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An '''anti-emetic''' is a [[medication|drug]] that is effective against [[vomit]]ing and [[nausea]]. Anti-emetics are typically used to treat [[motion sickness]] and the [[Adverse effect (medicine)|side effects]] of [[opioid]] [[analgesic]]s, [[general anaesthetic]]s and [[chemotherapy]] directed against [[cancer]]. 

==Types of Anti-emetics==
Anti-emetics include:

*[[5-HT3 antagonist|5-HT<sub>3</sub> 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]]
** [[Granisetron]]
** [[Ondansetron]]
** [[Tropisetron]]
** [[Palonosetron]] ('''Aloxi''', a new 5HT3 antagonist)
*[[Dopamine antagonist]]s 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]]
* [[Antihistamine]]s ([[Histamine receptor|H<sub>1</sub> 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]]
*[[Cannabinoid]]s are used in patients with cachexia, cytotoxic nausea & vomiting or are unresponsive to other agents.
** [[Medical cannabis|Cannabis]] (Marijuana).  Most patients prefer smoked or vaporized cannabis over pharmaceutical versions because they do not contain all 66 cannabinoids that are in cannabis, many of which have medicinal applications.  [[Cannabidiol|CBD]] is a main cannabinoid not in Marinol or Cesamet.
** [[Dronabinol]] (Marinol).  Ninety percent of sales are for cancer and AIDS patients. The other 10% of its sales thought to be for pain, [[Multiple Sclerosis]] and also for [[Alzheimer]]'s disease.
** [[Nabilone]] (Cesamet).  Put back on the market in late 2006.  A [[Schedule II]] substance unlike Marinol which is [[Schedule III]] and cannabis which is [[Schedule I]].
** [[Sativex]] is an oral spray containing THC and CBD.  It is currently legal in Canada and a few countries in Europe but not in the U.S. yet.
* [[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. 
** [[Lorazepam]] said to be very good as an adjunct treatment for nausea along with first line medications such as Compazine or Zofran.
*[[Anticholinergic]]s
** [[Hyoscine]] (also known as [[Scopolamine]])
*[[Steroid]]s
** [[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.
*Other
** [[Trimethobenzamide]]; thought to work on the [[chemoreceptor trigger zone|CTZ]]
** [[Ginger]]
** [[Emetrol]] also claimed to be an effective anti-emetic.
** [[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 <ref> [http://cameochemicals.noaa.gov/chemical/5082#section1 Chemical Data Sheet] </ref>

* Non-pharmaceutical therapies with some evidence of efficacy include acupuncture and hypnosis. All drugs have potential side effects. It is important to try to reduce the baseline risk of nausea and vomiting, particularly with respect to surgery.

==References==
{{reflist | 1}}

==See also==
* [[Emetic]]
* [[Hyperemesis gravidarum]]
* [[Chemotherapy]]

{{Major Drug Groups}}
{{Antiemetics and antinauseants}}
[[da:Antiemetika]]
[[de:Antiemetikum]]
[[es:Antiemético]]
[[fr:Antiémétique]]
[[hr:Antiemetici]]
[[nl:anti-emeticum]]
[[nn:Kvalmestillande lækjemiddel]]


[[Category:Antiemetics| ]]
[[Category:Pharmacology]]
[[Category:Drugs]]

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