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Antiemetic

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 CNS and GI 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
• 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.

• non-pharmaceutical therapies with some evidence of efficacy include acupuncture and hypnosis. 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

• Emetic
• Hyperemesis gravidarum
• Chemotherapy

Contents

• See also