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Anti-emetic)
An antiemetic is a drug that is effective against vomiting and nausea. Anti-emetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics and chemotherapy directed against cancer.
[edit] 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) Dolasetron can be administered in tablet form or in an injection. Tablets are administered one hour before chemotherapy or surgery. Injection is administered 30 minutes before certain chemotherapy or surgery.
- Granisetron (Kytril, Sancuso) Granisetron can be administered in tablet (Kytril), oral solution (Kytril), or in a single transdermal patch to the upper arm (SANCUSO). Tablet and Oral solution (Kytril) should be administered twice daily up to one hour before chemotherapy with 12 hours between doses. Granisetron in patch form (SANCUSO) should be applied to the upper arm a minimum of 24 to 48 hours before the chemotherapy regimen begins. One patch can be worn for up to 7 days depending on the chemotherapy regimen.
- Ondansetron (Zofran) Ondansetron is administered in an oral tablet form 30 minutes before chemotherapy. Further doses may be taken 1-2 days after chemotherapy ompletion.
- Tropisetron (Navoban) Tropisetron can be administered in oral capsules or in injection form. It is given as a single for 6 days after the first day of chemotherapy.
- Palonosetron (Aloxi) Palonosetron can be administered in an injection form 30 minutes before chemotherapy regimen begins or immediately before surgery. It can also be administered in oral capsule form one hour prior to the start of chemotherapy.
- Mirtazapine (Remeron)
- 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.
- Antihistamines (H1 histamine receptor antagonists), effective in many conditions, including motion sickness and severe morning sickness in pregnancy.
- Cannabinoids are used in patients with cachexia, cytotoxic nausea, and vomiting, or who are unresponsive to other agents.
- 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. Medical marijuana is also much less expensive than related pharmaceuticals. 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. In the US, it is 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.
- Benzodiazepines
- Midazolam given at the onset of anesthesia has been shown in recent trials to be as effective as ondansetron, a 5-HT3 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.
- Anticholinergics
- Steroids
- 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.
- NK1 receptor antagonist
- Aprepitant (Emend) Commercially available NK1 Receptor antagonist
- Casopitant Investigational NK1 receptor antagonist
- Other
- 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.
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