Delayed emesis: a dilemma in antiemetic control.

Delayed emesis remains a major factor limiting successful antiemetic treatment. It is well described in patients receiving cisplatin at doses of 100 mg/m2 or greater (occurring in nearly 90% of patients), but its incidence and severity in other settings is less well known. Several studies have indicated that combinations of oral metoclopramide plus dexamethasone can decrease the incidence of this problem by one-half; however, a large number of patients remain for whom delayed emesis is their main emetic problem. To date, studies with single-agent serotonin antagonists have not shown encouraging efficacy. In addition, it appears that delayed emesis may begin as early as 16 h after chemotherapy, yielding implications for new study designs. Proper methodology for clinical studies has been demonstrated in a few well-conducted trials, which should form a basis for future research.