Anthelmintics Flashcards Preview

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Flashcards in Anthelmintics Deck (19):
1

anthelminitic - define

A chemotherapeutic agent used to control
helminth infections

2

chemotherapy - define

Use of drugs to injure an invading organism
without injury to the host

3

classification of anthelminitics

spectrum of activity - broad vs narrow
chemical group/mode of action
target parasites
method of delivery/formulation

4

broad spec

Benzimidazoles – β-tubulin binding 2-LV
Imidazothiazoles – ACh agonist*
macrocyclic lactones – modulate glutamate-gated chloride channels
Amino-acetonitrile derivatives – targets specific Hco-MPTL receptors*
Spiroindole – ACh antagonist

5

potency is determined by ___

duration of exposure

6

potency

multiple low doses more potent than 1 large one
potency greater in ruminant/horse than dog
potency greater in ruminants if starved for 12-24h

7

Imidazothiazoles/Tetrahydropyrimidines

yellow drench
Imidazothiazoles -levamisole
Tetrahydropyrimizines - pyrantel
Cholinergic agonists - rapid and reversible spastic paralysis
oral only

8

levamisole - target parasites

Gutworms +++
Adult +++
Mucosal larvae ++
Hypobiotic larvae +
Lungworms +++

9

pharmacokinetics - levamisole

v.short half life in body
injection - 8h
oral - 14h
pour-on - 24h

10

macrolytic lactones (ML) - fermentation products

Avermectins - Streptomyces avermilitis
Milbemycins - Streptomyces cyanogriseus

11

macrolytic lactones (ML)

clear drench
avermectins + milbemycins
Open invertebrate specific glutamate-chloride channels in post-synaptic membrane leading to flaccid paralysis

12

macrolytic lactones (ML) - target parasites

Gutworms +++
Adult +++
Mucosal larvae +++
Hypobiotic larvae +++
Lungworms +++
arthropods ++

13

ML pharmacokinetics

long lasting - gives period of protection against re-infection - metaphylaxis
prevents pasture contamination - prophylaxis

14

roundwormers

benzimidazoles
macrolytic lactones
Imidazothiazoles + Tetrahydropyrimidines
aminoacetile derivatives
spiroindoles
narrow spec - depsipeptides, salicylanilides, piperazines, phenylisothiocyanates

15

tapewormers

benzimidazoles
broad - tetrahydropyrimidines
narrow - isoquinolones, phenylisothiocyanates

16

praziquantel

isoquinolone
Tegument destruction
Increased membrane permeability for calcium-ions, loss of intracellular Ca++
spastic paralysis and malabsorption

17

flukicides

Salicylanilides and Substituted Phenols
Narrow Spec – fluke and blood feeding nematodes
Uncouple oxidative phosphorylation decr the availability of high energy phosphate compounds - blocks energy availability

18

methods of delivery

oral - Drench, Paste, Tablet, in feed, Bolus (Intra-ruminal device)
parenterally - injection, subcutaneous, intramuscular
topical - tran-dermal, pour on

19

benzimidazoles

white drench
Albendazole, (Ricobendazole) Fenbendazole, Flubendazole, Mebendazole, Oxfendazole, Triclabendazole
bind to parasite tubulin - inhibits glucose uptake - starves parasite to death
low water solubility - oral only