Antifungal review Flashcards by Ramses Saavedra

Which conditions facilitate the overgrowth of opportunistic organisms?

Alteration of gut flora, immunosuppression, systemic diseases (HIV, diabetes, adrenal suppression).

How well did you know this?

Not at all

Perfectly

What are the targets for antifungal drugs? (

Ergosterol, B-glucan synthase, inhibit fungal CYP450 and prevent ergosterol synth, inhibit squalene oxidase, interfere with DNA synth

How well did you know this?

Not at all

Perfectly

Which drugs target ergosterol?

Amphotericin B, nystatin

How well did you know this?

Not at all

Perfectly

Which drugs target b-glucan synthase?

Echinocandins-micafungin

How well did you know this?

Not at all

Perfectly

Which drugs target CYP450?

Triazoles - fluconazole, itraconazole; Imidazoles - ketoconazole, clotrimazole, miconazole

How well did you know this?

Not at all

Perfectly

Which drugs target squalene oxidase?

terbinafine

How well did you know this?

Not at all

Perfectly

Which drugs target DNA synthesis?

flucytosine

How well did you know this?

Not at all

Perfectly

What the the mechanism of action of amphotericin B?

binds to ergosterol and opens pores causing leakage of cell components and cell death.

How well did you know this?

Not at all

Perfectly

How is ampho B absorbed?

Poor oral, so given IV or topically. Can be used in bladder irrigation or injected in to the ventricles

How well did you know this?

Not at all

Perfectly

How is ampho B distributed?

Rapidly sequestered in tissues and slowly released but little CNS penetration

How well did you know this?

Not at all

Perfectly

T or F: Ampho B is the most reliable agent against most fungal pathogens.

True. Drug of choice for life-threatening systemic fungal infections.

How well did you know this?

Not at all

Perfectly

What are the adverse side effects of ampho B?

nephrotoxicity and anemia. Will often see fever, chills, rigor, hypotension (shake and bake). Can give acetaminophen-diphenhydramine or hydrocortisone. Also give merperidine for rigors

How well did you know this?

Not at all

Perfectly

What does nystatin do?

Similar mechanism of action as ampho B.

How well did you know this?

Not at all

Perfectly

How is nystatin given?

topical treatment of candida infections

How well did you know this?

Not at all

Perfectly

T or F: Nystatin is given systemically by IV.

False. toxic so no IV use

How well did you know this?

Not at all

Perfectly

What do echinocandins target?

b-glucan synthase, a cell wall component

How well did you know this?

Not at all

Perfectly

How are echinocandins given?

How well did you know this?

Not at all

Perfectly

How are echinocandins eliminated?

renal, require dosing for renal insufficiency

How well did you know this?

Not at all

Perfectly

Which infections are enchinocandins used to treat?

aspergilosis that is refractory to ampho or intraconazole

How well did you know this?

Not at all

Perfectly

What are the adverse side effects of echinocandins?

allerigic type reaction, fever, nausea, headache, phlebitis

How well did you know this?

Not at all

Perfectly

T or F: Itracon and Flucon are fungistatic.

TRUE

How well did you know this?

Not at all

Perfectly

How are itra and flucon given?

Orally

How are itra and flucon eliminated?

Flu - renal; Itra - hepatic

T or F: Itracon can enter the CNS.

False. Flucon can enter the CNS to treat fungal meningitis.

What are the clinical uses of flucon?

Vaginal candidiasis if topicals fail. Oropharyng and esophag candidiasis, serious systemic infections. Cryptococcal meningitis in AIDs patients.

What are the clinical uses of itracon?

dermatophytoses and onchomycosis. Also beneficial for aspergillosis and other system infection over flucon.

What are the adverse side effects of flucon?

Well tolerated, gi distress, rash, inc liver enzymes. Inhibit cyp450 metabolism so will have drug interactions. Pregnacy cat D

What are the adverse side effects of itracon?

same as flucon except preg cat C.

T or F: Imidazoles are fungicial.

True, but only at high concentrations

How is ketoconazole given?

oral or IV. systemic!

How is ketoconazole absorbed?

poorly but better at low pH (with food)

How is ketoconazole distributed?

well, but not in CNS. also crosses the placenta

How is ketoconazole eliminated?

hepatic, breast milk

How is ketoconazole used?

chronic mucocutaneous candidiasis

How is clotrimazole used?

oral and vaginal candidiasis as creams. not used systemically due to toxicity

How is ketoconazole toxic?

anorexia, nausea, pruritis, rash, dizziness, hepatotox. Can inhibit testosterone synthesis, drug interaction -strong inhibitor of CYP3A4

What is the mechanism of action of terbinafine?

inhibits squalene oxidase as part of the ergosterol synth pathway.

T or F: Terbinafine is fungicidal.

True. accumulation of squalene is toxic.

How is terbinafine used?

orally for onychomycosis - toe and nail infection, topically for athletes foot (tinea cruris and corporis)

How is terbinafine toxic?

gi upset, rash, headache, inhibition of CYP450 drug metabolism

What is the mechanism of action of flucytosine?

converted into 5-fluorouracil via fungal cytosine deaminase and interferes with DNA synthesis

How is flucytosine administered?

oral (qid)

How is flucytosine distributed?

all over including CNS

How is flucytosine eliminated?

renal

How is flucytosine used?

cryptococcus, candidiasis, chromoblastomycosis

How is flucytosine toxic?

rarely toxic, but can seen nausea, vomiting and rash. High levels have bone marrow depression and abnormal liver function, hair loss.

What is the mechanism of action of griseofulvin?

Binds microtubules and inhibits mitosis.

T or F: Griseofulvin is fungistatic

TRUE

How is griseo absorbed?

oral, but poorly

How is griseo distributed?

has a high affinity for keratin so it goes to keratin

How is griseo eliminated?

feces

How is griseo used?

severe dermatophytosis in skin/hair, nails

How is griseo toxic?

hypersensitivity reactions, occasionally headache, gi upset, mental confusion