Pharmacology of Antifungal Agents

Pharmacology of Antifungal Agents explains mechanisms and actions of drugs that inhibit fungal growth or kill fungi.

Pharmacology of Antifungal Agents

• Fungal infections (mycoses) may be:
• Superficial: Skin, nails, mucous membranes
• Systemic: In immunocompromised patients (e.g., candidiasis, aspergillosis)
• Fungi are eukaryotic organisms, so antifungal drugs must be selective to avoid host toxicity.

Classes of Antifungal Drugs

1. Polyenes

   • Examples: Amphotericin B (systemic), Nystatin (topical)
   • Mechanism: Bind to ergosterol in fungal cell membrane → pores → cell lysis
   • Use:
     • Amphotericin B: Severe systemic mycoses
     • Nystatin: Oral thrush, vaginal candidiasis
   • Adverse Effects:
     • Amphotericin B: Nephrotoxicity, fever, chills, electrolyte imbalance

2. Azoles

   • Examples:
     • Imidazoles: Clotrimazole, Miconazole (topical)
     • Triazoles: Fluconazole, Itraconazole, Voriconazole (systemic)
     • Mechanism: Inhibit lanosterol 14-α-demethylase → ↓ ergosterol synthesis
   • Use:
     • Fluconazole: Candidiasis
     • Itraconazole: Histoplasmosis, onychomycosis
   • Side Effects: Hepatotoxicity, drug interactions (CYP inhibition)

3. Echinocandins

   • Examples: Caspofungin, Micafungin
   • Mechanism: Inhibit β-glucan synthesis → disrupt fungal cell wall
   • Use: Invasive candidiasis, aspergillosis
   • Adverse Effects: Minimal; generally well-tolerated

4. Allylamines

   • Example: Terbinafine
   • Mechanism: Inhibits squalene epoxidase → ↓ ergosterol
   • Use: Dermatophytosis (e.g., tinea infections), onychomycosis

5. Others

   • Griseofulvin: Binds microtubules → inhibits fungal mitosis; used for skin and nail infections
   • Flucytosine: Converted to 5-FU → inhibits DNA synthesis; used with Amphotericin B in cryptococcal meningitis

Pharmacokinetics (General Overview)

Note: Dosing may vary with age, comorbidities, and concurrent medications.

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