Antifungal agents Flashcards
Risk factors of fungal infections
neutropenia, corticosteroids, TPN, plonged or excessive use, CVLs, mechanical ventilation, CRRT, immunosuppressants
Most commonly encountered fungi
candida species: c. albicans, c. glabrata, c. parapsilosis, C. krusei, asperigllus, histoplasmosis (midwest)
Azoles options
fluconazole (diflucan), itraconazole (Sporanox), voriconazole (Vfend), posaconazole (noxafil)
Echinocandins options
anidulafungin (Eraxis), caspofungin (Cancidas), micafungin (Mycamine)
Imidazole options
ketoconazole (Nizoral), clotrimazole, miconazole
Micallaneous options
amphotericin B (Fungizone), liposomal amphotericin B, flucytosine (Ancobon), nystatin, terbinafine (Lamisil)
Azole MOA
Inhibits synthesis of ergosterol by inhibiting fungal CY450 enzymes, blocked formation of the critical ergosterol component results in a damaged fungal cell membrane and leakage of cytoplasm to inhibit cell growth, fungistatic
difulcan spectrum of activity
candida, less against C. glabrata, histoplasma capsulatum, blastomyces dermatitides, coccidioides immitis
what are difulcan not affected against?
C. Krusei, aspergillus
PK of difulcan
great absorption orally regardless of gastric pH which is unique to this drug, IV/PO, great system wide penetration, excreted unchanged in urine, renal adjustment
Clinical use of difulcan
most commonly used antifungal, Candidiasis DOC, oropharyngeal, esophageal, systemic, UTI, fungemia, cryptococcal meningitis
ADR of Difulcan
very well tolerated, elevation of LFT, N/V
DI of difulcan
worry more about these, HCTZ, warfarin, phenytoin
Dosing of difulcan
topical candidiasis- 100-200 mg PO QD, non-invasive candidiasis- 200-400 mg/d, invasic=ve- push the dose- 400-800 mg/d
itraconazole MOA
inhibits ergosterol synthesis, fungistatic
Spectrum of activity of itraconazole
asperigillus, candida, cryptococcus neoformans, histoplasma capsulatum, blastomyces dermatitidis
clinical use of itraconazole
reserved for more rare fungal infections, blastomycosis, histoplasmosis, life-threatening infxn, aspergillosis, onchomycosis of finger and toes, esophageal/oropharyngeal
Voriconazole MOA
inhibits ergosterol synthesis, fungistatic
Voriconazole spectrum
aspergillus, including amphotericin resistant, all candida, cryptococcus neoformans
Voriconazole kinetics
IV/PO, great Vd, not nephrotoxic but vehicle it is compounded to is, IV contraindicated in
DI of voriconazole
lots, has activity of most cyp 450 enzymes, major limitation but still used when needed
Voriconazole clinical uses
invasive aspergillosis, pt usually get dual therapy and voriconazole, other serious fungal infxns, drug resistant candidiasis
Posaconazole (noxafil) MOA
inhibits ergosterol synthesis, fungistatic, similar to itraconazole, only available as a liquid
Spectrum of activity of posaconazole
aspergillus, candida, cryptococcus neoformans, very broad
posaconazole clinical use
long term as prophylaxis for aspergillosis in immunocompromised, must take with food
Ketoconazole moa
inhibits synthesis ergosterol, blocks formation of ergosterol damages fungal cell membrane and destroys structural integrity, fungistatic
Spectrum of ketoconazole
candida albicans, histoplasmosis capsu latum, cryptococcus neoformans, dermatophytes
PK of ketoconazole
PO, well absorbed but inversely related to gastric pH, don’t use with H2 blockers
Clinical use of ketoconazole
only for more rare conditions, chronic mucocutaneous candidiasis, histoplasmosis, blastomycosis
ADR of ketoconazole
very hepatotoxic, inhibits adrenal steroids and testosterone synthesis leads to gynecomastia, dec libido, alopecia
DI of ketoconazole
so many!!!
Clotrimazole options
Lotrimin, lotrimin AF, lotrisone (clotrimazole+betamethasone)
MOA of clotrimazole
binds phospholipids in fungal cell wall, alters cell wall permeability results in loss of essential intracellular components
Spectrum of clotrimazole
candida, limited in others
Clinical use of clotrimazole
use topically, available OTC, dermatophytosis candidiasis- topical, vulvovaginal candidiasis- topical, dermatologic infxn, topical
Miconazole options
vagistat, lotrimin af, many others
Miconazole MOA
inhibits synthesis of ergosterol
Spectrum of miconazole
candida
Clinical use of miconazole
tinea corposis, tinea pedis, vulvovaginal candidiasis
Echinocandins MOA
inhibits synthesis of an integral component of fungal cell wall, fungicidal vs candida, fungistatic vs aspergillus
Spectrum of activity of echinocandins
aspergillus, candida, great for C. Glabrata (DOC!)
echinocandins has limited activity against
histo, crypto, mucor
Echinocandins kinetics
IV, poor urine conc, no renal adjust required
ADR of echinocandins
well tolerated, some gi, some histamine rash
Echinocandins clinical use
candidiemia, severe esophageal candidiasis, invasive aspergillosis- not monotherapy
Amphotericin B MOA
binds to ergosterol, disrupts cell membrane which increases permeability and causes leakage of Na/K, metabolic cell death
Spectrum of amphotericin B
candida, cryptococcus neoformans, aspergillus, blastomyces dermatitidis, histoplasma capsulatum, mucor, coccidioides immitis
Pk/Pd
IV only, zero penetration into the CNS
ADRs of amphotericin B
lots of infusion related ADRs, HA, fever, chills, arthralgias, myalgias, N/V, hoTN, thrombophlebitis, also nephrotoxic, hypokalemia, hypomagnesemia (give K/Mg prophylaxis)
Uses of amphotericin B
requires a test of tolerance, histoplasmosis, cryptococcosis, aspergillosis, disseminated candidiasis, empiric therapy in immunocompromised
Liposomal amphotericin B pearls
better tolerated from ADR, able to treat CNS infxn, $$$
Flucytosine (Ancobon) MOA
incorporated into fungal RNA to interfere w/ protein synthesis
Spectrum of flucytosine (Ancobon)
cryptococcus neoformans, candida
ADRs of flucytosine
Gi, bone marrow suppression
Flucytosine uses
fes, usually combo w/ ampho B, crypto meningitis, invasive pulmonary cryptococcosis
Terbinafine (Lamisil), MOA
Inhibits squalene epoxidase, key enzyme in fungal sterol synthesis, used as systemic therapy
Clinical use terbinafine
onchomycosis (finger and toe), tinea capitis
Nystatin MOA
Binds to sterol in fungal cell membrane drastically changing permeability
Nystatin availability
PO suspension, powder, tablet, cream
Nystatin use
cutaneous and mucocutaneous infxn
Nystatin spectrum
candida
candidemia tx in non-neutropenic pts
fluconazole is DOC, alternative- LFAmB, AmB, voriconazole, remove lines where appropriate, treat 14 days after first neg culture
tx of candidemia in neutropenic pts
consider fungal infxn after 4 days of fever despite broad spectrum abx, initiate tx w/ LFAmB, voriconazole or schinocandin, fluconazole is only to be used if pts is not critically ill nad no recent exposure to azole antifungal agents
TX of UTI caused by candida
asymptomatic cystitis- no tx, symptomatic cystitis- fluconazole- DOC amB if resistant, pyelonephritis- fluconazole
TX of CNS candidiasis
LFAmB followed by fluconazole daily, tx continues until clinical improvement is evident
Candida isolated from respiratory secretions
tx not recommended, candida rarely causes LRTI, mostly seen in immunocompromized, neutropenic pts
Invasive pulmonary aspergillosis
voriconazole -DOC, alternative- LFAmB, salvage therapy- posaconazole, echinocandin, LFAmB, measure to improve clinical response- reduce immunosuppression- steroids, neurtopenia- surgery, duration 6-12 wk