Controlling cancer chemotherapy-induced emesis. An update.

Cytotoxic chemotherapy can induce acute, delayed and anticipatory nausea and vomiting. The efficacy and toxicity data of the available anti-emetics and their role in chemotherapy-induced emesis are reviewed. Moreover, some pitfalls in the methodology of anti-emetic trials as well as factors known to affect the individual sensitivity of patients for the emetic challenge are illustrated. So far, high-dose metoclopramide (3-6 mg.kg-1.d-1) was the most effective single agent in the control of acute emesis. However, extrapyramidal reactions caused by its dopamine antagonism remained a major drawback. The addition of dexamethasone and/or lorazepam decreases the incidence of extrapyramidal reactions, and further improves anti-emetic control. In animals, serotonin type 3 receptor antagonists have demonstrated promising anti-emetic results against chemotherapy-induced and radiotherapy-induced emesis; the results of clinical studies are awaited. Delayed nausea and vomiting have not been studied as extensively. At present, the combination of metoclopramide and dexamethasone offers an optimal protection in approximately 50% of patients on cisplatin chemotherapy. Anticipatory nausea and emesis remain major problems, and an effective pharmacological treatment is lacking. Attempts to control this type of emesis focus on drugs with amnesic properties and on behaviour therapy.