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.

Types of Antiemetics

Antiemetics 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 (Anzemet) - can be administered in tablet form or in an injection.
  • Granisetron (Kytril, Sancuso) - can be administered in tablet (Kytril), oral solution (Kytril), or in a single transdermal patch to the upper arm (SANCUSO).
  • Ondansetron (Zofran) - administered in an oral tablet form, oral dissolving tablet form, or in an injection.
  • Tropisetron (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), an antidepressant that also has antiemetic effects.
• 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 usefulness by their extra-pyramidal and sedative side-effects.
  • 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.
  • Alizapride
  • Prochlorperazine (Compazine, Stemzine, Buccastem, Stemetil, Phenotil)
• NK1 receptor antagonist
  • Aprepitant (Emend) Commercially available NK1 Receptor antagonist
  • Casopitant Investigational NK1 receptor antagonist
• Antihistamines (H₁ histamine receptor antagonists), effective in many conditions, including motion sickness, morning sickness in pregnancy, and to combat opiate nausea.
  • Cyclizine
  • Diphenhydramine (Benadryl)
  • Dimenhydrinate (Gravol, Dramamine)
  • Meclizine (Bonine, Antivert)
  • Promethazine (Pentazine, Phenergan, Promacot) Promethazine can be administered via a rectal suppository for adults and children over 2 years of age.
  • Hydroxyzine
• Cannabinoids are used in patients with cachexia, cytotoxic nausea, and vomiting, or who are unresponsive to other agents.
  • Cannabis - Medical marijuana, in the U.S., it is a Schedule I drug.
  • Dronabinol (Marinol) - a Schedule III drug in the U.S.
  • Nabilone (Cesamet) - Put back on the market in late 2006. In the U.S., it is a Schedule II substance.
  • 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 given at the onset of anesthesia has been shown in recent trials to be as effective as ondansetron.

• • Lorazepam 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 given in low dose at the onset of a general anaesthetic is an effective anti-emetic. The specific mechanism of action is not fully understood.
• Other
  • Trimethobenzamide; thought to work on the CTZ
  • Ginger - contains 5HT3 antagonists gingerols and shogaols ^[1]
  • Emetrol also claimed to be an effective antiemetic.
  • Propofol given intravenously. It has been used in an acute care setting in hospital as a rescue therapy for emesis.
  • Peppermint claimed to help nausea or stomach pain when added into a tea or peppermint candies.
  • Muscimol purported as such^[2]
  • Ajwain purported to be antiemetic. It is a popular spice in India, Ethiopia and Eritrea.
  • Zolpidem has been reported to be a newer antiemetic used for patients that have been unresponsive to other first-line typical antiemetics.
• Non-pharmaceutical therapies with some evidence of efficacy include acupuncture and hypnosis.

References

See also

• Emetic
• Hyperemesis gravidarum
• Chemotherapy