Antiprotozoals Flashcards
Albendazole
Origin: Non-sulfonamide; benzimidazole
MOA: causes structural changes to Giardia trophozoites, including damage to the adhesive disc and the internal microtubule cytoskeleton, but not to the flagella
Protozoal activity: 50x more effective against metronidazole for Giardia
Formulations: suspension and paste for dogs, humans, mice, cattle
Adverse effects: aplastic anemia in dogs, cats, humans, do not use in pregnant animals
Examples: Valbenzen
Amprolium
Origin: Non-sulfonamide
MOA: Coccidiostatic, mimics thiamine and competes for absorption of thiamine by the parasite.
Protozoal activity: Most effective against the 1st gen schizont phase
Formulations: Cattle and poultry for Eimeria; Extralbel for dogs, sheep, swine, and goats for coccidiosis
Adverse effects: Polioenchephalomalacia in sheep, neurological signs in dogs
Fun fact: Can reverse the anti-protozoal effect by feeding excess thiamine
Clindamycin
Origin: lincosamide antibiotic
MOA: Clindamycin is metabolized in the liver and excreted primarily in the urine and bile. It acts by binding to the 50S subunit of the bacterial (or parasitic) ribosome and blocking peptide bond formation
Protozoal activity: Drug of choice for toxoplasmosis
Formulations: Capsule, tablets, oral suspension, and injectable
Adverse effects: GI upset, esophageal stricture from dry pilling
Clopidol
Origin: Pyridinol coccidiostat
MOA: Inhibits cytochome c respiration with no-cross resistance
Protozoal activity: acts against the sporocyst stage, allowing host cell penetration without parasite development
Formulations: Feed additive for chicken with Eimeria; Aid in the prevention of Leucocytozoon smithi in turkeys
Decoquinate
Origin: quinolone product
MOA: coccidiostat (prevention), inhibits the cytochrome c respiration (electron transport)
Protozoal activity: kills the sporozoite stage
Formulations: On-label feed additive for cattle and medicated milk replacer for goats and calves. Extra-label for adult sheep and goats, prevent relapses of Hepatozoon americanum
Adverse effects: Should not be fed to laying or breeding animals or lactating animals
Diclazuril
Origin: Triazine class antiprotozoal
MOA: targets the apicoplast (plastid body), and organelle present in the members of the Apicomplexa, mechanism poorly understood
Protozoal activity: Coccidiostat in broilers (chickens and turkeys); EPM in horses
Formulations: Medicated feed-in chickens; medicated pellets in horses
Adverse effects: Do not use in breeding turkeys. Extra-label in lambs, calves, and dogs
Examples: Clinacox, Protazil
Fenbendazole
Origin: Benzimidazole
MOA: Inhibits microtubule polymerization
Protozoal activity: Extralabel in the USA for treatment of Giardia
Formulations: paste, powder, granules
Adverse effects: Safe during pregnancy for most animals except rabbits
Examples:
Imidocarb
Origin: aromatic diamidine antiprotozoal
MOA: binds to DNA to interfere with parasite replication
Protozoal activity: Extralabel for Hepatozoon, Cytauxzoon, Equine piroplasmosis, Cattle Babesia
Formulations: SQ, IM
Adverse effects: oncogenic in rats; parasympathetic, cholinergic signs; overdose targets liver and intestines. IV injection is fatal
Examples: Imizol
Lasalocid
Origin: Ionophore
MOA: forms complexes with sodium and K+ ions. This renders the parasite membranes permeable to ions, and mitochondrial function is inhibited
Protozoal activity: targets trophozoite stages
Formulations: Mediated feeds and milk additive for cattle, rabbits, broilers, turkeys, chukars, sheep for control of coccidiosis
Adverse effects: May kill horses
Examples: Avatec, Bovatec, ProBac-C
Metronidazole
Origin: Nitroimididazole antibiotic
MOA: interacts with the protozoal DNA, in which causes loss of helical structure and strand breakage (damages DNA)
Protozoal activity: Always used off-label in animals. Broad-spectrum against Giardia, Tritrichomonads, Entamoeba (trophs), Balantidium
Formulations:
Adverse effects: Do not use in food-producing animals; Neurologic signs in dogs
Examples: Flagyl
Monensin
Origin: Ionophore, produced from the fermentation product of Streptomyces cinnamoneisis
MOA: forms ionophores with sodium and potassium in the host and in the parasite. When the parasite mitochondrial membrane is affected, it is rendered permeable to potassium and sodium ions.
Protozoal activity: Cattle: feed additive for Eimeria prevention and control; Goats: Prevention of Eimeria as feed additive; Sheep: Not approved, though widely used; Poultry: feed additive for pullets and broilers; Bobwhite quail: prevention
Formulations: Feed additive
Adverse effects: Feeding to horses and guinea fowl is fatal; do not feed to veal calves
Examples: Rumensin
Narasin
Origin: Ionophone produced by Streptomyces aureofacens
MOA: disrupts Na/ K+ ion channels
Protozoal activity: Eimeria
Formulations: Broilers- Eimeria; Swine- not labeled for coccidiostat but for weight gain
Adverse effects: no withdrawal period; concurrent use with tiamulin may decrease the efficacy. Fatal in adult turkey, horses, and ponies
Examples: Monteban 45, Skysis
Nicarbazin
Origin: Synthetic coccidiostat
MOA: unknown
Protozoal activity: Eimeria in broilers (preventive)
Formulations: Feed additive
Adverse effects: Not used in laying hens because it interferes with egg production
Examples: Nicarb 25%
Nicarbazin and narasin
Approved in the USA
Protozoal activity: Eimeria in broiler chickens only
Formulations: Fed additive
Adverse effects: Not in hot weather or within 5 days of slaughter
Examples: Maxiban 72
Ponazuril (toltrazuril sulfone)
Origin: triazine class of antiprotozoal
MOA: targets the apicoplast (plastid body), and organelle present in the members of the phylum Apicomplexa, mechanism unknown
Protozoal activity: Labelled for treatment if EPM in horses; Extra label- prevention of EPM; Coccidostat in kittens; Neosporis and toxoplasmosis in dogs; Cattel with Neosporosis; Coccidiosis in beared dragons, camelids, and rabbit; respiratory cryptosporidium in falcons
Formulations: Oral paste
Examples: Marquis
