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An anti-emetic is a drug that is effective against vomiting and nausea. Anti-emetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics and chemotherapy directed against cancer.

Anti-emetics include:

• 5-HT₃ receptor antagonists - these block serotonin receptors in the central nervous system and gastrointestinal tract. As such, they can be used to treat post-operative and cytotoxic drug nausea & vomiting.
  • Dolasetron
  • Granisetron
  • Ondansetron
  • Tropisetron
  • Palonosetron (Aloxi, a new 5HT3 antagonist)
• Dopamine antagonists act in the brain and are used to treat nausea and vomiting associated with neoplastic disease, radiation sickness, opioids, cytotoxic drugs and general anaesthetics.
  • Domperidone
  • Droperidol, Haloperidol, Chlorpromazine, Promethazine, Prochlorperazine. Some of these drugs are limited in their usefullness by their extra-pyramidal and sedative side-effects.
  • Metoclopramide also acts on the GI tract as a pro-kinetic, and is thus useful in gastrointestinal disease; however, it is poor in cytotoxic or post-op vomiting.
  • Alizapride
• Antihistamines (H₁ histamine receptor antagonists), effective in many conditions, including motion sickness and severe morning sickness in pregnancy.
  • Cyclizine
  • Diphenhydramine
  • Dimenhydrinate
  • Meclizine
  • Promethazine (Pentazine, Phenergan, Promacot)
  • Hydroxyzine
• Anticholinergics
  • Hyoscine (also known as Scopolamine)
• Steroids
  • Dexamethasone given in low dose at the onset of a general anaesthetic for surgery is an effective anti-emetic. The specific mechanism of action is not fully understood.
• Benzodiazepines
  • Midazolam given at the onset of anaesthesia has been shown in recent trials to be as effective as ondansetron, a 5HT3 antagonist in the prevention of post-operative nausea and vomiting. Further studies need to be undertaken.
• Cannabinoids are second-line therapy, used in patients with cytotoxic nausea & vomiting unresponsive to other agents. Drowsiness and dizziness are frequent side-effects.
  • Cannabis
  • Marinol
• Other
  • Trimethobenzamide; thought to work on the CTZ
  • Ginger
  • Emetrol also claims to be an effective anti-emetic.
  • Propofol given intravenously has been used in an acute care setting in hospital as a rescue therapy for emesis.

Drugs for sorting

• Chlorprothixene
• Fluphenazine
• Perphenazine
• Piracetam
• Sulpiride

• non-pharmaceutical therapies with some evidence of efficacy include acupuncture^{[citation needed]} and hypnosis^{[citation needed]}. All drugs have potential side effects and it is important to try to reduce the baseline risk of nausea and vomiting, particularly with respect to surgery.

See also

• Cholinergic blocking drugs
• Emetic
• Hyperemesis gravidarum
• Hypnotic drugs
• Sedatives
• Tranquilizing drugs