Category		Action	Drug examples
5-HT3 receptor antagonists		Block serotonin receptors in the CNS associated with chemoreceptor trigger zone and “vomiting center”	Ondansetron (Zofran) 4 to 8 mg orally or IV every four to eight hours
			Granisetron (Kytril) 1 mg orally or IV twice daily
Anticholinergics		Block acetylcholine receptors, slow bowel function, dry secretions	Scopolamine one to two patches (1.5 mg) applied topically and changed every 48 to 72 hours
Antihistamines		Block histamine release, have anticholinergic properties	Diphenhydramine (Benadryl) 12.5 to 50 mg orally, rectally, or IV every four to 12 hours
			Promethazine (Phenergan) 25 to 50 mg orally, rectally, or IV every six hours
Benzodiazepines		CNS anxiolytic effects; enhances gamma-aminobutyric acid action, slowing neuronal function	Lorazepam (Ativan) 0.5 to 2 mg orally or IV every six hours
Cannabinoids		Brainstem cannabinoid receptor agonists, CNS anxiolytic effects	Nabilone (Cesamet) 1 to 2 mg orally every 12 hours
			Dronabinol (Marinol) 5 to 10 mg orally, rectally, or under the tongue every six to eight hours
			Marijuana (only where legal for medical use)
Corticosteroids		Anti-inflammatory, reduces tumor-related swelling centrally or peripherally	Dexamethasone 2 to 8 mg orally or IV every four to eight hours
Dopamine receptor blockers
	Benzamides	Peripheral (more than central) dopamine D2 receptor blocker, with some 5-HT antagonism and cholinergic stimulation at bowel level improving gastric emptying and increasing lower esophageal sphincter tone	Metoclopramide (Reglan) 5 to 20 mg orally or IV every six hours as needed
	Butyrophenones	Central (more than peripheral) dopamine D2 receptor blocker, with antimuscarinic activity	Haloperidol (formerly Haldol) 0.5 to 2 mg orally or IV every four to eight hours
			Droperidol 1.25 to 2.5 mg IV (one to three doses)
	Phenothiazines	Dopamine D2 receptor blocker, with some antimuscarinic and antihistaminic activity	Prochlorperazine (formerly Compazine) 5 to 10 mg orally or IV every six to eight hours; or 25 mg rectally every 12 hours
			Chlorpromazine 12.5 to 25 mg IV every six to eight hours; or 25 to 50 mg orally every eight hours