Antifungals Flashcards
Why do you have to be careful giving aminoglycosides with amphotericin B?
Both are nephrotoxic
What is the route of administration for terbinafine
Oral or topical
Why do we think amphotericin B is SO toxic?
Human cholesterol looks a lot like ergosterol, so it probably binds to human cholesterol
Is griseofulvin static or cidal?
Static ***
How long is treatment with griseofulvin?
6-12 months. You have to replace all of the infected keratin
What is the administration of fluconazole?
Oral and IV
What is the MOA of nystatin?
Just like amphotericin B- forms pores
What makes micafungin and anidulafungin different from caspofungin?
They are all very similar, just a few altered pharmacokinetic properties
Why is caspofungin an attractive treatment option?
Doesn’t kill kidneys
Few drug interactions
(Why don’t we use them more?! They are cidal Penicillins of antifungals)
What are the 2 types of toxicities that are caused by amphotericin B?
Due to either:
1. Infusion of drug
- Reactions occurring over time (much more of a problem)
How is amphotericin B administered?
IV only
This will be given in hospital setting
What is the main complaint with fluconazole?
Headache
If you’re getting bored with your itraconazole capsules, can you mix it up with some oral solution?
No, do not use the two dosage forms interchangeably
Would fluconazole be a good choice for fungal meningitis?
Yes**
What organisms can cause onychomycosis?
Dermatophytes
Candida
Nondermatophytic molds
What is the DOC for almost all systemic fungal infections?
Amphotericin B
How is caspofungin administered?
IV
What is the DOC for cryptococcus infections?
a COMBO of flucytosine+amphotericin B
synergistic effect on crypto*
What drugs are in the echinocandins class?
Caspofungin
Micafungin
Anidulafungin
What is the DOC for candida infections?
Nystatin
Oral for GI candidiasis
Topically for other infections
What are the main toxicities of ketoconazole?
POTENT inhibitor of P450-many many many drug interactions
Gynecomastia and impotence- inhibits adrenal and testicular function
Prolonged QT
What is the DOC for onychomycosis?
Griseofulvin
Is amphotericin kidney damaging?
Extraordinary so
Kills their kidneys but worth it to save their life
What are the azoles?
Ketoconazole
Fluconazole
Voriconazole
Itraconazole
Isavuconazonium
Posaconazole
Is amphotericin B broad spectrum?
Yes
What is the MOA of amphotericin B?
It binds to ergosterol (in membrane) that causes a depolarization of the membrane and formation of pores that causes everything to leak out.
fungicidal
What are the cumulative toxicities of amphotericin B?
NEPHROTOXICITY!!***
Dose dependent, irreversible kidney damage
Azotemia- increased nitrogen in blood (BUN and creatinine will be increased)
Is fluconazole a good choice for suppressive or prophylactic therapy in HIV patients?
Yes
For example when their CD4 levels drop and they’re open to infection, this would be good prophylactic therapy
What are the main toxicities of voriconazole?
Drug interactions (it even inhibits the same enzyme that it’s metabolized by)
Visual impairment (reversible if taken off)
Is oral terbinafine good for onychomycosis?
Yes but it is not the DOC
How does the oral bioavailability of itraconazole change depending on whether you took capsules vs an oral solution?
Capsules have better availability if taken with food or soda
Oral solution has better availability on an empty stomach
DO NOT TAKE TWO DIFFERENT TYPES
What is the target of most antifungals?
Cell membrane or cell wall
Griseofulvin and flucytosine are exceptions
How is voriconzaole administered?
IV and oral
What is the food source for dermatophytes?
Keratin in skin hair and nails
If your patient is on voriconazole + ampho B for their aspergillosis infection and they start to have photophobia and changes in their vision, what do you think is causing it and what should you do?
Voriconazole is causing it
Take them off of it while vision changes are still reversible
What are the contraindications to ketoconazole?
Liver disease
QT prolonged
Is amphotericin B a good choice for fungal meningitis?
No, it has poor CNS penetration
How is griseofulvin administered?
Orally only!
Yes, it treats Dermatophytosis and onychomycosis but it is oral
What is the main side effect of itraconazole?
Potent inhibitor of CYP 3A4 - drug interactions
What is the MOA of the azoles?
Inhibits synthesis of ergosterol
which inhibits fungal growth- static***
What are the antifungals that are used for dermatophytes?
Griseofulvin
Terbinafine
Nystatin
What is meant by systemic mycoses due to opportunistic pathogens?
Infections of patients with immunodeficiency who would otherwise not be infected
Ex: candidiasis, aspergillosis, cryptococcosis
What drug would you use for invasive aspergillosis if voriconazole didn’t work? (aka refractory patient)
Caspofungin** must know
What is the MOA of griseofulvin?
Binds to microtubules and destroys spindle structure
Fungistatic
Is amphotericin B fungicidal or static?
Cidal
Causes depolarization of the membrane and pores that allows everything to leak out
Of all the azoles, which 2 have the most drugs interactions and which 2 have the least?
Most: ketoconazole and itraconazole
Least: fluconazole and voriconazole
How is terbinafine administered?
Orally or topically
What is the spectrum of ketoconazole?
Very broad spectrum.
It has even been tried as a substitute for amphotericin B
What is the fluid penetration like for fluconazole?
Very good penetration into body fluids, especially CSF
Why is griseofulvin effective against dermatophytosis infections of the skin hair and nails?
It binds to keratin. Dermatophytes EAT keratin.
This prevents infection in new skin.
Is terbinafine fungicidal or fungistatic?
Cidal
What is the MOA of echinocandins?
The fungins
Inhibit synthesis of B(1,3)-D-glucan, a major fungal cell wall component
CIDAL
If an antifungal agent has “flu” in the name, what kind of infection is it good for?
CNS
What is the DOC for aspergillus infection?
Voriconazole + Amphotericin B***
Who should NOT take griseofulvin?***
Pregnant women 🤰
Men 6 months prior to fathering a child! 👨👦
Acute intermittent porphyria
Hepatocellular failure
How is nystatin administered?
Oral or topical
What is used for the primary treatment of invasive aspergillosis?
Voriconazole (plus amphotericin)
What are the toxicities of flucytosine?
Depression of bone marrow- anemia, leukopenia, thrombocytopenia
Elevated AST or ALT
GI- it is converted to 5-FU bu bacteria too and then kills your flora
(All worth it because crypto is life-threatening)
What is the MOA of flucytosine?
Gets converted to 5-fluorauracil which messes with DNA and RNA synthesis
What is known as “ringworm of the nail”
Dermatophytic onychomycosis
What is the MOA of terbinafine?
Interferes with sterol biosynthesis
What are the main toxicities of griseofulvin?
Headache
Disulfiram-like reaction- no alcohol for 6-12 months to treat your toenail infection!!!!!???! 😟
Photosensitivity- I CAN’T EVEN TAN? 👙
Does fluconazole have any drug interactions?
It does, but way less than the other azoles.
It inhibits CYP2C9, but way less drugs are metabolized by 2C9
What are the 2 polyene antibiotics?
Nystatin
Amphotericin B
Are echinocandins static or cidal?
Cidal**
They are the “penicillins of antifungals”
Inhibit synthesis of cell wall component!
When would we ever use ketoconazole?
Only when NO other antifungal therapy can be used
What is the MOA for terbinafine
Interferes with sterol biosynthesis.
Does terbinafine have a lot of side effects?
No
What are the 2 drugs on this exam that have visual side effects?
Ethambutol
Voriconazole
If someone is immunocompromised and develops a systemic fungal infection, can you give them amphotericin B to reduce the load until their kidneys cant take it anymore, and then maintain it with a static drug like an azole?
Yes this is a good plan
What is a a symptom of nephrotoxicity you need to look out for when your patient is on amphotericin B?
Azotemia (BUN and creatinine are increased)
Ketoconazole and Rifampin both affect the CYP450 system, but not in the same way. Which is which?
Keto inhibits P450
Rifampin induces
(So Keto would cause toxicity of the drugs it interacted with and rifampin would cause them to be less effective)
What drug would be the second line for aspergillus if voriconazole didn’t work?
Caspofungin