What medication is indicated for treating genital herpes simplex virus infection?

Valacyclovir is indicated for treating genital herpes simplex virus infection. This antiviral medication works by inhibiting viral DNA synthesis and thereby reducing the viral load during an active outbreak. It is effectively used to manage symptoms, shorten the duration of outbreaks, and can also be used for suppressive therapy in order to decrease the frequency of recurrent episodes.

The other medications mentioned serve different purposes. Cidofovir is primarily used for treating infections caused by cytomegalovirus, particularly in immunocompromised patients, and is not effective against herpes simplex virus. Ganciclovir is also used for cytomegalovirus infections and not indicated for genital herpes. Zanamivir is an antiviral medication used for influenza and does not have any activity against herpes viruses.

This makes valacyclovir the appropriate choice for treating genital herpes simplex virus infections, as it specifically targets the virus that causes this condition.