Which antifungal drug acts by inhibiting the synthesis of β-1,3-glucan, a major structural component of the fungal cell wall?

Explanation

## Mechanism of Echinocandins **Key Point:** Echinocandins (caspofungin, micafungin, anidulafungin) inhibit β-1,3-glucan synthase, an enzyme essential for fungal cell wall synthesis. This leads to cell wall disruption and fungal cell death. ## Comparison with Other Antifungals | Drug Class | Target | Mechanism | |---|---|---| | **Echinocandins** | β-1,3-glucan synthase | Cell wall synthesis inhibition | | Azoles | Lanosterol 14α-demethylase (CYP51) | Ergosterol synthesis inhibition | | Polyenes | Ergosterol | Cell membrane disruption | | Flucytosine | Thymidylate synthase | Nucleotide synthesis inhibition | **High-Yield:** Echinocandins are fungicidal (kill fungi directly) rather than fungistatic. They are the drug of choice for invasive candidiasis and aspergillosis in hospitalized patients. **Clinical Pearl:** β-1,3-glucan is unique to fungi and absent in mammalian cells, making echinocandins highly selective with minimal toxicity. ## Cell Wall Structure Context The fungal cell wall consists of: 1. Chitin and β-glucans (structural polymers) 2. Proteins and lipids (functional components) Echinocandins specifically disrupt the β-glucan scaffold, causing osmotic instability and cell lysis.