An antiemetic is a medication that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid , general anaesthetics, and chemotherapy directed against cancer. They may be used for severe cases of gastroenteritis, especially if the patient is dehydrated.
Some antiemetics previously thought to cause birth defects appear safe for use by pregnant women in the treatment of morning sickness and the more serious hyperemesis gravidarum.
Types
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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, xerostomia, and fatigue.
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Dolasetron ( Anzemet) can be administered in tablet form or in an injection.
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Granisetron ( Kytril, Sancuso) can be administered in tablet (Kytril), oral solution (Kytril), injection (Kytril), or in a single transdermal patch to the upper arm (SANCUSO).
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Ondansetron ( Zofran) is administered in an oral tablet form, orally dissolving tablet form, orally dissolving film, sublingual, or in an IV/IM injection.
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Tropisetron ( Setrovel, Navoban) can be administered in oral capsules or in injection form.
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Palonosetron ( Aloxi) can be administered in an injection or in oral capsules.
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Dopamine antagonists block dopamine receptors on the brainstem and gastrointestinal tract. They are used to treat nausea and vomiting associated with cancer, radiation sickness, opioids, cytotoxic drugs and general anaesthetics. Side effects include Akathisia and tardive dyskinesia.
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NK1 receptor antagonist which block NK1, also known as substance P. They are typically only used in the context of chemotherapy induced nausea and vomiting.
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Aprepitant ( Emend) is a commercially available NK1 receptor antagonist
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Casopitant is an investigational NK1 receptor antagonist
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Rolapitant ( Varubi) another recently approved drug from this class
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(H1 histamine receptor antagonists) are effective in many conditions, including motion sickness, morning sickness in pregnancy, and to combat opioid nausea. H1 receptors in central areas include area postrema and vomiting center in the vestibular nucleus. Also, many of the antihistamines listed here also block muscarinic acetylcholine receptors. They are known to cause significant sedation.
It is a potent histamine H1 receptor antagonist, K
i=1.6 nM,
[National Institute of Mental Health. PDSD Ki Database (Internet) cited. Chapel Hill (NC): University of North Carolina. 1998-2013. Available from: ] and also exhibits notable 5-HT
3 antagonism.
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Meclizine (Bonine, Antivert)
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Promethazine (Pentazine, Phenergan, Promacot) can be administered via a rectal suppository, intravenous injection, oral tablet or oral suspension for adults and children over 2 years of age.
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Hydroxyzine (Vistaril)
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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.
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Medical cannabis, also known as medical marijuana in the United States, is a Schedule I drug.
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Nabilone
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Dronabinol (Marinol/Syndros) is a Schedule II drug in the U.S. when in an oral solution (Syndros),
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Some synthetic cannabinoids such as Nabilone (Cesamet) or the JWH cannabinoids series.
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Sativex is an oral spray containing THC and CBD.
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Benzodiazepines (GABA receptor positive allosteric modulators)
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Midazolam (Versed) is given at the onset of anesthesia and has been shown in recent trials to be as effective as ondansetron, but most effective when used in combination with ondansetron.
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Lorazepam (Ativan) is said to be very good as an adjunct treatment for nausea along with first line medications such as Compazine.
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Hyoscine (also known as scopolamine)
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Atropine
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Dexamethasone ( Decadron) is given in low dose at the onset of a general anesthetic as an effective antiemetic. It is also used in chemotherapy as a single drug as well as with other antiemetics such as 5-HT3 receptor antagonists and NK1 receptor antagonist, but the specific mechanism of action is not fully understood.
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Other
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Trimethobenzamide is thought to work on the CTZ
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Ginger contains 5-HT3 antagonists , ,
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Emetrol is also claimed to be an effective antiemetic.
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Propofol is given intravenously. It has been used in an acute care setting in hospital as a rescue therapy for emesis.
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Muscimol is purported to have antiemetic activity.
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Ajwain is purported to be antiemetic. It is a popular spice in India, Ethiopia and Eritrea.
See also
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Cancer and nausea
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Emetic – substances that induce nausea and vomiting
