Nausea, which is the sensation of the need to vomit, is a common side effect of chemotherapy treatment for cancer. The probability of experiencing nausea is dependent upon the specific drug used, the dosage of the drug administered, and whether chemotherapy is an adjunct treatment with radiation. There is an increased incidence if several chemotherapy drugs are used. In most cases, preventative measures, specifically the administration of anti-emetic drugs prior to the infusion of the chemotherapy agents, can decrease the risk of nausea and vomiting.
Serotonin antagonists
According to Chemotherapy.com, chemotherapy causes the release of a substance called serotonin (5-HT) and other chemicals in the small intestines. Serotonin signals the area of the brain which controls emesis (vomiting). Anti-emetic drugs block the signal in the brain and gastrointestinal tract that causes nausea and vomiting.
Serotonin antagonists such as cistplatin inhibit nausea and vomiting induced by chemotherapy drugs. Anti-emetics including ondansetron, granisetron, tropisetron, and dolesetron are generally administered intravenously before the administration of the chemotherapy drugs and infused over a duration of 15 to 30 minutes. Oral forms of serotonin antagonist drugs have the same therapeutic uses but are intended for preventing nausea and vomiting of moderate intensity.
The adverse effects of this class of medications are headache, lack or loss of strength and energy, drowsiness, hypertension or hypotension, bradycardia, hiccups, and constipation.
Dexamethasone
Dexamethasone, a synthetic adrenocorticol steroid, is frequently administered to enhance the anti-emetic efficiency of serotonin antagonists. Combination therapy is prescribed for patients receiving a chemotherapy protocol with a high probability of causing nausea. According to Chemocare.com, the mechanism for the anti-emetic success of steroids is not fully understood. Dexamethasone is especially effective in the prevention of delayed nausea and vomiting.
Dopamine Antagonists
The dopamine antagonists, prochlorperazine and metoclopramide, relieve nausea associated with chemotherapy. Dopamine is a neurotransmitter or chemical messenger of neurological information between cells. Nervousness and tremors are side effects of dopamine antagonists.
Aprepitant
Aprepitant blocks the action of substance P, which triggers nausea and vomiting reflexes. It is often added to an anti-emetic protocol of corticosteroids and serotonin antagonists. Aprepitant is available in oral form and is taken prior to chemotherapy and for 2 days following treatment. Fosaprepitant dimeglumine is administered intravenously and converted to aprepitant in the body.
Cannabinoids
Dronabinol and nabilone are classified as cannabinoids and contain the active ingredient found in marijuana. Both drugs can cause sedation and mood changes.
According to the booklet, "Coping With Nausea and Vomiting From Chemotherapy" published by Cancer Care, dronabinol has been prescribed for years as a anti-emetic.
In 2006, the U.S. Food and Drug Administration approved nabilone for the treatment of chemotherapy-related nausea and vomiting which could not be controlled with other anti-emetics.
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