/reference/drugs/antiemetics
Ondansetron, droperidol, aprepitant, dexamethasone, metoclopramide
5-HT3 receptor antagonist
Blocks serotonin receptors at vagal afferents and chemoreceptor trigger zone.
Dopamine D2 receptor antagonist (prokinetic)
Central D2 antagonism at the chemoreceptor trigger zone (antiemetic). Peripherally, sensitizes upper-GI tissue to acetylcholine → increases lower esophageal sphincter tone, accelerates gastric emptying, speeds duodenal transit. Mild 5-HT4 agonism contributes to prokinesis.
Butyrophenone D2 receptor antagonist
Potent central D2 antagonism at the chemoreceptor trigger zone. Also α-adrenergic blockade and mild GABA-A facilitation. Highly effective antiemetic and sedative — historically a key component of neuroleptanalgesia.
NK-1 (substance P) receptor antagonist
Selective antagonist at central neurokinin-1 receptors in the area postrema and nucleus tractus solitarius. Blocks substance-P-mediated emesis, particularly the delayed phase (24–72 h post-stimulus) where 5-HT3 antagonists lose efficacy.