Use of an NK1 receptor antagonist to prevent delayed emesis after cisplatin

An assessment of the effects of neurokinin1 receptor antagonism against nausea and vomiting: Relative efficacy, sites of action and lessons for future drug development

A broad-spectrum anti-vomiting effect of neurokinin1 receptor antagonists (NK1 RA), shown in pre-clinical animal studies, has been supported by a more limited range of clinical studies in different indications. However, this review suggests that compared with vomiting, the self-reported sensation of nausea is less affected or possibly unaffected (depending on the stimulus) by NK1 receptor antagonism, a common finding for anti-emetics. The stimulus-independent effects of NK1 RAs against vomiting are explicable by actions within the central pattern generator (ventral brainstem) and the nucleus tractus solitarius (NTS; dorsal brainstem), with additional effects on vagal afferent activity for certain stimuli (e.g., highly emetogenic chemotherapy). The central pattern generator and NTS neurones are multifunctional so the notable lack of obvious effects of NK1 RAs on other reflexes mediated by the same neurones suggests that their anti-vomiting action is dependent on the activation state of the pathway leading to vomiting. Nausea requires activation of cerebral pathways by projection of information from the NTS. Although NK1 receptors are present in cerebral nuclei implicated in nausea, and imaging studies show very high receptor occupancy at clinically used doses, the variable or limited ability of NK1 RAs to inhibit nausea emphasizes: (i) our inadequate understanding of the mechanisms of nausea; and (ii) that classification of a drug as an anti-emetic may give a false impression of efficacy against nausea vs. vomiting. We discuss the potential mechanisms for the differential efficacy of NK1 RA and the implications for future development of drugs that can effectively treat nausea, an area of unmet clinical need.

Neurokinin-1 receptor antagonists for the prevention of postoperative nausea and vomiting

Despite the availability of several classes of antiemetics, postoperative nausea and vomiting (PONV) remains a substantial burden for patients following surgery, resulting in patient dissatisfaction and prolonged stays in post-anesthesia care units and ultimately increasing the cost of care. Enhanced recovery protocols and PONV management guidelines are now centered on the assessment of the individual patient's risk for developing PONV, as well as multimodal prophylaxis using antiemetics targeting different mechanisms of action. Over the last two decades, the neurokinin-1 receptor (NK1R) has emerged as a therapeutic target for the management of PONV. This review of the literature explains the role of the NK1R and its ligand-substance P-in vomiting, describes the pharmacologic and pharmacokinetic properties of NK1R antagonists (NK1RAs) and summarizes the clinical evidence supporting NK1RAs for PONV prophylaxis in patients undergoing surgery. In particular, we discuss the therapeutic application of NK1RA in PONV prophylaxis protocols owing to their advantages over other antiemetic classes in efficacy, duration of efficacy, safety, pharmacology, and ease of administration. Future studies will be aimed at further investigating the efficacy and safety of NK1RA-based multimodal combinations, particularly among vulnerable populations (e.g., children and elderly).

A pharmacological overview of aprepitant for the prevention of postoperative nausea and vomiting

INTRODUCTION

Post-operative nausea and vomiting (PONV) affects 30% of all patients undergoing surgery and up to 80% of high-risk patients. Antiemetics for PONV prophylaxis target a variety of receptor systems, with varying degrees of efficacy and side effect profile. Neurokinin -1 receptor antagonists are the most recent class of compounds investigated for PONV prophylaxis, with aprepitant being the only one currently approved for this indication.

AREAS COVERED

This review covers the pathophysiology of PONV, current recommendations for PONV prophylaxis, pharmacokinetics, and pharmacodynamics of aprepitant, and the evidence for its efficacy in the management of PONV as a single agent and in combination therapy.

EXPERT OPINION

Aprepitant is effective for PONV prophylaxis. It has superior antivomiting efficacy, long half-life, and favorable side effect profile. Data on antiemetic combinations involving aprepitant are limited, and it not clear if the addition of other antiemetics to aprepitant result in improved PONV prophylaxis. The oral route of administration of aprepitant is a potential limitation in a busy clinical practice. However, the recent approval of an intravenous formulation could provide a more convenient route of administration. Aprepitant remains more expensive than other antiemetics, and there are no studies assessing the cost effectiveness of its use.

Prevention of Chemotherapy-Induced Nausea and Vomiting in the Older Patient: Optimizing Outcomes

Chemotherapy-induced nausea and vomiting (CINV) are still two of the most feared side effects of cancer therapy. Although major progress in the prophylaxis of CINV has been made during the past 40 years, nausea in particular remains a significant problem. Older patients have a lower risk of CINV than younger patients, but are at a higher risk of severe consequences of dehydration and electrolyte disturbances following emesis. Age-related organ deficiencies, comorbidities, polypharmacy, risk of drug–drug interactions, and lack of compliance all need to be addressed in the older patient with cancer at risk of CINV. Guidelines provide evidence-based recommendations for the prophylaxis of CINV, but none of these guidelines offer specific recommendations for older patients with cancer. This means that the recommendations may lead to overtreatment in some older patients. This review describes the development of antiemetic prophylaxis of CINV focusing on older patients, summarizes recommendations from antiemetic guidelines, describes deficiencies in our knowledge of older patients, summarizes necessary precautions, and suggests some future perspectives for antiemetic research in older patients.

Optimizing antiemetic treatment for chemotherapy-induced nausea and vomiting in Japan: Update summary of the 2015 Japan Society of Clinical Oncology Clinical Practice Guidelines for Antiemesis

Patients with cancer should appropriately receive antiemetic therapies against chemotherapy-induced nausea and vomiting (CINV). Antiemetic guidelines play an important role in managing CINV. Accordingly, the first Japanese antiemetic guideline published in 2010 by the Japan Society of Clinical Oncology (JSCO) has considerably aided Japanese medical staff in providing antiemetic therapies across chemotherapy clinics. With the yearly advancements in antiemetic therapies, the Japanese antiemetic guidelines require revisions according to published evidence regarding antiemetic management worldwide. A revised version of the first antiemetic guideline that considered several upcoming evidences had been published online in 2014 (version 1.2), in which several updated descriptions were included. The 2015 JSCO clinical practice guideline for antiemesis (version 2.0) (in Japanese) has addressed clinical antiemetic concerns and includes four major revisions regarding (1) changes in emetogenic risk categorization for anti-cancer agents, (2) olanzapine usage as an antiemetic drug, (3) the steroid-sparing method, and (4) adverse drug reactions of antiemetic agents. We herein present an English update summary for the 2015 JSCO clinical practice guideline for antiemesis (version 2.0).

A History of Drug Discovery for Treatment of Nausea and Vomiting and the Implications for Future Research

The origins of the major classes of current anti-emetics are examined. Serendipity is a recurrent theme in discovery of their anti-emetic properties and repurposing from one indication to another is a continuing trend. Notably, the discoveries have occurred against a background of company mergers and changing anti-emetic requirements. Major drug classes include: (i) Muscarinic receptor antagonists-originated from historical accounts of plant extracts containing atropine and hyoscine with development stimulated by the need to prevent sea-sickness among soldiers during beach landings; (ii) Histamine receptor antagonists-searching for replacements for the anti-malaria drug quinine, in short supply because of wartime shipping blockade, facilitated the discovery of histamine (H1) antagonists (e.g., dimenhydrinate), followed by serendipitous discovery of anti-emetic activity against motion sickness in a patient undergoing treatment for urticaria; (iii) Phenothiazines and dopamine receptor antagonists-investigations of their pharmacology as "sedatives" (e.g., chlorpromazine) implicated dopamine receptors in emesis, leading to development of selective dopamine (D2) receptor antagonists (e.g., domperidone with poor ability to penetrate the blood-brain barrier) as anti-emetics in chemotherapy and surgery; (iv) Metoclopramide and selective 5-hydroxytryptamine3(5-HT3) receptor antagonists-metoclopramide was initially assumed to act only via D2 receptor antagonism but subsequently its gastric motility stimulant effect (proposed to contribute to the anti-emetic action) was shown to be due to 5-hydroxytryptamine4 receptor agonism. Pre-clinical studies showed that anti-emetic efficacy against the newly-introduced, highly emetic, chemotherapeutic agent cisplatin was due to antagonism at 5-HT3 receptors. The latter led to identification of selective 5-HT3 receptor antagonists (e.g., granisetron), a major breakthrough in treatment of chemotherapy-induced emesis; (v) Neurokinin1receptor antagonists-antagonists of the actions of substance P were developed as analgesics but pre-clinical studies identified broad-spectrum anti-emetic effects; clinical studies showed particular efficacy in the delayed phase of chemotherapy-induced emesis. Finally, the repurposing of different drugs for treatment of nausea and vomiting is examined, particularly during palliative care, and also the challenges in identifying novel anti-emetic drugs, particularly for treatment of nausea as compared to vomiting. We consider the lessons from the past for the future and ask why there has not been a major breakthrough in the last 20 years.

Corticosteroids, the oldest agent in the prevention of chemotherapy-induced nausea and vomiting: What about the guidelines?

Chemotherapy-induced nausea and vomiting (CINV) remains one of the most disturbing side effects of cancer treatment. Research in antiemetic therapy has progressed gradually since the early eighties, and the development of antiemetic agents continues. This review focuses on the current management of CINV based on the most recent guidelines, and adherence to the latter is examined more carefully. Setrons (5HT3 receptor antagonists), corticosteroids, and NK-1 receptor antagonists are the cornerstones of antiemetic therapy. Corticosteroids are one of the oldest agents in the prevention of CINV. They are highly effective, increase the effect of other antiemetic agents, and are cost-effective. The latest developed 5HT3 receptor antagonist palonosetron led to an update of the guidelines of CINV. Other types include benzodiazepines, cannabinoids, and olanzapine. Various factors contribute to the overall risk of developing CINV, such as patient characteristics, emetogenic potency of the chemotherapeutic agents, and correct prevention of CINV. Current guidelines determine which is the right preventive regimen for each cancer patient at risk for experiencing CINV. Adherence to these guidelines and implementation in daily practice seem to be below the optimal level. In Belgium, authorities use the guidelines as a base for reimbursement and this has increased the level of implementation.

Aprepitant: a neurokinin-1 receptor antagonist for the treatment of chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life, and although the use of 5-hydroxytryptamine-3 (5-HT3) receptor antagonists plus dexamethasone has significantly improved the control of acute CINV, delayed nausea and vomiting remain a significant clinical problem. Aprepitant (Emend), Merck) is the first agent available in the new drug class of neurokinin-1 receptor antagonists. When added to a standard regimen of a 5-HT3 receptor antagonist and dexamethasone in patients receiving highly emetogenic chemotherapy, it improves the complete response rate of acute CINV. Aprepitant also improves the complete response of delayed CINV when used in combination with dexamethasone compared with dexamethasone alone. Based on these studies, new guidelines for the prevention of CINV have been developed for patients receiving highly emetogenic chemotherapy. The use of aprepitant in patients receiving moderately emetogenic chemotherapy will await the review and analysis of recently completed Phase III trials. Aprepitant is a substrate, a moderate inhibitor and an inducer of cytochrome P450 (CYP)3A4 and CYP2C9. Drug interactions should be monitored when aprepitant is coadministered with agents affected by CYP3A4 and CYP2C9 isoenzymes. The safety and efficacy of aprepitant has not been established in pediatric or adolescent patients, and aprepitant has not been evaluated in the treatment of patients with established nausea and vomiting. Future studies may consider the use of aprepitant with current and other new agents in moderately and highly emetogenic chemotherapy, as well in the clinical settings of multiple-day chemotherapy and bone marrow transplantation.

Efficacy of the oral neurokinin-1 receptor antagonist aprepitant administered with ondansetron for the prevention of postoperative nausea and vomiting

Background

5-HT₃ receptor antagonist, dexamethasone and droperidol were used for the prevention of postoperative nausea and vomiting (PONV). Recently, neurokinin-1 (NK1) antagonist has been used for PONV. We evaluated the effect of oral aprepitant premedication in addition to ondansetron.

Methods

A total 90 patients scheduled for elective rhinolaryngological surgery were allocated to three groups (Control, Ap80, Ap125), each of 30 at random. Ondansetron 4 mg was injected intravenously to all patients just before the end of surgery. On the morning of surgery, 80 mg and 125 mg aprepitant were additionally administered into the Ap80 group and Ap125 group, respectively. The rhodes index of nausea, vomiting and retching (RINVR) was checked at 6 hr and 24 hr after surgery.

Results

Twelve patients who used steroids unexpectedly were excluded. Finally 78 patients (control : Ap80 : Ap125 = 24 : 28 : 26) were enrolled. Overall PONV occurrence rate of Ap125 group (1/26, 3.9%) was lower (P = 0.015) than the control group (7/24, 29.2%) at 6 hr after surgery. The nausea distress score of Ap125 group (0.04 ± 0.20) was lower (P = 0.032) than the control group (0.67 ± 1.24) at 6 hr after surgery. No evident side effect of aprepitant was observed.

Conclusions

Oral aprepitant 125 mg can be used as combination therapy for the prevention of PONV.

Inhibiting substance p pathway for prevention of chemotherapy-induced emesis: preclinical data, clinical trials of neurokinin-1 receptor antagonists

Neurokinin-1 (NK-1) receptor antagonists are a new class of antiemetic agents that have activity in controlling cisplatin-induced acute and delayed emesis. Preclinical data in animal models show that the NK-1 receptor antagonists have broad antiemetic activity. The NK-1 receptor antagonists have activity in controlling emesis induced by peripherally acting and centrally acting emetogens, suggesting a mechanism of action at multiple sites. The effects at central and peripheral sites to control acute and delayed emesis cannot be determined at this time based on available studies. When added to a standard regimen of a 5-hydroxytryptamine-3 (5- HT3) receptor antagonist and dexamethasone, the NK-1 receptor antagonists improve control of acute emesis. The NK-1 receptor antagonists improve delayed emesis compared with placebo, and when used in combination with dexamethasone, compared with dexamethasone alone. Acute and delayed nausea may also be improved by the NK-1 receptor antagonists when they are used in combination with a 5-HT3 receptor antagonist and dexamethasone prechemotherapy or with daily dosing for 5 days after chemotherapy. The current data suggest that the mechanism of action of the NK-1 receptor antagonists appears to be different from that of the 5-HT3 receptor antagonists. Future studies may consider using NK-1 receptor antagonists with moderately emetogenic chemotherapy as well as bone marrow transplantation.

Evaluation of new antiemetic agents and definition of antineoplastic agent emetogenicity--state of the art

Antiemetic drug development can follow the same logical path as antineoplastic drug development from appropriate preclinical models through Phase I, Phase II, and Phase III testing. However, due to the marked success of antiemetic therapy over the last 25 years, placebo antiemetic treatment against highly or moderately emetogenic chemotherapy is not acceptable. Promising antiemetic agents therefore rapidly reach Phase III testing, where they are substituted into or added to effective and accepted regimens. One challenge of antiemetic drug development is determining whether substitution is indeed acceptable or whether prior regimens must be maintained intact as a basis for further antiemetic drug development. An additional challenge is the classification of emetogenic level of new antineoplastic agents. Accurate reporting of emetogenicity of such antineoplastic agents in the absence of preventive antiemetic treatment may not be available. However, at the 2009 Multinational Association of Supportive Care in Cancer (MASCC)/European Society of Medical Oncology (ESMO) Consensus Conference, an expert panel used best available data to establish rankings of emetogenicity. Oral chemotherapeutic agents are ranked separately from intravenous agents, recognizing intrinsic differences in emetogenicity as well as differing schedules of administration. Since oral chemotherapeutic agents are often administered in extended regimens, the distinction between acute and delayed emesis is less clear, and cumulative emesis must be considered. As control of vomiting has improved, attention has shifted to control of nausea, a related but distinct and equally important problem. Additional efforts will be necessary to understand mechanisms of nausea and to identify optimal remedies.

Management of chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) remains one of the most disturbing side effects of cancer treatment. Research in anti-emetic therapy progressed gradually since the early eighties and the development of anti-emetic agents continues. This review focuses on the current management of CINV based on the most recent guidelines and adherence to the latter is examined more carefully. Setrons (5HT3 receptor antagonists), corticosteroids and NK-1 receptor antagonists are the cornerstones of anti-emetic therapy. The latest developed palonosetron and casopitant proved to be highly promising in clinical trials. Other types include benzodiazepines, cannabinoids and olanzapine. Various risk factors contribute to the overall risk of developing CINV, such as patient characteristics, emetogenic potency of the chemotherapeutic agents and correct prevention of CINV. Current guidelines determine which is the right preventive regimen for each cancer patient at risk for experiencing CINV. Adherence to this guidelines and implementation in daily practice seem to be below the optimal level. In Belgium, authorities use the guidelines as a base for reimbursement and this has increased the level of implementation.

Use of antipsychotic medication in chemotherapy-induced nausea and vomiting

Nausea and vomiting continue to present significant problems for cancer patients undergoing chemotherapy. Initial work suggested an important role for central dopamine transmission in the underlying pathophysiology. However, recent evidence has implicated central and peripheral serotonin release. Although the implementation of 5-HT(3) receptor antagonists has resulted in significant improvement in acute symptoms of nausea and vomiting, they have not demonstrated optimal efficacy in anticipatory and delayed emetic syndromes and are significantly more expensive than other antiemetic therapies. The use of typical antipsychotic medication to reduce nausea and vomiting in cancer patients is discussed, as is the potential efficacy of newer atypical antipsychotics, which have activity at receptors implicated in the control of chemotherapy-induced nausea and vomiting and demonstrate an improved side-effect profile.

Chemotherapy-induced nausea and vomiting: antiemetic trials that impacted clinical practice

Objective. To review the scientific evidence related to serotonin and substance P and the clinical impact targeting these two neurotransmitters have had managing chemotherapy-induced nausea and vomiting (CINV).

Data Source. A PubMed search (January 1968 to December 2008), restricted to English-language publications, was conducted using the key words antiemetics, cancer chemotherapy, cisplatin, serotonin, substance P, NK1, and 5-HT3. Abstracts emanating from the meetings of the American Society of Clinical Oncology and Multinational Association of Supportive Care in Cancer during the period May 2000 to June 2008 were also reviewed.

Data Synthesis. Two important outcomes emanated from well-conducted antiemetic clinical trials (Table 1): first, evidence that serotonin and substance P are major mediators of acute and delayed symptoms and second, improved, though not complete, control of CINV.

Conclusion. Serotonin-type 3 and neurokinin-1 receptor antagonists are the most effective agents currently available. In most cases, these agents are used in conjunction with glucocorticoids. The use of these three types of agents is incorporated into current clinical practice guidelines. Further understanding of the biological and biochemical basis of nausea and vomiting may enhance management of this potentially debilitating adverse effect.

[Chemotherapy induced emesis: pathophysiology and prevention]

Nausea and emesis are one of the most feared secondary effect of chemotherapy. The development of antiemetic therapies has increased after the introduction of cisplatin, a cytotoxin with the highest emetic potential. Chemotherapy-induced nausea and vomiting (CINV) have been classified into acute, delayed and anticipatory based on the time of onset. According to the percentage of nausea and emesis without any antiemetic treatment, chemotherapy is divised into highly, moderate, low and very low emetic potential. The discovery of emetics stimuli neurotransmitters and their receptors has led to the introduction of new molecules which associated with steroids have prevented nausea and vomiting chemotherapy-induced for 70 to 80% of the patients receiving chemotherapy with high emetic potential. Numerous studies have evaluated the various antiemetics and recommendations were issued by learned societies in US and Europe. This text discusses the physiopathology of nausea and vomiting, the development of anti-emetics and the new discovered antiemetics. Finally, a synthesis of the recommandations from the guidelines developed by the Multinational Association of Supportive Care in Cancer (MASCC), the American Society of Clinical Oncology (ASCO), the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO) is presented.

Antiemetic control: toward a new standard of care for emetogenic chemotherapy

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. 5-hydroxytryptamine-3 (5-HT(3)) receptor antagonists plus dexamethasone have significantly improved the control of acute CINV, but delayed CINV remains a significant clinical problem. Two new agents, palonosetron and aprepitant, have been approved for the prevention of both acute and delayed CINV. Palonosetron is a second-generation 5-HT(3) receptor antagonist with a longer half-life and a higher binding affinity than first-generation 5-HT(3) receptor antagonists. Aprepitant is the first agent available in the new drug class of neurokinin-1 (NK-1) receptor antagonists. Casopitant is another NK-1 receptor antagonist that is under review by the FDA after recent completion of Phase III clinical trials. The introduction of these new agents has generated revised antiemetic guidelines for the prevention of CINV. Future studies may consider the use of palonosetron, aprepitant and casopitant with other antiemetic agents (olanzapine, gabapentin, cannabinoids) in moderately and highly emetogenic chemotherapy, as well as in the clinical settings of multiple-day chemotherapy and bone marrow transplantation.

Fosaprepitant dimeglumine (MK-0517 or L-785,298), an intravenous neurokinin-1 antagonist for the prevention of chemotherapy induced nausea and vomiting

BACKGROUND

This paper reviews the existing literature on fosaprepitant, an intravenous neurokinin-1 anatgonist for the prevention of chemotherapy induced nausea and vomiting.

OBJECTIVES

To describe the development of fosaprepitant and to situate the intravenous form of aprepitant in the current market of available antiemetics.

METHODS

Literature was screened and selected in order to compare the intravenous form of the already commonly used NK-1 receptor antagonist aprepitant.

RESULTS

Aprepitant is the first and still the only marketed neurokinin-1 (NK-1) antagonist. Interestingly, the first studies were performed with fosaprepitant dimeglumine (MK-0517 or L-785,298), the water-soluble prodrug of aprepitant. Fosaprepitant is converted into aprepitant within 30 min after intravenous administration. Based on equivalence studies, 115 mg fosaprepitant seems to be the substitute for 125 mg orally administrated aprepitant. Tolerability of the prodrug is no different from the active drug. The number of efficacy studies with fosaprepitant is very limited and most data are derived from existing aprepitant results. Fosaprepitant has recently been approved by FDA and EMEA as an intravenous substitute for oral aprepitant on day 1 of the standard 3-day CINV prevention regimen, which also includes dexamethasone and a 5-HT3 antagonist.

Antiemetics: an update and the MASCC guidelines applied in clinical practice. ACTA ACUST UNITED AC. 2008;5:32-43. [PMID: 18097455 DOI: 10.1038/ncponc1021]

Nausea and vomiting are two of the most severe problems for patients treated with chemotherapy. Until the late 1970s, nausea and vomiting induced by chemotherapy was an almost neglected research area. With the introduction of cisplatin, the cytotoxin with the highest emetic potential, research was stimulated and has now resulted in the development of two new classes of antiemetics, the serotonin and neurokinin antagonists. A large number of trials have fine-tuned antiemetic therapy and made evidence-based recommendations possible for the majority of patients receiving chemotherapy. This Review discusses the pathophysiology of nausea and vomiting, the development of antiemetics, highlights some of the newest antiemetics, and finally summarizes recommendations from the evidence-based guidelines developed by the Multinational Association of Supportive Care in Cancer.

Anti-emetic therapy in cancer chemotherapy: current status

Nausea and vomiting are ranked as the most severe side effects to chemotherapy by cancer patients. Twenty years ago, treatment of nausea and vomiting from chemotherapy only had moderate effect and often unpleasant side effects. The drugs used included dopamine(2)-receptor antagonists and corticosteroids alone or combined. This review summarizes the development of anti-emetic therapy, but will focus on the importance of two new classes of anti-emetics: the serotonin(3)- and the neurokinin(1)-receptor antagonists. Furthermore, evidence-based guidelines for the treatment of chemotherapy-induced nausea and vomiting will be given. The serotonin(3)-receptor antagonists, the first group of drugs developed specifically as anti-emetics, have significantly improved the prophylaxis of chemotherapy-induced emesis especially in combination with a corticosteroid. The improvement in the prophylaxis of nausea with this combination is however modest. A new group of anti-emetics, the neurokinin(1)-receptor antagonists, has now been developed, and the first drug, aprepitant, was marketed in 2003. Aprepitant increases the effect of a serotonin(3)-receptor antagonist plus a corticosteroid against acute emesis induced by highly or moderately emetogenic chemotherapy and aprepitant is also active in the protection against delayed emesis. The importance of drug-drug interactions with anti-emetics and other drugs, especially cytotoxins, through their competition for cytochrome P450 enzymes, have been studied. At present, there is no evidence that such interactions are of major clinical importance. Evidence-based clinical guidelines are now available and regularly updated, but unfortunately clinical implementation is slow. Recommendations for some types of chemotherapy-induced emesis such as delayed emesis, is based on a low level of evidence. Furthermore, the majority of clinical trials include highly selected groups of patients not permitting definite conclusions for other and more heterogeneous patient groups. Development of new anti-emetics with other mechanisms of action is awaited with interest.

Comparative activity of antiemetic drugs

Nausea and vomiting continues to be an important problem for cancer patients receiving chemotherapy. Chemotherapy-induced nausea and vomiting (CINV) are classified as acute, occurring within the first 24h, or delayed, occurring after the first 24h. A number of antiemetic agents are available for the management of nausea and vomiting, including 5-HT3-receptor-antagonists, corticosteroids, NK-1-receptor-antagonists, dopamine-receptor antagonists, benzodiazepines, neuroleptics and cannabinoids. With modern antiemetic therapy, vomiting can be prevented in 70-80% of patients, whereas the control of nausea remains suboptimal. The development of acute emesis is known to depend on serotonin. The pathophysiology of delayed emesis is less well understood, and multiple mechanisms may contribute, including substance P. Here, the most recent developments in the antiemetic therapy, including new antiemetic drugs and the latest guidelines for antiemetic prophylaxis, are reviewed.

The neurokinin1 receptor antagonist aprepitant as an antiemetic for moderately emetogenic chemotherapy

The neurokinin-1 (NK1) receptor antagonist aprepitant has become part of standard antiemetic therapy for high-dose cisplatin. Recent results indicate that chemotherapy for breast cancer that contains an anthracycline plus cyclophosphamide is more emetogenic than has been previously realised. One large randomised trial demonstrated that aprepitant substantially reduces the risk of vomiting or retching when added to a corticosteroid and a 5-hydroxytryptamine 3 (HT3) receptor antagonist. The adverse effects of standard antiemetics and chemotherapy do not appear to be increased by the addition of this novel antiemetic agent. Aprepitant should now also be considered to be part of prophylactic antiemetic therapy for women who receive chemotherapy that contains an anthracycline and cyclophosphamide. The role of NK1 receptor antagonists in preventing emesis due to other cytotoxic agents that are deemed to be moderately emetogenic is still unclear.

American Society of Clinical Oncology guideline for antiemetics in oncology: update 2006

PURPOSE

To update the 1999 American Society of Clinical Oncology guideline for antiemetics in oncology.

UPDATE METHODOLOGY

The Update Committee completed a review and analysis of data published from 1998 thru February 2006. The literature review focused on published randomized controlled trials, and systematic reviews and meta-analyses of published phase II and phase III randomized controlled trials.

RECOMMENDATIONS

The three-drug combination of a 5-hydroxytryptamine-3 (5-HT(3)) serotonin receptor antagonist, dexamethasone, and aprepitant is recommended before chemotherapy of high emetic risk. For persons receiving chemotherapy of high emetic risk, there is no group of patients for whom agents of lower therapeutic index are appropriate first-choice antiemetics. These agents should be reserved for patients intolerant of or refractory to 5-HT3 serotonin receptor antagonists, neurokinin-1 receptor antagonists, and dexamethasone. The three-drug combination of a 5-HT3 receptor serotonin antagonist, dexamethasone, and aprepitant is recommended for patients receiving an anthracycline and cyclophosphamide. For patients receiving other chemotherapy of moderate emetic risk, the Update Committee continues to recommend the two-drug combination of a 5-HT3 receptor serotonin antagonist and dexamethasone. In all patients receiving cisplatin and all other agents of high emetic risk, the two-drug combination of dexamethasone and aprepitant is recommended for the prevention of delayed emesis. The Update Committee no longer recommends the combination of a 5-HT3 serotonin receptor antagonist and dexamethasone for the prevention of delayed emesis after chemotherapeutic agents of high emetic risk. CONCLUSION The Update Committee recommends that clinicians administer antiemetics while considering patients' emetic risk categories and other characteristics.

Gastrointestinal toxicity of chemotherapeutic agents

Chemotherapy-induced toxicities commonly occur in sites within the gastrointestinal (GI) tract and account for dose-limiting effects. These toxicities are major contributing factors to dose reduction, delays, and cessation of cancer treatment. Through intensive therapies including surgery, combination chemotherapy, hormonal therapy, and targeted therapy, an increasing number of patients with cancer are experiencing improved survival and long-term disease-free survival, as well as palliation of disease-related symptoms. Thus, GI toxicities should be predicted and appropriate interventions initiated to prevent them when possible and provide effective supportive measures and comprehensive follow-up care. This review will discuss the etiology, incidence, prevention, and treatment of GI toxicities of cancer chemotherapy.

Neurokinin-1-receptor antagonists: a new approach in antiemetic therapy

Aprepitant (Emend), the first neurokinin-1-receptor antagonist (NK-1-RA), represents a new class of antiemetics. Aprepitant has been approved for the prevention and treatment of acute (0-24 h after chemotherapy) and delayed (1-5 days after chemotherapy) emesis resulting from cisplatin-based chemotherapy and moderately emetogenic chemotherapy. The addition of aprepitant to standard antiemetic therapy in cisplatin-based chemotherapy significantly improves emesis protection in general and, in particular, in the delayed phase by approximately 20%. Results from a recently published study in patients receiving moderately emetogenic chemotherapy suggest a benefit of aprepitant when combined with dexamethasone and a 5-HT(3) receptor antagonist for the prevention of acute emesis, followed by aprepitant as a single agent in the prevention of delayed emesis. Altogether, the addition of aprepitant to the standard antiemetic regimen (5-HT(3) receptor antagonist and dexamethasone) significantly improves the protection against vomiting in the acute as well as in the delayed phase in highly and moderately emetogenic chemotherapies. Therefore, the combination of a 5-HT(3) receptor antagonist, dexamethasone and aprepitant should be considered as a new standard antiemetic therapy.

Emerging drugs for chemotherapy-induced emesis

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles and patient risk factors (female gender, younger age, no alcohol consumption, history of motion sickness) are the major risk factors for CINV. The use of 5-hydroxytryptamine-3 (5-HT3) receptor antagonists plus dexamethasone has significantly improved the control of acute CINV, but delayed nausea and vomiting remains a significant clinical problem. Two new agents, palonosetron and aprepitant, have recently been approved for the prevention of both acute and delayed CINV. Palonosetron is a 5-HT3 receptor antagonist with a longer half-life and a higher binding affinity than first-generation 5-HT3 receptor antagonists. Aprepitant is the first agent available in the new drug class of neurokinin-1 receptor (NK-1) antagonists. There are a number of 5-HT3 receptor antagonists and NK-1 receptor antagonists currently in Phase II and III clinical trials. Revised antiemetic guidelines for the prevention of CINV are reviewed. Future studies may consider the use of palonosetron and aprepitant with current and other new agents (olanzapine, gabapentin) in moderately and highly emetogenic chemotherapy, as well as in the clinical settings of multiple-day chemotherapy and bone marrow transplantation.

Management of chemotherapy-induced nausea, vomiting, oral mucositis, and diarrhoea

The past 10 years have seen substantial advances in molecularly targeted therapies for treatment of patients with cancer; however, chemotherapy will continue to be used. Therefore, the toxic effects of chemotherapy must be readily managed-especially nausea, vomiting, mucositis, and diarrhoea. For moderately to highly emetogenic chemotherapy, standard prophylactic treatment is an antagonist for 5-hydroxytryptamine 3 receptors (5-HT3R) combined with dexamethasone for the acute phase, and dexamethasone with another agent for prevention of the delayed phase. Palonoestron (a 5-HT3R antagonist) and aprepitant (an antagonist for the protachykinin 1 receptor) have been introduced for the prevention of emesis. Other agents such as cannabinoids, gabapentin, and olanzapine might also be effective. There is no standard prophylactic regimen for chemotherapy-induced mucositis. The most common treatment is optimum care of the mouth by use of mouthwashes. Keratinocyte growth factor, molgromastim, and transforming growth factor beta3 may also reduce chemotherapy-induced mucositis. Severe diarrhoea is another potentially fatal complication of chemotherapy and is most common in patients treated with irinotecan. Several interventions have been assessed for prevention and treatment of diarrhoea such as high-dose loperamide, non-absorbable antibiotics, budesonide, thalidomide, and fish oils, but only loperamide is used routinely. Symptom management has become a focus of clinical research, and development of personalised medicine should identify patients at increased risk of toxic effects because of molecular or biochemical factors, thus leading to changes in dose, early intervention, or use of alternative therapies.

Role of Neurokinin-1 Receptor Antagonists in Chemotherapy-Induced Emesis: Summary of Clinical Trials

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life, and although the use of 5-hydroxytryptamine3 (5-HT3) receptor antagonists plus dexamethasone has significantly improved the control of acute CINV, delayed nausea and vomiting remain a significant clinical problem. Aprepitant is the first agent available in the new drug class of neurokinin-1 receptor antagonists. When added to a standard regimen of a 5-HT3 receptor antagonist and dexamethasone in patients receiving highly emetogenic chemotherapy, it improves the complete response rate of acute CINV. Aprepitant also improves the complete response of delayed CINV when used in combination with dexamethasone compared to dexamethasone alone. The use of aprepitant in patients receiving moderately emetogenic chemotherapy will await the review and analysis of recently completed phase III trials. The control of nausea is improved in some studies with the use of aprepitant when it is combined with a 5HT3 receptor antagonist and dexamethasone, but nausea control remains suboptimal. The current data suggest that the mechanism of action of the NK-1s appears to be different from the 5-HT3 receptor antagonists. Future studies may explore the use of aprepitant and other NK-1s in moderately and highly emetogenic chemotherapy, as well in the clinical settings of multiple-day chemotherapy and bone marrow transplantation.

Chemotherapy-induced nausea and vomiting in routine practice: a European perspective

GOALS OF WORK

The aim of this study was to evaluate the occurrence of chemotherapy-induced nausea and vomiting (CINV) and its effect on patients' ability to carry out daily life activities following moderately to highly emetogenic, first-cycle chemotherapy in routine practice in cancer centers of four different European countries.

PATIENTS AND METHODS

This was a prospective, cross-sectional, nonrandomized, self-assessment study in 249 patients enrolled from cancer centers in Spain, Austria, Germany, and Switzerland. The study population consisted of 78% women, with a mean age of 54. Breast, lung, and ovarian cancers made up 75% of all cancers in the study. Patients received a mean of 2.0 chemotherapy agents and 2.5 antiemetic drugs.

MAIN RESULTS

A total of 450 emetic episodes experienced by 243 patients was recorded over 5 days following chemotherapy, with an average of 1.8 episodes per patient (range: 0-28). A higher percentage of patients (38%) suffered from delayed compared to acute emesis (13%). Between 42% and 52% of all patients suffered from nausea (visual analogue scale > or = 5 mm) on any one day, peaking at day 3. Using the Functional Living Index for Emesis (FLIE) questionnaire, 75% of patients with nausea and 50% with vomiting reported a negative impact of these conditions on performance of daily living.

CONCLUSIONS

CINV remains a significant problem in routine practice, particularly in the delayed phase posttreatment. Overall, CINV had a negative impact on patients' daily life.

Antiemetic effect of dexamethasone on cisplatin-induced early and delayed emesis in the pigeon

We investigated the ability of dexamethasone to attenuate cisplatin (4 mg/kg, i.v.)-induced early and delayed emesis. These appear within the first 8-h period (early phase) and between 8 and 48 h (delayed phase), respectively, after cisplatin administration in the pigeon. Dexamethasone (0.1 and 1 mg/kg, i.m.) reduced significantly the number of emetic responses to cisplatin by 56% and 82% (P<0.05), respectively, in the early phase, and by 41% and 66% (P<0.05), respectively, in the delayed phase. Dexamethasone (1 and 10 microg/kg, i.c.v.) reduced the number of emetic responses by 66% and 91% (P<0.05), respectively, in the early phase, and by 56% and 87% (P<0.05), respectively, in the delayed phase. Indomethacin (10 mg/kg, i.m.) did not suppress cisplatin-induced early and delayed emesis. Dexamethasone (1 mg/kg, i.m.) did not affect the content of platinum in the medulla oblongata after cisplatin administration. The above results suggest that dexamethasone has antiemetic effects on both the early and delayed emetic responses to cisplatin in pigeons, partially via its central site of action, and that the antiemetic mechanism of dexamethasone is related to factors other than its inhibition of prostanoid synthesis or its membrane stabilizing effect which reduces influx of cisplatin into the medulla oblongata.

Current position of 5HT3 antagonists and the additional value of NK1 antagonists; a new class of antiemetics

The advent of the 5HT(3) receptor antagonists (5HT(3) antagonists) in the 1990 s and the combination with dexamethasone has resulted in acute emesis protection in 70% of patients receiving highly emetogenic chemotherapy. Despite complete protection in the acute phase, however, 40% of patients as yet have symptoms in the delayed phase. 5HT(3) antagonists and dexamethasone are only modestly effective in this delayed phase. Moreover, the antiemetic protection over repeated cycles is not sustained. Neurokinine 1 receptor antagonists (NK(1) antagonists) belong to a new class of antiemetic agents that specifically target the NK(1) receptor, which is involved in both the acute and, particularly, the delayed phase of emesis. Clinical studies have demonstrated that the addition of NK(1) antagonists to dual therapy with a 5HT(3) antagonist plus dexamethasone improves the acute emesis protection by a further 10-15%. In the delayed phase, the proportion of patients remaining free of emesis increases by even 20-30%. Since the effectiveness of this triplet combination was found to be sustained over six cycles of chemotherapy, the chance for an individual patient to remain completely protected during both the acute and the delayed phase over six chemotherapy cycles is nearly doubled.

Roles of substance P and NK(1) receptor in the brainstem in the development of emesis

The emetic response is primarily a protective reflex occurring in a wide variety of vertebrates in response to the ingestion of toxic compounds. The role of the nuclei in the brainstem, including the area postrema, nucleus tractus solitarius, the dorsal motor nucleus of the vagus, and the central pattern generator for vomiting, as well as the involvement of the abdominal visceral innervation relevant to the emetic reflex, have all been discussed by many researchers. The introduction of serotonin 5-HT(3)-receptor antagonists into clinical practice allowed for a dramatic improvement in the management of vomiting. However, vomiting still remains a significant problem. The mechanism of the emetic response is even more complicated than was first thought. This review attempts to bring together some of the evidence suggesting the roles of substance P and its receptor, neurokinin NK(1) receptor, in the brainstem nuclei in the development of emesis. Accordingly, NK(1)-receptor antagonists might represent novel drugs for the management of major types of emesis.

Application of LC-NMR for the study of the volatile metabolite of MK-0869, a substance P receptor antagonist

LC-NMR was applied to identify the polar volatile metabolite of MK-0869. MK-0869, a morpholine-based compound containing a triazolone ring, is a very potent NK(1) receptor antagonist. Currently, it is in development as an anti-emesis agent in chemotherapy treatments. The primary metabolites of MK-0869, M1 and M2, are non-polar and lack the triazolone ring. Incubation of [14C]M1 with liver microsomes from male rats produced a very polar and volatile metabolite, M3. Analysis was not possible by LC-MS or by conventional NMR because of poor ionization, small molecular weight and volatility, leaving chemical derivatization and LC-NMR as alternative methods. Reduction of M3 with NaBH(4) resulted in a derivative that had the same retention time as p-fluorophenylethylene glycol on HPLC. A small aliquot of the solution containing M3 was passed through the LC of the LC-NMR system, which was connected on-line with a radioactivity detector. The simultaneous UV and radioactivity chromatograms thus identified the chromatographic UV peak that was associated with the metabolite. Analysis was carried out by stop-flow on another portion of this fraction. From the chemical derivatization and the analysis by LC-NMR, M3 is shown to be p-fluoro-alpha-hydroxyacetophenone. Further studies using LC-NMR showed that M3 could be generated from both M1 and M2 in NADPH-dependant reactions catalyzed by microsomes containing recombinant human CYP2C19, CYP1A2 or CYP3A4.

Anti-emetics in development

Despite important advances in pharmacotherapeutic options for the prevention and treatment of nausea and vomiting during the 1990s, a significant proportion of patients still suffer debilitating nausea and vomiting symptoms. The most problematic areas are chemotherapy-induced nausea and vomiting particularly delayed emesis, postoperative nausea and vomiting, opioid-induced nausea and vomiting and motion sickness. The most vigorous research into new anti-emetics has focused on the neurokinin-1 (substance P) antagonists. Clinical trials conducted to date indicate that these agents have similar efficacy to 5-HT(3) antagonists in acute chemotherapy-induced nausea and vomiting, superior efficacy to available agents in delayed emesis, possibly superior efficacy against emesis in postoperative nausea and vomiting and no evidence of efficacy versus opioid or motion-induced nausea and vomiting. Other pharmacological strategies in development include agonising CB1 (cannabinoid) receptors, "broad spectrum" receptor antagonists and 5-HT(1A) receptor agonists, although clinical trials of these types of agents are not yet available. The neurokinin-1 antagonists appear to be promising agents for some nausea and vomiting states, although further clarification of their role is required.

Substance P: a new era, a new role

Substance P has been extensively studied and is considered the prototypic neuropeptide of the more than 50 known neuroactive molecules. The understanding of substance P has evolved beyond the original concept as the pain transmitter of the dorsal horn. Animal and genetic research, recent developments of nonpeptide substance P antagonists, and important changes in the understanding of neurotransmission have each contributed to the current understanding of substance P After 7 decades, the physiologic role of substance P is known as a modulator of nociception, involved in signaling the intensity of noxious or aversive stimuli. Genetic studies in mice and development of substance P antagonists provide more recent results that support the redefinition of the central role of substance P Evidence suggests that this neuropeptide is an integral part of central nervous system pathways involved in psychologic stress.

Action of glucocorticoids to antagonise cisplatin-induced acute and delayed emesis in the ferret

Cisplatin 5 mg/kg, i.p. induced an acute (day 1) and delayed (days 2 and 3) emetic response in the ferret that was used to investigate the potential anti-emetic activity of several glucocorticoids. Betamethasone (0.3-3 mg/kg, i.p.) reduced the emesis occurring during the initial 0-24-h period by 71.1-99.5% (P<0.05). The action of methylprednisolone (1.0-10.0 mg/kg, i.p.) and hydrocortisone (1.0-30.0 mg/kg, i.p.) could not be assessed because the controls exhibited weak emetic responses and dexamethasone produced a non-significant 64.0% reduction at 0.3 mg/kg (P>0.05). However, all glucocorticoids dose-dependently reduced retching+vomiting during the subsequent 24-56-h period. The rank order of anti-emetic potency was betamethasone (ID(80)<0.3 mg/kg)>/=dexamethasone (ID(80)=0.32 mg/kg)>methylprednisolone (ID(80)=0.66 mg/kg)&z.Gt;hydrocortisone (ID(80)>30 mg/kg). Dexamethasone was ineffective to antagonise the retching+vomiting response during the 24-56-h period when the administration was delayed until 24 h post-cisplatin injection. None of the glucocorticoids reduced the retching+vomiting response occurring during the 56-72-h period. In conclusion, the rank order of anti-emetic potency suggests that inflammation, or mediators of inflammation, contribute to the retching+vomiting response induced by cisplatin.

Prevention of cisplatin-induced emesis by the oral neurokinin-1 antagonist, MK-869, in combination with granisetron and dexamethasone or with dexamethasone alone

PURPOSE

The NK1-receptor antagonist MK-869 (L-754,030) has demonstrated antiemetic activity in humans receiving chemotherapy. Objectives of the present trial included the first assessment of oral MK-869 plus dexamethasone compared with a 5HT(3) antagonist plus dexamethasone for prevention of acute and delayed emesis after high-dose cisplatin. Furthermore, the study sought to confirm that addition of MK-869 to a 5HT(3) antagonist plus dexamethasone was more effective than just the 5HT(3) antagonist plus dexamethasone for prevention of acute and delayed emesis.

METHODS

This multicenter, double-blind, parallel-group trial in 351 cisplatin-naïve patients evaluated prevention of acute (0 to 24 hours) and delayed emesis (primary efficacy parameter; days 2 to 5) after cisplatin (> or =70 mg/m(2)). Patients were randomized to four groups (I to IV) (n = number randomized; number evaluable): granisetron (10 microg/kg intravenously) pre-cisplatin followed by placebo on days 2 to 5 (group I) (n = 90; 90); granisetron and MK-869 (400 mg PO [by mouth]) pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group II) (n = 86; 84); MK-869 (400 mg PO) the evening before and pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group III) (n = 89; 88); or MK-869 (400 mg PO) pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group IV) (n = 86; 84). All patients also received dexamethasone (20 mg PO) before cisplatin. Additional medication was available to treat emesis or nausea at any time.

RESULTS

In the acute period, 57%, 80%, 46%, and 43% of patients were without emesis in groups I, II, III, and IV, respectively (P <.01 for group II v group I). In the delayed period, the proportion of patients without emesis in groups I, II, III, and IV was 29%, 63%, 51%, and 57%, respectively (P <.01 for groups II, III, and IV v group I). The distribution of nausea scores in the delayed period was lower when comparing group II with group I (P <.05 for days 1 to 5 and days 2 to 5). One serious adverse event (dizziness) was rated as possibly related to MK-869.

CONCLUSION

Once daily oral administration of MK-869 was effective in reducing delayed emesis and nausea after high-dose cisplatin. However, the combination of the 5HT3 antagonist plus dexamethasone was numerically superior to MK-869 plus dexamethasone in reducing acute emesis. Confirming and extending previous findings, the triple combination of a 5HT(3) antagonist, MK-869, and dexamethasone provided the best control of acute emesis.

Prevention and Management of Chemotherapy-Induced Nausea and Vomiting, Part 2

Credit

This lesson is good for 0.3 CE units, with a passing grade of 70%.

Goal

The goal of this program is to inform the participant about cost-effective ways to prevent, identify, and manage nausea and vomiting induced by antineoplastic agents.

Objectives

At the completion of this program the participant will be able to: 1. List antineoplastic agents associated with a high incidence of nausea and vomiting. 2. Identify patient-specific risk factors for developing chemotherapy-induced nausea and vomiting (CINV) and how these factors may influence treatment of this syndrome. 3. Compare the three major types of CINV, including the pathophysiologic mechanism, time of onset, and symptom duration of each type. 4. Explain the mechanism of action and appropriate place in therapy for each type of antiemetic agent. 5. Differentiate between pharmacologic regimens for the prevention and treatment of CINV in adults. 6. Identify drug-specific factors that must be considered when developing a formulary management strategy for the antiemetic agents. 7. Describe specific information that the pharmacist can share with patients to help them understand and manage CINV.

Potential of substance P antagonists as antiemetics

The introduction of serotonin 5-HT3 receptor antagonists into clinical practice allowed for a dramatic improvement in the management of nausea and vomiting. Despite this, postoperative and chemotherapy-induced emesis remains a significant, unresolved issue in many patients even when a combination of antiemetic drugs is used. Numerous neurotransmitters have been implicated in triggering emesis; however, the tachykinin substance P, by virtue of its localisation within both the gastrointestinal vagal afferent nerve fibres and brainstem emetic circuitry, and its ability to induce vomiting when administered intravenously, is thought to play a key role in emetic responses. Because substance P is the most likely endogenous ligand for the neurokinin-1 (NK1) receptor, the development of nonpeptide NK1 receptor antagonists led scientists to evaluate these compounds as antiemetics. The five NK1 receptor inhibitors that have been studied initially in humans are: vofopitant (GR-205171), CP-122721, ezlopitant (CJ-11974), MK-869 (L-754030) and its prodrug L-758298. Except for monotherapy in acute cisplatin-induced emesis, this new class of drugs has proven to be highly effective in the control of both chemotherapy-induced nausea and vomiting, and postoperative nausea and vomiting. No major adverse event was reported in the preliminary trials. Further investigation is mandatory in order to assess the optimal treatment regimen and to make sure the wide spectrum activity of the NK1 receptor inhibitors does not cause significant adverse effects in the context of the treatment of nausea and vomiting.

Comparison of the neurokinin-1 antagonist GR205171, alone and in combination with the 5-HT3 antagonist ondansetron, hyoscine and placebo in the prevention of motion-induced nausea in man

AIMS

In man a neurokinin-1 (NK1) receptor antagonist has previously been shown to be ineffective in the prevention of motion-induced nausea. The antiemetic efficacy of NK1 receptor antagonists against chemotherapy-induced emesis is, however, enhanced when combined with a 5-HT3 receptor antagonist. Hence the efficacy of the NK1 antagonist GR205171 in combination with the 5-HT3 antagonist ondansetron (Zofrantrade mark) was assessed in motion-induced nausea.

METHODS

GR205171 25 mg i.v., with and without concomitant administration of ondansetron 8 mg i.v., and hyoscine hydrobromide 0. 6 mg orally (positive control) were compared with placebo in a model of motion-induced nausea. The study was performed to a four-period, randomized, balanced, double-blind, crossover design in 16 healthy subjects. The end-point was the exposure to the motion stimulus required to produce moderate nausea in the subjects.

RESULTS

The motion stimulus required to produce moderate nausea was significantly greater for the positive control than placebo (P < 0. 001). There was no significant difference between either GR205171 or GR205171 plus ondansetron and placebo (P = 0.648 and 0.342, respectively).

CONCLUSIONS

The enhancement of NK1 receptor antagonist antiemetic activity through combination with a 5-HT3 receptor antagonist is not replicated in motion-induced nausea.