Peramivir is primarily used in the treatment of influenza, particularly for patients who are unable to take oral or inhaled antiviral medications. It is administered intravenously, making it a suitable option for hospitalized patients or those with severe influenza symptoms. The drug works by inhibiting the neuraminidase enzyme, which is essential for the replication and spread of the influenza virus within the body. This helps to reduce the duration and severity of flu symptoms, as well as the risk of complications such as pneumonia. Peramivir is often considered in cases where other antiviral treatments, like oseltamivir or zanamivir, are not effective or feasible. It is especially valuable during influenza outbreaks or pandemics, providing a critical treatment option for high-risk populations, including the elderly, immunocompromised individuals, and those with chronic medical conditions.