The primary objective of the study is to examine the efficacy of Ondissolve for the prevention/rescue of Acute and Delayed Phase radiation induced nausea and vomiting (RINV) in patients undergoing single or multiple fraction, emetogenic palliative radiation therapy for painful bone metastases. The study population will be 30 patients seen in the RRRP at the Sunnybrook Odette Cancer Centre receiving palliative radiation therapy considered emetogenic for bone metastases. Patients will take the study medication (Ondissolve 8 mg) twice on each day of radiation therapy, at least one hour prior to treatment and repeat approximately 6-8 hours later the same day. Patients undergoing multiple fraction radiation therapy will take Ondissolve on weekends or holidays in between treatment. Secondary objectives include to evaluate key secondary endpoints related to RINV, and to investigate the ease and length of administration of protocol medicine. We hypothesize that Ondissolve will be effective in the prophylaxis of RINV, and the ease of use and administration will provide an appropriate delivery method for those unable to tolerate the oral form of ondansetron.