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General Pharmacology 2 > Antiprotozoal Drugs > Flashcards

Antiprotozoal Drugs Flashcards

1
Q

Nitroimidazoles

A
  • Drugs included:
    • metronidazole, tinidazole, ronidazole
  • Indications:
    • metronidazole (FLAGYL) is effective agianst the following anaerobic protozoa:
      • Trichomonas, Giardia, Entamoeba, Balantidium
    • Also affect intestinal microflora
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2
Q

Nitroimidazoles:
Pharmacodynamics:

A
  • MOA: intermediates acting on proteins and on DNA
    • drug entry into the protozoan cell → reductive activation → toxic effect of reduced intermediates → release of inactive end products
    • Effect is due to short-lived intermediates or free radicals that damage proteins and DNA
      • loss of helical structure and stand breakage
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3
Q

Nitroimidazoles:

Pharmacokinetics

A
  • metronidazole:
    • well absorbed form the gastrointestinal tract, has low protein binding, and is well distributed in the body
  • Extensively metabolized in the liver
    • half-life of about 6-8 hours
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4
Q

Nitroimidazoles:

Safety / Toxicity

A
  • Usually well tolerated
  • Toxicity reactions include glossitis, stomatitis, vomiting and neurotoxicosis
  • Drug interactions:
    • Cimetide: increases metronidazole toxicity
    • Phenobarbital: reduces metronidazole efficacy

Suspected mutagens and carcinogens

Therefore, their use in food producing animals has been stricly prohibited by the US FDA

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5
Q

Nitroimidazoles:

Usage of Metronidazole

A
  • Dogs:
    • Giardiasis: BID X 5days
  • Cats:
    • Giardiasis: BID X 5-7 days
  • Metronidazole is notoriously unpalatable
    • after taste may be accompanied by a loss of appetite
  • An ester known as benzoylmetronidazole
    • not approved by the FDA
    • Available from compounding pharmacists and has been popular for use in cats
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6
Q

Nitroimidazoles:

Usage of Ronidazole

A

Kennel situation (dogs): BID X 7days

Ronidazole - available from compouding pharmacies

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7
Q

Benzimidazoles:

Anti-protozoal effects

A
  • Drugs included:
    • fenbendazole, febantel, albendazole
  • Indications:
    • Giardiasis
  • Unlikely to interfere with intestinal microflora during treatment
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8
Q

Benimidazoles:

Anit-protozoal effects:

Pharmacodynamics

A
  • MOA:
    • inhibition of microtubule polymerization
  • Bind to B-tubulin subunits of microtubules
  • Giardia trophozoites have microtubules internally and in adhesive disk
  • BZs interfere with microtubule polymerization and cause cytoskeletal changes
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9
Q

Benzimidazoles:

Anit-protozoal Effects:

Usage of Albendazole

A
  • Dogs:
    • exremely effective agianst giardia
    • BID X 4 doses
    • NOT RECOMMENDED
  • Albendazole: potentially teratogenic so it should be given to pregnant animals
  • Myelosuppression
  • Aplastic anemai in dogs and cats
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10
Q

Benzimidazoles:

Anti-protozoal:

Usage for Fenbendazole

A
  • Daily for 3 day min
  • Safer
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11
Q

Benzimidazoles:

Anti-protozoal effects:

Usage for fenbantel

A
  • Canine Diardiasis:
    • product for 3 days with successful clearance of cysts from most dogs
  • Cats have also been successfully treated with a combination of febantel, pyrantel, and praziquantel for 5 days
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12
Q

Anti-coccidials

A

Amprolium (thiamine analogues)

Decoquinate, Atovaquone (Quinolones)

Lasalocid, Monensin, Narsin, Semduramicin, Salinomycin (ionophores)

Anti-coccidials for poultry

Diclazuril, ponazuril

Sulfonamides

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13
Q

Amprolium

A
  • Drug class:
    • thiamine analogues
  • Indications:
    • more effective as a preventitive than as a treatment
    • Labeled for cattle and poultry for the treatment and prevention of coccidiosis
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14
Q

Amprolium:

Pharmacodynamics

A
  • MOA:
    • Competitive inhibitor of thiamine transport
  • Structurally related to vitamin B1
  • Competitive inhibition of active thiamine transport into the parasite
  • 50-fold greater sensitivity of hte parasite system compared with the host system
  • Acts on the first-generation schizont to prevent merozoite production
  • Has some activity against sexual stages ans the sporulating oocyst
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15
Q

Amprolium:

Pharmacokinetics

A
  • Long-term or high-dose administration:
    • clinical thiamine deficiency in treated animals
    • Resulting in cerebrocortical necrosis
      • stopping treatment and administering thiamine may restore health while negating the coccidiostatic effect of amprolium
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16
Q

Amprolium:

Usage

A
  • Oral:
    • calves and poultry for Eimeria spp.
  • Poultry:
    • given in the water for 3-5 days or up to 2 weeks
  • It can be fed for a few says or continuously at a concentration range
  • Cattle:
    • treatment of coccidiosis, administration of amprolium for 5-21 days
    • prevention of coccidiosis caused by coccidia, E. bovis, E. zuernii, Dosage 21 days
  • Extralabel in dogs, swine, sheep, goats for the control of coccidiosis
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17
Q

Decoquinate, Atovaquone

A
  • Drug class:
    • quinolones
  • Indication:
    • Decoquinate:
      • for prevention rather than treatment of coccidiosis
    • Atovaquone:
      • blood apicomplexans
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18
Q

Decoquinate, Atovaquone:

Pharmacodynamics

A
  • MOA:
    • inhibitor of parasite respiration
  • Inhibit coccidial respiration by interfering with cytochrome-mediated electron transport in the parasites mitochondria
  • Coccidiostatic and allow penetration of sporozoites but not development
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19
Q

Usage of decoquinate

A
  • Medicated feed supplement for cattle, as a medicated powder to add to milk for calves, and as a medicated milk replacer for young goats
  • Dog:
    • to prevent clinical relapses of Hepatozoon americanum in dogs
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20
Q

Usage of atovaquone

A
  • Dogs:
    • B. gibsoni
  • Babesia conradae:
    • removes clinical signs and clears the agent form the blood of infected dogs
  • Cats:
    • current treatment of choice for clinical cytauxzoonosis appears to be a 10 day course
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21
Q

Azithormycin:

A

Drug class: Macrolide

22
Q

Azithromycin:

Pharmacodynamics

A
  • Antibacterial MOA known
    • inhibition of protein synthesis by binding to the 50S ribosomal unit
  • Antiprotazoal MOA:
    • unknown
23
Q

Azithromycin:

Pharmacokinetics

A

azithromycin can accumulate within phagocytic cells

24
Q

Azithromycin:

Usage

A

Cats diagnosed with Cytauxzoon felis

Atovaquone administered concurrently with azithromycin

25
Q

Ionophores:

A
  • Drugs included:
    • lasalocid
    • Monensin
    • Narasin
    • Semduramicin
    • Salinomycin
  • Indication:
    • control of coccidia and improvement of feed efficiency
26
Q

Ionophores:

Pharmacodynamics

A
  • MOA:
    • Na+ ion transporter
    • Form a pore, by which ions can diffuse through the membrane of the parasite and down their concentration gratient
    • Alter membrane integrity and internal osmolarity
    • Develop membrane blebs and damage the parasites
    • Trophozoite stage is most susceptible to lasalocid
    • Act against extracellular sporozoites and merozoites
    • Cross-resistance between ionophores is common
27
Q

Ionophores:

Pharmacokinetics

A
  • Safety/toxicity
    • Lasalcoid:
      • least toxic of the ionophores
        • feeding undiluted or mixing errors may result in an excess lasalocid concentration which could be fatal to cattle an sheep.
      • Monensin:
        • will cause deaths in horses, and guinea fowl
        • Cardio-toxin for horses
28
Q

Ionophores:

Usage

A
  • Lasalocid is approved or use in cattle, sheep, rabbits, and poultry
    • products mixed into medicated feeds and is added to milk replacer
    • Pastured cattle
  • WARNING: DO NOT feed or horses
  • Rabbits:
    • approved for use in rabbits for the prevention of coccidiosis caused by Eimeria stiedae
29
Q

Ionophores in Poultry:

Lasalocid

A

approved in broilers, turkeys, and chukar partridges to prevent coccidiosis - in feed

30
Q

Ionophores in poultry:

Monensin

A

in poultry and trukeys - in feed

31
Q

Ionophores in poultry:

narasin

A
  • Labelled for prevention of coccidiosis in broiler chickens only - if feed
  • broilers only and should not be fed to other types of chickens
  • WARNING:
    • ingestion by adult turkeys, horses, and ponies may be fatal
32
Q

Ionophores in Poultry:

Semduramicin

A

Prevention of coccidiosis in broiler chickens only

Does not affect egg production

33
Q

Ionophores in poultry

Salinomycin

A

active against sporozoites and early and late asexual stages of chicken coccidia

Will cause deaths in horses, and adult turkeys that ingest feed containing it

Toxicity associated predominately with neurological signs, although elevations in muscle enzymes are often present

34
Q

Non-ionophores anti-coccideals in poultry:

clopidol

A

Active against the sporozoite stage, allowing host cell penetration but not parasite development

Broilers only - in feed; not laying hens

35
Q

Non-ionophore Anti-coccidials for poultry:

Robinidine

A
  • Active agianst the first generation schizont of eimeria tenella
  • Prevents fromation of merozoites
  • Broilers only - in feed
    • should not be given to laying hens as it is passed into the egg
36
Q

Non-ionophore anti-coccidials in poultry:

Nicarbazin

A

Prevents outbreaks of coccidiosis in chickens

Broilers only - in feed

Should not be given to laying hens

37
Q

Diclazuril, Ponazuril

A

Drug Class: Triazine Derivatives

Indications: EPM

38
Q

Diclazuril, Ponazuril

Pharmacodynamics

A

MOA: Inhibitor of apicoplast function

  • Act on the apicoplast
  • May inhibit biosynthesis of amino acids and fatty acids, assimilation of nitrate and sulfate, and starch storage
  • Mechanism against sarcocystis neurona is to inhibit merozoite production
39
Q

Diclazuril, ponazuril

Pharmacokinetics

A
  • Has the ability to enter the CNS and concentrations can be detected in CSF
40
Q

Diclazuril, Ponazuril

Usage

A
  • Horses:
    • FDA approved treatemnts for EPM
  • Poultry:
    • FDA-approved in the United states as a coccidiostat in broiler chickens and growing turkeys
  • Dogs and Cats:
    • off label use
41
Q

Sulfonamids and Diaminopyrimidines

A
  • Sulfonamide drugs include:
    • sulfadimethoxine, sulfaguanidine, sulfadiazine, sulfadoxine, sulfamethazine, sulfamethoxazole, sulfanitran, sulfaquinoxaline
  • Diaminopurimidine drugs:
    • trimethoprim, ormetoprim, pyrimethamine
  • Indications:
    • coccidiosis
    • primarily against the schizont stages of coccidia
42
Q

Sulfonamids and Diaminopyrimidines

Pharmacodynamics

Sulfonamide

A

MOA: inhibitor of folate synthesis

  • Structure similar to para-aminobebzoate, which is required by bacteria in the synthesis of folate
  • Sulfonamides interfere in the early phases of the folate synthesis pathway
  • Mammalian and avian cells use preformed folate and are therefore not affected by the sulfonamide treatments
43
Q

Sulfonamids and Diaminopyrimidines

Diaminopyrimidines

A

MOA: Potentiate the action of sulfa drugs by acting at another point of folate synthesis pathway

  • Sulfonamides often used in combination with dihydropyrimidines
  • Observed synergistic effects due to activity at two places in folate biosynthesis
44
Q

Sulfonamids and Diaminopyrimidines

Pharmacokinetics

A
  • Well absorbed from the GI tract and widely distributed in the body
  • High serum binding (long half life)
  • Sulfonamides tend to crystalized in urine
    • ensure adequate water intake
  • Important differences in solubility, duration of action, and activity against pathogens
45
Q

Sulfonamids and Diaminopyrimidines

usage

A
  • treatment of choice for small animal coccidia
  • Dogs and cats:
    • FDA approved for cystoisospora
  • Poultry:
    • sulfadimethoxine with ormetoprim
  • Horses:
    • sulfadiazine with pyrimethamine
  • Sulfadiazine with trimethropirm
46
Q

Clindamycin

A

Drug class: Lincosamides

Indications: Toxoplasmosis

47
Q

Clindamycin

Pharmacodynamics

A

MOA: inhibitor of protein synthesis

  • Acts by binding to 50S subunit of ribosome and blocking peptide bond formation during protein synthesis
48
Q

Clindamycin:

Pharmacokinetics

A

Well absorbed after oral administration and widely distributed

oral and parenteral formulations

49
Q

Clindamycin:

Usage

A

it is initially coccidiostatic but becomes coccidiocidal after a few days of treatment

Drug of choice in dogs and cats agianst clinical toxoplasmosis

WARNING:

In cats, give with water/food to prevent esophagitis and oesphageal trictures

GI upsets reported

50
Q

Imidocarb Dipropionate

A

Drug Class: Diamidine derivative

Spectrum: Piroplasmosis

One of the treatments for babesial infections

51
Q

Imidocarb dipropionate

Pharmacodynamics

A

MOA: affects DNA synthesis

  • Binds to DNA and interferes with parasite replication
  • Imodocarb may interfere with the efficacy of some babesial vaccines in certain species

General Pharmacology 2 (17 decks)

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