Delayed vomiting can occur in patients treated with other chemotherapeutic agents. Since this appears to involve bowel inflammatory factors, the use of corticosteroids plus metoclopramide may provide limited benefit. However, serotonin antagonists have dominated CIE treatment protocols for the past decade. Cytotoxic agents release serotonin from enterochromaffin cells in the gut. These stimulate intestinal mucosal 5-HT 3 receptors and, via the vagus, stimulate the chemoreceptor trigger zone that sends impulses to the vomiting center.
Antiemetic effect correlates with receptor blockade rather than with plasma levels.
All three agents can be administered as a single daily dose. The choice of agent should rest on cost differences. Since acquisition costs of the different serotonin antagonists may vary among institutions, the choice varies depending on locale. The most commonly used prophylactic regimen for moderately and highly emetogenic chemotherapy includes a corticosteroid and a serotonin antagonist. 5 Low emetogenic chemotherapy may be treated on an as-needed basis.