Chapter 47: Antifungal Drugs – Systemic & Topical Infections

Fungal infections vary in severity, ranging from localized skin infections (dermatomycoses) to potentially fatal systemic mycoses that commonly target immunocompromised patients, transplant recipients, or those taking immunosuppressive therapy. The pharmacology of antifungals is detailed across four primary chemical classes, each featuring a distinct mechanism of action against fungal cell structures. For instance, polyenes like amphotericin B bind to ergosterol—the critical sterol in fungal cell membranes—leading to cell leakage and death. Azole antifungals (triazoles and imidazoles, such as fluconazole and voriconazole) inhibit the fungal cytochrome P450 enzymes necessary for ergosterol production, causing structural defects. A newer class, the echinocandins (e.g., caspofungin), prevent the synthesis of glucans, which are vital components of the fungal cell wall. Although amphotericin B remains the drug of choice for many severe systemic mycoses, its use is often limited by significant adverse effects, including infusion syndrome, necessitating careful pre-treatment with antiemetics and antipyretics. Crucial nursing responsibilities for patients receiving antifungal therapy include thorough baseline assessment of liver and kidney function, monitoring for drug interactions (often due to metabolism by the cytochrome P450 enzyme system), and administering IV infusions (like amphotericin B) slowly while continuously monitoring vital signs. Specific patient education is also required for oral suspensions, such as the "swish and swallow" method for nystatin, to ensure therapeutic efficacy against oral candidiasis.