Antiemetics in children receiving cancer chemotherapy.

Nausea and vomiting are debilitating side effects that often accompany the administration of chemotherapy and may lead to adverse physiological and psychological effects. Chemotherapy agents usually stimulate the chemoreceptor trigger zone, which then sends signals to the vomiting center in the medullary lateral reticular formation. The neurochemistry of vomiting involves serotonin and serotonin S3 receptors. Nausea and vomiting are difficult to treat once they have occurred, and prior poor antiemetic control may lead to future anticipatory nausea and vomiting. Thus, good antiemetic regimens must be prophylactic, scheduled, and individualized. Specific regimens must be adjusted to account for the emetogenic potential of the chemotherapy drug(s) being administered and the individual patient's preferences. The major classes of antiemetics include serotonin S3 receptor antagonists, phenothiazines and metoclopramide. Steroids are ineffective antiemetics alone but good potentiators of other antiemetics. We usually recommend a serotonin S3 receptor antagonist alone for less emetogenic regimens or in conjunction with dexamethasone for more emetogenic regimens. For breakthrough vomiting, we usually add lorazepam and/or scopolamine.