Which virus is foscarnet sodium primarily used to treat?

Foscarnet sodium is primarily used to treat infections caused by cytomegalovirus (CMV), particularly in patients with weakened immune systems, such as those with AIDS or those undergoing organ transplantation. CMV can cause serious complications, especially in immunocompromised individuals, making effective treatment crucial.

Foscarnet works as an antiviral by inhibiting viral DNA synthesis, which is essential for the replication of CMV. Its usage is particularly significant when patients cannot tolerate other antiviral medications like ganciclovir, making it an important therapeutic option for managing CMV infections.

In contrast, while foscarnet can have activity against other viruses, it is not the first-line treatment for HIV, influenza, or herpes simplex virus infections, wherein alternative antiviral agents are typically preferred. This specificity highlights the importance of understanding the unique applications of antiviral medications in the context of different viral infections.