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.
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.
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.
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.
Midazolam given at the onset of anesthesia 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.
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.
Ajwain purported to be antiemetic. Also known as Bishop's weed, it is a popular spice in India, Ethiopia and Eritrea.
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.
