Other Anthelmintic Drugs Flashcards
What is the spectrum of Emodepside? In what animals is it used? What is its only formulation available?
ascarids and hookworms (mature and immature) of cats
topical with praziquantel for the treatment of nematodes in cats
- absorbed through the skin and deposited in adipose
What is the mechanism of action of Emodepside?
selective agonist of the presynaptic lactrophillin-receptor (LTP) in parasitic nematodes, resulting in flaccid paralysis and death
What 3 adverse effects may occur with the use of Emodepside?
- alopecia at application site
- salivation and vomiting due to licking application site
- tremors with overdose
What effect does Emodepside have on rats and rabbits?
interferes with fetal development
- pregnant women should wear gloves if product handling is necessary
When is Derquantel commonly used? What is its mechanism of action?
active against both benzimidazole and ivermectin-resistant Haemonchus contortus
acts as an antagonist of neuronal nicotinic cholinergic receptors in nematodes causing flaccid paralysis
- has a markedly lower affinity for mammalian receptors also
What are the 4 steps to the life cycle of heartworm?
- mosquito gets microfilariae while sucking blood of an infected host
- microfilaria (L1) develops into L3 inside mosquito and migrates to the oral portion of the mosquito
- mosquito punctures new host, depositing L3 that will develop into L5 to penetrate veins to reach the heart and pulmonary arteries
- adult heartworm lives in the right cardiac ventricle and in the pulmonary artery and females produce larvae into circulation
- both adults and microfilariae of Dirofilaria immitis are responsible for clinical signs associated with heartworm disease
How does a large number of Dirofilaria immitis deposition affect the heart?
cause greater pulmonary hypertension, thromboembolism, and risks vena caval syndrome
What 3 aspects are considered when treating and preventing heartworm disease?
- remove adults - adulticide
- prevent infection - larvicide
- use of microfilaricides is not common, adulticides will decrease microfilaria population
What adulticide is commonly used to treat heartworm disease? Where does it tend to concentrate? Metabolized and excreted?
Melarsomine (Immiticide)
liver and kidneys
metabolized in the liver and excreted in bile
How is Melarsomine (Immiticide) administered? When is its use contraindicated?
deep IM in L3-L5 lumbar epaxial muscles
caval syndrome where worms block the caudal vena cava, which requires immediate surgical removal
Why is it especially important to have an accurate weight before administering Melarsomine (Immiticide)? What is a possible antidote for reversing toxicity?
has a low margin of safety
Dimercaprol (BAL)
How does Dimercaprol (BAL) act as an antidote for Melarsomine (Immiticide) toxicity?
its sulfhydryl groups for heterocyclic rings and complexes with metals, principally arsenic, lead, mercury, and gold, allowing them to be excreted via renal and fecal routes
No drug is approved for use as a microfilaricide in heartworm disease. What 2 drugs tend to have microfilaricide effects?
- Ivermectin
- Milbemycin**
What larvicides are commonly used for heartworm prevention? How do they work?
macrocyclic lactones
- Ivermectin
- Moxidectin
- Milbemycin oxime
- Selamectin
kill larval stages (L3-L4) of Dilofilaria immitis in dogs and cats
How does the severity of cestode infections compare in farm animals and companion animals?
FARM ANIMALS - may be a minor problem and usually does not require treatment with specific cestocidal drugs
COMPANION ANIMALS - treatment is necessary, since dogs and cats are DH for cestodes and larval stages cause zoonosis
What is a common treatment of Anoplocephala perfoliate infections in horses?
pyrantel pamoate paste at 2x nematode dose
(most common tapeworm in horses)
What is the spectrum of action of Praziquantal?
highly efficacious against adult stages of all tapeworms in farm and companion antimals, along with trematodes
- Taenia hydatigena, T. pisiformis, T. ovis, T. taeniaeformis, D. caninum, Mesocestoides corti, E. multilocularis, E. granulosus
What is the mechanism of action of Praziquantal?
induces the release of intracellularly stored calcium in addition to an increase in calcium influx across the tegument
- causing rapid and sustained muscle contraction and tegumental disruption
Where is Praziquantal absorbed, metabolized, and excreted?
completely absorbed in the GI tract in most species
hepatic metabolism forms a metabolite that exerts similar pharmacologic effect
renal
What is Epsiprantel (Cestex)? What is its mechanism of action?
anticestodal drug chemically related to Praziquantal that is used specifically for the treatment of common tapeworms of dogs and cats (D. caninum, T, pisiformis, T. taeniaeformis, E. granulosus, E. multilocularis)
affects calcium homeostasis within the parasite and damages the tegument, making it vulnerable to lysis and digestion
What allows for the action of Epsiprantel (Cestex) against intestinal cestodes?
poorly absorbed in the GIT and is available to act on the tapeworm and induces elimination in FECES
Praziquantel vs. Epsiprantel:
What causes fasciolosis?
liver fluke, Fasciola hepatica and Fasciola gigantica; it is the most economically important diseased caused by trematodes in domestic animals worldwide
(drugs active against one works on the other)
What rumen fluke commonly infects cattle and sheep? Why are immature stages seriously pathogenic?
Paramphistomum spp.
migrate within the gut lumen from the duodenum to the rumen, causing inflammation