Antiprotozoan Drugs Flashcards
What 5 protozoa are of veterinary importance?
- Babesia divergens
- Trichomonas foetus
- Toxoplasma gondii
- Trypanosomas cruzi
- Giardia duodenalis
What benzimidazoles and pro-benzimidazole have antiprotozoan characteristics? What activity does it have? What activity does it lack?
- Albendazole
- Fenbendazole
- Febentel
Giardia spp.
antibiotic activity —> avoids affecting the normal flora, just affects Giardia
What aminoglycoside has antiprotozoal characteristics? How is it used in different species?
Paromomycin
- approved for use in cattle
- extra-label use in cats, dogs, cattle, and goats
What is the mechanism of action of Paromomycin? What is a common adverse effect?
aminoglycoside - interferes with bacterial protein synthesis
renal toxicity —> GI damage allows it to reach systemic circulation
What 2 protozoal diseases is Paromomycin used against? What activity does it lack?
- Giardiasis
- Cryptosporidiosis
little activity against intestinal bacteria
What azalide (macrolide) has antiprotozoal activity? What is its mechanism of action? What activity does it have?
Azithromycin (used in cattle)
inhibits protein synthesis by binding to the 50S ribosomal unit
activity against mycoplasma and cryptosporidium
What lincosamide has antiprotozoal activity? What is its mechanism of action? What 2 protozoal diseases is it used to treat?
Clindamycin (used in dogs and cats)
inhibits protein synthesis at the 50S ribosome subunit
- Toxoplasmosis
- Neosporosis
What 3 dihydrofolate reductase/thymidylate synthase (DHFR/TS) inhibitors have antiprotozoal activity?
- Trimethoprim
- Pyrimethamine
- Ormetoprim
What 2 DHFR/TS inhibitors are used to treat equine protozoal myelitis?
Trimethoprim or Pyrimethamine combines with sulfadiazine
What 2 DHFR/TS inhibitors are used to treat coccidiosis, toxoplasmosis, and neosporosis in dogs and cats?
- Trimethoprim combined with sulfadiazine in dogs and cats
- Ormetoprim combined with sulfadimethoxine in dogs
What DHFR/TS inhibitors are used to treat coccidiosis in broiler chickens and turkeys?
Ormetoprim combines with suldadimethoxine
What is the mechanism of action of DHFR/TS inhibitors? What other drug is it most commonly combined with?
blocks dihydrofolate reductase responsible for the synthesis of tetrahydrofolic acid, the active form of folic acid
sulfonamides (1:5)
What 4 nitroimidazoles have antiprotozoal activity? How is their use controlled in food-producing animals?
- Metronidazole
- Tinidazole
- Ronidazole
- Benznidazole
prohibited by the FDA —> cattle receiving metronidazole should no enter the food chain
What 2 nitroimidazoles are used to treat trichomoniasis? What animals are they used in?
- Metronidazole - cats and cattle
- Tinidazole - cats
Ronidazole no longer approved for use in cats
What 2 nitroimidazoles are used to treat giardiasis? What animals are they used in?
- Metronidazole - dogs, cats, and horses
- Tinidazole - dogs, cats
What nitroimidazole is used to treat trypanosomiasis in dogs?
Benznidazole
The mechanism of action of nitroimidazoles is not completely understood. What is suspected to be the mechanism of action?
disrupts DNA and nucleic acid synthesis
Where are nitroimidazoles metabolized? Eliminated?
liver
urine and feces - metabolites/unchanged drug
How is the use of hydroxyquinolones (Decoquinate) monitored by the FDA?
approved as a monotherapy or combination with Lincomycin, Monesin, or Chlortetracycline, BUT it is not approved for use in animals producing milk for human consumption or laying hens
- alters taste
What hydroxyquinolone has antiprotozoal activity? What 3 protozoal diseases is it used to treat?
Decoquinate
- equine protozoal myelitis
- sarcocystis in dogs
- coccidiosis in chickens, turkeys, cattle, sheep, and goats
What is the mechanism of action of hydroxyquinolones? What is its absorption like in the intestinal tract?
Decoquinate - inhibit coccidial respiration by interfering with cytochrome-mediated electron transport in the parasite mitochondria
poorly absorbed
What 2 diamidine derivatives have antiprotozoal activity? What is their mechanism of action? What do they tend to do?
- Diminazene diaceturate
- Imidocarb dipropianate
bind to DNA and interfere with parasite replication
accumulate in tissues
What diamidine derivatives are used to treat babesiosis and trypanosomiasis?
BABESIOSIS - Diminazene diaceturate (horses, cattle); Imidocarb dipropianate (dogs, cats)
TRYPANOSOMIASIS - Diminazene diaceturate (cattle)
What protozoal disease are tetracyclines used to treat? What 3 are most commonly used?
Babesiosis
- Doxycycline (+ enrofloxacin or metronidazole) - dogs
- Chlortetracycline - horses
- Oxytetracycline - cattle
What is the mechanism of action of tetracyclines?
bind to 30S ribosomal unit to interfere with protein synthesis in growing and multiplying organisms
What thiamine analog has antiprotozoal activity? What is it commonly used to treat? What is its mechanism of action?
Amprolium (Corid, Amprol) - coccidiosis in chickens, turkeys, cattle, dogs, and cats
competitively inhibits active thiamine transport into the parasute
What is Amprolium approved for use? What is it structurall related to? What can prolonged high doses cause in the host?
preventative against and treatment for coccidiosis in growing chickens, turkeys, and laying hens
vitamin B1 (thiamine)
thiamine deficiency
What 3 triazine derivates have antiprotozoal activity? What are they used to treat?
- Diclazuril
- Ponazuril
- Toltrazuril
- EPM: D, P
- COCCIDIOSIS: T and P in dogs and cats; D for chickens and turkeys
What is Diclazuril approved for use in? Not approved?
(triazine derivative) coccidiosis prevention
laying hens and turkeys
What is the mechanism of action of triazine derivatives?
(Diclazuril, Ponazuril, Toltrazuril)
act on and block the apicoplast (plastid) present in apicomplexan parasites thought to be responsible for amino acid biosynthesis
What are the 2 most common sulfonamides with antiprotozoal activity? What are they used to treat? What is their mechanism of action?
- Suldadimethoxine** - dogs and cats
- Sulfamethazine - chickens, turkeys, cattle
coccidiosis
interfere with the early phases of folate (folic acid) synthesis
What are sulfonamides commonly combined with? In what animals should they not be administered?
DHFR/TS inhibitors
Sulfamethazine should not be administered to animals producing eggs
What polyether ionophore has antiprotozoal activity? What is its mechanism of action?
Monensin - chickens, turkeys, goats, cattle
facilitates the transport of Na+ and H+ into cells by forming lipophilic complexes with alkali metal cations to alter membrane integrity
What is the most common use of Monensin? How is it used in goats? Cattle?
fed for prevention of coccidiosis in broilers and turkeys
prevents coccidiosis in goats, but it not given to those producing milk for human consumption
can be given with no withdrawal time
What guanidine derivative has antiprotozoal activity? What is its mechanism of action? What is its most common use?
Robenidine
prevents the formation of merozoites in E. tenella
prevents coccidiosis in chickens
Why is a withdrawal time necessary for Robenidine in chicken? When should it not be given to chickens?
flesh will have an unpleasant taste —> no toxicity to humans
laying hens
Trichomoniasis treatment in cats and cattle:
Trypanosomiasis treatment in dogs and cattle:
Giardiasis treatment in dogs, cats, horses, and cattle:
Babesiosis treatment in dogs, cats, horses, and cattle:
Neosporosis and Toxoplasmosis treatment in dogs and cats:
Cryptosporidiosis treatment in dogs, cats, cattle, and goats:
Leishmaniasis and Sarcocystis treatment in dogs:
Equine protozoal myelitis treatment:
Coccidiosis treatment in dogs and cats:
Coccidiosis treatment in food animals:
