Chemotherapy-induced nausea and vomiting

5-HT₃ receptor antagonists are very effective antiemetics and constitute a great advance in the management of CINV. These drugs block one or more of the nerve signals that cause nausea and vomiting. During the first 24 hours after chemotherapy, the most effective approach appears to be blocking the 5-HT₃ nerve signal. Approved 5-HT₃ inhibitors include dolasetron (Anzemet), granisetron (Kytril, Sancuso), and ondansetron (Zofran). Their antiemetic effect due to blockade of 5HT3 receptor on vagal afferent in the gut. in addition they also block 5-HT3 receptors in CTZ and STN. The newest 5-HT₃ inhibitor, palonosetron (Aloxi), also prevents delayed nausea and vomiting, which can occur during the 2–5 days after treatment. Since some patients have trouble swallowing pills, these drugs are often available by injection, as orally disintegrating tablets, or as transdermal patches.

A newer class of drugs known as the NK₁ antagonists are a recently developed class of very efficacious drugs for controlling CINV. These drugs are often used alongside 5HT₃ inhibitors and corticosteroids to form a very potent cocktail of antiemetics that verge on achieving a nearly complete patient response (that is, completely stopping CINV).[10] The substance P inhibitor aprepitant (Emend), which became available in 2005, is highly effective in controlling nausea and vomiting associated with cancer chemotherapy.[10] Aprepitant has been shown to inhibit both the acute and delayed emesis induced by cytotoxic chemotherapeutic drugs by blocking substance P landing on receptors in the brains neurons. Indeed, positron emission tomography (PET) studies have shown that aprepitant can penetrate the brain and NK₁ receptors in the brain.[11] Aprepitant has also been shown to increase the activity of the 5-HT₃ receptor antagonists ondansetron and the corticosteroid dexamethasone, which are also used to prevent nausea and vomiting caused by chemotherapy.[10] Netupitant has recently been approved by USFDA. It has also been marketed in combination with palonosetron. Rolapitant is the newest addition in the approved NK1 antagonist list. It has advantage of a very long half life, duration of action is around 150 hours. Rolapitant got its approval by USFDA in 2015.

Olanzapine, as well as several other neuroleptic drugs, have also has been investigated for the control of CINV.[12] A 2007 study demonstrated Olanzapine's successful potential for this use, achieving a complete response in the acute prevention of nausea and vomiting in 100% of patients treated with moderately and highly emetogenic chemotherapy, when used in combination with palonosetron and dexamethasone.[13] Neuroleptic agents are now indicated for rescue treatment and the control of breakthrough nausea and vomiting.[12]

Some studies[14] and patient groups say that the use of cannabinoids derived from cannabis during chemotherapy greatly reduces the associated nausea and vomiting, and enables the patient to eat. Synthesized tetrahydrocannabinol (also one of the main active substances in marijuana) is marketed as Marinol and may be practical for this application. Natural medical cannabis is also used and recommended by some oncologists, though its use is regulated and it is not legal in all jurisdictions.[15] However, Marinol was less effective than megestrol acetate in helping cancer patients regain lost appetites.[16] A phase III study found no difference in effects of an oral cannabis extract or THC on appetite and quality of life (QOL) in patients with cancer-related anorexia-cachexia syndrome (CACS) to placebo.[17]

Dexamethasone, a corticosteroid, is often used alongside other antiemetic drugs, as it has synergistic action with many of them, although its specific antiemetic mechanism of action is not fully understood. Metoclopramide, a dopamine D₂ receptor antagonist with possible other mechanisms, is an older drug that is sometimes used, either on its own or in combination with others. Histamine blockers such as diphenhydramine or meclozine may be used in rescue treatment. Lorazepam and diazepam may sometimes be used to relieve anxiety associated with CINV before administration of chemotherapy, and are also often used in the case of rescue treatment.[12]

There are several compounds that have been identified within ginger that have been shown to possess properties that are likely to be beneficial in the treatment of CINV. This includes 5-HT3 and substance P antagonism, modulation of gastrointestinal motility, and antioxidant properties.[18][19] There have been multiple clinical trials that have investigated the use of ginger supplementation as a treatment for CINV. However, due to conflicting results and methodological issues, a 2013 systematic review of seven clinical trials summarized the current evidence as stating that "Despite the widespread use of ginger in the treatment of nausea in other contexts such as gestational nausea, the current literature provides mixed support for the use of ginger as a standard part of anti-CINV control for patients undergoing chemotherapy."[20]

Non-pharmacological approaches to remedy CINV typically involve small lifestyle alterations, such as using unscented deodorants and soaps, avoiding strong scents altogether, and dietary modifications such as eating several small meals throughout the day, eating high-protein, high-calorie food, drinking many clear liquids, and removing spicy, fatty, fried, or acidic foods from the diet.[21] Patients may also participate in alternative practices such as self-hypnosis, relaxation and imagery therapy, distraction, music therapy, biofeedback, desensitization, or acupressure.[2]