Chapter 35: Fungal Infections Flashcards
Flucytosine MOA?
converted to 5 FdUMP, which goes on to inhibit thymidylate sythase –> inhibit DNA synthesis!
Flucytosine is used to treat 1) 2) 3) ?
fluCytosine –> the three Cs
Candiasis
Cyptococcosis
Chromomycosis
How does flucytosine resistance manifest?
mutations in cytosine permease/deaminase lead to resistance
Which antifungal drug works by binding to tubulin and and a microtubule assc protein, thus disrupting assembly of the mitotic spindle?
Griseofulvin
Grizzly-fulvin comes in and RIPS APART THE MITOTIC SPINDLE!!!
Griseofulvin is used to treat __? But cannot
skin hair or nail infections
caused by trichophyton, microsporum, epidermophyton
You cannot use griseofulvin in patients with what medical conditions?
pregnancy; porphyria; hepatic failure
Giving barbituates with griseofulvin causes what?
increases GI absorption of griseofulvin
Which inhibitor of squalene epoxidase has a really long half life (~300 hr) because it accumulates in the nails, skin, and fat?
terbinafine
What is the drug of choice for onychomycosis (nail fungus tinea unguum)?
terbinafine
What class of drugs are used to treat the “tineas?”
squalene epoxidase inhibitors –> “fines”
terbinaFINE, naftiFINE, butenaFINE
that chick Tinea is sooo FINE!
Which inhibitor of sqaulene epoxidase is available only as a cream or gel?
naftifine
A lot of stuff interferes with ketoconazole - what?
amphotericin B
oral triazolam
anything that decreases gastric acidity
inhibits p450 so anyting like warfarin, h1 antihistamines…
which imidazole antifungal is NOT used for superficial eye infections?
ketoconazole
triazole antifungals include –?
fluconazole itraconazole posaconazole terconazole noriconazole
which triazole can be used to treat aspergillosis, blastomycosis, cadidiasis, histoplasmosis, onychomycosis?
itraconazole
Which triazole does not penetrate the CSF but may have strong effects on the meninges anyways?
intraconazole
amphotericin B MOA?
binds to ergosterol and forms pores that alter fungal membrane stability
what are the major adverse effects of amphotericin B?
renal toxicity cytokine storm (fever, chills, hypotension)
What measures are taken to reduce renal toxicity of ampho B?
lipid formulations reduce drug exposure to the proximal tubule
Ampho B should be combined with what other antifungal to tx acute cryptococcal meningitis?
flucytosine
Which ergosterol inhibitor is used to treat only mucocutaneous candidiasis?
nystatin
what is the MOA of the “fungins”
noncomp inhibition of B 1 3 D glucans synthesis –> disrupts cell wall integrity
Echinocandins, the “fungins” are fungicidal against ___ and fungistatic against ___?
candidiasis species
aspergillus species
CSF sample reveals crytococcus neoformans. Tx begins with ampho B for two weeks then you switch to oral tx with __? Why?
fluconazole
bc it has good CNS penetration (unlike itraconazole and ketoconazole…so are not used to tx meningitis)
