Azole antifungals were launched with the imidazole miconazole nearly 2 decades ago. The introduction of systemically available triazole antifungals fluconazole and itraconazole solidified the azoles’ place in the prevention and treatment of fungal infections. Three new azole antifungals, voriconazole (Pfizer Vfend)), posa-conazole (Schering Plough), and ravuconazole (Bristol-Myers Squibb) have recently been introduced. All of the new triazoles have excellent in vitro activity against a wide variety of fungal pathogens Minimum inhibitory concentration (MIC) values are lower than those of older triazoles. Voriconazole, has superior in vitro activity against isolates of Candida albicans, Candida parapsilosis, Candida tropicalis, and C. krusei compared with fluconazole. Of the Candida sp, these drugs are least active against C. glabrata. The new azoles all have in vitro activity against Aspergillus sp that is comparable with or superior to that of amphotericin B and itraconazole, and much superior to that of flucanozole. These two drugs are comparable for Candida but Voricazole is superior for Aspergillus, which is what this patient’s prophylaxis is for. However, there is no comparable information on the efficacy of prophylxis with Vfend versus flucanozole, rather than treatment of established infections. There are concerns about breakthrough Candidal infections in patients on Vfend prophylxis. NCCN on p. 79 of Cancer Related Infection Prophylaxis cites one study available only in abstract and considers it to be a level 2b recommendation.
Chavez M, Bernal S, Valverde A, Gutierrez M, Quindos G, Mazuelos E. In-vitro activity of voriconazole (UK-109,496), LY303366 and other antifungal agents against oral Candida sp isolates from HIV-infected patients. J Antimicrob Chemother 2000;44(5):697-700. Girmenia C, Tuccinardi C, Santilli S, et al. In vitro activity of fluconazole and voriconazole against isolates of Candida albicans from patients with haematological malignancies. J Antimicrob Chemother 2000;46(3):479-84.
Vfend, Prescribing Information 2018
Marks D etal, Voriconazole for prophylaxis of invasive fungal infections after allogeneic hematopoietic stem cell transplantation. Expert Rev Anti Infect Ther. 2017 May;15(5):493-502.
NCCN, Supportive 2018