Antimycotics Flashcards
are mycoses acute or chronic in nature?
chronic usu
do fungal infections stay local or become systemic?
can be superficial and local but can go systemic if individual is immunocompromised
how hard is it to treat systemic fungal infections?
VERY DIFFICULT and commonly life threatening
how do many anti-fungals act?
act by binding to the fungal cell wall or cell membrane and disrupting permeability
others disrupt fungal DNA and/or RNA synthesis
anti-fungal meds may be fungi-static or fungi-cidal
drug that affects membrane fxn?
amphotericin B
drug that effects ergosterol synthesis?
fluconazole, itraconazole, voriconazole, naftifine, terbinafine
drug that can inhibit cell wall synthesis?
caspofungin
drug that can inhibit nucleic acid synthesis?
5-fluorocytosine
3 topical anti-fungals?
clotrimazole/lotrimin, nystatin/mycostatin, miconazole/monistat
systemic antifungal categories?
polenes
azoles
echinocandins
gold standard to tx fungal infxn? how to give it? MOA? ADRs? pre-medicate w/what?
amphotericin B= GOLD STANDARD
give IV
MOA: binds to ergosterol in fungal cell membrane forming pores= increased permeability= cell death
ADRs: legendary “shake and bake”- related to IV infusion, cumulative toxicity can lead to renal damage
pre-medicate w/antihistamines, antipyretics, corticosteroids
strengths of amophotericin B? limitations? indications?
strengths: broad spectrum, inexpensive
limitations: toxicity “shake and bake”
indications: broadest spectrum of activity, activity against all clinically significant yeasts, life threatening infections
MOA of azole antifungals? -cidal or -static drug?
MOA: inhibit cytochrome P450, interacts w/cytochrom P450 drug metabolism (can cause inhibition or stimulate metabolism), block formation of ergosterol
considered a “static”
two classes of azole antifungals?
imidazoles triazoles (used less often b/c more drug-drug interactions and more SEs)
ADRs of azole antifungals?
GI upset, hepatitis, drug interactions through cytochrome P450 system of enzymes, increases levels of warfarin
most commonly used systemic antifungal? strengths? weaknesses?
fluconazole
strengths: lack of toxicity, oral bioavailability is excellent, extremely active against c. albicans
weakness: spectrum low, often underdosed
3 echinocandins? MOA?
caspofungin, micafungin, andiulafungin
MOA: cause disruption of fungal cell wall= cell death
echinocandins are potent against what fungus? how to administer? cidal or static? strengths?
potent against candida esp
IV only
fungicidal
strengths: well tolerated, excellent pharmokinetics, few drug-drug interactions, no cross-resistance w/azoles
weaknesses of echinocandins?
limited spectrum, oral formulation not available, $$$
SE: mild GI and flushing
preferred formulation for superficial mycoses (location dependent)?
cream of solution
but powders for feet/groin
topical administration not successful for nails and hair
indication for clotrimazole/lotrimin? MOA?
superficial mycoses such as the tineas, ring worm, yeast vaginitis, oral thrush
MOA: binds to ergosterol molecules on fungal cell membrane and causes membrane leakage during cell division
how to administer clotrimazole?
topical creams, lotions, ointments for tinea and candida
cream, lotion, powder, aerosol, vaginal cream, vaginal tablets, troches (for thrush)
how is nystatin commonly used? indications? MOA?
used topically- creams, ointments, lotions, solution
indications: superficial mycoses, oral candidiasis as well as esophageal and vaginal candida
MOA: binds to ergosterol molecules on fungal cell membrane= cell death
when is nystatin often used??
prophylaxis in pts who are at risk for fungal infxns, such as AIDS pts w/low CD4+ count and patients receiving chemo
tx options for thrush?
clotrimazole troches, nystatin suspension, fluconazole orally
terbinafine class? MOA? used for?
class: synthetic allylamine
MOA: interferes w/ergosterol biosynthesis
used primarily for dermatophyte infxns (nail/skin)
strengths of terbinafine? weaknesses?
strengths: good oral bioavailability, very active against dermatophytes, active against candida spp
weaknesses: no IV formulation, very limited clinical experience outside dermatophyte infxns
how to dose terbinafine/lamisil?
250 mg per day for 6 continuous wks to treat fingernail fungal infxns and 12 wks to treat toenail infnxs
SEs of terbinafine/lamisil?
abd discomfort, diarrhea, nausea, h/a, elevated liver enzymes, hepatitis, liver damage, liver failure
