Antifungal Medications and Their Mechanisms

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Questions and Answers

Which of the following antifungal agents is used for mucocutaneous infections?

Nystatin

Griseofulvin (correct)

Flucytosine

Amphotericin B

What is the mechanism of action of Amphotericin B?

It inhibits the enzyme cytosine permease

It binds to chitin and alters its permeability

It binds to ergosterol and alters its permeability (correct)

It inhibits the synthesis of fungal cell walls

Which of the following is a characteristic of Flucytosine?

It is a broad-spectrum antifungal

It is used for topical infections

It is a fungicidal agent

It is a narrow-spectrum antifungal (correct)

Which of the following antifungal agents is used for topical infections?

Nystatin Signup and view all the answers

What is the major adverse effect of Amphotericin B?

Renal damage Signup and view all the answers

Which of the following antifungal agents is used for dermatophytosis?

Griseofulvin Signup and view all the answers

What is the mechanism of action of Echinocandins?

They inhibit the synthesis of fungal cell walls Signup and view all the answers

Which of the following is a characteristic of Azole antifungals?

They are used for systemic and topical infections Signup and view all the answers

What is the mechanism of action of ciclopirox?

Inhibiting the transport of essential elements in the fungal cell Signup and view all the answers

Which of the following is a characteristics of polyene macrolides?

Toxic for parenteral administration Signup and view all the answers

What is the primary use of terbinafine?

Treatment of dermatophytosis Signup and view all the answers

Which echinocandin is used for the treatment of esophageal candidiasis and invasive candidiasis?

Anidulafungin Signup and view all the answers

What is the mechanism of action of azole antifungals?

Reducing the fungal CYP 450 enzymes Signup and view all the answers

Which of the following is a side effect of voriconazole?

Blurring in vision Signup and view all the answers

What is the primary use of clotrimazole?

Treatment of vulvovaginal candidiasis Signup and view all the answers

Which echinocandin is used for empiric antifungal therapy during febrile neutropenia?

Caspofungin Signup and view all the answers

What is the mechanism of action of griseofulvin?

Interfering with fungal DNA synthesis Signup and view all the answers

Which of the following is a characteristic of itraconazole?

Azole of choice for treatment of dimorphic fungi Signup and view all the answers

Study Notes

Antifungal Agents

Flucytosine (5-FC): Fungistatic, narrow spectrum, converted to 5-FU, 5-FdUMP, and FUTP, inhibiting DNA and RNA synthesis; used only for candidal infections, with adverse reactions including bone marrow toxicity (anemia, leukopenia, and thrombocytopenia).

Azoles

Classified as Imidazoles or Triazoles based on the number of nitrogen atoms in the 5-membered azole ring
MOA: Reduce ergosterol synthesis by inhibiting fungal CYP 450 enzymes
Imidazoles:
- Ketoconazole: Prototype, less selective for fungal P450 than newer azoles
- Miconazole
- Clotrimazole
Triazoles:
- Itraconazole: Azole of choice for dimorphic fungi (histoplasma), used extensively for dermatophytoses and onychomycosis
- Fluconazole: Azole of choice for treatment and prophylaxis of cryptococcal meningitis, mucocutaneous candidiasis, and reducing fungal disease in bone marrow
- Voriconazole: Azole of choice for invasive aspergillosis, similar to itraconazole but less toxic than Amphotericin, with adverse reactions including blurring of vision
- Posaconazole: Newest triazole, broadest spectrum, used as salvage therapy for invasive aspergillosis, with activity against zygomycosis and mucormycosis

Echinocandins

Newest class of antifungal agents, large cyclic peptides linked to long-chain fatty acids
MOA: Inhibit synthesis of 1-3 glucan, disrupting fungal cell wall and causing cell death
Adverse reactions: Elevated liver enzymes, minor GI symptoms
Uses:
- Caspofungin: Disseminated and mucocutaneous candida infections, empiric antifungal therapy for febrile neutropenia
- Micafungin: Mucocutaneous candidiasis, prophylaxis for candida infections in bone marrow transplant patients
- Anidulafungin: Esophageal candidiasis, invasive candidiasis

Griseofulvin

Fungistatic, derived from Penicillium griseofulvum, insoluble, and replaced by newer antifungals (itraconazole, terbinafine)
Used for systemic treatment of dermatophytosis
Adverse reactions: Allergic syndrome, induce serum sickness, hepatitis

Terbinafine

Synthetic allylamine
Used for dermatophytoses, onychomycosis
MOA: Interferes with ergosterol biosynthesis, inhibiting fungal enzyme squalene epoxidase, leading to accumulation of toxic squalene
Adverse reactions: GI upset, headache

Nystatin

Polyene macrolide, similar to Amphotericin B
Too toxic for parenteral administration, only topical use
Active against Candida, used for suppression of local candidal infections (oropharyngeal thrush, vaginal candidiasis, intertriginous candidal infections)

Topical Azoles

Clotrimazole and Miconazole: Used for vulvovaginal candidiasis, dermatophytic infections (tinea corporis, tinea pedis, tinea cruris)
Oral Clotrimazole troches: Used for oral thrush, a pleasant-tasting alternative to Nystatin
Topical and shampoo forms of Ketoconazole: Used for seborrheic dermatitis and pityriasis versicolor

Topical Antifungals

Ciclopirox: Inhibits transport of essential elements in fungal cells, disrupting DNA, RNA, and protein synthesis

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Description

This quiz covers various antifungal medications, their mechanisms of action, and potential adverse effects. It includes information on fluoropyrimidine antifungals and azole antifungals, as well as their uses and side effects.