Name the antifungal that is primarily effective against fungal biofilms.

Caspofungin is an antifungal agent that belongs to the echinocandin class and is particularly effective against fungal biofilms. Fungal biofilms are communities of microorganisms adhering to surfaces and surrounded by a self-produced matrix of extracellular polymeric substances, making them significantly more resistant to antifungal treatment. Caspofungin works by inhibiting the synthesis of β-(1,3)-D-glucan, a critical component of the fungal cell wall, which not only compromises the integrity of the cell wall but also reduces the ability of the fungus to maintain its biofilm structure.

This makes caspofungin an excellent choice for treating infections caused by Candida species and Aspergillus species, especially in cases where biofilm formation is a significant factor, such as in implanted devices or chronic infections. The other antifungals listed generally do not have the same level of efficacy against established biofilms due to differences in their mechanisms of action or formulation.