Antiemetics and Drugs for Motion Sickness

Key points

• • Vomiting is driven by several signals, so antiemetics are chosen to block the pathway that is most active in a given cause.
• • Antihistamines and antimuscarinics such as hyoscine work well for motion sickness, which is driven by the balance organ of the inner ear.
• • Dopamine antagonists such as metoclopramide act on the brain's vomiting centre and also speed the emptying of the stomach.
• • The 5-HT3 antagonists such as ondansetron are powerful against the sickness caused by cancer chemotherapy and after surgery.
• • Because these drugs act on different pathways, more than one may be combined for vomiting that is hard to control.