Antifungal Flashcards
Three forms of fungal infections
Superficial, subcutaneous, systemic
Griseofulvin- source
Penicillin
Griseofulvin method-
Fungistatic
Griseofulvin- effective against
Dermatophytosis- Microsporum, epidermophyton, trichophyton- no effect on others!
Most common fungal disease in cats
Dermatophytosis
Griseofulvin- mechanism
Active on growing cells, binds to intracellular microtubules to inhibit mitosis, nucleic acid and protein synthesis, chitin synthesis
Griseofulvin- how does it reach skin
In sweat, incorporated in keratin loosely- undetectable in skin 2-3 days
Griseofulvin- time to reach skin after admin’n
4-8 hours
Griseofulvin- absorption dependent on
Formulation (microsize or ultramicrosize particles in polyethylene glycol) and food (increase absorption with fatty meal)
Griseofulvin- metabolism
Oxidation by hepatic enzyme; 6 times faster than in people
Griseofulvin- duration of tx
min 4 weeks, sometimes over 3 months
Griseofulvin- interactions
phenobarb decreases absorption
Griseofulvin- adverse
Bad taste- nausea, V, D; bone marrow suppression in cats with FIV or persians/himalayans/siamese/abyss - CBC q 2 weeks
Griseofulvin- Contraindications
HIGHLY teratogenic- DO NOT GIVE TO PREGNANT ANIMALS - brain and skeletal malformations, eye issues, absence of nostrils, soft palate
Amphotericin B- method
static or cidal depending on dose; Punches holes in cell membrane by binding to sterols (fungal and mammalian = not specific)- leakage until death
Amphotericin B- uses
Cryptococcosis, blasto, histoplasmosis, coccidiomycosis - only in serious cases due to possible toxicity due to lack of sterol specificity (Think ampho blasto histo, cocco)
Amphotericin B- route
IV only- no oral absorption
Amphotericin B- cautions
Dehydration increases toxicity so administer in 5% dextrose after saline diuresis; max cumulative dose before danger
Amphotericin B- metabolism
KIDNEY- high protein binding, 24 hour half life
Amphotericin B- limit
4-8 mg/kg (higher if done subcutaneous)
Amphotericin B-best formulations
liposomal- better brain penetration and longer half life leads to less dose needed
Amphotericin B- side effects
Thrombophlebitis, nephrotixicity (vasoconstriction and renal tubule toxicity), hypokalemia, resistance over time
Ketoconazole- method
static/cidal
Ketoconazole- mechanism
Inhibit lanosterol 12-demethylase; suppresses p450!!!!!
All azoles do what?
Interfere with p450- ex. cyclosporin dose lowered when on azole
Ketoconazole- cautions-
inhibits p450; affinity but not 100% specificity for fungal vs mammalian
Ketoconazole- uses
Broad - systemic, dematophytosis, malassezia,
Ketoconazole- administration
Oral with acidic environment (with food!)
Ketoconazole- metabolize
LIVER, halflife 2 hours, peak level in 2 hours, lipophilic
Ketoconazole- speed of action
5-10 days
Itraconazole- specificity
more affinity for fungal enzyme
Itraconazole- effective against
Broad spectrum
Itraconazole- metabolism
LIVER, high skin and fat concentration (lipo and ketratophilic), poor CSF and eye penetration
Itraconazole- half life
8-12 hours dogs, 40-120 hours in cats; stays in nails for 6 months
Itraconazole- administration
Oral with food
Itraconazole- side effects
Better in cats than ketocon
Fluconazole- effective against
Broad spectrum
Safest most specific azole
Fluconazole
Fluconazole- metabolism
No liver, long half life, good absorption, excellent brain penetration
Fluconazole- administration
oral, lasts 10 days after administration
Fluconazole- side effects
ok for cats, safe for liver
What drug is best for patients with immune compromise
Vfend- voriconazole
What drug is best for aspergillus
Vfend- voriconazole
Vfend- voriconazole- metabolism
LIVER - p450 suppression
Which azoles are safe in cats
itraconazole and fluconazole (think FIC)
Which antifungals are metabolized by the liver
most azoles- (Itraconazole, ketoconazole, vfend- not fluconazole) and griseofulvin
Which antifungal is metabolized by the kidney
amphotericin b
Which azole does not get metabolized by the liver
Fluconazole
Terbinafine (lamisil) - mechanism
Inhibition of ergosterol synthesis via squalene epoixdase- HIGHLY fungal specific
Terbinafine (lamisil) - uses
Dermatophytosis, malassezia
Iodides- uses
Sporotrichosis in horses
Iodides- Side effects
GI (give with food), twitching, hypothermia, alopecia/scaling
Caspofungin- uses
Aspergillus, candida, **oomyces (think O-fungin)
Caspofungin- administration
IV
Ketoconazole shampoo- uses
dermatophytes, malassezia
Chlorhexadine- uses
Limited antifungal topical, can be irritating
Miconazole- uses
Topical for Malassezia dermatitis, yeast otitis
Chlortrimazole- uses
topical for yeasts and dermatophytes
Enizconazle- uses
Dermatophytes, malassezia, aspergillus
Selenium disulfide (selsun)- uses
Malassezia
Selenium disulfide (selsun)- contraindications
cats, can be drying
Lyme sulfur- uses
VERY effective against dermatophytosis
Thiabendazole (tresaderm) - type
Antihelmintic imidazole
Thiabendazole (tresaderm) - uses
Malassezia otitis, ear mites