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Antifungal agents. Part II. The azoles
1Division of Allergy and Outpatient Infectious Disease and Internal Medicine, Mayo Clinic Rochester, Minnesota 55905, USA.
Abstract:
Before 1978, amphotericin B and flucytosine were the only drugs available for the treatment of systemic fungal infections. The imidazoles, miconazole and ketoconazole, were introduced during the next 3 years. Intravenously administered miconazole served a limited therapeutic role and is no longer available. Orally administered ketoconazole, an inexpensive, effective, and convenient option for treating mucosal candidiasis, was widely used for a decade because it was the only available oral therapy for systemic fungal infections. During the 1990s, use of ketoconazole diminished because of the release of the triazoles--fluconazole and itraconazole. Fluconazole is less toxic and has several pharmacologic advantages over ketoconazole, including penetration into the cerebrospinal fluid. In addition, it has superior efficacy against systemic candidiasis, cryptococcosis, and coccidioidomycosis. Despite a myriad of drug interactions and less favorable pharmacologic and toxicity profiles in comparison with fluconazole, itraconazole has become a valuable addition to the antifungal armamentarium. It has excellent activity against sporotrichosis and seems promising in the treatment of aspergillosis. Itraconazole has replaced ketoconazole as the therapy of choice for nonmeningeal, non-life-threatening cases of histoplasmosis, blastomycosis, and paracoccidioidomycosis and is effective in patients with cryptococcosis and coccidioidomycosis, including those with meningitis. Further investigation into the development of new antifungal agents is ongoing.
Insights
New antifungal drugs like fluconazole and itraconazole have largely replaced older treatments for systemic fungal infections, offering improved efficacy and safety profiles. Research continues for even newer antifungal agents.
Area of Science:
- Mycology
- Pharmacology
- Infectious Diseases
Background:
- Systemic fungal infections were primarily treated with amphotericin B and flucytosine before 1978.
- The introduction of imidazoles (miconazole, ketoconazole) marked advancements in antifungal therapy.
- Ketoconazole was a widely used oral antifungal for a decade due to limited alternatives.
Purpose of the Study:
- To review the evolution of antifungal drug therapy for systemic fungal infections.
- To compare the efficacy and safety profiles of older and newer antifungal agents.
- To highlight the therapeutic roles of triazoles (fluconazole, itraconazole).
Main Methods:
- Literature review of antifungal drug development and clinical use.
- Comparative analysis of pharmacologic properties, efficacy, and toxicity.
- Examination of treatment guidelines and therapeutic outcomes.
Main Results:
- Fluconazole offers improved safety and efficacy over ketoconazole, with better cerebrospinal fluid penetration.
- Itraconazole, despite drug interactions, is valuable for specific infections like sporotrichosis and aspergillosis.
- Itraconazole has replaced ketoconazole for certain endemic mycoses and is effective in cryptococcosis and coccidioidomycosis.
Conclusions:
- The development of triazoles (fluconazole, itraconazole) has significantly advanced systemic fungal infection treatment.
- Fluconazole and itraconazole represent major improvements over older antifungal agents.
- Ongoing research aims to develop novel antifungal agents to combat resistant fungal strains.