Oral ondansetron is highly active as rescue antiemetic treatment for moderately emetogenic chemotherapy: results of a randomized phase II study

In the present phase II randomized study, two different schedules of ondansetron were investigated as rescue antiemetic treatment for delayed emesis related to moderately emetogenic chemotherapy (MEC). Patients scheduled to receive a first course of MEC were randomized to ondansetron 8 mg intramuscularly (arm A) or ondansetron 16 mg orally (arm B) as rescue antiemetic treatment for delayed emesis. Efficacy and safety evaluation was performed from days 2 to 6 through the administration of a diary plus a questionnaire in which the emetic episodes and the use of the assigned rescue treatment were recorded. All patients received standard prophylaxis for delayed emesis with oral dexamethasone 8 mg daily for 4 days starting on day 2. Eighty-nine patients were enrolled into the study, of whom 44 were randomized to arm A and 45 to arm B. Twenty-two patients in each arm developed grade 1-2 delayed nausea/vomiting, all of which recurred to the rescue study treatment. Oral ondansetron resulted superior to intramuscular ondansetron in terms of complete response for nausea (77.3% vs 40.9%, respectively, p=0.01) and vomiting (81.8% vs 31.8%, respectively, p=0.001). Both schedules resulted to be very well tolerated, and no differences in toxicity were observed between the two arms of treatment. Furthermore, personal satisfaction about the use of the assigned rescue study medication was significantly higher in arm B. Due to its high efficacy and excellent tolerability, oral ondansetron is an important option in the management of MEC-related delayed emesis refractory to standard antiemetic prophylaxis.