Chemotherapy induced nausea and vomiting

Why patients receiving systemic anti-cancer treatment will have nausea and vomiting? 

Chemotherapy-induced nausea and vomiting (CINV) involve complex pathways in the body, with different processes contributing to CINV. Chemotherapy drugs stimulate the release of serotonin in the gastrointestinal tract, which then triggers the vomiting reflex in the brain through specific receptors. This process involves the central nervous system (CNS) pathways, including the nucleus of the solitary tract (NTS) and the chemoreceptor trigger zone (CTZ). In addition, the neurotransmitter substance P, which is released in response to chemotherapy drugs and binds to receptors in the brain to induce vomiting. Signals from various pathways are coordinated in the vomiting center in the brainstem and are converged to produce the symptoms of nausea and vomiting during cancer treatment.

Three different types of CINV have been categorized and defined. Acute emesis is defined as emesis occurring within 24 hours of chemotherapy. It commonly starts within one to two hours of chemotherapy treatment and usually peaks at four to six hours. Delayed emesis occurs 24 hours after chemotherapy and usually peaks at 48 to 72 hours. Lastly, there is anticipatory emesis that happens prior to chemotherapy as a conditioned response in patients who have had significant nausea and vomiting during previous treatments with chemotherapy.

Are all chemotherapies having same level of nausea/ vomiting?

Not all chemotherapies are having the same level of nausea/vomiting. Due to varying mechanisms of action, dose, route, schedule and the combination with other chemotherapy agents, chemotherapy agents can vary with respect to their relative risk to induce emesis. In addition, patient-related risk factors can influence the severity of CINV, the common patient factors include age, gender, history of motion sickness and/or pregnancy-related nausea and vomiting, a history of alcohol use and emesis with prior chemotherapy. Patients who are younger than 50 years have a higher risk for CINV. Gender appears to be a factor with a higher risk generally associated with females. Patients who have a history of motion sickness and/or pregnancy-related nausea and vomiting have a higher risk of developing CINV. A history of high alcohol intake (eg, ≥5 drinks per week) tends to lower the risk of CINV, possibly because of desensitization of the CTZ.

The drugs for different levels of CINV

Abbreviation: NK-1 RA = Neurokinin-1 receptor antagonists; 5HT3 RA serotonin receptor antagonist

Use of anti-depressants or anti-convulsants for anti-emesis?

The use of anti-depressants and anti-convulsants for anti-emesis, or the prevention of vomiting and nausea, has shown varying degrees of effectiveness in cancer patients undergoing chemotherapy.

Anti-depressants such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants have been used off-label to help manage CINV. These medications work by influencing the levels of neurotransmitters in the brain that are involved in regulating nausea and vomiting. Some studies have shown that certain anti-depressants can be effective in reducing chemotherapy-induced nausea and vomiting, especially when used in combination with standard anti-emetic medications.

On the other hand, anti-convulsants such as gabapentin and pregabalin have also been explored for their potential anti-emetic properties. These medications are thought to modulate neurotransmitters involved in nausea and vomiting pathways. While some studies have shown promising results in reducing chemotherapy-induced nausea and vomiting with anti-convulsants, more research is needed to establish their efficacy and safety in this context.

It is important for you to consult with your oncologist before considering the use of anti-depressants or anti-convulsants for anti-emesis. Your doctor can provide personalized recommendations based on your medical history, current medications and treatment plan.

Non-medical methods sometimes can be effective in helping you manage nausea and vomiting, Some non-medical methods that may help alleviate nausea and vomiting include:

• Mind-body techniques such as meditation, deep breathing exercises, guided imagery and progressive muscle relaxation can help you reduce stress and anxiety
• Dietary modifications such as eating small, frequent meals, avoiding strong odors, staying hydrated and consuming bland foods

It is important for you to discuss non-medical methods with your oncologists before trying them, to ensure they are safe and appropriate for you. Integrating non-medical approaches into a comprehensive nausea and vomiting management plan can help improve your overall well-being.

Special thanks to Dr May Lam, Department of Pharmacology and Pharmacy, LKS Faculty of Medicine, the University of Hong Kong, for authoring this article.