Antiviral Drugs: Acyclovir
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Questions and Answers

What type of interferon is Interferon-ω (omega) closely related to?

  • Beta interferon
  • Alpha interferon (correct)
  • Delta interferon
  • Gamma interferon

    • What is the mechanism of action of Interferon-ω (omega)?

  • Inhibiting the activity of neuraminidase
  • Inhibiting mRNA synthesis and translation proteins (correct)
  • Stimulating the immune system
  • Enhancing the replication of viruses

    • What is Oseltamivir phosphate converted to by hepatic esterases?

  • Oseltamivir phosphate
  • Oseltamivir sulfate
  • Oseltamivir hydrochloride
  • Oseltamivir carboxylate (correct)

    • What is the mechanism of action of Oseltamivir?

    <p>Competitive inhibition of the enzyme neuraminidase</p> Signup and view all the answers

    What is the effect of Zidovudine (AZT) on viral DNA synthesis?

    <p>Inhibition of viral DNA synthesis</p> Signup and view all the answers

    What is the bioavailability of Zidovudine (AZT) in cats?

    <p>90%</p> Signup and view all the answers

    What is the half-life of Zidovudine (AZT) in cats?

    <p>1.5 hours</p> Signup and view all the answers

    What is a potential adverse effect of Zidovudine (AZT)?

    <p>All of the above</p> Signup and view all the answers

    What is the drug interaction between Zidovudine (AZT) and Doxorubicin?

    <p>Antagonism</p> Signup and view all the answers

    What is the mechanism of action of Trifluorothymidine (TFT)?

    <p>Inhibiting the replication of viral DNA</p> Signup and view all the answers

    What is the mechanism of action of acyclovir?

    <p>It inhibits viral DNA polymerase</p> Signup and view all the answers

    What is the primary use of amantadine in veterinary medicine?

    <p>Adjunct treatment to chronic pain in dogs and cats</p> Signup and view all the answers

    What is the contraindication for amantadine in patients with?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of famciclovir?

    <p>It competes with deoxyguanosine triphosphate to inhibit herpes viral DNA synthesis</p> Signup and view all the answers

    What is the adverse effect of acyclovir in cats?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of interferons?

    <p>They increase transcription of host cell DNA and activate endonuclease in cells</p> Signup and view all the answers

    What is the use of interferon alfa-2a in veterinary medicine?

    <p>For treatment of non-neoplastic Feline Leukemia (FeLV) disease</p> Signup and view all the answers

    What is the adverse effect of interferon alfa-2a in cats?

    <p>Malaise and general discomfort</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of amantadine?

    <p>It has a variable absorption of 40-60%</p> Signup and view all the answers

    What is the contraindication for famciclovir?

    <p>All of the above</p> Signup and view all the answers

    What is the therapeutic use of acyclovir in veterinary medicine?

    <p>Treatment of Pacheco's parrot disease</p> Signup and view all the answers

    What is a contraindication for the use of amantadine?

    <p>Hypersensitivity to amantadine</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of amantadine in horses?

    <p>Variable absorption with a bioavailability of 40-60%</p> Signup and view all the answers

    What is the mechanism of action of famciclovir?

    <p>Inhibition of viral DNA polymerase</p> Signup and view all the answers

    What is the therapeutic use of interferon alfa-2a in veterinary medicine?

    <p>Treatment of non-neoplastic feline leukemia virus</p> Signup and view all the answers

    What is a contraindication for the use of famciclovir?

    <p>Hypersensitivity to famciclovir</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of acyclovir?

    <p>Wide distribution throughout body tissues and fluids</p> Signup and view all the answers

    What is the mechanism of action of amantadine?

    <p>Inhibition of viral uncoating through binding to M2 protein</p> Signup and view all the answers

    What is the adverse effect of amantadine in dogs?

    <p>Agitation</p> Signup and view all the answers

    What is the therapeutic use of amantadine in veterinary medicine?

    <p>Adjunct treatment of chronic pain</p> Signup and view all the answers

    What is the therapeutic use of Interferon-ω (omega) in cats?

    <p>Treating feline viral infections, including calici virus and FIV</p> Signup and view all the answers

    What is the contraindication for Oseltamivir phosphate in veterinary medicine?

    <p>Extralabel use in poultry due to the fear of resistance development</p> Signup and view all the answers

    What is the mechanism of action of Zidovudine (AZT)?

    <p>Competing with host thymidine to inhibit viral DNA synthesis</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Zidovudine (AZT) in cats?

    <p>It is widely distributed, including the CSF</p> Signup and view all the answers

    What is the therapeutic use of Oseltamivir phosphate in veterinary medicine?

    <p>Treating mixed bacterial and viral infections</p> Signup and view all the answers

    What is the potential adverse effect of Zidovudine (AZT) in cats?

    <p>Anemia and reduction in hemoglobin</p> Signup and view all the answers

    What is the mechanism of action of Trifluorothymidine (TFT)?

    <p>Having a higher affinity for viral DNA than mammalian DNA</p> Signup and view all the answers

    What is the potential drug interaction between Zidovudine (AZT) and Interferon alfa?

    <p>Increased risk of hematologic and hepatotoxicity</p> Signup and view all the answers

    What is the contraindication for Zidovudine (AZT) in cats?

    <p>Use in cats with bone marrow, renal, or hepatic dysfunction</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Oseltamivir phosphate?

    <p>It is converted to its active metabolite by hepatic esterases</p> Signup and view all the answers

    What is the primary therapeutic use of Interferon-ω (omega) in cats?

    <p>Treating feline viral infections, including calici virus and FIV</p> Signup and view all the answers

    What is a common adverse effect of Zidovudine (AZT) in cats?

    <p>Anemia and reduction in hemoglobin</p> Signup and view all the answers

    What is a contraindication for the use of Oseltamivir phosphate in veterinary medicine?

    <p>Extralabel drug use in poultry</p> Signup and view all the answers

    What is the mechanism of action of Oseltamivir phosphate?

    <p>Competitive inhibition of the enzyme neuraminidase</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Zidovudine (AZT) in cats?

    <p>90% bioavailability and wide distribution</p> Signup and view all the answers

    What is the therapeutic use of Trifluorothymidine (TFT) in veterinary medicine?

    <p>Treating feline viral infections, including herpesvirus and poxvirus</p> Signup and view all the answers

    What is a potential adverse effect of Interferon-ω (omega) in cats?

    <p>Hyperthermia and vomiting</p> Signup and view all the answers

    What is the mechanism of action of Zidovudine (AZT) in cats?

    <p>Phosphorylation of host cell enzymes, leading to the termination of viral DNA synthesis</p> Signup and view all the answers

    What is a contraindication for the use of Zidovudine (AZT) in cats?

    <p>Bone marrow, renal, or hepatic dysfunction</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Oseltamivir phosphate?

    <p>Converted to active metabolite by hepatic esterases</p> Signup and view all the answers

    What is the primary therapeutic use of amantadine in veterinary medicine?

    <p>Adjunct treatment to chronic pain in dogs and cats</p> Signup and view all the answers

    What is a potential adverse effect of acyclovir in cats?

    <p>Leukopenia</p> Signup and view all the answers

    What is a contraindication for the use of amantadine in veterinary medicine?

    <p>Patients with untreated angle-closure glaucoma</p> Signup and view all the answers

    What is the mechanism of action of famciclovir?

    <p>Inhibiting viral DNA polymerase</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of acyclovir?

    <p>Widely distributed throughout body tissues and fluids</p> Signup and view all the answers

    What is a potential adverse effect of interferon alfa-2a in cats?

    <p>Malaise and general discomfort</p> Signup and view all the answers

    What is the therapeutic use of famciclovir in veterinary medicine?

    <p>Treatment of feline herpes virus</p> Signup and view all the answers

    What is a contraindication for the use of famciclovir in veterinary medicine?

    <p>Hypersensitivity to famciclovir</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of amantadine in horses?

    <p>Not described in horses</p> Signup and view all the answers

    What is the mechanism of action of acyclovir?

    <p>Inhibiting viral DNA polymerase</p> Signup and view all the answers

    What is the primary mechanism of action of Amphotericin B?

    <p>Binding to ergosterol in the fungal membrane to form pores</p> Signup and view all the answers

    What is the primary indication for the use of Itraconazole?

    <p>Systemic mycoses such as Aspergillosis, Blastomycosis, and Histoplasmosis</p> Signup and view all the answers

    What is a common adverse effect of Amphotericin B?

    <p>Renal toxicity</p> Signup and view all the answers

    What is the primary mechanism of action of Polyene macrolides?

    <p>Binding to ergosterol in the fungal membrane</p> Signup and view all the answers

    What is the primary indication for the use of Nystatin?

    <p>Candidiasis infecting the skin, mucous membranes, and intestinal tract</p> Signup and view all the answers

    What is a common use of Natamycin?

    <p>Treating ophthalmic fungal infections</p> Signup and view all the answers

    What is the primary mechanism of action of Fluconazole?

    <p>Inhibiting fungal cytochrome P450 enzymes</p> Signup and view all the answers

    What is a common adverse effect of Itraconazole?

    <p>Anorexia</p> Signup and view all the answers

    What is the primary indication for the use of Amphotericin B?

    <p>Systemic mycoses such as Aspergillosis, Blastomycosis, and Histoplasmosis</p> Signup and view all the answers

    What is the primary mechanism of action of Polyene macrolides?

    <p>Binding to ergosterol in the fungal membrane</p> Signup and view all the answers

    What is the primary difference between ketoconazole and fluconazole?

    <p>Fluconazole is water soluble, while ketoconazole is not</p> Signup and view all the answers

    What is the mechanism of action of fluconazole?

    <p>It alters the cell membrane, leading to leakage of cellular contents</p> Signup and view all the answers

    What is a common adverse effect of ketoconazole?

    <p>Anorexia, vomiting, and diarrhea</p> Signup and view all the answers

    What is the primary therapeutic use of miconazole?

    <p>Fungal infections caused by Microsporum canis, Microsporum gypseum, and Trichophyton mentagraphytes</p> Signup and view all the answers

    What is a contraindication for the use of fluconazole?

    <p>All of the above</p> Signup and view all the answers

    What is the difference in the metabolism of ketoconazole and fluconazole?

    <p>Ketoconazole is metabolized in the liver and excreted in the bile, while fluconazole is metabolized in the kidney and excreted in the urine</p> Signup and view all the answers

    What is the primary therapeutic use of ketoconazole?

    <p>Hyperadrenocorticism in dogs and cats</p> Signup and view all the answers

    What is the primary advantage of fluconazole over ketoconazole?

    <p>Fluconazole is more water soluble, making it easier to administer</p> Signup and view all the answers

    What is the primary therapeutic use of miconazole in horses?

    <p>Fungal keratitis caused by Aspergillus sp.</p> Signup and view all the answers

    What is the effect of ketoconazole on adrenal or gonadal steroids?

    <p>It suppresses their production transiently</p> Signup and view all the answers

    What is the mechanism of action of Flucytosine?

    <p>Inhibiting thymidylate synthetase</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in dogs and cats?

    <p>Treating cryptococcosis, especially meningeal cryptococcosis</p> Signup and view all the answers

    What is the adverse effect of Flucytosine?

    <p>Gastrointestinal disturbances and bone marrow depression</p> Signup and view all the answers

    What is the mechanism of action of Terbinafine?

    <p>Inhibiting the conversion of squalene to sterols</p> Signup and view all the answers

    What is the therapeutic use of Terbinafine?

    <p>Treating dermatophytic infections in dogs and cats</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Flucytosine?

    <p>Well absorbed orally, widely distributed, and excreted unchanged in the urine</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in birds?

    <p>Treating systemic mycotic infections</p> Signup and view all the answers

    What is the mechanism of action of other antifungals?

    <p>Inhibiting the synthesis of ergosterol</p> Signup and view all the answers

    What is the therapeutic use of Terbinafine in birds?

    <p>Treating systemic mycotic infections</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Terbinafine?

    <p>Lipophilic, well tolerated by animals, and pharmacokinetics are not well established</p> Signup and view all the answers

    What is the mechanism of action of Griseofulvin?

    <p>Binding to microtubules and inhibiting spindle formation and mitosis</p> Signup and view all the answers

    Which of the following is a characteristic of Griseofulvin?

    <p>High oral absorption, especially with high-fat foods</p> Signup and view all the answers

    What is the effect of Griseofulvin on infected cells?

    <p>It causes the infected cells to shed and be replaced with uninfected cells</p> Signup and view all the answers

    Which of the following is a type of Azole antifungal drug?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of Azole antifungal drugs?

    <p>Altering cell membrane permeability of susceptible yeasts and fungi</p> Signup and view all the answers

    What is the effect of Ketoconazole on mammalian steroid synthesis?

    <p>It inhibits mammalian steroid synthesis</p> Signup and view all the answers

    What is the mechanism of action of Ketoconazole?

    <p>Inhibiting the synthesis of ergosterol by blocking cytochrome P-450 enzymes</p> Signup and view all the answers

    Which of the following is a characteristic of Ketoconazole?

    <p>It is well absorbed orally</p> Signup and view all the answers

    What is the use of Ketoconazole?

    <p>It is used both topically and orally for various infections</p> Signup and view all the answers

    What is a potential adverse effect of Ketoconazole?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of Flucytosine?

    <p>Inhibits DNA and RNA synthesis in susceptible fungi</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in dogs and cats?

    <p>Combines with amphotericin B to treat cryptococcosis</p> Signup and view all the answers

    What is the adverse effect of Flucytosine?

    <p>Mild gastrointestinal disturbances</p> Signup and view all the answers

    What is the mechanism of action of Terbinafine?

    <p>Inhibits the synthesis of ergosterol by blocking the enzyme squalene monooxygenase</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Terbinafine?

    <p>Lipophilic</p> Signup and view all the answers

    What is the therapeutic use of Terbinafine in animals?

    <p>Treats dermatophytic infections in dogs and cats</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in psittacine birds?

    <p>Treats aspergillosis</p> Signup and view all the answers

    What is the mechanism of action of amphotericin B?

    <p>Forms pores in fungal cell membranes</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in combination with amphotericin B?

    <p>Treats cryptococcosis, especially meningeal cryptococcosis</p> Signup and view all the answers

    What is the therapeutic use of Terbinafine in birds?

    <p>Treats systemic mycotic infections</p> Signup and view all the answers

    Which of the following antifungal drugs is water soluble?

    <p>Fluconazole</p> Signup and view all the answers

    What is the primary indication for Ketoconazole?

    <p>Systemic mycoses and severe yeast infections</p> Signup and view all the answers

    Which of the following antifungal drugs is contraindicated in patients with hepatic diseases?

    <p>Fluconazole</p> Signup and view all the answers

    What is the mechanism of action of Fluconazole?

    <p>Inhibiting the uptake of purine and pyrimidine precursors</p> Signup and view all the answers

    Which of the following antifungal drugs is used to treat fungal keratitis in horses?

    <p>Miconazole</p> Signup and view all the answers

    What is the route of excretion for Ketoconazole?

    <p>Bile</p> Signup and view all the answers

    Which of the following antifungal drugs is effective against Microsporum canis?

    <p>Miconazole</p> Signup and view all the answers

    What is a common adverse effect of Ketoconazole?

    <p>All of the above</p> Signup and view all the answers

    Which of the following antifungal drugs is used to treat systemic mycoses?

    <p>Fluconazole</p> Signup and view all the answers

    What is a contraindication for the use of Fluconazole?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of Amphotericin B?

    <p>Binds to ergosterol of fungal membrane, forming pores or channels which results in leakage of cellular contents</p> Signup and view all the answers

    What is the main use of Nystatin?

    <p>Candidiasis infecting the skin, mucous membranes and intestinal tract of small animals and birds</p> Signup and view all the answers

    What is the adverse effect of Amphotericin B?

    <p>Renal toxicity</p> Signup and view all the answers

    What is the fungicidal or fungistatic activity of Flucytosine?

    <p>Fungicidal against Cryptococcus, Candida, and Aspergillus spp.</p> Signup and view all the answers

    What is the indication for Natamycin?

    <p>Fungal keratomycosis in horses</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Amphotericin B?

    <p>Not absorbed in the GIT</p> Signup and view all the answers

    What is the combination therapy with Amphotericin B?

    <p>Ketoconazole, fluconazole, and itraconazole</p> Signup and view all the answers

    What is the mechanism of action of Flucytosine?

    <p>Converts to 5-fluorouracil, which inhibits thymidylate synthase</p> Signup and view all the answers

    What is the indication for Nystatin?

    <p>Candidiasis infecting the skin, mucous membranes and intestinal tract of small animals and birds</p> Signup and view all the answers

    What is the adverse effect of Flucytosine?

    <p>Rare, but not specified</p> Signup and view all the answers

    Which type of microorganisms is fungi classified as?

    <p>Eukaryotic, saprophytic, parasitic</p> Signup and view all the answers

    What is the mechanism of action of Griseofulvin?

    <p>Binds to microtubules and inhibits spindle formation and mitosis</p> Signup and view all the answers

    What is the effect of Griseofulvin on infected cells?

    <p>Infected cells shed and are replaced with uninfected cells</p> Signup and view all the answers

    How is Griseofulvin administered?

    <p>PO, for dogs, cats, and horses</p> Signup and view all the answers

    What is a rare adverse effect of Griseofulvin in kittens?

    <p>Anemia and Leukopenia</p> Signup and view all the answers

    What is the mechanism of action of Azoles?

    <p>Alters cell membrane permeability of susceptible yeasts and fungi</p> Signup and view all the answers

    Which of the following is a characteristic of Ketoconazole?

    <p>It is an Imidazole</p> Signup and view all the answers

    What is the mechanism of action of Ketoconazole?

    <p>Inhibits synthesis of ergosterol in fungal cytoplasmic membranes</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Ketoconazole?

    <p>It is well absorbed orally</p> Signup and view all the answers

    What is the effect of high doses of Azoles on mammalian systems?

    <p>They inhibit mammalian steroid synthesis</p> Signup and view all the answers

    What is the mechanism of action of Griseofulvin?

    <p>Bind to microtubules and inhibit spindle formation and mitosis</p> Signup and view all the answers

    What type of fungi is Griseofulvin effective against?

    <p>Microsporum spp. and Trichophyton spp.</p> Signup and view all the answers

    What is the absorption of Griseofulvin affected by?

    <p>High-fat foods</p> Signup and view all the answers

    What is the mechanism of action of Azoles?

    <p>Alter cell membrane permeability and block synthesis of ergosterol</p> Signup and view all the answers

    What is the effect of high doses of Azoles?

    <p>Inhibition of mammalian steroid synthesis</p> Signup and view all the answers

    What is the mechanism of action of Ketoconazole?

    <p>Block synthesis of ergosterol by inhibiting cytochrome P-450 enzymes</p> Signup and view all the answers

    What is the administration route of Ketoconazole?

    <p>Oral</p> Signup and view all the answers

    What is the distribution of Griseofulvin?

    <p>Distributed to keratin precursor cells of the skin, hair shafts, and nails</p> Signup and view all the answers

    What is the metabolism of Griseofulvin?

    <p>Demethylation and glucuronide conjugation</p> Signup and view all the answers

    What is the excretion route of Griseofulvin?

    <p>Urine</p> Signup and view all the answers

    What is the unique property of fluconazole?

    <p>Water solubility</p> Signup and view all the answers

    What is ketoconazole used to treat in dogs and cats?

    <p>Hyperadrenocorticism</p> Signup and view all the answers

    What is the effect of fluconazole on fungal cells?

    <p>Alteration of cell membrane permeability</p> Signup and view all the answers

    What is miconazole effective against?

    <p>Fungal infections caused by Microsporum canis, Microsporum gypseum, and Trichophyton mentagraphytes</p> Signup and view all the answers

    What is a contraindication for fluconazole?

    <p>All of the above</p> Signup and view all the answers

    What is a common adverse effect of ketoconazole?

    <p>All of the above</p> Signup and view all the answers

    How is fluconazole excreted?

    <p>Through the kidneys</p> Signup and view all the answers

    What is miconazole used for in horses?

    <p>Fungal keratitis</p> Signup and view all the answers

    What is ketoconazole metabolized in?

    <p>Liver</p> Signup and view all the answers

    What can happen to patients with impaired renal function taking ketoconazole?

    <p>Extended half-life of the drug</p> Signup and view all the answers

    What is the primary mechanism of action of Flucytosine?

    <p>Inhibiting thymidylate synthetase</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in psittacine birds?

    <p>For treating aspergillosis and candidiasis</p> Signup and view all the answers

    What is the characteristic of Flucytosine in terms of toxicity?

    <p>Low toxicity</p> Signup and view all the answers

    What is the mechanism of action of Terbinafine?

    <p>Blocking the enzyme squalene monooxygenase</p> Signup and view all the answers

    What is the therapeutic use of Terbinafine in dogs and cats?

    <p>For treating dermatophytic infections</p> Signup and view all the answers

    What is the characteristic of Terbinafine in terms of its effect on dermatophytes?

    <p>Fungicidal</p> Signup and view all the answers

    What is the route of administration for Terbinafine?

    <p>Both orally and topically</p> Signup and view all the answers

    What is the pharmacokinetic characteristic of Terbinafine?

    <p>Lipophilic</p> Signup and view all the answers

    What is the therapeutic use of Flucytosine in combination with amphotericin B?

    <p>For treating cryptococcosis</p> Signup and view all the answers

    What is the effect of Flucytosine on the synthesis of DNA and RNA in susceptible fungi?

    <p>Inhibits the synthesis of DNA and RNA</p> Signup and view all the answers

    What is the mechanism of action of Amphotericin B?

    <p>It binds to ergosterol of fungal membrane, forming pores or channels which results in leakage of cellular contents.</p> Signup and view all the answers

    What is the primary use of Nystatin?

    <p>For fungal infections of the skin, mucous membranes, and intestinal tract of small animals and birds.</p> Signup and view all the answers

    What is the unique characteristic of Natamycin?

    <p>It is an ophthalmic preparation approved for treating fungal infections of the eye.</p> Signup and view all the answers

    What is the mechanism of action of Flucytosine?

    <p>It is a fluorinated pyrimidine that is converted to a toxic compound that inhibits fungal DNA synthesis.</p> Signup and view all the answers

    What is the common adverse effect of Amphotericin B?

    <p>Renal toxicity.</p> Signup and view all the answers

    What is the primary advantage of Itraconazole over Ketoconazole?

    <p>It has fewer side effects in small animals.</p> Signup and view all the answers

    What is the unique characteristic of Polyene macrolides?

    <p>They are poorly soluble in water.</p> Signup and view all the answers

    What is the primary indication for using Flucytosine in combination with Amphotericin B?

    <p>For treating fungal infections of the central nervous system.</p> Signup and view all the answers

    What is the unique characteristic of Nystatin?

    <p>It is used for treating fungal infections of the skin, mucous membranes, and intestinal tract.</p> Signup and view all the answers

    What is the primary advantage of using Amphotericin B in combination with other antifungals?

    <p>It reduces the toxicity of the treatment.</p> Signup and view all the answers

    Study Notes

    Antiviral Drugs

    Acyclovir

    • Guanosine derivative, selective for herpesviruses
    • Metabolized to monophosphate via thymidine kinase, then converted to triphosphate, which inhibits viral DNA polymerase
    • Widely distributed throughout body tissues and fluids, including the brain, semen, and CSF
    • Excreted by kidneys through glomerular filtration and tubular secretion
    • Used to treat ocular and respiratory infections of herpes virus 1 in cats, and active against equine herpes virus type-1 in vitro
    • Adverse effects: low WBC, leukopenia, anemia in cats, and necrosis at injection site in birds

    Amantadine

    • 1-aminoadamantane, binds to M2 protein and blocks its ion channel activity, inhibiting viral uncoating and replication
    • N-methyl-D-aspartate (NMDA) receptor antagonist, important in pain sensation
    • Used to treat influenza viruses, replicate within host cells, and M2 protein
    • Therapeutic use: adjunct treatment to chronic pain in dogs and cats, and treatment of equine-2 influenza via IV
    • Pharmacokinetics: variable absorption, bioavailability 40-60%, excretion renal, half-life ~3.5 hours
    • Adverse effects: agitation, loose stools, flatulence, diarrhea, contraindications: hypersensitivity, untreated angle-closure glaucoma, liver and renal diseases, CHF, active psychoses, eczematoid dermatitis, seizure disorders
    • Drug interactions: anticholinergics, CNS stimulants, urinary acidifiers, TMPS

    Famciclovir

    • Converted to penciclovir, which is phosphorylated to penciclovir monophosphate, then triphosphate, inhibiting herpes virus DNA polymerase
    • Used to treat feline herpes (FHV-1), and active against varicella zoster virus
    • Pharmacokinetics: cats require higher doses due to poor conversion to penciclovir
    • Contraindications: hypersensitivity, patients with renal problems
    • Adverse effects: not well documented, but well tolerated when used up to three weeks

    Interferons

    • Human recombinant IFN-α, feline recombinant IFN-ω
    • MOA: released by host cells in response to viral infection, attached to receptors on adjacent cells, increasing transcription of host cell DNA and activating endonuclease, increasing cell resistance to virus infection
    • Used to treat non-neoplastic Feline Leukemia (FeLV) disease, and oral administration for ocular herpes infection
    • Effects: antiviral, antiproliferative, immunomodulating, well distributed throughout the body except in CNS
    • Adverse effects: dose-related, malaise, fever, allergic reactions, myelotoxicity, myalgia, hyperthermia, vomiting, decrease RBCs, platelets, WBCs, increase ALT, soft feces, mild diarrhea, transient fatigue, anorexia, and weight loss

    Oseltamivir phosphate

    • Ester prodrug converted to its active metabolite, oseltamivir carboxylate, by hepatic esterases
    • Competitive inhibitor of the enzyme neuraminidase, used by influenza viruses for budding of replicative viral particles from infected cells
    • May be effective for parvovirus infections in dogs, and mixed bacterial/viral infections
    • Public health issues: prohibited by the FDA for extralabel drug use in poultry due to fear of resistance that avian influenza virus would develop against oseltamivir

    Zidovudine (AZT)

    • Analog of thymidine, phosphorylated by host cell enzymes to AZT 5-triphosphate, which competes with host 5-thymidine, essential for proviral DNA formation by reverse transcriptase of the virus
    • Antiretroviral agent, virustatic effect, converted to active metabolite- triphosphate, inhibiting viral RNA-directed DNA polymerase
    • Used to treat FIV, and as adjunct treatment for FeLV
    • Pharmacokinetics: well absorbed orally, 90% bioavailability in cats, widely distributed including the CSF, metabolized in liver by glucuronide conjugation, excreted in urine, t ½ = 1.5 hours
    • Adverse effects: anemia, reduction in hemoglobin, diarrhea, weakness, bone marrow, renal or hepatic dysfunction
    • Drug interactions: antifungals, azole, atovaquone, doxorubicin, interferon alfa, probenecid, rifampin, myelo-/cytotoxic drugs

    Other Antiviral Agents

    • Trifluorothymidine (TFT): thought to have higher affinity for viral DNA than mammalian, and is more potent
    • Idoxuridine: thymidine analogs active against DNA viruses, herpesvirus, and poxvirus

    Interferon-ω (Omega) / Cat Omega Interferon

    • Produced by genetic engineering, type 1 interferon closely related to alpha interferon
    • Half-life: 1-2 hours in dogs and cats
    • Mechanism of action: Acts on virus-infected cells by inhibiting mRNA synthesis and translation proteins, leading to inhibition of viral replication
    • Used to treat cat viral infections, including calici virus, FeLV, FIV, and others, as well as canine parvovirus
    • Adverse effects: Hyperthermia, vomiting, decrease in RBCs, platelets, and WBCs (myelotoxicity), increase in ALT, soft feces/mild diarrhea, transient fatigue, anorexia, and weight loss

    Oseltamivir Phosphate

    • Ester prodrug converted to active metabolite, oseltamivir carboxylate by hepatic esterases
    • Mechanism of action: Competitive inhibitor of the enzyme neuraminidase, which influenza viruses use for budding and release of viral particles
    • May be effective for parvovirus infections in dogs and other mixed bacterial/viral infections
    • Public health controversy: use in veterinary medicine may lead to resistance in avian influenza virus

    Zidovudine (AZT)

    • Analog of thymidine, phosphorylated by host cell enzymes to AZT 5-triphosphate, which competes with host 5-thymidine for proviral DNA formation by reverse transcriptase
    • Antiretroviral agent with virustatic effect, inhibiting viral RNA-directed DNA polymerase
    • Used to treat FIV, with clinical improvement seen 14 days after treatment
    • Pharmacokinetics: Well absorbed orally, widely distributed, metabolized in liver, and excreted in urine, with a half-life of 1.5 hours
    • Adverse effects: Non-regenerative anemia, diarrhea, and weakness

    Other Antiviral Agents

    • Trifluorothymidine (TFT): Thought to have higher affinity for viral DNA than mammalian DNA, making it more potent
    • Idoxuridine: Thymidine analog active against DNA viruses, including herpesvirus and poxvirus

    Acyclovir

    • Guanosine derivative selective for herpesviruses
    • Metabolized to monophosphate via thymidine kinase, then converted to triphosphate, which inhibits viral DNA polymerase
    • Used to treat ocular and respiratory infections of herpes virus 1 in cats
    • Adverse effects: Low WBC, leukopenia, and anemia in cats; necrosis at injection site in birds

    Amantadine

    • 1-aminoadamantane, binds to M2 protein, and blocks its ion channel activity, inhibiting viral uncoating and replication
    • Used as an adjunct treatment for chronic pain in dogs and cats, and for equine-2 influenza via IV
    • Pharmacokinetics: Not described in dogs and cats, but has variable absorption and bioavailability of 40-60% in horses
    • Adverse effects: Agitation, loose stools, flatulence, and diarrhea

    Famciclovir

    • For feline herpes (FHV-1), converted into penciclovir, which inhibits herpes virus DNA polymerase
    • Pharmacokinetics: Cats require higher doses due to poor conversion to penciclovir
    • Contraindication: Hypersensitivity
    • Adverse effects: Not well documented, but well-tolerated when used up to three weeks

    Interferon-ω (Omega) / Cat Omega Interferon

    • Produced by genetic engineering, type 1 interferon closely related to alpha interferon
    • Half-life: 1-2 hours in dogs and cats
    • Mechanism of action: Acts on virus-infected cells by inhibiting mRNA synthesis and translation proteins, leading to inhibition of viral replication
    • Used to treat cat viral infections, including calici virus, FeLV, FIV, and others, as well as canine parvovirus
    • Adverse effects: Hyperthermia, vomiting, decrease in RBCs, platelets, and WBCs (myelotoxicity), increase in ALT, soft feces/mild diarrhea, transient fatigue, anorexia, and weight loss

    Oseltamivir Phosphate

    • Ester prodrug converted to active metabolite, oseltamivir carboxylate by hepatic esterases
    • Mechanism of action: Competitive inhibitor of the enzyme neuraminidase, which influenza viruses use for budding and release of viral particles
    • May be effective for parvovirus infections in dogs and other mixed bacterial/viral infections
    • Public health controversy: use in veterinary medicine may lead to resistance in avian influenza virus

    Zidovudine (AZT)

    • Analog of thymidine, phosphorylated by host cell enzymes to AZT 5-triphosphate, which competes with host 5-thymidine for proviral DNA formation by reverse transcriptase
    • Antiretroviral agent with virustatic effect, inhibiting viral RNA-directed DNA polymerase
    • Used to treat FIV, with clinical improvement seen 14 days after treatment
    • Pharmacokinetics: Well absorbed orally, widely distributed, metabolized in liver, and excreted in urine, with a half-life of 1.5 hours
    • Adverse effects: Non-regenerative anemia, diarrhea, and weakness

    Other Antiviral Agents

    • Trifluorothymidine (TFT): Thought to have higher affinity for viral DNA than mammalian DNA, making it more potent
    • Idoxuridine: Thymidine analog active against DNA viruses, including herpesvirus and poxvirus

    Acyclovir

    • Guanosine derivative selective for herpesviruses
    • Metabolized to monophosphate via thymidine kinase, then converted to triphosphate, which inhibits viral DNA polymerase
    • Used to treat ocular and respiratory infections of herpes virus 1 in cats
    • Adverse effects: Low WBC, leukopenia, and anemia in cats; necrosis at injection site in birds

    Amantadine

    • 1-aminoadamantane, binds to M2 protein, and blocks its ion channel activity, inhibiting viral uncoating and replication
    • Used as an adjunct treatment for chronic pain in dogs and cats, and for equine-2 influenza via IV
    • Pharmacokinetics: Not described in dogs and cats, but has variable absorption and bioavailability of 40-60% in horses
    • Adverse effects: Agitation, loose stools, flatulence, and diarrhea

    Famciclovir

    • For feline herpes (FHV-1), converted into penciclovir, which inhibits herpes virus DNA polymerase
    • Pharmacokinetics: Cats require higher doses due to poor conversion to penciclovir
    • Contraindication: Hypersensitivity
    • Adverse effects: Not well documented, but well-tolerated when used up to three weeks

    Antifungal Drugs

    • Antifungal drugs are used to treat fungal infections in animals.
    • Fungi can be unicellular or multicellular, and are classified into molds, mushrooms, and yeasts.

    Azoles

    • Azoles are a group of antifungal drugs that include imidazoles and triazoles.
    • Azoles have antibacterial, antifungal, antiprotozoal, and anthelmintic activity.
    • Azoles are poorly water-soluble, except for fluconazole.
    • Azoles can be divided into imidazoles (e.g., clotrimazole, miconazole, econazole) and triazoles (e.g., ketoconazole, itraconazole, fluconazole).

    Ketoconazole

    • Ketoconazole is an imidazole antifungal drug used for systemic fungal infections.
    • Mechanism of action: inhibits synthesis of ergosterol in fungal cytoplasmic membranes by blocking cytochrome P-450 enzymes.
    • Pharmacokinetics: well-absorbed orally, widely distributed, and metabolized in the liver.

    Itraconazole

    • Itraconazole is a triazole antifungal drug used for systemic fungal infections.
    • Mechanism of action: inhibits synthesis of ergesterol in fungal cytoplasmic membranes.
    • Indications: systemic mycoses, including aspergillosis, blastomycosis, and histoplasmosis.
    • Adverse effects: fewer side effects than ketoconazole, but can cause hepatic toxicity, anorexia, weight loss, and vomiting.

    Fluconazole

    • Fluconazole is a triazole antifungal drug used for systemic fungal infections.
    • Mechanism of action: inhibits synthesis of ergosterol in fungal cytoplasmic membranes.
    • Indications: systemic mycoses, including cryptococcal meningitis, blastomycosis, and histoplasmosis.
    • Pharmacokinetics: well-absorbed orally, widely distributed, and excreted in the urine.

    Miconazole

    • Miconazole is an imidazole antifungal drug used topically or orally for fungal infections.
    • Indications: fungal keratitis in horses, canine and feline dermatophytoses.

    Polyene Macrolides

    • Polyene macrolides are a group of antifungal drugs that include amphotericin B, nystatin, and natamycin.
    • Mechanism of action: binds to ergosterol in fungal membranes, forming pores and causing leakage of cellular contents.

    Amphotericin B

    • Amphotericin B is a polyene macrolide antifungal drug used for systemic fungal infections.
    • Mechanism of action: binds to ergosterol in fungal membranes, forming pores and causing leakage of cellular contents.
    • Pharmacokinetics: not absorbed orally, distributed to most tissues except CNS, eye, and bone, and excreted in the urine.
    • Adverse effects: renal toxicity, renal vasoconstriction, and decreased renal glomerular filtration.

    Nystatin

    • Nystatin is a polyene macrolide antifungal drug used topically or orally for fungal infections.
    • Indications: candidiasis, dermatophytosis, and gastrointestinal fungal infections.

    Natamycin

    • Natamycin is a polyene macrolide antifungal drug used topically for fungal eye infections.
    • Indications: fungal keratitis in horses and humans.

    Flucytosine

    • Flucytosine is a fluorinated pyrimidine antifungal drug used orally for systemic fungal infections.
    • Mechanism of action: inhibits synthesis of DNA and RNA in susceptible fungi.
    • Indications: cryptococcosis, aspergillosis, and candidiasis.
    • Pharmacokinetics: well-absorbed orally, widely distributed, and excreted in the urine.

    Griseofulvin

    • Griseofulvin is a benzofuran antifungal drug used orally for dermatophytic infections.
    • Mechanism of action: binds to microtubules, inhibiting spindle formation and mitosis in dermatophytes.
    • Pharmacokinetics: absorbed orally, distributed to keratin precursor cells, and metabolized in the liver.

    Terbinafine

    • Terbinafine is an allylamine derivative antifungal drug used orally or topically for fungal infections.
    • Mechanism of action: inhibits synthesis of ergosterol by blocking the enzyme squalene monooxygenase.
    • Indications: dermatophytic infections in dogs and cats, and aspergillosis in birds.

    Other Antifungals

    • Chlorhexidine, iodine, tolnaftate, benzoic acid, salicylic acid, and thiabendazole are other antifungal drugs used topically or orally for various fungal infections.

    Antifungal Drugs

    • Itraconazole: Delivered by subconjunctival route, used for systemic mycoses (Aspergillosis, Cryptococcal meningitis, Blastomycosis, Histoplasmosis), no effects on hormone synthesis.
      • Can cause hepatic toxicity, anorexia, weight loss, and vomiting.

    Polyene Macrolides

    • Amphotericin B: Mechanism of action: binds to ergosterol of fungal membrane, forming pores or channels that result in leakage of cellular contents, fungicidal or fungistatic.
      • Used for systemic mycoses in dogs, cats, horses, and birds.
      • Can be combined with ketoconazole, fluconazole, or itraconazole to reduce toxicity.
      • Adverse effects: renal toxicity, renal vasoconstriction, decreased renal glomerular filtration, and damage to tubular epithelium.
    • Nystatin: Fungistatic or fungicidal, used for candidiasis in small animals and birds.
      • Combined with other drugs: neomycin, thiostrepton, and triamcinolone acetonide.
    • Natamycin: Ophthalmic preparation approved as an antifungal for eyes, used for fungal dermatitis (Fusarium keratomycosis) in horses.

    Other Antifungals

    • Flucytosine: Fluorinated pyrimidine, mechanism of action: inhibits thymidylate synthetase, inhibits DNA and RNA synthesis in susceptible fungi.
      • Well absorbed orally, widely distributed, and excreted unchanged in the urine.
      • Effective against Cryptococcus, Candida, and Aspergillus spp.
      • Adverse side effects: low toxicity, mild gastrointestinal disturbances, and rare bone marrow depression.
    • Terbinafine: Allylamine derivative, mechanism of action: inhibits the synthesis of ergosterol by blocking the enzyme squalene monooxygenase.
      • Fungicidal vs. dermatophytes, fungistatic vs. yeast.
      • Can be administered orally or topically, useful for treating dermatophytic infections in dogs and cats.

    Griseofulvin

    • Griseofulvin: From Penicillium griseofulvum, actively taken up by growing dermatophytes, binds to microtubules, inhibiting spindle formation and mitosis.
      • Fungistatic vs. Microsporum spp. and Trichophyton spp.
      • Action is slow, infected cells shed and replaced with uninfected cells.
      • Absorption: high oral absorption, high-fat foods, and preparation of micronized particles.
      • Pharmacokinetics: distributed to keratin precursor cells of the skin, hair shafts, and nails, metabolized in the liver, and excreted in urine.

    Azoles

    • Azoles: Have antibacterial, antifungal, antiprotozoal, and anthelmintic activity, poorly water soluble except for fluconazole.
      • Divided into Imidazoles and Triazoles.
      • Mechanism of action: alter cell membrane permeability of susceptible yeasts and fungi, block synthesis of ergosterol, and inhibit other enzyme systems.
    • Ketoconazole: Imidazole antifungal for systemic use, mechanism of action: inhibits synthesis of ergosterol in fungal cytoplasmic membranes by blocking cytochrome P-450 enzymes.
      • Fungistatic, often given orally, and topical preparations available.
    • Fluconazole: Synthetic, water soluble, fungistatic, and excreted via kidney.
      • Mechanism of action: cell membrane alteration, leakage of cellular contents, and impaired uptake of purine and pyrimidine precursors.
      • Indications: systemic mycoses, cryptococcal meningitis, blastomycosis, and histoplasmosis.

    Antifungal Drugs

    • Flucytosine:
      • Inhibits thymidylate synthetase
      • Inhibits DNA and RNA synthesis in susceptible fungi
      • Effective against Cryptococcus, Candida, and Aspergillus
      • Well absorbed orally, widely distributed, and excreted unchanged in the urine
      • Therapeutic uses: combined with amphotericin B for cryptococcosis, aspergillosis, and candidiasis
      • Adverse side effects: low toxicity, mild gastrointestinal disturbances, and rare bone marrow depression

    Terbinafine

    • Allylamine derivative
    • MOA: inhibits the synthesis of ergosterol by blocking squalene monooxygenase
    • Fungicidal vs dermatophytes and fungistatic vs yeast
    • Can be administered orally or topically for treating dermatophytic infections and systemic mycotic infections

    Other Antifungals

    • Chlorhexidine
    • Iodine
    • Tolnaftate
    • Benzoic acid
    • Salicylic acid
    • Thiabendazole

    Griseofulvin

    • MOA: binds to microtubules, inhibiting spindle formation and mitosis
    • Fungistatic against Microsporum spp. and Trichophyton spp.
    • Action is slow, and infected cells shed and are replaced with uninfected cells
    • Pharmacokinetics: high oral absorption, distributed to keratin precursor cells, metabolized in the liver, and excreted in the urine
    • Administration and use: PO in dogs, cats, and horses for multifocal dermatophyte infections
    • Adverse effects: rare, idiosyncratic reaction in kittens, leukopenia, and anemia

    Azoles

    • Have antibacterial, antifungal, antiprotozoal, and anthelmintic activity
    • Divided into Imidazoles and Triazoles
    • MOA: alter cell membrane permeability, block synthesis of ergosterol, and inhibit other enzyme systems
    • Fungistatic against Blastomyces, Coccidioides, Cryptococcus, and Histoplasma spp.

    Ketoconazole

    • Imidazole antifungal for systemic use
    • MOA: inhibits synthesis of ergosterol in fungal cytoplasmic membranes by blocking cytochrome P-450 enzymes
    • Fungistatic
    • Often given orally or topically

    Itraconazole

    • For systemic mycoses: aspergillosis, cryptococcal meningitis, blastomycosis, and histoplasmosis
    • No effects on hormone synthesis
    • Adverse effects: hepatic toxicity, anorexia, weight loss, and vomiting

    Polyene Macrolides

    • From various strains of Actinomyces
    • Include Amphotericin B, Nystatin, and Pimaricin (natamycin)
    • Poorly soluble in water

    Amphotericin B

    • Polyene macrolide
    • MOA: binds to ergosterol of fungal membrane, forming pores or channels, leading to leakage of cellular contents
    • Fungicidal or fungistatic
    • Spectrum of activity: systemic mycoses of dog, cats, horses, and birds
    • Pharmacokinetics: not absorbed in the GIT, distributed to most tissues except CNS, eye, and bone, and secreted unchanged in the urine
    • Adverse effects: renal toxicity, renal vasoconstriction, and decreased renal glomerular filtration

    Nystatin

    • Fungistatic or fungicidal
    • From Streptomyces noursei
    • Combined with other drugs: Neomycin, Thiostrepton, and Triamcinolone acetonide
    • For candidiasis infecting the skin, mucous membranes, and intestinal tract of small animals and birds
    • Adverse side effects: rare

    Natamycin

    • Ophthalmic preparation: approved antifungal for eyes
    • Poorly water soluble
    • For fungal dermatitis and Fusarium keratomycosis in horses

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