Antifungals, Antiprotozoals, Antivirals, Paraciticides Flashcards
What are the mechanisms of action of the antifungal agents?
- Amphotericin B binds ergosterol to form pores
- Azoles inhibit ergosterol synthesis
- Griseofulvin and Fenbendazole bind microtubules to inhibit mitosis
What are the mechanisms of action of the antiprotozoal agents?
- Folate acid synthesis inhibitors: Blocks successive steps in folate synthesis of protozoa needed for protein/NA metabolism
- Metronidazole: reduced metabolite causes breakage of DNA
- Clindimycin: binds 50s ribosome to disrupt protein synthesis
- Amprolium: Thiamine analog
- Ponazuril: Activity against important organelles
- Nitazoxanide: Interferes with pyruvate:ferrodoxin oxidoreductase enzyme (PFOR) essential for anaerobic energy reactions (same pathway that metronidazole requires)
What are the mechanisms of action of the antiviral agents?
- AZT: inhibits reverse transcriptase
- Purine nucleoside analogs: Analogue of guanosine- inhibits viral DNA polymerase
- L-lysine: competes with arginine, herpesvirus needs to make proteins
What are the most important side effects of the antifungal agents?
- Amphotericin B- Very Nephrotoxic, acute anaphylactic reactions
- Azoles- GI (mild) and rare hepatotoxicity
- Griseofulvin- Common, Cats most serious side effects: neutropenia,
anemia, neurotoxicosis - Fenbendazole- OFF LABEL use for dermatophytes in LA
What are the most important side effects of the antiprotozoal agents?
- Folic Acid Synthesis Inhibitors: Bone marrow suppression, Keratoconjunctivitis sicca, teratogenic
- Metronidazole: Carcinogenic/mutagenic! BANNED FOOD ANIMALS!
- Clindimycin: DO NOT USE IN HORSES,RUMINANTS, RODENTS,
LAGOMORPHS- Serious GI side effects that can cause death - Amprolium: Thiamine deficiency Polioencephalomalacia high doses
- Ponazuril: Few
- Nitazoxanide: disrupts normal GI flora, some deaths caused by
enterocolitis reported, laminitis
What are the most important side effects of the antiviral agents?
AZT:cats–anemia
What are the distinguishing differences in the pharmacokinetics of the antifungal agents?
- Amphotericin B not water soluble- IV or topical only
- Azoles- oral or topical
- Griseofulvin accumulates in keratin (skin, nails, etc), need to administer for extended lengths for effect
What are the spectrum of activity of the anti fungals?
Amphotericin B is most effective against all EXCEPT ringoworm (dermatophytes), Azoles have wide spectrum, Griseofulvin DERMATOPHYTES ONLY, Fenbendazole OFF LABEL for dermatophytes in Large Animals
What are the major indications for use for the anti-protozoal agents?
- Folic acid inhibitors: aerobic organisms
- Metronidazole: anaerobic only, Entamoeba, Trichomonas, Giardia
- Clindimycin: Toxoplasmosis
- Amprolium: Coccidiosis in food animals
- Ponazuril: Sarcocystis neurona horses (EPM), off label SA coccidiosis
- Nitazoxanide: EPM in horses
What are the indications for use of antivirals?
- AZT: retroviruses (FIV, FeLV)
- Purine analogs: Herpesviruses
- L-lysine: cats with Herpes conjunctivitis
Which antiviral agent is not a drug?
L-lysine is a nutritional supplement
What drug should you use to treat a nematode infection?
Fenbendazole (Benzimidazole), Pyrantel (nicotinic anthelmintic), Ivermectin (Macrocyclic Lactone)
What drug should you use to treat a trematode infection?
Fenbendazole (Benzimidazole)
What drug should you use to treat a cestode infection?
Praziaquantel (Isoquinolone)
What drug should you use to treat a flea infestation?
Permethrin (Synthetic pyrethroids), Fluralaner (Isoxazolines)
