- Prophylactic medication for the prevention of nausea and vomiting 24 hours prior to the start of radiation therapy through the full course of radiation therapy is prohibited, with the exception of the study drug. Corticosteroids will be allowed for treatment of cerebral swelling. Rescue medication for treatment of nausea and vomiting is permitted after radiation therapy at the discretion of the investigator. The agent, dose, and time of administration will be recorded in the patient diary;