Antibiotic, Antifungal, Antiviral Drugs

Efficacy has been demonstrated in clinical studies in patients for primary therapy of invasive aspergillosis, for primary and salvage therapy of invasive aspergillosis, and for treatment of invasive aspergillosis in patients whose disease was refractory to, or who were intolerant of, other antifungal therapy. Aspergillus fumigatus was the most frequent isolate in patients with aspergillosis participating in clinical trials with the drug. A complete or partial response was achieved in 48% of patients in this study, with lower response rates observed in patients with definite disease (38%) than in those with probable disease (58%).

Voriconazole, a triazole antifungal agent, is a synthetic derivative of fluconazole. Like other azole antifungal agents, voriconazole presumably exerts its antifungal activity by altering cellular membranes, resulting in increased permeability, secondary metabolic effects, and growth inhibition. Although the exact mechanism of action of voriconazole has not been fully determined, the drug inhibits cytochrome P-450-dependent sterol 14-a-demethylase in susceptible fungi, which leads to accumulation of C-14-methylated sterols (e.g., lanosterol) and decreased concentrations of ergosterol. Voriconazole is active in vitro against Aspergillus fumigatus, A. flavus, A. niger, and A. terreus.

Ketoconazole is administered orally. To ensure absorption in patients with achlorhydria, it has been recommended that each 200 mg of ketoconazole be dissolved in 4 mL of 0.2N hydrochloric acid solution or taken with 200 mL of 0.1N hydrochloric acid.

Oral ketoconazole is used in the treatment of blastomycosis, candidal infections (i.e., oropharyngeal and/or esophageal candidiasis, vulvovaginal candidiasis, candiduria, chronic mucocutaneous candidiasis),chromomycosis (chromoblastomycosis), coccidioidomycosis, histoplasmosis, and paracoccidioidomycosis.

Itraconazole generally is well tolerated. However, serious potentially life-threatening adverse effects, including congestive heart failure, pulmonary edema, and hepatotoxicity, have occurred rarely in patients receiving IV or oral itraconazole. In clinical studies evaluating itraconazole for the treatment of systemic fungal infections, adverse effects requiring discontinuance of the drug occurred in up to 11% of patients; the median duration of therapy before discontinuance was 81 days (range: 2-776 days).

While fluconazole can alter the pharmacokinetics of certain drugs that undergo hepatic metabolism, the magnitude of such alterations appears to be less than those associated with ketoconazole; however, comparative studies have not been performed to date. In addition, the possibility that the risk of developing such interactions may be increased at relatively high fluconazole dosages (e.g., 200 mg daily or more) should be considered. Results of studies evaluating combined use of fluconazole and amphotericin B in animal models of aspergillosis, candidiasis, or cryptococcosis have been conflicting.

Fluconazole is administered orally or by IV infusion. Since absorption of fluconazole from the GI tract is rapid and almost complete, IV therapy with the drug generally is reserved for patients who do not tolerate or are unable to take the drug orally.

Terbinafine hydrochloride is a synthetic allylamine antifungal agent. Terbinafine is structurally and pharmacologically related to naftifine.