In this article, we will explain how to treat nausea and vomiting in cancer patients.
Nausea is an unpleasant feeling or urge to vomit. Nausea is a symptom, which is experienced by a person and not visible to other.
Vomiting can be described as “throwing up” the content of the stomach due to abrupt contraction of stomach muscles that push the stomach contents out through mouth via esophagus (food pipe). Vomiting is a sign, that is it is visible to others. Vomiting may or may not preceded by nausea.
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Nausea and/or vomiting (N/V) are 2 of the most common and distressing side effects associated with cancer or its treatment. The N/V mostly occur simultaneously, but these are considered as 2 different problems in medical science. It is important to control both N/V in cancer patients so that they can remain compliant with their cancer treatment. Thus, cancer patients generally receive medicines that help in controlling N/V, also known as anti-emetics.
The N/V are side effects that are subjective in nature and each individual’s experience of N/V is unique. With the same type and severity of disease, and with the same treatment, N/V may occur in an individual while it may not for the others due to different threshold levels of activation for vomiting center among different individuals.
It can vary in intensity, duration, pattern, and response to treatment with anti-emetics.
Based on such characteristics, N/V can be divided into the following types:
1. Acute N/V: This type of N/V is usually intense and short-lived. Treatment-related acute N/V generally happen within a few minutes to hours after cancer treatment is administered or during the treatment administration.
2. Delayed N/V: Delayed N/V happen more than 24 hours to few days after cancer treatment administration. This type of N/V is usually mild to moderate in intensity and take more time than acute N/V to resolve.
3. Anticipatory N/V: This type of N/V occurs prior to a cancer-treatment administration. Patients usually experience this due to prior experience with the same kind of treatment that led to N/V. Experts believe that the brain pairs the cancer treatment’s taste, smell, sight, sound, or pain with the N/V. Anticipatory N/V is more common among children.
4. Breakthrough N/V: This type of N/V is usually intense and short-lived. It happens even when a patient is receiving anti-emetic treatment to prevent it. Higher dose or a different type of anti-emetic is generally required for the management of this type of N/V.
5. Refractory N/V: This is the most severe type of N/V that do not respond to anti-emetics being used for preventing it. It is usually intense and long-lived. Higher dose or a different type of anti-emetic is generally required for a longer duration of time for the management of this type of N/V.
Vomiting is a reflex action that is triggered upon activation of the vomiting center, a part of the brain. It may occur as a result of many unpleasant things related to the disease or its treatment, for example, foul smell or taste of the drug used, patient experiencing anxiety or pain due to disease or treatment administration, disease/treatment-related inflammation, poor blood flow, or irritation in the upper GIT.
Following are the factors that can induce nausea or vomiting in cancer patients:
The likelihood that a patient will have cancer-related N/V depends on many factors as detailed below:
Although cancer-related N/V is difficult to be relieved completely, in most cases, it can be reduced to a level that does not bother. Medicines that are used to control N/V are called as anti-emetics.
Cancer-related N/V can be best managed by preventing it rather than after it has happened. This is why anti-emetics are usually given on a regular schedule rather than after the occurrence of N/V. The anti-emetic treatment continues for the time cancer-treatment is expected to cause N/V.
Appropriate anti-emetic drug or combination of drugs for a patient is selected based on many factors, as described below:
A. Treatment related factors
For example, the likelihood of primary treatment for causing N/V should be considered for selecting the appropriate anti-emetics. Some chemotherapeutic drugs are more likely to trigger N/V compared to the other drugs. Thus, various chemotherapeutic drugs have been classified according to their emetogenic potential into the following four categories: high, moderate, low, or minimal risk. And the antiemetic drug combination used for each category is different.
B. Patient Related factors
For example, prior history of N/V with the same kind of treatment, anti-emetics that have been effective in past; side effects associated with the anti-emetics; the efficacy of ongoing anti-emetic medicine, etc are some of the patient related factors.
Based on the above-listed factors, an appropriate anti-emetic is selected.
Types of Antiemetic Drugs
1. Serotonin (5-hydroxytryptamine or 5-HT3) receptor antagonists: These drugs block the effects of serotonin on its receptor (a mechanism that commonly causes nausea and vomiting). Examples of drugs included in this category are ondansetron, granisetron, dolasetron, azasetron, ramosetron, tropisetron etc.
These are very effective anti-emetics that are usually given before cancer-treatment administration and then continued until few days after cancer-treatment cessation. They have a favorable side-effect profile with common side effects including a low-grade headache, malaise, and constipation.
2. Neurokinin-1 (NK-1) receptor antagonists: These drugs block the action of neurokinin via its binding to the NK-1 receptor. These can delay or prevent the occurrence of both acute and delayed N/V in cancer patients. Example of such medicines includes aprepitant, rolapitant, netupitant, casopitant etc.
3. Glucocorticoids: These drugs can be used alone or in combination with other anti-emetic drugs. These are also very effective anti-emetics with favorable side-effect profile. Examples of glucocorticoids that are commonly employed as anti-emetics include dexamethasone and prednisone.
4. Dopamine antagonists: These block the action of dopamine, a neurotransmitter generally released in response to noxious stimuli, on its receptor present in vomiting center of the brain. This prevents N/V cancer patients. Examples of such drugs include prochlorperazine and metoclopramide. These are now rarely used for the management of N/V in cancer patients.
5. Antipsychotic Drugs: For example, olanzapine blockS the action of serotonin on 5-hydroxytryptamine (5-HT2) receptors and dopamine on D2 receptors. This dual action of olanzapine makes it a very effective antiemetic medicine. It can be used alone or in combination with other drugs.
Cancer-related N/V are 2 of the most common side effects observed in cancer patients.
Overall, the nausea and vomiting have a detrimental effect on the quality of life of the cancer patient.
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