A REVIEW OF ONDANSETRON IN THE MANAGEMENT OF RADIOTHERAPY-INDUCED EMESIS

This paper reviews experience with ondansetron in radiotherapy-induced emesis. The efficacy of ondansetron is assessed following a number of different radiotherapy regimens: single-dose radiotherapy, fractionated radiotherapy, total body irradiation (TBI) and hemi-body irradiation. In single-dose radiation-induced emesis, ondansetron (8 mg orally 3 times daily) provided superior anti-emetic control compared with metoclopramide (10 mg orally 3 times daily): 92 and 46% of patients, respectively, experienced complete control of emesis (0 emetic episodes) in the first 24 h following treatment (p < 0.001). Similarly, ondansetron (8 mg orally 3 times daily) was significantly (p < 0.00 1) more effective than prochlorperazine (I 0 mg orally 3 times daily) with 59 and 35% of patients, respectively, achieving complete control of emesis on the 'worst day' of a fractionated radiotherapy regimen (up to 20 fractions). Two studies evaluating the efficacy of ondansetron in TBI-induced emesis have demonstrated that ondansetron is effective in paediatric and adult patients receiving chemotherapy and TBI prior to bone marrow transplantation. In these studies, 57-81% of patients experienced 2 or fewer emetic episodes during TBI. For hemi-body irradiation, ondansetron (8 mg) and dexamethasone (8 mg) given orally produced complete control of emesis in 12 out of 14 patients. The effectiveness of this regimen now enables patients receiving hemi-body irradiation to be treated as outpatients in many cases. Anecdotal data also shows that ondansetron is effective when given as intervention treatment in patients with established emesis. In none of the studies were there any serious adverse events following ondansetron treatment. It can therefore be concluded that ondansetron is an effective and well tolerated antiemetic for the prophylaxis and treatment of radiation-induced emesis and nausea. The use of effective anti-emetic treatments may have resource implications such as reducing bed occupancy and enabling the use of fewer, larger fractions of radiotherapy.