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.[1][2]
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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.[3][4]
- 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 (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, sublingual, 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.
- Dopamine antagonists act on the brainstem and are used to treat nausea and vomiting associated with cancer, radiation sickness, opioids, cytotoxic drugs and general anaesthetics. Side effects include muscle spasms and restlessness.
- NK1 receptor antagonist
- Aprepitant (Emend) is a commercially available NK1 receptor antagonist
- Casopitant is an investigational NK1 receptor antagonist
- Rolapitant (Varubi) another recently approved drug from this class
- Antihistamines (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.
- 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.
- Benzodiazepines (GABA receptor positive allosteric modulators)
- 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.[15]
- Lorazepam (Ativan) is said to be very good as an adjunct treatment for nausea along with first line medications such as Compazine. [citation needed]
- Anticholinergics
- Steroids
- 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.[16]
- Other
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Huang, Q.; Iwamoto, Y.; Aoki, S.; Tanaka, N.; Tajima, K.; Yamahara, J.; Takaishi, Y.; Yoshida, M.; Tomimatsu, T.; Tamai, Y. (1991). "Anti-5-hydroxytryptamine3 effect of galanolactone, diterpenoid isolated from ginger". Chemical & Pharmaceutical Bulletin. 39 (2): 397–399. doi:10.1248/cpb.39.397. PMID 2054863.