Macrocyclic lactones

Answer 7

ivermectin, moxidectin, milbemycin oxime, selamectin, eprinomectin

Question 8

Examples of Tetrahydropyrimidine

Answer 8

Pyrantel

Question 9

Benzimidazole mechanism of action

Answer 9

Binds helminth tubulin and prevents microtubules formation
Tubules absent 6-24 hours
Starves parasite

Question 10

Macrocyclic lactones mechanism of action

Answer 10

Endectocide
Stimulate glutamate-gated chloride channels in invertebrate nerve and muscle cells, results in flaccid paralysis

Question 11

Tetrahydropyrimidines mechanism of action

Answer 11

Depolarising neuromuscular blocking agents
Higher affinity for parasite receptor
Paralyses worm

Question 12

Praziquantel mechanism of action

Answer 12

Tetanic contraction of parasite musculature
Rapid vacuolisation of the syncytial tegument

Question 13

Spectrum of activity of Praziquantel

Answer 13

Cestodes, trematodes

Question 14

Cyclooctadepsipeptides mechanism of action

Answer 14

Inhibition of acetylcholine-elicited muscle contraction
Pre-synaptic action (latrophilin-like receptor)
Ultimately flaccid paralysis / death

Question 15

Cyclooctadepsipeptides spectrum of activity

Answer 15

adult nematodes