Antifungal Agents MCQs

This is a case of oral thrush, an overgrowth of the oral cavity with Candida albicans, which is a normal flora organism that may cause several disorders including oral thrush, esophagitis, and pneumonia in immunosuppressed patients. In HIV-infected individuals, oral and/or pharyngeal candidiasis infections are generally treated with clotrimazole lozenges or fluconazole oral tablets. Fluconazole acts as an inhibitor of the fungal cytochrome P-450 dependent enzyme lanosterol 14-a-demethylase. In a fungus, lanosterol 14-0-demethylase functions to convert lanosterol to ergosterol. This is responsible for the fungistatic effect of the "azole" antifungals. Reference: Basic & Clinical Pharmacology, Fourteenth Edition by Bertram G. Katzung Pg no. 880-882

Sertaconazole has additional anti inflammatory and anti pruritic activity. The imidazole derivatives oxiconazole, sulconazole, and sertaconazole are used for the topical treatment of infections caused by the common pathogenic dermatophytes. Oxiconazole nitrate is available as a 1% cream and lotion; sulconazole nitrate is supplied as a 1% solution or cream. Sertaconazole is a 2% cream marketed for tinea pedis.

A travel history can be important in the diagnosis of fungal disease. If this patient has a fungal infection of the lungs, it is probably due to C. immitis, which is endemic in dry regions of the western US. Pulmonary symptoms of coccidioidomycosis are usually self-limiting, and drug therapy is not commonly required in an otherwise healthy patient. Tender red nodules on extensor surfaces constitute a good prognostic sign. Erythema nodosum is a delayed hypersensitivity response to fungal antigens. No organisms are present in the lesions, and it is not a sign of disseminated disease. Reference- Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 862-863

Option A- A-27-year-old HIV+ man with suspected cryptococcal meningitis: Amphotericin B along with fluconazole is the treatment of choice. Option B- A-65-year-old diabetic with rhino-cerebral mucormycosis, has s.creat of 2.2 : Amphotericin B is the drug of choice in mucormycosis, it may cause transient rise in s.creat after large dose, but the benefit of continuing the drug outweigh the risk. It may be prevented by pre-loading patient with 1-2 L of NS. Renal replacement therapy can be done if required. Option C- A-34-year-old HIV+ woman with severe invasive histoplasmosis = Amphotericin B is preferred option in severe histoplasmosis. Option D- A-9-year-old immunosuppressed man with invasive aspergillosis = IV Itraconazole is better option compare to Amphotericin B for invasive aspergillosis. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 877-879

This patient with Candidemia with identified organism C. Glabrata is resistant to fluconazole and amphotericin B. Echinocandins like Caspofungin is Preferred drug for patient Symptoms of Candidemia may vary from fever to sepsis. It's hard to distinguish from bacterial sepsis. Infiltration of organs may occur either directly (e.g., ventriculoperitoneal shunt in meningitis) or hematogenous (e.g., endocarditis with IV drug use). Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 882-884

Explanation: ]There is no significant interaction between voriconazole and pyrazinamide . Voriconazole primarily interacts with drugs metabolized by CYP2C19, CYP2C9, and CYP3A4 . Explanation of other options: It should be taken on an empty stomach (Option A): Correct - food, especially high-fat meals, reduces voriconazole absorption. It requires therapeutic drug monitoring (Option B): Correct - maintain serum levels between 1-5 mg/L for efficacy and safety. It requires a loading dose (Option D): Correct- a loading dose helps achieve steady-state levels quickly in severe fungal infections. Key Takeaways: Voriconazole → triazole antifungal for invasive aspergillosis. Taken on an empty stomach. Requires therapeutic drug monitoring and loading dose. No known interaction with pyrazinamide.

Voriconazole causes immediate but transient visual disturbances including blurring of vision of unknown cause in more than 30% of patients. Based on animal studies voriconazole is a class D drug in terms of pregnancy risk. Option B- Infusion-related effects of Caspofungin include headache, gastrointestinal distress, fever, rash, and flushing (histamine release). Option C- Visual dysfunction has not been reported with Posaconazole, but the drug is an inhibitor of CYP3A4, increasing the levels of cyclosporine and tacrolimus. Option D- Prolonged high plasma levels of flucytosine cause reversible bone marrow depression, alopecia, and liver dysfunction. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 885-886

The polyene antifungal drugs amphotericin B and nystatin are amphipathic molecules that can interact with ergosterol in fungal cell membranes to form artificial pores. In these structures, the lipophilic groups on the drug molecule are arranged on the outside of the pore, and the hydrophilic regions are located on the inside. The fungicidal action of the polyenes derives from this interaction, which results in leakage of intracellular constituents. Reference- Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 858-859