Which medication is NOT classified as an antifungal?

Ganciclovir is not classified as an antifungal medication; it is an antiviral drug primarily used to treat infections caused by cytomegalovirus (CMV). CMV can lead to serious complications, particularly in immunocompromised patients, such as those undergoing organ transplantation or with HIV/AIDS.

In contrast, the other options listed are all antifungal agents. Natamycin, Amphotericin B, and Nystatin are specifically designed to combat fungal infections. Natamycin is often used for treating fungal infections in the eyes, Amphotericin B can treat a variety of systemic fungal infections, and Nystatin is typically used for oral and topical fungal infections, particularly those caused by Candida species. Understanding these classifications is crucial for effective pharmacological treatment of infections.