Chapter 48: Antifungal Agents
Interactions between this drug and cell membrane components can result in the formation of pores lined by hydrophilic groups present in the drug molecule.
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. The answer is D.
Which statement about fluconazole is accurate?
(A) Does not penetrate the blood-brain barrier
(B) Drug of choice in treatment of aspergillosis
(C) Induces hepatic drug-metabolizing enzymes
(D) Has the least effect of all azoles on drug metabolism
(E) Oral bioavailability is less than that of ketoconazole
The azoles with activity against Aspergillus are itraconazole and voriconazole. Fluconazole is the best absorbed member of the azole group by the oral route and the only one that readily penetrates into cerebrospinal fluid. Although fluconazole may inhibit the metabolism of some drugs, it has the least effect of all azoles on hepatic microsomal drug-metabolizing enzymes. The answer is D.
A 37-year-old woman with leukemia was undergoing chemotherapy with intravenous antineoplastic drugs. During treatment, she developed a systemic infection from an opportunistic pathogen. There was no erythema or edema at the catheter insertion site. A white vaginal discharge was observed. After appropriate specimens were obtained for culture, empiric antibiotic therapy was started with gentamicin, nafcillin, and ticarcillin intravenously. This regimen was maintained for 72 h, during which time the patient’s condition did not improve significantly. Her throat was sore, and white plaques had appeared in her pharynx. On day 4, none of the cultures had shown any bacterial growth, but both the blood and urine cultures grew out Candida albicans.
At this point, the best course of action is to
(A) Continue current antibiotics and start griseofulvin
(B) Continue current antibiotics and start amphotericin B
(C) Stop current antibiotics and start itraconazole