Key Terms: Antiemetics, Emesis, Retching.
Description
Nausea and vomiting are recognized as two separate and distinct conditions. Nausea is the subjective, unpleasant feeling or urge to vomit, which may or may not result in vomiting. Vomiting is the forceful expelling of the contents of the stomach and intestines through the mouth. To some, nausea is a more distressing symptom than vomiting. Nausea and vomiting are major problems for patients being treated with cancer, with approximately 50% of patients experiencing nausea and vomiting as a result of cancer treatments even though antiemetics (anti-nausea and vomiting medications) were used. In addition, more than 50% of cancer patients experience nausea and vomiting as a result of progression of the disease, or as a result of exposure to other therapies used to treat the cancer.
Not all patients diagnosed with cancer will experience nausea and vomiting. However, nausea and vomiting remain two of the side effects associated with cancer and cancer treatment that patients and their families fear the most. The negative aspects of nausea and vomiting can influence all facets of a patient's life. If nausea and vomiting are not controlled in the patient with cancer, the result can be serious metabolic problems such as disturbances in fluid and electrolyte balance and nutritional status. Psychological problems associated with nausea and vomiting include anxiety and depression. Uncontrolled nausea and vomiting can also lead to the decision by the patient to stop potentially curative cancer therapy.
Causes
The most common causes of nausea and vomiting in cancer patients include treatment with chemotherapy and radiation therapy; tumor spread to the gastrointestinal tract, liver, and brain; constipation; infection; and use of some opioids, which are drugs used to treat cancer pain. The mechanisms that control nausea and vomiting are not fully understood, but both are controlled by the central nervous system. Nausea is thought to arise from stimulation of the autonomic nervous system. It is theorized that chemotherapy causes vomiting by stimulating areas in the gastrointestinal tract and the brain. The areas in the brain that are stimulated are the chemoreceptor trigger zone (CTZ) and the emetic or vomiting center (VC). When the VC is stimulated, muscular contractions of the abdomen, chest wall, and diaphragm occur, which result in the expulsion of stomach and intestinal contents.
Chemotherapy-Induced Nausea and Vomiting
Not all chemotherapeutic agents cause nausea and vomiting. Chemotherapy drugs vary in their ability or potential to cause nausea and vomiting. This variation is known as the emetogenic potential of the drug, or the potential of the drug to cause emesis. Chemotherapy drugs are classified as having severe (greater than 90% of patients exposed to this drug will experience nausea and vomiting), high (60–90% of patients will experience nausea and vomiting), moderate (30–60% will experience nausea and vomiting), low (10–30% will experience nausea and vomiting), and very low (less than 10% experience nausea and vomiting) emetogenic potential.
The incidence and severity of chemotherapy-induced nausea and vomiting varies and is related to the following factors: the emetogenic potential of the drug, the drug dosage, the schedule of administration of the drug, and the route of the drug. For example, even a drug with a low emetogenic potential may cause nausea and vomiting if given at higher doses. Factors that are associated with increased nausea and vomiting after chemotherapy include female gender, age greater than six in children, age less than 50 in adults, history of motion sickness, and history of vomiting in pregnancy.
When nausea and vomiting result from chemotherapy administration, the nausea and vomiting can be classified as anticipatory, acute, or delayed. Anticipatory nausea and vomiting occur prior to the actual chemotherapy treatment and are a response primarily to an environmental stimulus, such as a specific odor, which is then associated with the chemotherapy treatment in the future. That is, the smell of the odor alone can be enough to induce or trigger nausea and vomiting in the sensitized patient. Acute nausea and vomiting occur within 24 hours of administration of the chemotherapeutic agent. Delayed nausea and vomiting occur after the acute phase and may last 48 or more hours after chemotherapy administration.
Radiation Therapy Induced Nausea and Vomiting
Although not all patients receiving radiation therapy will experience nausea and vomiting, patients receiving radiation therapy to the gastrointestinal tract and brain are most likely to experience those side effects. Radiation therapy to the brain is believed to stimulate the CTZ, the VC, or both. The higher the radiation therapy dose and the greater the body surface area irradiated, the higher the potential for nausea and vomiting. Also, the larger the amount of gastrointestinal tract tissue exposed to radiation the more likely nausea and vomiting will occur. Nausea and vomiting associated with radiation therapy usually occurs one-half hour to several hours after treatment and usually does not occur on the days when the patient is not undergoing treatment.
Treatments
Pharmacologic Management
The most commonly used intervention to manage nausea and vomiting in cancer patients is the use of antiemetic drugs. Many of these drugs work by inhibiting stimulation of the CTZ and perhaps the VC. Most of the drugs used today to clinically treat nausea and vomiting are classified into one of the following groups: dopaminergic antagonists, neurokinin receptor antagonists, corticosteroids, cannabinoids, and serotonin receptor antagonists. Antiemetics can be utilized as single agents or several drugs can be prescribed together as combination therapy.
Examples of dopaminergic antagonists include phenothiazines such as prochlorperazine (Compazine), substituted benzamides such as metaclopramide (Reglan), and butyrophenones such as droperidol (Inapsine) and haloperidol (Haldol). Side effects of the dopaminergic antagonists include extrapyramidal reactions (e.g., tremors, slurred speech, anxiety, distress, paranoia) and sedation. In 2004, the FDA approved a new drug called aprepitant (Emend) for use in cancer patients. It is used in combination with other antiemetics for relief of acute and delayed nausea and vomiting caused by high-dose chemotherapy, most often caused by the chemotherapy drug cisplatin. Side effects of aprepitant include fatigue, dizziness, stomach pain, nausea, hiccups, diarrhea, constipation, and loss of appetite.
Steroids may be used to treat mild to moderately emetogenic chemotherapy. However, long-term corticosteroid use is considered inappropriate due to the multiple adverse effects associated with long-term use. Cannabinoids (substances similar to, or derived from, marijuana) may be effective in selected patients but are usually not prescribed as first line therapy due to generally low rates of effectiveness. Controversy continues to exist related to the use of cannabinoids, which may not be accepted cultural or societal practice for some patients. Side effects of cannabinoids include physical and psychogenic effects such as acute withdrawal syndrome, dizziness, dry mouth, sedation, depression, anxiety, paranoia, and panic.
The newest class of antiemetics is the serotonin or 5-HT3 antagonists. In 2001, three serotonin receptor antagonists were available in the United States: granisetron (Kytril), ondansetron (Zofran), and dolasetron (Anzemet). Serotonin receptor antagonists are better tolerated, are generally more effective, and result in fewer side effects than previously available antiemetics. A common adverse effect of the serotonin antagonists is asthenia, a state of unusual fatigue and weakness. Asthenia usually occurs two to three days after treatment with serotonin antagonists and may last one to four days. Serotonin receptor antagonists may not be offered or made available to all patients due to the relatively high cost of the drugs. Controversy exists related to the optimal role of serotonin receptor antagonists. Some clinicians argue there is the potential for overuse of the serotonin receptor antagonists when used to treat patients who are not receiving chemotherapeutic agents with moderate to severe emetogenic potential and when less expensive agents would be as effective.
Another class of drugs, the benzodiazepines including lorazepam (Ativan), midazolam (Versed), and alprazolam (Xanax), may be used in conjunction with antiemetics in the prevention and treatment of anxiety and expected chemotherapy-induced nausea and vomiting. These agents appear to be especially effective in highly emetogenic regimens administered to children. The benzodiazepines have only modest antiemetic properties. Therefore, they are usually used as adjuncts to antiemetic agents. Adverse effects of the benzodiazepines include sedation, confusion, hypotension (unusually low blood pressure), and visual disturbances.
Alternative and Complementary Therapies
The use of antiemetics is considered the cornerstone of therapy to treat chemotherapy-induced vomiting. Nonpharmacologic therapies may be used in conjunction with pharmacologic agents to enhance the effects of the drugs. Nonpharmacologic strategies include behavioral interventions such as guided imagery, hypnosis, systematic desensitization, and attentional distraction. Dietary interventions such as eating cold or room temperature foods and foods with minimal odors while avoiding spicy, salty, sweet, or high-fat foods may be beneficial to some patients while undergoing chemotherapy treatments. Another dietary recommendation is the use of ginger or ginger capsules to decrease episodes of nausea and vomiting. Acupressure, specifically stimulation of the Nei-Guan point (P6) of the dominant arm or stimulation of the Inner Gate and ST36 or Three Miles point (below the knee and lateral—outside area—to the tibia) has proven helpful to some patients. Music therapy interventions have also been effective as diversional interventions to reduce incidence and severity of chemotherapy-induced nausea and vomiting.
Resources
Books
Wickham, R. "Nausea and Vomiting." In Cancer Symptom Management, edited by C. H. Yarbro, M. H. Frogge, and M. Goodman. Boston: Jones and Bartlett Publishers, 1999, pp. 228–253.
Periodicals
American Society of Health-System Pharmacists. "ASHP Therapeutic Guidelines on the Pharmacologic Management of Nausea and Vomiting in Adult and Pediatric Patients Receiving Chemotherapy or Radiation Therapy or Undergoing Surgery." American Journal of Health System Pharmacy 56 (1999): 729–764.
Boothby, Lisa A., and Paul L. Doering. "New Drug Update 2003: Part 1." Drug Topics February 23, 2004: 54.
Other
"Nausea and Vomiting." WebMDHealth. WebMD. [cited June 26, 2005].
"Symptom Management: Nausea/Vomiting." Oncolink. Oncolink. [cited June 26, 2005].
—Melinda Granger Oberleitner, R.N., D.N.S.; Teresa G. Odle




