Antifungals (Kays) Flashcards
What is amphotericin B’s mechanism of action?
binds ergosterol and increases cell permeability, leading to leakage of Na/K/cellular constituents and ultimately cell death
What is flucytosine’s mechanism of action?
deaminates to 5-FU, when converts to 5-fluorodeoxyuridylic acid monophosphate and inhibits thymidylate synthetase, ultimately interfering with DNA synthesis
What is the azole drugs’ mechanism of action?
inhibits ergosterol synthesis via inhibition of lanosterol 14-α-demethylase (damages cell membrane, causes cytoplasmic leakage, and inhibits growth)
Are azole antifungals fungicidal or -static?
fungistatic
What is the echinocandins’ mechanism of action?
inhibits glucan synthesis, leading to noncompetitive inhibition of 1,3-β-D-glucan (nothing can bind to chitin to help provide cell wall structure)
Are the echinocandins fungicidal or -static?
fungicidal
What is ibrexafungerp’s mechanism of action?
inhibits glucan synthesis, leading to noncompetitive inhibition of 1,3-β-D-glucan (nothing can bind to chitin to help provide cell wall structure)
Which antifungal covers Pneumocystis jirovecii?
ibrexafungerp
What antifungal(s) cover Fusarium?
voriconazole and echinocandins (limited)
What antifungal covers Scedosporium apiospermum?
voriconazole
What antifungal covers Sporothrix schenckii?
itraconazole
What antifungal(s) cover Coccidioides immitis?
- amphotericin B
- itraconazole
- fluconazole
- posaconazole
“AND IT FUCKS PUSSIES” (cocc sounds like cock)
What antifungal(s) cover Blastomyces?
- amphotericin B
- itraconazole
- fluconazole
- voriconazole
“AWAY IT FLIES VERTICALLY” (blast=fireworks)
What antifungal(s) cover Histoplasma capsulatum?
- amphotericin B
- ketoconazole
- itraconazole
- fluconazole
- voriconazole
- posaconazole
- echinocandins (limited)
“ANIMALS KEEP INTENTIONALLY FLYING VERY POOR ENVIRONMENTS” (bats spread histoplasma)
What antifungal(s) cover Mucor?
- amphotericin B
- posaconazole
- isavuconazole
- echinocandins (limited)
“ALLERGIES PROBABLY, IT’S EXHAUSTING” (Mucor = mucus)
What antifungal covers Absidia?
amphotericin B
What antifungal(s) cover Rhizopus?
- amphotericin B
- isavuconazole
What antifungal(s) cover Cryptococcus neoformans?
- amphotericin B
- flucytosine
- ketoconazole
- itraconazole
- fluconazole
- voriconazole
- posaconazole
- echinocandins (limited)
everything except for isavuconazole and ibrexafungerp
What antifungal(s) cover Aspergillus?
- amphotericin B
- itraconazole
- voriconazole
- posaconazole
- isavuconazole
- echinocandins
- ibrexafungerp
“ASPARAGUS IS VERY POPULAR IN ENTREES INTERNATIONALLY” (Aspergillus = asparagus)
What antifungal(s) cover Candida?
- amphotericin B
- flucytosine
- ketoconazole
- itraconazole
- fluconazole
- voriconazole
- posaconazole
- echinocandins
- ibrexafungerp
everything covers Candida on some level, except isavuconazole
What happens with amphotericin B in low concentrations?
K+ channel activity is increased
What happens with amphotericin B in higher concentrations?
pores are formed in the fungal cell membrane
Amphotericin B’s onset can be described as __________.
rapid
Through which two routes could resistance to amphotericin B develop?
- decreased ergosterol biosynthesis
- alternative sterol synthesis
What is the pharmacodynamic parameter for amphotericin B?
peak/MIC
Which Candida type is not covered by amphotericin B?
C. lusitaniae
Amphotericin B has reduced activity against which Aspergillus?
A. terreus
Describe amphotericin B deoxycholate’s oral absorption.
poor
Describe amphotericin B deoxycholate’s intramuscular absorption.
poor
Although amphotericin B deoxycholate widely distributes into tissues, where does it primary deposit?
reticuloendothelial tissues (liver, spleen, bone marrow)
Describe amphotericin B deoxycholate’s CSF penetration.
poor, even with inflamed meninges
Amphotericin B deoxycholate is highly protein-bound, mainly to _____________.
β-lipoproteins
Describe amphotericin B deoxycholate’s metabolism.
not appreciably metabolized (most of the drug is degraded in situ)
Amphotericin B deoxycholate’s elimination pattern can best be described as ______________.
tri-exponential
Amphotericin B deoxycholate can be detected in serum concentrations for at least ___________ after the end of therapy.
7 weeks
Does amphotericin B deoxycholate need to be renally/hepatically dose-adjusted?
no
True or false: all lipid-associated formulations of amphotericin B have similar PK patterns.
false
What are the clinical uses for amphotericin B?
- disseminated candidiasis
- cryptococcosis
- aspergillosis
- histoplasmosis
- blastomycosis
- coccidioidomycosis
- mucormycosis
Should you pre-medicate when giving a test dose of amphotericin B deoxycholate?
no
What are the dosing rules for amphotericin B deoxycholate?
- test dose of 0.1 mg/kg or 1 mg over 20-30 minutes
- total daily dose of 0.3-1.0 mg/kg/day over 4-6 h (generally)
What can happen if amphotericin B deoxycholate is too rapidly infused in a patient with severely compromised renal function?
- acute hyperkalemia
- ventricular fibrillation
Data suggest that there are significantly fewer adverse events if amphotericin B deoxycholate is administered as a continuous infusion over ___________.
24 hours
How should you administer intrathecal/intraventricular amphotericin B deoxycholate?
start with 0.1 mg and gradually increase to max 0.5 mg q48-72 h
How should liposomal amphotericin B be dosed/administered?
1.5-6 mg/kg daily, infused over 2 h
What is the recommended daily dose for ABLC?
5 mg/kg
Which patient weight should be used for dosing amphotericin B?
ideal body weight (or adjusted body weight)
What infusion-related adverse reactions can occur with amphotericin B deoxycholate?
- headache
- fever/chills
- arthralgias/myalgias
- N/V
- tachypnea
- hypotension
- thrombophlebitis
What should be used to pre-treat infusion-related reactions from amphotericin B deoxycholate?
- APAP or aspirin
- antihistamines
- meperidine
- phenothiazine
What can be used to combat thrombophlebitis reactions from amphotericin B deoxycholate?
add heparin 500-1000 units to infusion bag
What can be used to combat the non-thrombophlebitic infusion-related reactions from amphotericin B deoxycholate?
add hydrocortisone 25-50 mg to the infusion bag
What non-infusion-related adverse reactions are associated with amphotericin B deoxycholate?
- nephrotoxicity (inreased SCr and BUN)
- HYPOkalemia
- HYPOmagnesemia
- bicarbonate wasting
- anemia
How can we attempt to prevent thrombophlebitis from amphotericin B deoxycholate?
- infuse slowly (4-6 h)
- rotate infusion sites
- use in-line filters (>0.22 micron)
Through what mechanism does amphotericin B deoxycholate produce nephrotoxic effects?
direct vasocontriction of afferent renal arterioles resulting in cortical ischemia and decrease in GFR
Is amphotericin B deoxycholate nephrotoxicity reversible?
no; permanent loss of renal function related to total dose
How can we prevent/manage nephrotoxicity associated with amphotericin B deoxycholate?
- sodium repletion (0.5-1 L NS 30 minutes before and after completion)
- hydration
- adjustment of daily dose
Is amophotericin B deoxycholate-associated anemia reversible?
yes
What adverse reactions can happen when amphotericin B deoxycholate is intrathecally administered?
- peripheral nerve pain
- headache
- vomiting
- paresthesias
- paraplegia
- seizures
- difficulty voiding
- impaired vision
True or false: lipid-associated amphotericin B formulations generally cause more nephrotoxicity and infusion-related toxicities.
false; less nephrotoxicity and infusion-related toxicities
High-dose liposomal amphotericin (7.5 mg/kg/d) is associated with high _______________ rates.
nephrotoxicity
How should we manage infusion-related reactions from liposomal amphotericin B?
diphenhydramine
Amphotericin B can interact with what drugs?
- other nephrotoxic drugs
- digoxin
- skeletal muscle reactions
- flucytosine (used together for cryptococcal meningitis)
Describe flucytosine’s oral absorption.
well-absorbed orally
Does flucytosine penetrate the CSF adequately?
yes
How is flucytosine affected by hemodialysis and peripheral dialysis?
removed by HD and PD
What is flucytosine’s primary clinical use?
in combination with amphotericin B for cryptococcal meningitis
What adverse reactions are associated with flucytosine?
- Hematologic (bone marrow suppression)
- GI (N/V/D, abdominal pain, enterocolitis)
What is the recommended dose range for flucytosine in patients with normal renal function?
25-37.5 mg/kg q6h
Should flucytosine be renally/hepatically dose adjusted?
yes for renal, no for hepatic
How should flucytosine be renally dose adjusted?
as ClCr worsens, continue to double the dosing interval