antifungal

An antifungal is a drug that kills fungi or stops them from growing, used for everything from athlete's foot to life-threatening bloodstream infections. The catch is that fungi, like us, are eukaryotes — their cells are built much like ours — so finding a target that hurts the fungus but not the patient is genuinely difficult.

Antifungals exploit the few real differences. The most-used drugs target ergosterol, the fungal version of cholesterol in the cell membrane: azoles block the enzyme that makes ergosterol, while polyenes physically punch holes in membranes that contain it. Echinocandins instead attack the fungal cell wall, a structure animal cells lack entirely, making them among the most selective antifungals.

Because the fungal and human cell are so alike, antifungals tend to be more toxic and slower-acting than antibacterials, and serious infections may need weeks of therapy. Resistance is a growing worry too — drug-resistant Candida species are spreading in hospitals — which keeps the search for new fungal-specific targets an active and honest challenge.