Which antiemetic is known to cause sedation as a common side effect?

Prochlorperazine is an antiemetic that belongs to the class of medications known as phenothiazines, which are primarily used to treat nausea and vomiting. One of the hallmark side effects of prochlorperazine, as well as other medications in this category, is sedation. This sedative effect arises because prochlorperazine works by blocking dopamine receptors in the brain, particularly in the area of the chemoreceptor trigger zone of the central nervous system, which is involved in the vomiting reflex. By inhibiting the activity of dopamine, these medications can also impact other neurotransmitter systems leading to drowsiness and sedation.

In contrast, the other medications listed have a different profile. Palonosetron, granisetron, and ondansetron are all serotonin 5-HT3 receptor antagonists primarily used for nausea related to chemotherapy, postoperative states, or other causes. These agents are generally well-tolerated and are less likely to cause sedation since their mechanism of action does not significantly interfere with the central nervous system pathways responsible for promoting wakefulness or alertness.