Antifungals Flashcards
Systemic mycoses
Histoplasmosis, aspergillosis, coccidiomysosis, blastomycosis, cryptococcosis, and sporotrichosis
Topical antifungals include:
Local antifungals EXCEPT griseofulvin
Systemic antifungals include:
Systemic antifungals PLUS Griseofulvin
List the Broad-Spectrum topical antifungals:
Azoles Polyenes Haloprogin Cuprimyxin Ciclopirox olamine
List the Narrow spectrum topical antifungals:
Tolfanate
Terbinafine
Other topical antifungals that do not fall under a ‘spectrum;
Iodides (tissue damage at high conc)
Lime sulfer
Thymol
Hexachlorphene (stains skin)
Which ‘azole’ was originally an antihelmenthic?
Thiabendazole
Which ‘azole’ is often made into an antifungal medicated shampoo?
Miconazole
List the systemically administered antifungal drugs.
Griseofulvin Amphotericin B Flucytosine Azoles Allylamines Lufenuron
Fungi cell membrane is made out of what
Ergesterol
What is the synthesis pathway of ergosterol?
Squalene (+Squalene epoxidase)
- -> Squalene epoxide
- -> Lanosterol (+14alphaDimethylase)
- -> Ergosterol
What drug blocks Squalene epoxidase?
Terbinafine (allylamines)
**Fungicidal
What drug blocks 14 alpha dimethylase?
‘Azoles’
**fungistatic
What is the mechanism of action for Amphotericin B/Polyenes?
binding irreversibly to ergosterol
**fungicidal
What is flucytosine mechanism of action?
inhibiting thymidylate synthase (like anticancer?)
**fungicidal
What is the mechanism of action of Griseofulvin?
Inhibiting mitosis
**fungistatic
What is the mechanism of action of Lufenuron?
inhibiting chitin
What is Griseofulvin used for?
Oral treatment of dermatophytes (deposits in keratin)
Contraindications/Adverse effect of Griseofulvin?
Enzyme inducer (drug-drug), GI irritation, idisyncratic liver dysfunction AND bone marrow suppresion in cats
What is the most dangerous side effect of Amphotericin B?
NEPHROTOXIC
What is Amphotericin used for?
Most effective drug for systemic mycosis in immuno-compromised animals (combined with azoles)
*Also can be used topically for candida
How can you make Amphotericin B less nephrotoxic
use the liposomal encapsulate preparation as it is less toxic
What is flucytosine used for?
Used to be used for cryptococcal meningitis with Amphotericin B (penetrates CNS while AmpB doesnt)
Why do you need to give food before administering ketoconazole?
requires an acidic pH
Contraindications effects of ketoconazole?
- Inhibits 14 alpha Dimethylase in the fungi as well as the liver and adrenal cortex (not good)
What does ketoconazole work on?
broad spectrum!
Local: dermatophytes, candida, and malassezia
Systemic: Blastomycosis, Histoplasmosis (in immunocompetant)
Adverse effects of ketoconazole?
inappetance, pruritis/alopecia, inhibited cortisol and testosterone synthesis, and teratogenic (DONT GIVE TO PREGNANT ANIMALS)
*cats are more sensitive
What is Itraconazole the dug of choice for? (three things)
Systemic mycoses (Blastomycosis/Histoplasmosis), ASPERGILLOSIS, and SPOROTRICHOSIS
Why is itraconazole better than ketoconazole?
Does not inhibit cortisol or testosterone synthesis at therapeutic doses
Can you give ketoconazole or itraconazole to pregnant animals?
Hell nah
What is the drug of choice for treating cryptococcal meningitis?
Fluconazole
What is Terbinafine used for?
topical against dermatophytosis
What enzyme can Terbinafine elevate in cats?
ALT
What is Lufenuron used for?
Oral tx of dermatophytosis
*can also treat ectoparasites as they also have chitin
Drug of choice for Aspergillus Keratitis in a horse?
Clotrimazole
Drug of choice for Canine nasal aspergillosis?
Clotrimazole or Enilconazole
Drug of choice for systemic aspergillosis?
Itraconazole
Local fungal infections
Dermatophytes - ringworm (trichohyton/microsporum) and Candida
