Ciclopirox (also known as CPX, Penlac, Loprox, Ciclodan, CNL8 Nail, and others) is a widely-used synthetic anti-fungal and anti-yeast agent used to treat external skin infections.

Its specific mechanism of action is not yet clear.

It's possible that the antifungal activity may be partially caused by iron limitation in the infecting organism (ref. Antimicrobial Agents and Chemotherapy 47(6); 2003). Alternatively, other research groups suggest that ciclopirox may be disrupting DNA repair, cell division signals and structures (mitotic spindles) as well as some elements of intracellular transport. (ref. Molecules and Cells 28;15(1):55-61)