Antifungals Flashcards
True or False: Fungal treatment should be topical if possible
True, because of the adverse effects of giving it systemically
What are the three principles of antifungal therapy?
- Fungal infections often occur in immunosuppressed patients or patients on prolonged antimicrobial therapy
- Long term therapy often required
- Often have severe systemic side effects, so local or topical use is preferable
Which fungi are systemic?
- Histoplasma capsulatum
- Cryptococcus neoformans
- Coccidioides immiti
- Blastomyces dermatitidis
- Candida spp.
- Aspergillus spp
What is the mechanism of action of polyene antifungals?
Polyene antifungals attack the cell membrane of fungal organisms (bind to egosterol in the fungal cell membrane and increase membrane permeability, causing leakage and death)
What class of antifungal is Amphotericin B?
Polyene antifungal
Is Amphotericin B a systemic or local antifungal?
Systemic
Is Amphotericin B fungicidal or fungistatic?
Fungicidal
What is the main adverse effect of Amphotericin B?
Nephrotoxicity (basically all animals that take this medication will show this)
Amphotericin B is _________ dependent
Concentration
What class of antifungal is nystatin and natamycin?
Polyene antifungals
What condition is natamycin commonly used to treat?
Keratomycosis (fungal infection of the cornea)
Is natamycin a systemic or local antifungal?
Local (topical)
Is nystatin a systemic or local antifungal?
Local (topical) is not absorbed from the GI tract
What is the mechanism of action of azoles?
They inhibit ergosterol synthesis
Are azoles fungicidal or fungistatic?
Fungistatic
What are the systemic azoles?
Triazoles
What are the local azoles?
Imidazoles
Which azole affects mammalian steroid synthesis?
Imidazoles
What are the two triazoles?
Itraconazole and fluconazole
What are the three imidazoles?
- Ketoconazole
- Clotrimazole
- Miconazole
What is unique about ketoconazole?
Although it’s an imidazole, it is used systemically as well
What are the main adverse effects of ketoconazole? What should you give it with?
- Inhibits sex hormone synthesis
- Inhibition of mammalian P450
- Do not use in pregnant animals
- Give with food (acid-soluble)
What is a main contraindication of ketoconazole?
Patients with liver disease
What is the first line treatment for non-life-threatening systemic mycoses that do not involve the CNS?
Itraconazole
Which antifungal is commonly used to treat dermatophytes?
Itraconazole (accumulates in keratin)
What is pulse therapy?
Pulse therapy consists of administering usual dose for 2 consecutive days per week for duration of treatment (for skin treatments only)
What is the first line treatment for systemic mycoses with ocular or CNS involvement?
Fluconazole (because it crosses BBB - okay to use in renal patients, just reduce the dose)
What is a main contraindication of fluconazole?
Patients with kidney disease
What is miconazole commonly used to treat?
Malassezia dermatitis (topical)
Which antifungal is commonly used to treat Malassezia dermatitis that doesn’t respond to topical therapy?
Itraconazole
Which antifungal is combined with steroids and antibiotics for treatment of otitis in dogs?
Clotrimazole
What is the mechanism of action of allylamines?
They inhibit ergosterol synthesis
Name a drug in the allylamine class
Terbinafine
Is terbinafine a systemic or local antifungal?
Both
Is terbinafine fungicidal or fungistatic?
Fungicidal
Which antifungal is synergistic with Amphotericin B?
Flucytosine
True or False: Chlorhexidine alone is effective in the treatment of dermatophytosis
False
Which compound can be used to treat white line disease in horses?
Chlorine dioxide gas
