“Dopamine antagonists, such as metoclopramide, block dopamine stimulation in the chemoreceptor trigger zone, thereby limiting emetic input to the medullary vomiting center (SOR C). SSRIs, such as ondansetron, also work in the chemoreceptor trigger zone. They inhibit serotonin at the 5-HT3 receptor in the small bowel, vagus nerve, and chemoreceptor trigger zone.
Antihistamines and anticholinergics limit stimulation of the vomiting center through inhibition of the H1 receptor and acetylcholine, respectively. These medications are particularly beneficial in vestibular-mediated nausea, such as motion sickness.” ABFM
References
Practical selection of antiemetics in the ambulatory setting. Am Fam Physician 2015;91(5):293-296.