Advances in anti-emetic therapy.

Evaluation of the activity of anti-emetic drugs in randomized controlled trials has, in most cases, demonstrated the superiority of treatment over placebo administration for the control of chemotherapy-induced emesis (see Table 15). The degree of control of emesis relates both to the intensity of the emetogenic stimulus and to the effectiveness of the anti-emetic agent employed. Prochlorperazine is a relatively weak anti-emetic. The drug exhibits modest activity in the treatment of emesis produced by mild emetogenic stimuli, but is relatively ineffective in the treatment of patients on moderate to severely emetogenic drugs. Domperidone has demonstrated activity against moderately emetogenic stimuli but has not been evaluated in cisplatin-treated patients. The cannabinoids have proved efficacious in the treatment of emesis induced by more severe emetogenic stimuli. THC therapy, however, has been limited in some studies by toxicity. High-dose metoclopramide has demonstrated efficacy in small series of patients in the treatment of cisplatin-induced vomiting. Dexamethasone activity as a single agent is in doubt but the drug may improve the efficacy of metoclopramide when used in combination. For the future, the use of combinations of anti-emetics with differing sites of action and non-overlapping toxicities, may lead to further improvement in efficacy. Combinations of centrally-acting drugs such as the cannabinoids plus dopamine antagonists such as metoclopramide or domperidone, are worth evaluating. The control of anticipatory nausea and vomiting is another major area of interest which has, as yet, not been studied in any depth. A single comparative trial has been reported in the literature (50) and in this study, behavioural therapy rather than drug therapy was evaluated. There may be a place for the evaluation of behavioural therapy in combination with drugs exhibiting anxiolytic properties such as the benzodiazepines and the cannabinoids. Finally, new anti-emetic drugs with an improved therapeutic index will be welcomed by the patient.