Ganciclovir sodium is primarily used in the treatment of cytomegalovirus (CMV) infections, particularly in immunocompromised patients such as those with HIV/AIDS or organ transplant recipients. It is effective in managing CMV retinitis, a serious eye infection that can lead to blindness if untreated. Additionally, it is used to prevent CMV disease in transplant patients who are at high risk of infection. The drug works by inhibiting viral DNA replication, thereby controlling the spread of the virus. It is administered intravenously or orally, depending on the severity of the infection and patient condition. Regular monitoring of kidney function and blood counts is essential during treatment due to potential side effects.