Physiology of chemotherapy-induced emesis and antiemetic therapy. Predictive models for evaluation of new compounds

Childhood dystonic reactions in the middle Black Sea region

Acute dystonic reactions are a worrying reason for presentation to the pediatric emergency department and the pediatric neurology clinic in childhood. It must be diagnosed and treated quickly. The aim of this study was to examine the clinical presentations, etiological factors, and prognosis of patients presenting to our regional tertiary pediatric neurology clinic with a diagnosis of acute dystonic reactions in children.Nine pediatric patients who were treated for acute dystonic reactions between May, 2018 and May, 2020 and had adequate follow-up were included in the study. Medical record data were reviewed age, gender, etiology, features of family, treatment, and results.Three of the patients were female and 6 were male. Their average age was 11 years (4-17). All patients were evaluated as a drug-induced acute dystonic reaction. Of the 9 patients, 5 were due to metoclopramide, 3 were due to risperidone, and 1 was due to aripiprazole. It was learned that a similar situation against other drugs developed in the family history of 3 patients. As a treatment, all of them were intramuscularly applied biperiden suitable for their weight and 30 minutes dramatic improvement was observed. Additional dose had to be administered in only 1 case. All cases were discharged for 24 hours. No problem was observed in their follow-up.Drug-induced acute dystonic reaction can be diagnosed and has a clinical picture that completely resolves when effective treatment is applied. However, it should not be forgotten that it can reach life-threatening dimensions clinically.

Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems

Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, and corresponding receptors, as well as intracellular emetic signaling pathways involved in the processes of nausea and vomiting in diverse animal models as well as humans. While blockade of emetic receptors in the prevention of vomiting is fairly well understood, the potential of new classes of antiemetics altering postreceptor signal transduction mechanisms is currently evolving, which is also reviewed. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide potential answers.

[Prevention and treatment of antineoplastic drug-induced nausea and vomiting in pediatric onco-hematology: An update]

Antineoplastic drug induced nausea and vomiting are common adverse events in cancer care of paediatric patients ; therefore, prevention and management of these adverse events is a major concern for healthcare professionals. There are common features between paediatric and adult patients in terms of the emetogenic level depending on antineoplastic agents or about available medicines. However, there are also specificities for paediatric population including individual risk factors of emesis or nausea assessment for example. Knowledge relative to available medicines is also limited in the paediatric population, especially for recent medicines. This review aims to provide a comprehensive overview about antiemetics in paediatric oncology to clinicians and other healthcare professionals involved in paediatric cancer care. First of all, we describe physiopathological paediatric specificity, risk factors and clinical assessment of antineoplastic drug induced nausea and vomiting. Secondly, we focus on available medicines and also address the issue of complementary and alternative medicines.

Suppression of Cisplatin-Induced Vomiting by Cannabis sativa in Pigeons: Neurochemical Evidences

Cannabis sativa (CS, family Cannabinaceae) has been reported for its anti-emetic activity against cancer chemotherapy-induced emesis in animal models and in clinics. The current study was designed to investigate CS for potential effectiveness to attenuate cisplatin-induced vomiting in healthy pigeons and to study the impact on neurotransmitters involved centrally and peripherally in the act of vomiting. High-performance liquid chromatography system coupled with electrochemical detector was used for the quantification of neurotransmitters 5-hydroxytryptamine (5HT), dopamine (DA) and their metabolites; Di-hydroxy Phenyl Acetic acid (Dopac), Homovanillic acid (HVA), and 5-hydroxy indole acetic acid (5HIAA) centrally in specific brain areas (area postrema and brain stem) while, peripherally in small intestine. Cisplatin (7 mg/kg i.v.) induce emesis without lethality across the 24 h observation period. CS hexane fraction (CS-HexFr; 10 mg/kg) attenuated cisplatin-induced emesis ∼ 65.85% (P < 0.05); the reference anti-emetic drug, metoclopramide (MCP; 30 mg/kg), produced ∼43.90% reduction (P < 0.05). At acute time point (3^rd h), CS-HexFr decreased (P < 0.001) the concentration of 5HT and 5HIAA in the area postrema, brain stem and intestine, while at 18^th h (delayed time point) CS-HexFr attenuated (P < 0.001) the upsurge of 5HT caused by cisplatin in the brain stem and intestine and dopamine in the area postrema. CS-HexFr treatment alone did not alter the basal neurotransmitters and their metabolites in the brain areas and intestine except 5HIAA and HVA, which were decreased significantly. In conclusion the anti-emetic effect of CS-HexFr is mediated by anti-serotonergic and anti-dopaminergic components in a blended manner at the two different time points, i.e., 3^rd and 18^th h in pigeons.

Protein calorie malnutrition, nutritional intervention and personalized cancer care

Cancer patients often experience weight loss caused by protein calorie malnutrition (PCM) during the course of the disease or treatment. PCM is expressed as severe if the patient has two or more of the following characteristics: obvious significant muscle wasting, loss of subcutaneous fat; nutritional intake of <50% of recommended intake for 2 weeks or more; bedridden or otherwise significantly reduced functional capacity; weight loss of >2% in 1 week, 5% in 1 month, or 7.5% in 3 months. Cancer anorexia-cachexia syndrome (CACS) is a multifactorial condition of advanced PCM associated with underlying illness (in this case cancer) and is characterized by loss of muscle with or without loss of fat mass. Cachexia is defined as weight loss of more than 5% of body weight in 12 months or less in the presence of chronic disease. Hence with a chronic illness on board even a small amount of weight loss can open the door to cachexia. These nutritional challenges can lead to severe morbidity and mortality in cancer patients. In the clinic, the application of personalized medicine and the ability to withstand the toxic effects of anti-cancer therapies can be optimized when the patient is in nutritional homeostasis and is free of anorexia and cachexia. Routine assessment of nutritional status and appropriate intervention are essential components of the effort to alleviate effects of malnutrition on quality of life and survival of patients.

This CE is published through an unrestricted educational grant from Bristol-Myers Squibb

Credit

This lesson is good for 0.2 CE units, with a passing grade of 70%.

Goal

The goal of this program is to inform the participant of costeffective 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 chemotherapyinduced 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 in 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.

5-Hydroxyindoleacetic acid and substance P profiles in patients receiving emetogenic chemotherapy

Background. Even though direct cause and effect has not been proved, clinical evidence suggests serotonin and substance P (SP) are involved in the emetic response following chemotherapy. Because of several parallels, we hypothesized that SP release, like serotonin, may be propagated by chemotherapy and both substances can be measured in biological fluids, and correlated with a particular phase of emesis.

Methods. Urinary 5-hydroxyindoleacetic acid (5-HIAA) was assessed by HPLC; serum and urine SP were measured by immunoassay. In addition to construction of neurotransmitter profiles, all SP data were grouped according to cisplatin dosages, = or>75 mg/m 2 versus <75 mg/m2, and phase of emesis, acute versus delayed. Analyses of these data were performed by repeated measures analysis of variance.

Results. Samples were collected over a 72-hour period from 26 adult patients who received cisplatin-( n=13) or non-cisplatin-containing ( n=13) chemotherapy. Mean baseline 5-HIAA: creatinine ratios were 5.23 and 5.16 in females and males, respectively; mean baseline SP levels were 392 and 181 pg/mL in females and males, respectively. Comparisons between SP data stratified by cisplatin dosage and emetic phase were significantly different, P <0.0001.

Conclusions. Laboratory studies provide additional evidence that serotonin and SP are involved primarily, though not exclusively, in acute and delayed vomiting, respectively.

Anti-emetic mechanisms of Zingiber officinale against cisplatin induced emesis in the pigeon; behavioral and neurochemical correlates

BACKGROUND

Zingiber officinale (ZO, family Zingiberaceae) has been reported for its antiemetic activity against cancer chemotherapy induced emesis in animal models and in clinics. Current study was designed to investigate ZO for potential usefulness against cisplatin induced vomiting in pigeon and its effects on central and peripheral neurotransmitters involved in the act of vomiting.

METHODS

Zingiber officinale acetone fraction (ZO-ActFr) was investigated for attenuation of emesis induced by cisplatin in healthy pigeons. Neurotransmitters DA, 5HT and their metabolites DOPAC, HVA and 5HIAA were analyzed using High Performance Liquid Chromatography system coupled with electrochemical detector in area postrema, brain stem and intestine. Antiemetic effect of ZO-ActFr was correlated with central and intestinal neurotransmitters levels in pigeon.

RESULTS

Cisplatin (7 mg/kg i.v.) induced emesis without lethality upto the observation period. ZO-ActFr (25, 50 & 100 mg/kg) attenuated cisplatin induced emesis ~ 44.18%, 58.13% (P < 0.05) and 27.9%, respectively; the reference drug, metoclopramide (MCP; 30 mg/kg), produced ~ 48.83% reduction (P < 0.05). ZO-ActFr reduced (P < 0.05 - 0.001) 5-hydroxytryptamine (5HT) concentration in the area postrema, brain stem and intestine at 3(rd) hour of cisplatin administration, while at the 18(th) hour ZO treatments attenuated the dopamine upsurge (P < 0.001) caused by cisplatin in the area postrema and 5HT concentration (P < 0.01 - 0.001) in the brain stem and intestine. ZO treatments alone did not altered the basal neurotransmitters and their metabolites in the brain areas and intestine.

CONCLUSION

The behavioral study verify the antiemetic profile of ZO against cisplatin induced emesis in the pigeon, where central and peripheral neural evidences advocate the involvement of serotonergic mechanism at initial time point (3(rd) hr), while the later time point (18(th) hr) is associated with serotonergic and dopaminergic component in the mediation of its antiemetic effect.

The effects of intravenous fosaprepitant and ondansetron for the prevention of postoperative nausea and vomiting in neurosurgery patients: a prospective, randomized, double-blinded study

The incidence of postoperative nausea and vomiting (PONV) is 30–50% after surgery. PONV occurs frequently, especially after craniotomy. In this study, we investigated the preventive effects on PONV in a randomized study by comparing patients who had been administered fosaprepitant, a neurokinin-1 (NK1) receptor antagonist, or ondansetron intravenously. Sixty-four patients undergoing craniotomy were randomly allocated to receive fosaprepitant 150 mg i.v. (NK1 group, n = 32) or ondansetron 4 mg i.v. (ONS group, n = 32) before anesthesia. The incidence of vomiting was significantly less in the NK1 group, where 2 of 32 (6%) patients experienced vomiting compared to 16 of 32 (50%) patients in the ONS group during the first 24 and 48 hours following surgery. Additionally, the incidence of complete response (no vomiting and no rescue antiemetic use) was significantly higher in the NK1 group than in the ONS group, and was 66% versus 41%, respectively, during the first 24 hours, and 63% versus 38%, respectively, during the first 48 hours. In patients undergoing craniotomy, fosaprepitant is more effective than ondansetron in increasing the rate of complete response and decreasing the incidence of vomiting at 24 and 48 hours postoperatively.

Nasal route: an alternative approach for antiemetic drug delivery

INTRODUCTION

Antiemetic drugs are used in the treatment of nausea and emesis. Development of novel delivery systems for antiemetic drugs, as an alternative to conventional preparations, is important in terms of good patient compliance and improving bioavailability. The nasal route offers unique superiorities, such as fast and high drug absorption, and high patient compliance. Therefore, a considerable amount of research has been carried out on the development of nasal delivery systems for antiemetic drugs.

AREAS COVERED

This review deals with the importance of nasal delivery of antiemetic drugs and the studies performed on this subject. The first part of this review summarizes the properties of the nasal route, its advantages and limitations, parameters affecting drug absorption through nasal mucosa, nasal passage pathways and general approaches to improve nasal transport. The second part reviews the studies conducted on the development of nasal delivery systems.

EXPERT OPINION

Due to its superiorities, the nasal route could be considered as an attractive alternative to oral and parenteral routes. To overcome the barrier properties of the nasal epithelium and to enhance transport of antiemetic drugs, several approaches, including permeation enhancers, in situ gel formulations and micro- and nanoparticulate systems, have been evaluated. The results obtained are promising and indicate that nasal formulations of some antiemetic drugs may enter the market in the near future.

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.

Receptor-selective agonists induce emesis and Fos expression in the brain and enteric nervous system of the least shrew (Cryptotis parva)

Research on the mechanisms of emesis has implicated multiple neurotransmitters via both central (dorsal vagal complex) and peripheral (enteric neurons and enterochromaffin cells) anatomical substrates. Taking advantage of advances in receptor-specific agonists, and utilizing Fos expression as a functional activity marker, this study demonstrates a strong, but incomplete, overlap in anatomical substrates for a variety of emetogens. We used cisplatin and specific agonists to 5-HT(3) serotonergic, D(2)/D(3) dopaminergic, and NK(1) tachykininergic receptors to induce vomiting in the least shrew (Cryptotis parva), and quantified the resulting Fos expression. The least shrew is a small mammal whose responses to emetic challenges are very similar to its human counterparts. In all cases, the enteric nervous system, nucleus of the solitary tract, and dorsal motor nucleus of the vagus demonstrated significantly increased Fos immunoreactivity (Fos-IR). However, Fos-IR induction was notably absent from the area postrema following the dopaminergic and NK(1) receptor-specific agents. Two brain nuclei not usually discussed regarding emesis, the dorsal raphe nucleus and paraventricular thalamic nucleus, also demonstrated increased emesis-related Fos-IR. Taken together, these data suggest the dorsal vagal complex is part of a common pathway for a variety of distinct emetogens, but there are central emetic substrates, both medullary and diencephalic, that can be accessed without directly stimulating the area postrema.

Ablation of least shrew central neurokinin NK1 receptors reduces GR73632-induced vomiting

The neurocircuitry mediating the emetic reflex is still incompletely understood, and a key question is the degree to which central and/or peripheral components contribute to the overall vomiting mechanism. Having previously found a significant peripheral component in neurokinin NK-receptor mediated emesis, the authors undertook this study to examine the putative central component. Adult least shrews were injected intracerebroventricularly (icv) with saline or the blood-brain barrier impermeable toxin, stable substance P-saporin (SSP-SAP), which ablates cells expressing NK receptors. After 3 days, shrews were challenged intraperitoneally with the emetogenic NK agonist GR73632 at different doses, and vomiting and scratching behaviors were quantified. Ablation of NK1-bearing cells was verified immunohistochemically. Although SSP-SAP injection reduced emesis at GR73632 doses of 2.5 and 5 mg/kg, no injections completely eliminated emesis. These data demonstrate that there is both a major central nervous system component and a minor peripheral nervous system component to tachykinin-mediated vomiting. Side effects of the current generation of antiemetics could potentially be reduced by improving bioavailability of the drugs in the more potent central nervous system compartment while reducing bioavailability in the less potent peripheral compartment.

The antiemetic interaction of Delta9-tetrahydrocannabinol when combined with tropisetron or dexamethasone in the least shrew

5-HT3 receptor antagonists (e.g. tropisetron) combined with dexamethasone are effective for the acute phase of cisplatin (CIS)-induced emesis. This study determined the possible additive or synergistic antiemetic efficacy of Delta9-THC when combined with tropisetron or dexamethasone (DEX). Delta9-THC (0-10 mg/kg i.p.) was injected in combination with tropisetron (0-5 mg/kg i.p.) or dexamethasone (0-20 mg/kg i.p.) prior to CIS (20 mg/kg i.p.) in the least shrew, and the induced emesis was recorded for 60 min. CIS-induced vomiting was dose-dependently and significantly attenuated by individual administration of Delta9-THC (59-97% reductions) and tropisetron (79-100% attenuation), but not dexamethasone (26-40%), although a trend (p<0.1) towards reduced vomiting frequency following DEX was noted. Low doses of Delta9-THC (0.25 or 0.5 mg/kg) when combined with low doses of tropisetron (0.025, 0.1, or 0.25 mg/kg) were more efficacious in reducing emesis frequency than when given individually, but Delta9-THC had no antiemetic interactions with DEX. However, no tested combination provided a significantly greater effect on the number of animals vomiting than their individually-administered counterparts. The modest interaction of Delta9-THC with tropisetron suggests they activate overlapping antiemetic mechanisms, while the lack of interaction with dexamethasone needs further clarification.

Utilization of the least shrew as a rapid and selective screening model for the antiemetic potential and brain penetration of substance P and NK1 receptor antagonists

Substance P (SP) is thought to play a cardinal role in emesis via the activation of central tachykinin NK1 receptors during the delayed phase of vomiting produced by chemotherapeutics. Although the existing supportive evidence is significant, due to lack of an appropriate animal model, the evidence is indirect. As yet, no study has confirmed that emesis produced by SP or a selective NK1 receptor agonist is sensitive to brain penetrating antagonists of either NK1, NK2, or NK3 receptors. The goals of this investigation were to demonstrate: 1) whether intraperitoneal (i.p.) administration of either SP, a brain penetrating (GR73632) or non-penetrating (e.g. SarMet-SP) NK1 receptor agonist, an NK2 receptor agonist (GR64349), or an NK3 receptor agonist (Pro7-NKB), would induce vomiting and/or scratching in the least shrew (Cryptotis parva) in a dose-dependent manner; and whether these effects are sensitive to the above selective receptor antagonists; 2) whether an exogenous emetic dose of SP (50 mg/kg, i.p.) can penetrate into the shrew brain stem and frontal cortex; 3) whether GR73632 (2.5 mg/kg, i.p.)-induced activation of NK1 receptors increases Fos-measured neuronal activity in the neurons of both brain stem emetic nuclei and the enteric nervous system of the gut; and 4) whether selective ablation of peripheral NK1 receptors can affect emesis produced by GR73632. The results clearly demonstrated that while SP produced vomiting only, GR73632 caused both emesis and scratching behavior dose-dependently in shrews, and these effects were sensitive to NK1-, but not NK2- or NK3-receptor antagonists. Neither the selective, non-penetrating NK1 receptor agonists, nor the selective NK2- or NK3-receptor agonists, caused a significant dose-dependent behavioral effect. An emetic dose of SP selectively and rapidly penetrated the brain stem but not the frontal cortex. Systemic GR73632 increased Fos expression in the enteric nerve plexi, the medial subnucleus of nucleus tractus solitarius, and the dorsal motor nucleus of the vagus, but not the area postrema. Ablation of peripheral NK1 receptors attenuated the ability of GR73632 to induce a maximal frequency of emesis and shifted its percent animals vomiting dose-response curve to the right. The NK1-ablated shrews exhibited scratching behavior after systemic GR73632-injection. These results, for the first time, affirm a cardinal role for central NK1 receptors in SP-induced vomiting, and a facilitatory role for gastrointestinal NK1 receptors. In addition, these data support the validation of the least shrew as a specific and rapid behavioral animal model to screen concomitantly both the CNS penetration and the antiemetic potential of tachykinin NK1 receptor antagonists.

Recent advances, trends and economic considerations in the risk assessment, prevention and treatment of postoperative nausea and vomiting

During the last two decades there have been considerable achievements regarding the management of postoperative nausea and vomiting (PONV). Due to the importance of these symptoms in the aim to streamline clinical processes and to improve patient satisfaction, the debate on the best strategies and also research that focuses on PONV continues. This review summarises the recent developments with respect to the management of PONV. Following a brief review on what is already known on the risk assessment, prevention and treatment of PONV, newer trends in the pharmacological prevention (dexamethasone, neurokinin-1 antagonists, multimodal prevention) will be discussed as well as new insights regarding the value of algorithms for the prevention of PONV. Further, pharmacogenetically based algorithms (according to the metaboliser status) as well as new treatment strategies (dexamethasone, multimodal treatment) will be covered. No drug so far can achieve a reduction of PONV of more than one third. Furthermore, all clinical studies consistently demonstrated that a combination treatment has a simple additive effect without any relevant interaction between different drugs or classes of drugs. The relative reduction of approximately 30% can also be expected from dexamethasone and it is likely that the substances presently in development and in an early clinical use (e.g., neurokinin-1 antagonists) will not represent the new panacea. However, they will probably replenish the existing antiemetic portfolio to better cope with high risk patients. Stratified prevention using pharmacogenetic knowledge is still in the early stages. Algorithms need to be customized to the local settings in order to prove efficient. Treatment remains a most important pillar and there is evidence that the principles of combining antiemetics to prolong effects and improve protection can be similarly applied to treatment. Recent developments in the area of PONV are more related to implementing the already existing evidence than based on the introduction of new molecules. New molecules replenish the pharmacological antiemetic portfolio, which is needed due to the limited efficacy of any single agent available so far. The new neurokinin-1 receptor antagonist, aprepitant, and the long lasting 5-HT(3) receptor antagonist palonosetron are the latest developments in this context. Treatment is most important and can also be regarded as a secondary prevention. Due to limited efficacy of single treatment interventions, combination therapy may gain more widespread use in the future.

Single-dose aprepitant vs ondansetron for the prevention of postoperative nausea and vomiting: a randomized, double-blind phase III trial in patients undergoing open abdominal surgery

BACKGROUND

The neurokinin(1) antagonist aprepitant is effective for prevention of chemotherapy-induced nausea and vomiting. We compared aprepitant with ondansetron for prevention of postoperative nausea and vomiting.

METHODS

Nine hundred and twenty-two patients receiving general anaesthesia for major abdominal surgery were assigned to receive a single preoperative dose of oral aprepitant 40 mg, oral aprepitant 125 mg, or i.v. ondansetron 4 mg in a randomized, double-blind trial. Vomiting episodes, use of rescue therapy, and nausea severity (verbal rating scale) were documented for 48 h after surgery. Primary efficacy endpoints were complete response (no vomiting and no use of rescue therapy) 0-24 h after surgery and no vomiting 0-24 h after surgery. The secondary endpoint was no vomiting 0-48 h after surgery.

RESULTS

Aprepitant at both doses was non-inferior to ondansetron for complete response 0-24 h after surgery (64% for aprepitant 40 mg, 63% for aprepitant 125 mg, and 55% for ondansetron, lower bound of 1-sided 95% CI > 0.65), superior to ondansetron for no vomiting 0-24 h after surgery (84% for aprepitant 40 mg, 86% for aprepitant 125 mg, and 71% for ondansetron; P < 0.001), and superior for no vomiting 0-48 h after surgery (82% for aprepitant, 40 mg, 85% for aprepitant, 125 mg, and 66% for ondansetron; P < 0.001). The distribution of peak nausea scores was lower in both aprepitant groups vs ondansetron (P < 0.05).

CONCLUSIONS

Aprepitant was non-inferior to ondansetron in achieving complete response for 24 h after surgery. Aprepitant was significantly more effective than ondansetron for preventing vomiting at 24 and 48 h after surgery, and in reducing nausea severity in the first 48 h after surgery. Aprepitant was generally well tolerated.

A randomized, double-blind comparison of the NK1 antagonist, aprepitant, versus ondansetron for the prevention of postoperative nausea and vomiting

BACKGROUND

Antiemetics currently in use are not totally effective. Neurokinin-1 receptor antagonists are a new class of antiemetic that have shown promise for chemotherapy-induced nausea and vomiting. This is the first study evaluating the efficacy and tolerability of the neurokinin-1 receptor antagonist, aprepitant, for the prevention of postoperative nausea and vomiting.

METHODS

In this multicenter, double-blind trial, we randomly assigned 805 patients receiving general anesthesia for open abdominal surgery to a preoperative dose of aprepitant 40 mg orally, aprepitant 125 mg orally, or ondansetron 4 mg IV. Vomiting, nausea, and use of rescue therapy were assessed over 48 h after surgery. Treatments were compared using logistic regression.

RESULTS

Incidence rates for the primary end point (complete response [no vomiting and no use of rescue] over 0-24 h after surgery, tested for superiority of aprepitant) were not different across groups (45% with aprepitant 40 mg, 43% with aprepitant 125 mg, and 42% with ondansetron). The incidence of no vomiting (0-24 h) was higher with aprepitant 40 mg (90%) and aprepitant 125 mg (95%) versus ondansetron (74%) (P < 0.001 for both comparisons), although between-treatment use of rescue and nausea control was not different. Both aprepitant doses also had higher incidences of no vomiting over 0-48 h (P < 0.001). No statistically significant differences were seen among the side effect profiles of the treatments.

CONCLUSIONS

Aprepitant was superior to ondansetron for prevention of vomiting in the first 24 and 48 h, but no significant differences were observed between aprepitant and ondansetron for nausea control, use of rescue, or complete response.

Learned flavor preferences induced by intragastric administration of rewarding nutrients: role of capsaicin-sensitive vagal afferent fibers

Learned flavor preferences can be established after intragastric nutrient administration by two different behavioral procedures, concurrent and sequential. In a concurrent procedure, two flavored stimuli are offered separately but at the same time on a daily basis: one stimulus is paired with the simultaneous intragastric administration of partially digested food and the other with physiological saline. In sequential learning, the two stimuli are presented during alternate sessions. Neural mechanisms underlying these learning modalities have yet to be fully elucidated. The aim of this study was to examine the role of vagal afferent fibers in the visceral processing of rewarding nutrients during concurrent (experiment 1) and sequential (experiment 2) flavor preference learning in Wistar rats. For this purpose, capsaicin, a neurotoxin that destroys slightly myelinated or unmyelinated sensory axons, was applied to the subdiaphragmatic region of the esophagus to selectively damage most of the vagal afferent pathways that originate in the gastrointestinal system. Results showed that capsaicin [1 mg of capsaicin dissolved in 1 ml of vehicle (10% Tween 80 in oil)] blocked acquisition of concurrent but not sequential flavor preference learning. These results are interpreted in terms of a dual neurobiological system involved in processing the rewarding effects of intragastrically administered nutrients. The vagus nerve, specifically capsaicin-sensitive vagal afferent fibers, would only be essential in concurrent flavor preference learning, which requires rapid processing of visceral information.

Receptor mechanism and antiemetic activity of structurally-diverse cannabinoids against radiation-induced emesis in the least shrew

Xenobiotic cannabinoid CB1/CB2-receptor agonists appear to possess broad-spectrum antiemetic activity since they prevent vomiting produced by a variety of emetic stimuli including the chemotherapeutic agent cisplatin, serotonin 5-HT3-receptor agonists, dopamine D2/D3-receptor agonists and morphine, via the stimulation of CB1-receptors. The purpose of this study was to evaluate whether structurally-diverse cannabinoids [Delta9-THC, (delta-9-tetrahydrocannabinol); (Delta8-THC, delta-8-tetrahydrocannabinol); WIN55,212-2, (R (+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)), methyl] pyrolol [1,2,3-de]-1,4 benzoxazinyl]-(1-naphthalenyl) methenone mesylate); and CP55,940, ((-)-3-[2-hydroxy-4-(1,1-dimethylheptyl]-4-[3-hydroxypropyl] cyclohexane-1-ol)), can prevent radiation-induced emesis. Exposure to total body radiation (0, 5, 7.5 and 10 Gy) caused robust emesis in the least shrew (Cryptotis parva) in a dose-dependent manner (ED50=5.99 (5.77-6.23) Gy) and all animals vomited at the highest tested dose of radiation. In addition, the radiation exposure reduced locomotor behaviors to a significant but mild degree in a non-dose-dependent fashion up to one hour post-treatment. Radiation-induced emesis (10 Gy) was blocked in a dose-dependent manner by the CB1/CB2-receptor agonists with the following ID50 potency order: CP55,940 (0.11 (0.09-0.12) mg/kg)>WIN55,212,2 (3.65 (3.15-4.23) mg/kg)=Delta8-THC (4.36 (3.05-6.22) mg/kg)>Delta9-THC (6.76 (5.22-8.75) mg/kg). Although the greater antiemetic potency and efficacy of Delta8-THC relative to its isomer Delta9-THC is unusual as the latter cannabinoid possesses higher affinity and potency for cannabinoid receptors in functional assays, the current data support the results of a clinical study in children suggestive of complete protection from emesis by Delta8-THC. This effect has not been clinically observed for Delta9-THC in cancer patients receiving chemo- or radiation-therapy. Cannabinoids prevented the induced emesis via the stimulation of cannabinoid CB1-receptors because the CB1 (SR141716A)--and not the CB2 (SR144528)--receptor antagonist reversed both the observed reduction in emesis frequency and shrew emesis protection afforded by either Delta9-THC or CP55,940 against radiation-induced emesis. These findings further suggest that the least shrew can be utilized as a versatile and inexpensive small animal model to rapidly screen the efficacy of investigational antiemetics for the prevention of radiation-induced emesis.

The anti-cancer drug-induced pica in rats is related to their clinical emetogenic potential

Cancer chemotherapy is frequently accompanied by severe emesis. The anti-cancer drugs are classified according to their clinical emetogenic potential. We have already found that kaolin ingestion behavior "pica" is analogous to emesis in rats. The aim of this study was to examine the effects of the clinical emetogenic potential of anti-cancer drugs on the induction of the pica in rats. Rats were housed in individual cages with free access to food and kaolin pellets and the daily food and kaolin intakes were measured for 3 days after the intraperitoneal administration of anti-cancer drugs (cisplatin, cyclophosphamide, actinomycin D, 5-fluorouracil and vincristine). The drugs with high potential for inducing emesis, such as cisplatin and cyclophosphamide, induced pica in all animals on the day of administration and the behavior lasted during the observation period. The drugs with moderate emetogenic potential, i.e. actinomycin D and 5-fluorouracil, also induced pica on the first and second day after the drug administration but the kaolin intake was less than that of the drugs with high potential. Vincristine, a drug with low emetogenic potential, slightly increased the kaolin intake in rats on the only first day of the administration. Cyclophosphamide, actinomycin D and vincristine induced anorexia and decreased their body weight during the observation period. These results suggested that the both amounts of kaolin intake and duration of behavior in the anti-cancer drug-induced pica are related to the clinical emetogenic potential of the drugs and the incidence of the anorexia is not related to their emetogenic potential.

Behavioural and hypothalamic molecular effects of the anti-cancer agent cisplatin in the rat: A model of chemotherapy-related malaise?

Many cancer patients receiving chemotherapy experience fatigue, disturbed circadian rhythms, anorexia and a variety of dyspeptic symptoms including nausea. There is no animal model for this 'chemotherapy-related malaise' so we investigated the behavioural and molecular effects of a potent chemotherapeutic agent, cisplatin (CP, 6 mg/kg, i.p.) in rats. Dark-phase horizontal locomotor activity declined post-CP reaching a nadir on day 3 (P < 0.001), before recovering after 7 days. CP's effect was most marked in the late part (05.00-07.00) of the dark-phase. Food intake reached a nadir (P > 0.001) at 2 days, coincident with an increase in gastric contents (cisplatin 9.04+/-0.8 vs. saline 2.32+/-0.3 g; P < 0.001). No changes occurred in hypothalamic mRNA expression for AGRP, NPY, HCRT, CRH, IL-1, IL-6, TNFalpha, ABCG1, SLC6A4, PPIA and HPRT mRNA but tryptophan hydroxylase (TPH) mRNA was decreased (47%, P < 0.05) at day 21 post-CP. This shows that despite marked behavioural effects of cisplatin, only a discrete change (TPH) was found in hypothalamic mRNA expression and that occurred when the animals' behaviour had recovered. Findings are discussed in relation to the neuropharmacology of chemotherapy-induced malaise.

The Pathophysiology of Chemotherapy-Induced Nausea and Vomiting

Chemotherapy-induced nausea and vomiting is a major debilitating side effect of oncology treatment despite recent advances in pharmaceutical management. Nurses who provide care to patients experiencing nausea and vomiting are often only marginally aware of the pathophysiological processes involved in the treatment. A better understanding of the science behind current interventions to reduce nausea and vomiting may help nurses use those interventions more effectively. This article reviews current knowledge about the pathophysiology of chemotherapy-induced nausea and vomiting. By understanding the pathophysiology behind this patient experience, gastroenterology nurses can develop a better understanding of the common symptoms of nausea and vomiting in general. When a nurse understands the complexity of factors causing nausea and vomiting, he or she will be better able to provide appropriate interventions to reduce these symptoms.

Benzimidazole derivatives. Part 5: design and synthesis of new benzimidazole-arylpiperazine derivatives acting as mixed 5-HT1A/5-HT3 ligands

A series of new mixed benzimidazole-arylpiperazine derivatives were designed by incorporating in general structure III the pharmacophoric elements of 5-HT(1A) and 5-HT(3) receptors. Compounds 1-11 were synthesized and evaluated for binding affinity at both serotoninergic receptors, all of them exhibiting high 5-HT(3)R affinity (K(i)=10-62nM), and derivatives with an o-alkoxy group in the arylpiperazine ring showing nanomolar affinity for the 5-HT(1A)R (K(i)=18-150nM). Additionally, all the synthesized compounds were selective over alpha(1)-adrenergic and dopamine D(2) receptors (K(i)>1000-10,000nM). Compound 3 was selected for further pharmacological characterization due to its interesting binding profile as mixed 5-HT(1A)/5-HT(3) ligand with high affinity for both receptors (5-HT(1A): K(i)=18.0nM, 5-HT(3): K(i)=27.2nM). In vitro and in vivo findings suggest that this compound acts as a partial agonist at 5-HT(1A)Rs and as a 5-HT(3)R antagonist. This novel mixed 5-HT(1A)/5-HT(3) ligand was also effective in preventing the cognitive deficits induced by muscarinic receptor blockade in a passive avoidance learning test, suggesting a potential interest in the treatment of cognitive dysfunction.

Central and peripheral mechanisms contribute to the antiemetic actions of delta-9-tetrahydrocannabinol against 5-hydroxytryptophan-induced emesis

Delta-9-tetrahydrocannabinol (delta-9-THC) prevents cisplatin-induced emesis via cannabinoid CB(1) receptors. Whether central and/or peripheral cannabinoid CB(1) receptors account for the antiemetic action(s) of delta-9-THC remains to be investigated. The 5-hydroxytryptamine (5-HT=serotonin) precursor, 5-hydroxytryptophan (5-HTP), is an indirect 5-HT agonist and simultaneously produces the head-twitch response (a centrally mediated serotonin 5-HT(2A) receptor-induced behavior) and emesis (a serotonin 5-HT(3) receptor-induced response, mediated by both peripheral and central mechanisms) in the least shrew (Cryptotis parva). The peripheral amino acid decarboxylase inhibitor, carbidopa, prevents the conversion of 5-HTP to 5-HT in the periphery and elevates 5-HTP levels in the central nervous system (CNS). When administered i.p. alone, a 50 mg/kg dose of 5-HTP failed to induce either behaviour while its 100 mg/kg dose produced robust frequencies of both head-twitch response and emesis. Pretreatment with carbidopa (0, 10, 20 and 40 mg/kg) potentiated the ability of both doses of 5-HTP to produce the head-twitch response in a dose-dependent but bell-shaped manner, with maximal potentiation occurring at 20 mg/kg carbidopa. Carbidopa dose-dependently reduced the frequency of 5-HTP (100 mg/kg)-induced emesis, whereas the 10 mg/kg dose potentiated, and the 20 and 40 mg/kg doses suppressed the frequency of vomits produced by the 50 mg/kg dose of 5-HTP. The peripheral and/or central antiemetic action(s) of delta-9-THC (0, 1, 2.5, 5, 10 and 20 mg/kg) against 5-HTP (100 mg/kg)-induced head-twitch response and emesis were investigated in different groups of carbidopa (0, 10 and 20 mg/kg) pretreated shrews. Irrespective of carbidopa treatment, delta-9-THC attenuated the frequency of 5-HTP-induced head-twitch response in a dose-dependent manner with similar ID(50) values. Although delta-9-THC also reduced the frequency of 5-HTP-induced emesis with similar ID(50s), at the 5 mg/kg delta-9-THC dose however, 5-HTP induced significantly less vomits in the 10 and 20 mg/kg carbidopa-treated groups relative to its 0 mg/kg control group. Moreover, increasing doses of carbidopa significantly shifted the inhibitory dose-response effect of delta-9-THC in protecting shrews from 5-HTP-induced emesis to the left. Relatively, a large dose of delta-9-THC (20 mg/kg) was required to significantly reduce the number of vomits produced by direct acting serotonergic 5-HT(3) receptor agonists, serotonin and 2-methylserotonin. Low doses of delta-9-THC (0.1-1 mg/kg) nearly completely prevented 2-methylserotonin-induced, centrally mediated, head-twitch and ear-scratch responses. The results indicate that delta-9-THC probably acts pre- and postsynaptically to attenuate emesis produced by indirect and direct acting 5-HT(3) receptor agonists via both central and peripheral mechanisms. In addition, delta-9-THC prevents 5-HTP-induced head-twitch and emesis via cannabinoid CB(1) receptors since the CB(1) receptor antagonist, SR 141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide], countered the inhibitory actions of an effective dose of delta-9-THC against both behaviours.

The oral neurokinin-1 antagonist aprepitant for the prevention of chemotherapy-induced nausea and vomiting: a multinational, randomized, double-blind, placebo-controlled trial in patients receiving high-dose cisplatin--the Aprepitant Protocol 052 Study Group

PURPOSE

In early clinical trials with patients receiving highly emetogenic chemotherapy, the neurokinin antagonist aprepitant significantly enhanced the efficacy of a standard antiemetic regimen consisting of a type-three 5-hydroxytryptamine antagonist and a corticosteroid. This multicenter, randomized, double-blind, placebo-controlled phase III study was performed to establish definitively the superiority of the aprepitant regimen versus standard therapy in the prevention of chemotherapy-induced nausea and vomiting (CINV).

PATIENTS AND METHODS

Patients receiving cisplatin > or = 70 mg/m2 for the first time were given either standard therapy (ondansetron and dexamethasone on day 1; dexamethasone on days 2 to 4) or an aprepitant regimen (aprepitant plus ondansetron and dexamethasone on day 1; aprepitant and dexamethasone on days 2 to 3; dexamethasone on day 4). Patients recorded nausea and vomiting episodes in a diary. The primary end point was complete response (no emesis and no rescue therapy) on days 1 to 5 postcisplatin, analyzed by a modified intent-to-treat approach. Treatment comparisons were made using logistic regression models. Tolerability was assessed by reported adverse events and physical and laboratory assessments.

RESULTS

The percentage of patients with complete response on days 1 to 5 was significantly higher in the aprepitant group (72.7% [n = 260] v 52.3% in the standard therapy group [n = 260]), as were the percentages on day 1, and especially on days 2 to 5 (P <.001 for all three comparisons).

CONCLUSION

Compared with standard dual therapy, addition of aprepitant was generally well tolerated and provided consistently superior protection against CINV in patients receiving highly emetogenic cisplatin-based chemotherapy.

Design and synthesis of new benzimidazole-arylpiperazine derivatives acting as mixed 5-HT1A/5-HT3 ligands

A series of new benzimidazole-arylpiperazine derivatives III were designed, synthesized and evaluated for binding affinity at serotoninergic 5-HT(1A) and 5-HT(3) receptors. Compound IIIc was identified as a novel mixed 5-HT(1A)/5-HT(3) ligand with high affinity for both serotonin receptors and excellent selectivity over alpha(1)-adrenergic and dopamine D(2) receptors. This compound was characterized as a partial agonist at 5-HT(1A)Rs and a 5-HT(3)R antagonist, and was effective in preventing the cognitive deficits induced by muscarinic receptor blockade in a passive avoidance learning test.

Benefits and risks of newer treatments for chemotherapy-induced and postoperative nausea and vomiting

Nausea and vomiting are common adverse effects of chemotherapy, radiation therapy, anaesthesia and surgery. The incidence of chemotherapy-induced nausea and vomiting (CINV) is estimated to vary from 30 to 90%, depending on the type of chemotherapeutic agent used. Radiation-induced emesis varies with anatomical site radiated but is estimated to have an overall incidence of approximately 40%. The incidence of postoperative nausea and vomiting (PONV) depends on the type of anaesthesia and surgery, but overall is estimated to be 20-30%. Evidence-based medicine and meta-analysis have been used to direct medical therapy to help determine equivalence, optimal dose, timing, safety and efficacy of antiemetic medications. Concepts such as the number needed to treat and number needed to harm are helpful to guide the clinician regarding the benefits and risks of a particular treatment. The serotonin 5-HT(3) receptor antagonists ondansetron, granisetron, tropisetron and dolasetron have been important additions to the antiemetic armamentarium. The 5-HT(3) receptor antagonists are similar in chemical structure, efficacy and adverse effect profile. They appear to have no important differences among themselves in clinical outcomes for CINV and PONV. Headache, dizziness, constipation and diarrhoea are their most common adverse effects, and when they occur they are usually mild and easily managed. Haemodynamic changes and extrapyramidal adverse effects are uncommon. ECG changes such as prolonged corrected QT (QTc) interval are infrequent, dose-related and overall judged to be clinically insignificant. As most studies with the 5-HT(3) antagonists have been conducted on relatively healthy patients, caution should be exercised when these drugs are used in susceptible patients with co-morbidities. The clinician must weigh the benefit of administering an antiemetic for CINV or PONV against the risk of occurrence of an adverse event.

Behaviorally active doses of the CB1 receptor antagonist SR 141716A increase brain serotonin and dopamine levels and turnover

Large doses (10-40 mg/kg) of the selective cannabinoid CB(1) receptor antagonist, SR 141716A, produce the head-twitch response (HTR) and scratching in rodents and vomiting in the least shrew (Cryptotis parva). Agents that increase brain serotonin (5-HT) levels induce the HTR in rodents, whereas enhancements in either brain 5-HT or dopamine concentrations can lead to production of emesis in vomiting species. The present study was undertaken to demonstrate whether large doses of SR 141716A can (1) induce the HTR and scratching in the least shrew and (2) cause concurrent biochemical changes in brain 5-HT and dopamine concentrations. SR 141716A (0, 1, 5, 10, 20 and 40 mg/kg i.p.) administration induced the HTR, scratching and vomiting. The HTR effect was bell shaped with a maximum frequency occurring at the 20 mg/kg SR 141716A dose, whereas the scratching and vomiting behaviors displayed dose-dependent effects. The selective 5-HT(2A/C) receptor antagonist, SR 46349B (0, 0.1, 0.25, 1, 3 and 6 mg/kg i.p.), differentially attenuated all SR 141716A (20 mg/kg)-induced behaviors because the HTR was relatively more potently and completely blocked. In the shrew forebrain, SR 141716A (20 and 40 mg/kg ip) caused dose- and time-dependent increases in the levels of 5-HT and dopamine and the concentrations of their major metabolites [5-hydroxyindole acetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA)] and the turnover of both monoamines. Although the effects of SR 141716A on brainstem concentrations of both monoamines and their metabolites were not always consistent, the CB(1) antagonist did increase the turnover of both 5-HT and dopamine. The present findings suggest that the mechanism and the neurochemical substrate for SR 141716A-induced HTR and scratching behaviors is enhancement of 5-HT release, whereas increased release of 5-HT and dopamine probably contributes to the production of emesis.

Differential involvement of neurotransmitters through the time course of cisplatin-induced emesis as revealed by therapy with specific receptor antagonists

Advances in antiemetic therapy for chemotherapy-induced emesis have resulted in improved protection against symptoms occurring within 24 h of chemotherapy. However, the vomiting which tends to occur beyond 24 h after chemotherapy (delayed-phase vomiting) is still relatively poorly controlled by the currently available drugs, suggesting that more than one mechanism may mediate these symptoms. The standard antiemetic regimen currently recommended for prevention of chemotherapy-induced emesis includes a serotonin (5-HT(3)) antagonist and a corticosteroid. The neurokinin-1 (NK(1)) antagonist aprepitant represents a new class of antiemetic currently in clinical development. Using data obtained in 2 Phase II clinical trials of aprepitant in patients receiving chemotherapy based on the highly emetogenic chemotherapeutic agent cisplatin, we compared the time course of antiemetic effect of aprepitant, a 5-HT(3) antagonist, or a combination of both. Over the entire observation period (up to 7 days post-cisplatin), patients who received the NK(1) antagonist had a superior prevention of emesis. However, in the first 24 h after cisplatin, emesis occurred in fewer patients who received the 5-HT(3) antagonist than in patients who did not receive this class of drug. Furthermore, the majority of treatment failures in patients who received the NK(1) antagonist occurred within the first 8-12 h of chemotherapy, whereas the treatment failures in patients who received a 5-HT(3) antagonist were more evenly distributed over time. Patients who received both drugs had superior control of symptoms compared with patients who received one or the other. The difference in the time course of emesis blockade observed with two different classes of receptor antagonists provides substantial evidence for involvement of separate pathophysiological mechanisms in chemotherapy-induced vomiting. Serotonin mediates the early vomiting process that occurs within 8-12 h following cisplatin-based chemotherapy, after which time substance P acting at NK(1) receptors becomes the dominant mediator of vomiting

Antiemetic and motor-depressive actions of CP55,940: cannabinoid CB1 receptor characterization, distribution, and G-protein activation

Dibenzopyran (Delta(9)-tetrahydrocannabinol) and aminoalkylindole [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrolol[1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl) methanone mesylate; (WIN55,212-2)] cannabinoids suppress vomiting produced by cisplatin via cannabinoid CB(1) receptors. This study investigates the antiemetic potential of the "nonclassical" cannabinoid CP55,940 [1alpha,2beta-(R)-5alpha]-(-)-5-(1,1-dimethyl)-2-[5-hydroxy-2-(3-hydroxypropyl) cyclohexyl-phenol] against cisplatin-induced vomiting and assesses the presence and functionality of cannabinoid CB(1) receptors in the least shrew (Cryptotis parva) brain. CP55,940 (0.025-0.3 mg/kg) reduced both the frequency of cisplatin-induced emesis (ID(50)=0.025 mg/kg) and the percentage of shrews vomiting (ID(50)=0.09 mg/kg). CP55,940 also suppressed shrew motor behaviors (ID(50)=0.06- 0.21 mg/kg) at such doses. The antiemetic and motor-suppressant actions of CP55,940 were countered by SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide], indicating both effects are cannabinoid CB(1) receptor-mediated. Autoradiographic studies with [3H]-SR141716A and [35S]-GTPgammaS binding revealed that the distribution of the cannabinoid CB(1) receptor and its activation pattern are similar to rodent brain and significant levels are present in brain loci (e.g., nucleus tractus solitarius (NTS)) that control emesis. The affinity rank order of structurally diverse cannabinoid ligands for cannabinoid CB(1) receptor in shrew brain is similar to rodent brain: HU-210=CP55,940=SR141716A>/=WIN55,212-2>/=delta-9-tetrahydrocannabinol>methanandamide=HU-211=cannabidiol=2-arachidonoylglycerol. This affinity order is also similar and is highly correlated to the cannabinoid EC(50) potency rank order for GTPgammaS stimulation except WIN55,212-2 and delta-9-tetrahydrocannabinol potency order were reversed. The affinity and the potency rank order of tested cannabinoids were significantly correlated with their antiemetic ID(50) potency order against cisplatin-induced vomiting (CP55,940>WIN55,212-2=delta-9-tetrahydrocannabinol) as well as emesis produced by 2-arachidonoylglycerol or SR141716A (CP55,940>WIN55,212-2>delta-9-tetrahydrocannabinol).

Management of Chemotherapy-Induced Nausea and Vomiting

Nausea and vomiting are among the most distressing adverse effects of cancer chemotherapy. They can lead to both physical and psychological complications if uncontrolled. The exact mechanism for chemotherapy-induced nausea and vomiting is not known; it is thought to occur through numerous neuronal pathways acting on different sites. Chemotherapy-induced nausea and vomiting are broken down into 3 phases: acute, delayed, and anticipatory. The incidence of each phase depends largely on the chemotherapy agent used and is primarily treated with different antiemetic agents. Pharmacists can assist in optimizing antiemetic use by selecting appropriate antiemetics based on the emetogenicity of the cancer treatment and helping to individualize therapy to each patient’s specific needs.

Ondansetron: a review of its use as an antiemetic in children

Ondansetron, a selective serotonin (5-hydroxytryptamine; 5-HT) 5-HT3 receptor antagonist, is an antiemetic agent available for use in adults and children. In children receiving ondansetron (multiple 5 mg/m2 or 0.15 mg/kg intravenous and/or oral doses) in addition to chemotherapy in 2 large (n > 100) non-comparative analyses, < or =2 emetic episodes were observed in 33 and 40% of cisplatin recipients, 48 and 68% of ifosfamide recipients, and 70 and 72% of patients receiving other chemotherapeutic regimens. In comparative trials, ondansetron was significantly more effective at reducing nausea and vomiting than metoclopramide or chlorpromazine (both combined with dexamethasone), although the incidence of delayed symptoms were similar between children receiving ondansetron and metoclopramide. In addition, dexamethasone significantly improved the antiemetic efficacy of ondansetron in 1 randomised trial. When used in children undergoing conditioning therapy (including total body irradiation) prior to bone marrow transplantation, ondansetron was significantly better at controlling nausea and vomiting than combined perphenazine and diphenhydramine therapy. In dose-ranging and large placebo-controlled trials, intravenous (0.075 to 0.15 mg/kg) or oral (0.1 mg/kg) ondansetron was significantly more effective than placebo in preventing emesis in children undergoing surgery associated with a high risk of postoperative nausea and vomiting (PONV) including tonsillectomy or strabismus repair. In comparative studies, intravenous administration of ondansetron 0.1 to 0.15 mg/kg was significantly superior to droperidol 0.02 to 0.075 mg/kg or metoclopramide 0.2 to 0.25 mg/kg in preventing emesis in children undergoing various surgical procedures. In comparison with other antiemetics, including prochlorperazine and dimenhydrinate, ondansetron generally showed greater prophylactic antiemetic efficacy. Ondansetron combined with dexamethasone was significantly more effective than ondansetron or dexamethasone alone, as was the combination of ondansetron with a propofol-based anaesthetic compared with either agent alone. Ondansetron is generally well tolerated in children, rarely necessitating treatment withdrawal. The most frequently reported adverse events were mild to moderate headache, constipation and diarrhoea in patients receiving chemotherapy. Wound problems, anxiety, headache, drowsiness and pyrexia were reported most frequently in patients postsurgery.

CONCLUSIONS

Ondansetron has shown good efficacy in the prevention of acute nausea and vomiting in children receiving moderately or highly emetogenic chemotherapy and/or irradiation, particularly when combined with dexamethasone. In the chemotherapy setting, ondansetron is significantly better than metoclopramide and chlorpromazine and has a more favourable tolerability profile. In children undergoing surgery, ondansetron demonstrated superior prophylactic antiemetic efficacy compared with placebo, droperidol and metoclopramide, and was relatively free of adverse events. Ondansetron is thus an effective first-line antiemetic in children undergoing chemotherapy, radiotherapy and surgery.

Pharmacokinetics and pharmacological effect of lerisetron, a new 5-HT3 antagonist, in rats

The pharmacokinetics of lerisetron, a novel 5HT(3) antagonist, are studied together with its efficacy in inhibiting the serotonin (5-HT)-evoked transient bradycardia reflex (von Bezold-Jarisch reflex) in Sprague Dawley rats. [(14)C]Lerisetron (50, 100, and 200 microg/kg) was given to rats by intravenous (iv) injection and plasma levels of unchanged (UL) and total (unchanged + changed, TL) drug were measured by liquid chromatography with radioactivity monitoring and scintillation counting, respectively. Linearity of UL and TL pharmacokinetics over the dose range was established by noncompartmental analysis. Protein binding of lerisetron was measured in vitro by ultrafiltration. The unbound fraction was 14.4 +/- 1.4%. A nonlinear mixed effects ("population") bicompartmental pharmacokinetic analysis showed that volume of distribution and clearance (CL) were high for both forms of the drug, but CL was significantly smaller for TL [(mean +/- SEM) 0.014 +/- 0.03 L/min for UL versus 0.006 +/- 0.03 L/min for TL, p < 0.05)]. Large interindividual variabilities were observed for both forms. The response to lerisetron administration (inhibition of bradycardia) was evaluated at different doses (2, 3, 5, 6, and 10 microg/kg, iv) at times 2-180 min after dose administration and related to simulated concentrations. Inhibition was 100% 5 min after the 10-microg/kg dose and, 3 h later, it was still > 10%. Response to lerisetron was dose related in the range studied. Pharmacodynamic parameters were estimated by a sigmoid E(max) naive-pooled model. The parameters were also different between the two forms: EC(50) was 0.44 ng/mL (CV = 5.9%) for UL and 0.88 ng/mL (CV = 4.9%) for TL. We conclude that UL and TL pharmacokinetics were linear and that the differences in the kinetics and dynamics between the two forms suggest the presence of at least one metabolite.

The cannabinoid CB1 receptor antagonist SR 141716A reverses the antiemetic and motor depressant actions of WIN 55, 212-2

The dibenzopyran cannabinoids (delta-9 (Delta9)-tetrahydrocannabinol and nabilone) are clinically used to suppress nausea and vomiting produced by chemotherapeutic agents such as cisplatin. The purpose of this investigation was to investigate the antiemetic potential of the aminoalkylindole cannabinoid receptor agonist WIN 55, 212-2 [R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl) methyl] pyrolol [1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl) methanone mesylate] against cisplatin-induced vomiting. Different doses of WIN 55, 212-2 (0, 1, 2.5 and 5 mg/kg, i.p.) reduced both the frequency of cisplatin (20 mg/kg, i.p.)-induced emesis (ID(50)=0.5 mg/kg) as well as the percentage of shrews vomiting (ID50=1.2 mg/kg) in a dose-dependent manner. Significant reductions in emesis frequency occurred from 2.5 mg/kg dose of WIN 55, 212-2, whereas significant total protection from vomiting was afforded at its 5 mg/kg dose. The antiemetic actions of a 5-mg/kg dose of WIN 55, 212-2 against cisplatin (20 mg/kg, i.p.)-induced vomiting were reversed by nonemetic subcutaneous doses (0, 0.25, 0.5 and 1 mg/kg) of the cannabinoid CB1 receptor antagonist/inverse agonist SR 141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] (ID50=0.27 and 0.47 mg/kg, respectively) but not by a 5-mg/kg dose of the cannabinoid CB2 receptor antagonist SR 144528 [N-[(1S)-endo-1,3,3-trimethylbicyclo [2.2.1] heptan-2-yl]5-(4-chloro-3-methylphenyl)-1-(4-methybenzyl) pyrazole-3-carboxamide]. The effects of the cited doses of WIN 55, 212-2 were also investigated on several motor parameters (spontaneous locomotor activity, duration of movement and rearing frequency). Significant reductions in motor parameters were only observed at its highest tested dose (ID50=1.97, 2.75 and 2.8 mg/kg; respectively). SR 141716A (0, 0.5, 1, 5 and 10 mg/kg) also reversed the motor suppressant effects of a 5-mg/kg dose of WIN 55, 212-2 (ID50=0.39, 0.1 and 0.3 mg/kg, respectively) and significant reversals were seen from its 0.5 and 1 mg/kg doses. These results suggest that WIN 55, 212-2 reduces both emesis and indeces of locomotion via the stimulation of cannabinoid CB1 receptors. However, cannabinoid CB1 receptors in different loci are most likely responsible for the antiemetic and motor suppressive effects of WIN 55, 212-2 since reduction in the frequency of vomiting occurred at lower doses relative to its sedative actions.

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.

The novel NK1 receptor antagonist MK-0869 (L-754,030) and its water soluble phosphoryl prodrug, L-758,298, inhibit acute and delayed cisplatin-induced emesis in ferrets

The anti-emetic profile of the novel brain penetrant tachykinin NK1 receptor antagonist MK-0869 (L-754,030) 2-(R)-(1-(R)-(3,5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluor o)phenyl-4-(3-oxo-1,2,4-triazol-5-yl)methylmorpholine and its water soluble prodrug, L-758,298, has been examined against emesis induced by cisplatin in ferrets. In a 4 h observation period, MK-0869 and L-758,298 (3 mg/kg i.v. or p.o.) inhibited the emetic response to cisplatin (10 mg/kg i.v.). The anti-emetic protection afforded by MK-0869 (0.1 mg/kg i.v.) was enhanced by combined treatment with either dexamethasone (20 mg/kg i.v.) or the 5-HT3 receptor antagonist ondansetron (0.1 mg/kg i.v.). In a model of acute and delayed emesis, ferrets were dosed with cisplatin (5 mg/kg i.p.) and the retching and vomiting response recorded for 72 h. Pretreatment with MK-0869 (4-16 mg/kg p.o.) dose-dependently inhibited the emetic response to cisplatin. Once daily treatment with MK-0869 (2 and 4 mg/kg p.o.) completely prevented retching and vomiting in all ferrets tested. Further when daily dosing began at 24 h after cisplatin injection, when the acute phase of emesis had already become established, MK-0869 (4 mg/kg p.o. at 24 and 48 h after cisplatin) prevented retching and vomiting in three out of four ferrets. These data show that MK-0869 and its prodrug, L-758,298, have good activity against cisplatin-induced emesis in ferrets and provided a basis for the clinical testing of these agents for the treatment of emesis associated with cancer chemotherapy.

Benzimidazole derivatives. 2. Synthesis and structure-activity relationships of new azabicyclic benzimidazole-4-carboxylic acid derivatives with affinity for serotoninergic 5-HT(3) receptors

A new series of azabicyclic benzimidazole-4-carboxamides 2-21 and -carboxylates 22-30 were synthesized and evaluated for binding affinity at serotoninergic 5-HT(3) and 5-HT(4) receptors in the CNS. Most of the synthesized compounds exhibited high or very high affinity for the 5-HT(3) binding site and low to no significant affinity for the 5-HT(4) receptor. SAR observations indicated that a halogen atom at the 6-position and a nitro group at the 7-position of the benzimidazole ring is the best substitution pattern for 5-HT(3) affinity and 5-HT(3)/5-HT(4) selectivity, as well as no substitution in this ring. (S)-(-)-N-(Quinuclidin-3-yl)benzimidazole-4-carboxamides 2, 8, and 14 bound at central 5-HT(3) sites with high affinity (K(i) = 2.6, 0. 13, and 1.7 nM, respectively) and excellent selectivity over serotonin 5-HT(4) and 5-HT(1A) receptors (K(i) > 1000-10000 nM). Furthermore, these new 5-HT(3) receptor ligands were pharmacologically characterized as potent and selective 5-HT(3) antagonists in the isolated guinea pig ileum (pA(2) = 9.6, 9.9, and 9.1, respectively).

Ondansetron/promethazine combination or promethazine alone reduces nausea and vomiting after middle ear surgery

STUDY OBJECTIVES

To determine the incidence of postoperative nausea and vomiting when a combination of ondansetron and promethazine is given prophylactically, and to ascertain the effect of postoperative nausea and vomiting on recovery room duration and patient satisfaction.

DESIGN

Prospective, randomized, placebo-controlled, double-blind study.

SETTING

University-affiliated tertiary-care hospital.

PATIENTS

87 ASA physical status I and II adult patients scheduled for middle ear surgery.

INTERVENTIONS

Patients were randomly assigned to receive one of the following interventions intravenously: ondansetron 4 mg (Group 1), promethazine 25 mg (Group 2), ondansetron 2 mg plus promethazine 12.5 mg (Group 3, combination), or placebo (Group 4).

MEASUREMENTS AND MAIN RESULTS

Independent, study blinded observers recorded complaints of nausea and number of episodes of vomiting for 24 hours following the patient's first response to commands. All patients were contacted the day after discharge to inquire about nausea and vomiting. The awakening time, postanesthesia care unit and day surgery unit durations, opioid use, and side effects were recorded. At the end of the 24-hour period, the study blinded observers asked patients for an overall assessment of their global anesthesia experience using an 11-point scale. During the 24-hour period, the incidence of postoperative nausea and vomiting was reduced from 74% (placebo) to 39% (promethazine; p = 0.03) and 29% (combination; p = 0.003). Compared with placebo, the severity of vomiting was significantly less in the combination group (p = 0.04). The number of very satisfied patients correlated negatively with the incidence of postoperative nausea and vomiting (p < 0.0001) and with the severity of vomiting (p = 0.003).

CONCLUSION

The prophylactic use of an antiemetic with middle ear surgery may reduce postoperative nausea and vomiting over 24 hours, and the ondansetron/promethazine combination or promethazine alone are cost-effective choices. Finally, the combination reduced significantly the severity of vomiting.

Pyrroloquinoxaline derivatives as high-affinity and selective 5-HT(3) receptor agonists: synthesis, further structure-activity relationships, and biological studies

The synthesis, pharmacological evaluation, and structure-activity relationships (SARs) of a series of novel pyrroloquinoxalines and heteroaromatic-related derivatives are described. The new pyrroloquinoxaline-related ligands were tested in rat cortex, a tissue expressing high density of 5-HT(3) receptors, and on NG108-15 cells and exhibited IC(50) values in the low nanomolar or subnanomolar range, as measured by the inhibition of [(3)H]zacopride binding. The SAR studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1, L2, and L3 in the 5-HT(3) receptor cleft, while the 7-OH pyrroloquinoxaline analogue was designed to investigate hydrogen bonding with a putative receptor site H1 possibly interacting with the serotonin hydroxy group. The most active pyrroloquinoxaline derivatives showed subnanomolar affinity for the 5-HT(3) receptor. In functional studies ([(14)C]guanidinium accumulation test in NG108-15 hybrid cells, in vitro) most of the tested compounds showed clear-cut 5-HT(3) agonist properties, while some others were found to be partial agonists. Several heteroaromatic systems, bearing N-substituted piperazine moieties, have been explored with respect to 5-HT(3) affinity, and novel structural leads for the development of potent and selective central 5-HT(3) receptor agonists have been identified. Preliminary pharmacokinetic studies indicate that these compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio between 2 and 20, unless they bear a highly hydrophilic group on the piperazine ring. None of the tested compounds showed in vivo anxiolytic-like activity, but potential analgesic-like properties have been possibly disclosed for this new class of 5-HT(3) receptor agonists.