Antiemetic

An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics, and chemotherapy directed against cancer. They may be used for severe cases of gastroenteritis, especially if the patient is dehydrated.

Antiemetics, though previously thought to cause birth defects, have been proven safe for use by pregnant women in the treatment of morning sickness and the more serious hyperemesis gravidarum.

Types of antiemetics

Antiemetics include:

• 5-HT₃ receptor antagonists 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. However, they can also cause constipation or diarrhea, dry mouth, and fatigue.
  • Dolasetron (Anzemet) can be administered in tablet form or in an injection.
  • Granisetron (Kytril, Sancuso) can be administered in tablet (Kytril), oral solution (Kytril), injection D(Kytril), or in a single transdermal patch to the upper arm (SANCUSO).
  • Ondansetron (Zofran) is administered in an oral tablet form, orally dissolving tablet form, orally dissolving film, or in an IV/IM injection.
  • Tropisetron (Setrovel, Navoban) can be administered in oral capsules or in injection form.
  • Palonosetron (Aloxi) can be administered in an injection or in oral capsules.
  • Mirtazapine (Remeron) is an antidepressant that also has antiemetic effects and is also a potent histamine H1 receptor antagonist, K_i=1.6 nM.
• 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. Side effects include muscle spasms and restlessness.
  • Domperidone (Motilium)
  • Olanzapine (Zyprexa)
  • Droperidol, haloperidol, chlorpromazine, prochlorperazine. Some of these drugs are limited in their usefulness by their extra-pyramidal and sedative side-effects.
  • Alizapride
  • Prochlorperazine (Compazine, Stemzine, Buccastem, Stemetil, Phenotil)
  • Metoclopramide (Reglan) 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. also a 5-HT₃ receptor antagonists
• NK1 receptor antagonist
  • Aprepitant (Emend) is a commercially available NK1 Receptor antagonist
  • Casopitant is an investigational NK1 receptor antagonist
• Antihistamines (H₁ histamine receptor antagonists) are effective in many conditions, including motion sickness, morning sickness in pregnancy, and to combat opioid nausea.
  • Cyclizine
  • Diphenhydramine (Benadryl)
  • Dimenhydrinate (Gravol, Dramamine)
  • Doxylamine
  • Meclizine (Bonine, Antivert)
  • Promethazine (Pentazine, Phenergan, Promacot) can be administered via a rectal suppository for adults and children over 2 years of age.
  • Hydroxyzine (Vistaril)
• Cannabinoids are used in patients with cachexia, cytotoxic nausea, and vomiting, or who are unresponsive to other agents. These may cause changes in perception, dizziness, and loss of coordination.
  • Cannabis, also known as medical marijuana in the United States, is a Schedule I drug.
  • Dronabinol (Marinol) is a Schedule III drug in the U.S.
  • Some synthetic cannabinoids such as Nabilone (Cesamet) or the JWH series.
  • Sativex is an oral spray containing THC and CBD. It is currently legal in Canada and a few countries in Europe but not legal in the U.S.
• Benzodiazepines
  • Midazolam is given at the onset of anesthesia has been shown in recent trials to be as effective as ondansetron.
  • Lorazepam (Ativan) is said to be very good as an adjunct treatment for nausea along with first line medications such as Compazine or Zofran.
• Anticholinergics
  • Hyoscine (also known as scopolamine)
• Steroids
  • Dexamethasone (Decadron) is given in low dose at the onset of a general anaesthetic is an effective antiemetic. The specific mechanism of action is not fully understood.
• Other
  • Trimethobenzamide is thought to work on the CTZ
  • Ginger contains 5-HT₃ antagonists gingerols, shogaols, and galanolactone. Preliminary clinical data suggests ginger may be effective for treatment of nausea and/or vomiting in a number of settings.
  • Emetrol is also claimed to be an effective antiemetic.
  • Propofol is given intravenously. It has been used in an acute care setting in hospital as a rescue therapy for emesis.
  • Peppermint is claimed to help nausea or stomach pain when added into a tea or peppermint candies.
  • Muscimol is purported to have antiemetic activity.
  • Ajwain is purported to be antiemetic. It is a popular spice in India, Ethiopia and Eritrea.

See also

• Emetic — substances that induce nausea and vomiting
• Hyperemesis gravidarum
• Chemotherapy
• Cancer and nausea