Onitryl

Dosage and Administration:

For chemotherapy-induced nausea / vomiting prophylaxis (CINV prophylaxis) and radiation-induced nausea/vomiting prophylaxis (RINV prophylaxis):
Adults receiving moderately emetogenic chemotherapy: 8 mg PO twice daily. Give first dose 30 minutes before the start of emetogenic chemotherapy, with a subsequent dose 8 hours after the initial dose. Further doses may be given every 12 hours for 1 to 2 days after completion of chemotherapy.
Adults receiving highly emetogenic chemotherapy: 24 mg dose PO once given 30 minutes before administration of single-day highly emetogenic chemotherapy, including cisplatin 50 mg/m2 or more. Multiday, single dose administration of ondansetron 24 mg has not been studied.
Adults receiving radiotherapy (general dosage): 8 mg PO 3 times daily.
Adults receiving total body irradiation: 8 mg PO 1 to 2 hours prior to each fraction of radiotherapy each day.
Adults receiving daily fractionated radiotherapy or single high-dose fraction radiotherapy to the abdomen: Initially, 8 mg PO 1 to 2 hours prior to radiotherapy. Then, 8 mg PO every 8 hours after the first dose for 1 to 2 days following completion of radiotherapy. 
Children and Adolescents 12 years and older: 8 mg PO twice daily. Give the first dose 30 minutes prior to chemotherapy with a subsequent dose 8 hours after the initial dose. For radiation, give the first dose 1 to 2 hours prior to therapy. Further doses may be given every 8 to 12 hours for 1 to 5 days after completion of therapy. Alternatively, a single 24 mg PO dose may be given prior to chemotherapy. 
Children 4 to 11 years: 4 mg PO 3 times daily. Give the first dose 30 minutes prior to chemotherapy, with subsequent doses 4 and 8 hours after the initial dose. For radiation, give the first dose 1 to 2 hours prior to therapy. Further doses may be given every 8 hours for 1 to 5 days after completion of therapy. Alternatively, a single 12 mg PO dose may be given prior to chemotherapy.
For the short-term treatment of nausea/vomiting associated with acute gastroenteritis:
Children and Adolescents weighing more than 30 kg: 6 to 8 mg PO as a single dose along with oral or IV rehydration. Alternatively, 0.2 mg/kg/dose PO every 8 hours for 3 doses has also been studied. 
Children weighing 15 to 30 kg: 4 mg PO as a single dose along with oral or IV rehydration. Alternatively, 0.2 mg/kg/dose PO every 8 hours for 3 doses has also been studied.