Substance P (Neurokinin-1) antagonist prevents postoperative vomiting after abdominal hysterectomy procedures

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.

Postoperative Nausea and Vomiting in Female Patients Undergoing Breast and Gynecological Surgery: A Narrative Review of Risk Factors and Prophylaxis

Postoperative nausea and vomiting (PONV) have been widely studied as a multifactorial entity, being of female gender the strongest risk factor. Reported PONV incidence in female surgical populations is extremely variable among randomized clinical trials. In this narrative review, we intend to summarize the incidence, independent predictors, pharmacological and non-pharmacological interventions for PONV reported in recently published clinical trials carried out in female patients undergoing breast and gynecologic surgery, as well as the implications of the anesthetic agents on the incidence of PONV. A literature search of manuscripts describing PONV management in female surgical populations (breast surgery and gynecologic surgery) was carried out in PubMed, MEDLINE, and Embase databases. Postoperative nausea and vomiting incidence were highly variable in patients receiving placebo or no prophylaxis among RCTs whereas consistent results were observed in patients receiving 1 or 2 prophylactic interventions for PONV. Despite efforts made, a considerable number of female patients still experienced significant PONV. It is critical for the anesthesia provider to be aware that the coexistence of independent risk factors such as the level of sex hormones (pre- and postmenopausal), preoperative anxiety or depression, pharmacogenomic pleomorphisms, and ethnicity further enhances the probability of experiencing PONV in female patients. Future RCTs should closely assess the overall risk of PONV in female patients considering patient- and surgery-related factors, and the level of compliance with current guidelines for prevention and management of PONV.

comparison of palonosetron and aprepitant for prevention of post operative nausea and vomiting in females undergoing laparoscopic hysterectomy under general anesthesia

Background: Postoperative nausea and vomiting (PONV) is the second most common complaint following pain after surgery. In this era of daycare and outpatient-based surgery, PONV is the cause of delayed recovery and discharge from hospital settings. This study was designed to compare Palonosetron and Aprepitant for the prevention of PONV in patients undergoing laparoscopic hysterectomy under general anesthesia. Methods: 70 patients were included in this randomized double-blind study. Each group was allocated to receive either 0.075 mg of intravenous Palonosetron or 40mg of oral Aprepitant for PONV prophylaxis. A standard regimen of general anesthesia was administered to both groups for surgery. The primary outcome was the PONV impact severity scale (PISS) score at 48 hours following surgery in both groups. Secondary outcomes were the incidence of clinically significant PONV in both groups and the requirement of rescue antiemetics.  Results: Mean PISS score at 48 hours was significantly lower (0.91±0.13 vs 3.43±0.2) in the Palonosetron group than in the Aprepitant Group. Incidence of PONV (16/35 vs 33/35) was significantly lower with Palonosetron. Incidence of clinically significant PONV and requirement of rescue antiemetics was significantly lower (2/35 vs 13/35) in the Palonosetron group. 

Is Prevention of Postoperative Vomiting Surgery Dependent? A Retrospective Cohort Study of Total Knee Arthroplasty

The study of postoperative nausea and vomiting (PONV) has been ongoing since the early days of general anesthesia. The search for risk factors of PONV and the development of new agents to treat PONV are the two main strategies to combat the adverse side effects of general anesthesia. Female sex, non-smoking status, a history of PONV/motion sickness, and postoperative opioid use are the four independent risk factors for PONV derived after a series of prospective studies, evidence-based systematic reviews, and meta-analyses. The two frequently asked questions that arise ask whether risk factors apply to different clinical settings and whether prevention measures of PONV can be surgery dependent. We conducted a comprehensive review of 665 patients who underwent primary total knee arthroplasty (TKA) between January and December 2019. As nausea is subjective and its measurement is not standardized, postoperative vomiting (POV) was used as a study endpoint. The exclusion criteria were desflurane anesthesia, spinal anesthesia, anesthesia without bispectral index monitoring, and day surgery. Three well-recognized risk factors, consisting of body weight, sevoflurane consumption, and postoperative opioid consumption, were not considered as independent risk factors of POV, while female sex, preoperative adductor canal block (ACB), and dexamethasone were identified as being so in this study. The risk of POV in the female sex was 2.49 times that in the male sex; however, when dexamethasone was used, this risk was reduced by >40% compared with no antiemetic use, and by >50% when patients received preoperative ACB compared with those without the block. The clinical characteristics of our TKA patients—female dominance, old age, and their fairly constant body weights that were distinct from those of other surgical patients—suggested that age may play a crucial role in determining the relative contributions of the different risk factors of POV. We concluded that risk factors of POV are dependent on clinical settings. Based on these results, it is reasonable to speculate that a surgery-dependent plan for the prevention of POV is feasible for patients in similar clinical settings.

Neurokinin-1 Antagonists for Postoperative Nausea and Vomiting

Postoperative nausea and vomiting (PONV) are the second most frequent adverse events after surgery second only to postoperative pain. Despite the advances in antiemetics and implementation of multimodal prophylactic interventions, the clinical management of PONV remains problematic. Neurokinin-1 (NK-1) receptor is a tachykinin receptor found throughout the central and peripheral nervous systems, with a particular affinity towards substance P. NK-1 receptors interact with several parts of the neuronal pathway for nausea and vomiting. This includes the chemoreceptor trigger zone, the gastrointestinal tract, and dorsal motor nucleus of the vagus. NK-1 antagonists are thought to prevent nausea and vomiting by downregulating the emetogenic signals at those points. As more head-to-head trials are conducted between the various anti-emetics, there is emerging evidence that NK-1 antagonists may be more effective in preventing PONV than several other antiemetics currently in use. In this review, we will discuss the pharmacology of NK-1 antagonists, their efficacy in clinical practice, and how they could fit into the framework of PONV management.

Risk Factors of Postoperative Vomiting in the Eye of "Real-World Evidence"-Modifiable and Clinical Setting-Dependent Risk Factors in Surgical Trauma Patients

Numerous studies on postoperative nausea and vomiting (PONV) have been carried out since the early days of contemporary surgery. The incidence of PONV has been greatly reduced in recent years and new drugs for PONV keep evolving in the market; however, a substantial number of patients are still under the threat of PONV. Female gender, non-smokers, a history of PONV/motion sickness, and postoperative opioid use are four well-recognized risk factors of PONV. Many potential risk factors reported in previous studies were not consistently presented as predictors for PONV. Two questions then arise; are risk factors clinical setting dependent and are risk factors modifiable? We attempted to answer the questions through a comprehensive review of perioperative records of surgical patients from the Trauma Department of our hospital. As nausea is subjective and no standard is applicable for its measurement, postoperative vomiting (POV) was used as an endpoint in this study. To the best of our knowledge, this is the first study to address the POV issue in surgical trauma patients. A total of 855 patients were enrolled in this study after excluding age below 20 years old, total intravenous anesthesia, desflurane anesthesia, or records with missing data. Our results showed that female gender (OR 4.89) is the strongest predicting factor, followed by a less potent predicting factor—more intraoperative opioid consumption (OR 1.07)—which favor more POV. More intraoperative crystalloid supply (OR 0.71) and a higher body weight (OR 0.9) favor less POV. Other potential risk factors did not reach statistical significance in this study as independent risk factors. Our results also showed that when the intraoperative crystalloid infusion rate is greater than 4 mL/kg/h (OR 0.20), it favors a lower rate of POV; when intraoperative opioid consumption is greater than 12 mg morphine equivalents, MME (OR 1.87), it favors a higher rate of POV. We concluded that dominance of any independent risk factor over other risk factors depends on how individual factors interact with the clinical setting. Some risk factors could be modified, and a cut-off value could be derived to facilitate a better plan for POV prevention.

Drugs for preventing postoperative nausea and vomiting in adults after general anaesthesia: a network meta-analysis

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common adverse effect of anaesthesia and surgery. Up to 80% of patients may be affected. These outcomes are a major cause of patient dissatisfaction and may lead to prolonged hospital stay and higher costs of care along with more severe complications. Many antiemetic drugs are available for prophylaxis. They have various mechanisms of action and side effects, but there is still uncertainty about which drugs are most effective with the fewest side effects.

OBJECTIVES

• To compare the efficacy and safety of different prophylactic pharmacologic interventions (antiemetic drugs) against no treatment, against placebo, or against each other (as monotherapy or combination prophylaxis) for prevention of postoperative nausea and vomiting in adults undergoing any type of surgery under general anaesthesia • To generate a clinically useful ranking of antiemetic drugs (monotherapy and combination prophylaxis) based on efficacy and safety • To identify the best dose or dose range of antiemetic drugs in terms of efficacy and safety SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, and reference lists of relevant systematic reviews. The first search was performed in November 2017 and was updated in April 2020. In the update of the search, 39 eligible studies were found that were not included in the analysis (listed as awaiting classification).

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing effectiveness or side effects of single antiemetic drugs in any dose or combination against each other or against an inactive control in adults undergoing any type of surgery under general anaesthesia. All antiemetic drugs belonged to one of the following substance classes: 5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, corticosteroids, antihistamines, and anticholinergics. No language restrictions were applied. Abstract publications were excluded.

DATA COLLECTION AND ANALYSIS

A review team of 11 authors independently assessed trials for inclusion and risk of bias and subsequently extracted data. We performed pair-wise meta-analyses for drugs of direct interest (amisulpride, aprepitant, casopitant, dexamethasone, dimenhydrinate, dolasetron, droperidol, fosaprepitant, granisetron, haloperidol, meclizine, methylprednisolone, metoclopramide, ondansetron, palonosetron, perphenazine, promethazine, ramosetron, rolapitant, scopolamine, and tropisetron) compared to placebo (inactive control). We performed network meta-analyses (NMAs) to estimate the relative effects and ranking (with placebo as reference) of all available single drugs and combinations. Primary outcomes were vomiting within 24 hours postoperatively, serious adverse events (SAEs), and any adverse event (AE). Secondary outcomes were drug class-specific side effects (e.g. headache), mortality, early and late vomiting, nausea, and complete response. We performed subgroup network meta-analysis with dose of drugs as a moderator variable using dose ranges based on previous consensus recommendations. We assessed certainty of evidence of NMA treatment effects for all primary outcomes and drug class-specific side effects according to GRADE (CINeMA, Confidence in Network Meta-Analysis). We restricted GRADE assessment to single drugs of direct interest compared to placebo.

MAIN RESULTS

We included 585 studies (97,516 randomized participants). Most of these studies were small (median sample size of 100); they were published between 1965 and 2017 and were primarily conducted in Asia (51%), Europe (25%), and North America (16%). Mean age of the overall population was 42 years. Most participants were women (83%), had American Society of Anesthesiologists (ASA) physical status I and II (70%), received perioperative opioids (88%), and underwent gynaecologic (32%) or gastrointestinal surgery (19%) under general anaesthesia using volatile anaesthetics (88%). In this review, 44 single drugs and 51 drug combinations were compared. Most studies investigated only single drugs (72%) and included an inactive control arm (66%). The three most investigated single drugs in this review were ondansetron (246 studies), dexamethasone (120 studies), and droperidol (97 studies). Almost all studies (89%) reported at least one efficacy outcome relevant for this review. However, only 56% reported at least one relevant safety outcome. Altogether, 157 studies (27%) were assessed as having overall low risk of bias, 101 studies (17%) overall high risk of bias, and 327 studies (56%) overall unclear risk of bias. Vomiting within 24 hours postoperatively Relative effects from NMA for vomiting within 24 hours (282 RCTs, 50,812 participants, 28 single drugs, and 36 drug combinations) suggest that 29 out of 36 drug combinations and 10 out of 28 single drugs showed a clinically important benefit (defined as the upper end of the 95% confidence interval (CI) below a risk ratio (RR) of 0.8) compared to placebo. Combinations of drugs were generally more effective than single drugs in preventing vomiting. However, single NK₁ receptor antagonists showed treatment effects similar to most of the drug combinations. High-certainty evidence suggests that the following single drugs reduce vomiting (ordered by decreasing efficacy): aprepitant (RR 0.26, 95% CI 0.18 to 0.38, high certainty, rank 3/28 of single drugs); ramosetron (RR 0.44, 95% CI 0.32 to 0.59, high certainty, rank 5/28); granisetron (RR 0.45, 95% CI 0.38 to 0.54, high certainty, rank 6/28); dexamethasone (RR 0.51, 95% CI 0.44 to 0.57, high certainty, rank 8/28); and ondansetron (RR 0.55, 95% CI 0.51 to 0.60, high certainty, rank 13/28). Moderate-certainty evidence suggests that the following single drugs probably reduce vomiting: fosaprepitant (RR 0.06, 95% CI 0.02 to 0.21, moderate certainty, rank 1/28) and droperidol (RR 0.61, 95% CI 0.54 to 0.69, moderate certainty, rank 20/28). Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol showed clinically important benefit, but low doses showed no clinically important benefit. Aprepitant was used mainly at high doses, ramosetron at recommended doses, and fosaprepitant at doses of 150 mg (with no dose recommendation available). Frequency of SAEs Twenty-eight RCTs were included in the NMA for SAEs (10,766 participants, 13 single drugs, and eight drug combinations). The certainty of evidence for SAEs when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to low. Droperidol (RR 0.88, 95% CI 0.08 to 9.71, low certainty, rank 6/13) may reduce SAEs. We are uncertain about the effects of aprepitant (RR 1.39, 95% CI 0.26 to 7.36, very low certainty, rank 11/13), ramosetron (RR 0.89, 95% CI 0.05 to 15.74, very low certainty, rank 7/13), granisetron (RR 1.21, 95% CI 0.11 to 13.15, very low certainty, rank 10/13), dexamethasone (RR 1.16, 95% CI 0.28 to 4.85, very low certainty, rank 9/13), and ondansetron (RR 1.62, 95% CI 0.32 to 8.10, very low certainty, rank 12/13). No studies reporting SAEs were available for fosaprepitant. Frequency of any AE Sixty-one RCTs were included in the NMA for any AE (19,423 participants, 15 single drugs, and 11 drug combinations). The certainty of evidence for any AE when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to moderate. Granisetron (RR 0.92, 95% CI 0.80 to 1.05, moderate certainty, rank 7/15) probably has no or little effect on any AE. Dexamethasone (RR 0.77, 95% CI 0.55 to 1.08, low certainty, rank 2/15) and droperidol (RR 0.89, 95% CI 0.81 to 0.98, low certainty, rank 6/15) may reduce any AE. Ondansetron (RR 0.95, 95% CI 0.88 to 1.01, low certainty, rank 9/15) may have little or no effect on any AE. We are uncertain about the effects of aprepitant (RR 0.87, 95% CI 0.78 to 0.97, very low certainty, rank 3/15) and ramosetron (RR 1.00, 95% CI 0.65 to 1.54, very low certainty, rank 11/15) on any AE. No studies reporting any AE were available for fosaprepitant. Class-specific side effects For class-specific side effects (headache, constipation, wound infection, extrapyramidal symptoms, sedation, arrhythmia, and QT prolongation) of relevant substances, the certainty of evidence for the best and most reliable anti-vomiting drugs mostly ranged from very low to low. Exceptions were that ondansetron probably increases headache (RR 1.16, 95% CI 1.06 to 1.28, moderate certainty, rank 18/23) and probably reduces sedation (RR 0.87, 95% CI 0.79 to 0.96, moderate certainty, rank 5/24) compared to placebo. The latter effect is limited to recommended and high doses of ondansetron. Droperidol probably reduces headache (RR 0.76, 95% CI 0.67 to 0.86, moderate certainty, rank 5/23) compared to placebo. We have high-certainty evidence that dexamethasone (RR 1.00, 95% CI 0.91 to 1.09, high certainty, rank 16/24) has no effect on sedation compared to placebo. No studies assessed substance class-specific side effects for fosaprepitant. Direction and magnitude of network effect estimates together with level of evidence certainty are graphically summarized for all pre-defined GRADE-relevant outcomes and all drugs of direct interest compared to placebo in http://doi.org/10.5281/zenodo.4066353.

AUTHORS' CONCLUSIONS

We found high-certainty evidence that five single drugs (aprepitant, ramosetron, granisetron, dexamethasone, and ondansetron) reduce vomiting, and moderate-certainty evidence that two other single drugs (fosaprepitant and droperidol) probably reduce vomiting, compared to placebo. Four of the six substance classes (5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, and corticosteroids) were thus represented by at least one drug with important benefit for prevention of vomiting. Combinations of drugs were generally more effective than the corresponding single drugs in preventing vomiting. NK₁ receptor antagonists were the most effective drug class and had comparable efficacy to most of the drug combinations. 5-HT₃ receptor antagonists were the best studied substance class. For most of the single drugs of direct interest, we found only very low to low certainty evidence for safety outcomes such as occurrence of SAEs, any AE, and substance class-specific side effects. Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol were more effective than low doses for prevention of vomiting. Dose dependency of side effects was rarely found due to the limited number of studies, except for the less sedating effect of recommended and high doses of ondansetron. The results of the review are transferable mainly to patients at higher risk of nausea and vomiting (i.e. healthy women undergoing inhalational anaesthesia and receiving perioperative opioids). Overall study quality was limited, but certainty assessments of effect estimates consider this limitation. No further efficacy studies are needed as there is evidence of moderate to high certainty for seven single drugs with relevant benefit for prevention of vomiting. However, additional studies are needed to investigate potential side effects of these drugs and to examine higher-risk patient populations (e.g. individuals with diabetes and heart disease).

Management strategies for the treatment and prevention of postoperative/postdischarge nausea and vomiting: an updated review

Postoperative nausea and vomiting (PONV) and postdischarge nausea and vomiting (PDNV) remain common and distressing complications following surgery. The routine use of opioid analgesics for perioperative pain management is a major contributing factor to both PONV and PDNV after surgery. PONV and PDNV can delay discharge from the hospital or surgicenter, delay the return to normal activities of daily living after discharge home, and increase medical costs. The high incidence of PONV and PDNV has persisted despite the introduction of many new antiemetic drugs (and more aggressive use of antiemetic prophylaxis) over the last two decades as a result of growth in minimally invasive ambulatory surgery and the increased emphasis on earlier mobilization and discharge after both minor and major surgical procedures (e.g. enhanced recovery protocols). Pharmacologic management of PONV should be tailored to the patient’s risk level using the validated PONV and PDNV risk-scoring systems to encourage cost-effective practices and minimize the potential for adverse side effects due to drug interactions in the perioperative period. A combination of prophylactic antiemetic drugs with different mechanisms of action should be administered to patients with moderate to high risk of developing PONV. In addition to utilizing prophylactic antiemetic drugs, the management of perioperative pain using opioid-sparing multimodal analgesic techniques is critically important for achieving an enhanced recovery after surgery. In conclusion, the utilization of strategies to reduce the baseline risk of PONV (e.g. adequate hydration and the use of nonpharmacologic antiemetic and opioid-sparing analgesic techniques) and implementing multimodal antiemetic and analgesic regimens will reduce the likelihood of patients developing PONV and PDNV after surgery.

The Significance of NK1 Receptor Ligands and Their Application in Targeted Radionuclide Tumour Therapy

To date, our understanding of the Substance P (SP) and neurokinin 1 receptor (NK1R) system shows intricate relations between human physiology and disease occurrence or progression. Within the oncological field, overexpression of NK1R and this SP/NK1R system have been implicated in cancer cell progression and poor overall prognosis. This review focuses on providing an update on the current state of knowledge around the wide spectrum of NK1R ligands and applications of radioligands as radiopharmaceuticals. In this review, data concerning both the chemical and biological aspects of peptide and nonpeptide ligands as agonists or antagonists in classical and nuclear medicine, are presented and discussed. However, the research presented here is primarily focused on NK1R nonpeptide antagonistic ligands and the potential application of SP/NK1R system in targeted radionuclide tumour therapy.

WITHDRAWN: Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

Prevention of Postoperative Nausea and Vomiting

Objective:

To review the literature on the prevention of postoperative nausea and vomiting (PONV) in adults.

Data Sources:

Literature retrieval was accessed through MEDLINE (1966–December 2006) using the terms postoperative nausea and vomiting, prevention and treatment. Article references were hand-searched for additional relevant articles and abstracts.

Study Selection And Data Extraction:

All studies published in English were evaluated. Those dealing with prevention and treatment of PONV in adults were included in the review.

Data Synthesis:

Evidence suggests that providing prophylactic antiemetic medications in high-risk surgical patients is warranted. 5-HT3 receptor antagonists are widely used, with no one agent being clearly superior. However, studies have shown other types of agents to ho more cost-effective.

Conclusions:

The first step in the prevention of PONV is assessment and reduction of risk factors. Although nonpharmacologic therapies may play a role in the treatment of PONV, the mainstay of therapy for PONV is pharmacologic modalities. Patients at moderate to high risk for PONV need prophylactic antiemetic therapy. High-risk patients may require combination therapy with 2 or 3 agents from different antiemetic classes. Rescue antiemetic therapy is needed by patients who actually develop PONV. The agents of choice in such cases should be from antiemetic classes different from those used for prophylaxis of PONV.

Neurokinin-1 receptor antagonists in preventing postoperative nausea and vomiting: a systematic review and meta-analysis

Newly developed neurokinin-1 receptor (NK-1R) antagonists have been recently tried in the prevention of postoperative nausea and vomiting (PONV). This systematic review and meta-analysis was conducted to explore whether NK-1R antagonists were effective in preventing PONV.The PRISMA statement guidelines were followed. Randomized clinical trials (RCTs) that tested the preventive effects of NK-1R antagonists on PONV were identified by searching EMBASE, CINAHL, PubMed, and the Cochrane Library databases followed by screening. Data extraction was performed using a predefined form and trial quality was assessed using a modified Jadad scale. The primary outcome measure was the incidence of PONV. Meta-analysis was performed for studies using similar interventions. Network meta-analysis (NMA) was conducted to compare the anti-vomiting effects of placebo, ondansetron, and aprepitant at different doses.Fourteen RCTs were included. Meta-analysis found that 80 mg of aprepitant could reduce the incidences of nausea (3 RCTs with 224 patients, pooled risk ratio (RR) = 0.60, 95% confidence interval (CI) = 0.47 to 0.75), and vomiting (3 RCTs with 224 patients, pooled RR = 0.13, 95% CI = 0.04 to 0.37) compared with placebo. Neither 40 mg (3 RCTs with 1171 patients, RR = 0.47, 95% CI = 0.37 to 0.60) nor 125 mg (2 RCTs with 1058 patients, RR = 0.32, 95% CI = 0.13 to 0.78) of aprepitant showed superiority over 4 mg of ondansetron in preventing postoperative vomiting. NMA did not find a dose-dependent effect of aprepitant on preventing postoperative vomiting.Limited data suggested that NK-1R antagonists, especially aprepitant were effective in preventing PONV compared with placebo. More large-sampled high-quality RCTs are needed.

Aprepitant's prophylactic efficacy in decreasing postoperative nausea and vomiting in morbidly obese patients undergoing bariatric surgery

BACKGROUND

Postoperative nausea and vomiting is a major cause of patient dissatisfaction towards surgery. For bariatric surgery, increased vomiting/retching is detrimental to surgical anastomosis. The present study evaluated the efficacy of aprepitant (neurokinin-1 inhibitor) as a prophylactic antiemetic in morbidly obese patients for laparoscopic bariatric surgery.

METHODS

After institutional review board approval, 125 morbidly obese patients were recruited into this double-blind placebo-controlled trial. On random division, the patients received a tablet of aprepitant (80 mg) in group A, or a similar-appearing placebo in group P, an hour prior to surgery. All patients received intravenous ondansetron (4 mg) intraoperatively. Postoperatively, the patients were evaluated for nausea and vomiting by a blinded evaluator at 30 min, 1, 2, 6, 24, 48, and 72 h.

RESULTS

Both groups were evenly distributed for age, body mass index, type, and length of surgery. Cumulative incidence of vomiting at 72 h was significantly lower in group A (3%) compared to group P (15%; p = 0.021). Odds ratio for vomiting in group P compared to group A was 5.47 times. On Kaplan-Meier plot, time to first vomiting was also significantly delayed in group A (p = 0.019). A higher number of patients showed complete absence of nausea or vomiting in group A compared to group P (42.18 vs. 36.67%). On the other hand, nausea scores were unaffected by aprepitant, and no significant difference between groups was found at any of the measured time points.

CONCLUSIONS

In morbidly obese patients undergoing laparoscopic bariatric surgery, addition of aprepitant to ondansetron can significantly delay vomiting episodes simultaneously lowering the incidence of postoperative vomiting.

Safety of neurokinin-1 receptor antagonists

INTRODUCTION

The substance P (SP)/neurokinin (NK)-1 receptor system is involved in many pathological processes. NK-1 receptor antagonists have many promising therapeutic indications. However, the only NK-1 receptor antagonist used in clinical practice is the drug aprepitant and its intravenously administered prodrug, fosaprepitant. In general, NK-1 receptor antagonists are safe and well tolerated.

AREAS COVERED

A search was carried out in Medline using the following terms: adverse events, aprepitant, casopitant, clinical trials, CP-122,721, ezlopitant, fosaprepitant, NK-1 receptor antagonists, randomized, safety, side effects, tolerability and vofopitant.

EXPERT OPINION

Most clinical trials have focused on the antiemetic action of aprepitant in cancer patients treated with chemotherapy. However, the efficacy and safety of aprepitant have not been fully tested in other diseases in which the SP/NK-1 receptor system is involved (e.g., cancer, HIV, alcoholism); thus, clinical trials are required. The use of NK-1 receptor antagonists in oncology therapy is quite promising, but to date pharmacological therapy has not exploited the many possible therapies offered by such antagonists.

The effect of aprepitant for the prevention of postoperative nausea and vomiting in patients undergoing gynecologic surgery with intravenous patient controlled analgesia using fentanyl: aprepitant plus ramosetron vs ramosetron alone

BACKGROUND

The purpose of this study was to evaluate the effect of an aprepitant, neurokinin-1(NK1) receptor antagonist, for reducing postoperative nausea and vomiting (PONV) for up to 24 hours in patients regarded as high risk undergoing gynecological surgery with intravenous patient-controlled analgesia (IV PCA) using fentanyl.

METHODS

In this randomized, open label, case-control study 84 gynecological surgical patients receiving a standardized general anesthesia were investigated. Patients were randomly allocated to receive aprepitant 80 mg P.O. approximately 2-3 hours before operation (aprepitant group) or none (control group). All patients received ramosetron 0.3 mg IV after induction of anesthesia. The incidence of PONV, severity of nausea, and use of rescue antiemetics were evaluated for up to 24 hours postoperatively.

RESULTS

The incidence of nausea was significantly lower in the aprepitant group (50.0%) compared to the control group (80.9%) during the first 24 hours following surgery. The incidence of vomiting was significantly lower in the aprepitant group (4.7%) compared to the control group (42.8%) during the first 24 hours following surgery. In addition, the severity of nausea was less among those in the aprepitant group compared with the control group over a period of 24 hours post-surgery (P < 0.05). Use of rescue antiemetics was lower in the aprepitant group than in the control group during 24 hours postoperatively (P < 0.05).

CONCLUSIONS

In patients regarded as high risk undergoing gynecological surgery with IV PCA using fentanyl, the aprepitant plus ramosetron ware more effective than ramosetron alone to decrease the incidence of PONV, use of rescue antiemetics and nausea severity for up to 24 hours postoperatively.

Current concepts in the management of postoperative nausea and vomiting

Postoperative nausea and vomiting (PONV) are still common following surgery. This is not only distressing to the patient, but increases costs. The thorough understanding of the mechanism of nausea and vomiting and a careful assessment of risk factors provide a rationale for appropriate management of PONV. Strategy to reduce baseline risk and the adoption of a multimodal approach will most likely ensure success in the management of PONV.

Pharmacologic management of postoperative nausea and vomiting

INTRODUCTION

As advances in the safety and efficacy of surgery and anesthesia have been made, other complications such as postoperative nausea and vomiting (PONV) have become more apparent. PONV occurs after 30% of all surgeries, and incidences as high as 80% have been reported among patients at high risk.

AREAS COVERED

This review provides a brief overview of the etiology and mechanisms of emesis and of known risk factors for PONV. It also covers pharmacologic therapies, appropriate management strategies, prophylactic strategies, multimodal therapy and rescue treatment.

EXPERT OPINION

The main triggers for PONV are general anesthesia with inhalational anesthetics and opioids. When given to susceptible patients, e.g., females, the risk may be as high as 80%. In such patients, opioid-free regional anesthesia would be the most logical approach. However, if general anesthesia is needed, we prefer total intravenous anesthesia as it eliminates the use of inhalational anesthetics and reduces the risk for PONV. Importantly, efficacy of antiemetic interventions is independent as long as interventions have different mechanisms. Thus, for practical purposes, we prefer to titrate the use of antiemetics according to the validated Apfel simplified risk score. If a patient has 0, 1, 2, 3 or 4 of the four risk factors, we apply a similar number of antiemetic strategies.

A comparison of the combination of aprepitant and dexamethasone versus the combination of ondansetron and dexamethasone for the prevention of postoperative nausea and vomiting in patients undergoing craniotomy

BACKGROUND

Postoperative nausea and vomiting (PONV) occur commonly after craniotomy. In patients receiving prophylaxis with ondansetron and dexamethasone, vomiting occurred in 45% of patients at 48 hours. In addition to causing patient discomfort, the physical act of vomiting may increase intracranial pressure or cerebral intravascular pressure, jeopardizing hemostasis and cerebral perfusion. Aprepitant is a neurokin-1 receptor antagonist with a long duration of action and no sedative side effect. In a large multicenter study in patients undergoing abdominal surgery, aprepitant was significantly more effective than was ondansetron in preventing vomiting at 24 and 48 hours postoperatively. We hypothesized that the combination of aprepitant with dexamethasone will decrease the incidence of postoperative vomiting when compared with the combination of ondansetron and dexamethasone in patients undergoing craniotomy under general anesthesia.

METHODS

Patients scheduled to undergo craniotomy under general anesthesia were enrolled in this prospective, double-blind, randomized study. Patients were randomized to receive oral aprepitant 40 mg (or matching placebo) 1 to 3 hours before induction of anesthesia or ondansetron 4 mg IV (or placebo) within 30 minutes of the end of surgery. All patients received dexamethasone 10 mg after induction of anesthesia. The anesthetic technique was standardized. Data were collected at regular intervals by blinded personnel for 48 hours after surgery. Statistical analysis was performed using Wilcoxon's ranked sum test and χ(2) test. P < 0.05 was considered statistically significant.

RESULTS

One hundred four patients completed the study. The cumulative incidence of vomiting at 48 hours was 16% in the aprepitant group and 38% in the ondansetron group (P = 0.0149). The incidence of vomiting was also decreased in the aprepitant group at 2 hours (6% vs. 21%, P = 0.0419) and 24 hours (14% vs. 36%, P = 0.0124). From 0 to 48 hours, there was no difference between the aprepitant and ondansetron groups in the incidence of nausea (69% vs. 60%), nausea scores, need for rescue antiemetics (65% vs. 60%), complete response (no PONV and no rescue, 22% vs. 36%), or patient satisfaction with the management of PONV.

CONCLUSION

The combination of aprepitant and dexamethasone was more effective than was the combination of ondansetron and dexamethasone for prophylaxis against postoperative vomiting in adult patients undergoing craniotomy under general anesthesia. However, there was no difference between the groups in the incidence or severity of nausea, need for rescue antiemetics, or in complete response between the groups.

Neurokinin-1 and novel serotonin antagonists for postoperative and postdischarge nausea and vomiting

PURPOSE OF REVIEW

This review will address novel options for the prevention and treatment of postoperative and postdischarge nausea and vomiting (PONV and PDNV) after ambulatory anesthesia. In particular, this paper will review the characteristics of neurokinin-1 receptor antagonists (NK1-RAs) and the new serotonin receptor antagonist (5HT3-RA) palonosetron. Finally, we will discuss strategies for prophylaxis and treatment of PONV and PDNV that address the unique concerns in ambulatory surgery patients.

RECENT FINDINGS

First, although PONV has previously been recognized to be a problem for inpatients, new research suggests that the incidence of PDNV after ambulatory surgery may be as high as 35%. Second, NK1-RAs, including aprepitant, the first approved member of this family, are significantly more efficacious than any other antiemetic for the prevention of vomiting. They are however not more effective than other interventions for the control of nausea. Third, the next generation of 5HT3-RAs, such as palonosetron, does not affect the QT interval and has a half-life of 40 h that should be advantageous for the prevention of PDNV.

SUMMARY

Because of the high incidence of PDNV, a predictive model for PDNV would be helpful to determine appropriate antiemetic interventions for each individual patient. Drugs that may be particularly favorable are the novel NK1-RA aprepitant and the next generation 5HT3-RA palonosetron.

The relationship between patient risk factors and early versus late postoperative emetic symptoms

BACKGROUND

Postoperative nausea and vomiting (PONV) remain common complications after elective surgery. Prophylactic antiemetic drugs are frequently administered to patients with well known risk factors for developing PONV. We designed this prospective observational study to assess the relationship between common patient risk factors for developing PONV and the occurrence of early (0-24 h) versus late (24-72 h) emetic symptoms.

METHODS

One hundred thirty patients undergoing elective laparoscopic (n = 88) or plastic (n = 42) surgery were assigned a risk score for developing PONV based on the Apfel risk scoring system, which assigns one point each for female gender, nonsmoking status, history of PONV or motion sickness, and postoperative opioid use. It was assumed that all patients would receive an opioid analgesic in the postoperative period. The patients received 0, 1, 2, or 3 antiemetic drugs for prophylaxis. The occurrence of nausea, vomiting, and need for rescue antiemetics was assessed at specific time intervals from 0 to 6, 6-24, and 24-72 h after surgery. In addition, the impact of PONV on recovery of normal activities of daily living was assessed using a standardized patient questionnaire.

RESULTS

One or more prophylactic antiemetics were administered to 87%, 90%, and 95% of the patients in the two, three, and four Apfel risk-factor groups, respectively. In the presence of three or four risk factors, >/=2 antiemetics were administered to 56% and 75% of the patients, respectively. Vomiting was reported in 11% and 22% of patients in the three and four risk factor groups compared with 6% in the two risk factor group at 0-6 h, and 13% and 27% (vs 0%) at 6-24 h, respectively. However, in the 24-72 h postoperative period, the incidences of emesis were low and did not differ in the three risk groups (9%, 5%, and 11%, respectively). The occurrence of moderate-to-severe nausea was increased in the higher risk groups at 0-6 h and 6-24 h (19%-28% vs 6% and 20%-30% vs 9%, respectively). However, the incidences of nausea in the 24-72 h period in the three and four risk factor groups were not different from the two-risk factor group (5% and 8% vs 6%, respectively). The need for rescue antiemetics and interference of emetic symptoms with normal activities was greater in the four risk factor group compared with the two and three risk factor groups.

CONCLUSION

Despite the frequent use of multiple antiemetic drugs for prophylaxis, an Apfel risk score of three or four (vs 2) was associated with a higher incidence of emetic sequelae in the first 24 h after surgery. However, the occurrence of late (24-72 h) emetic symptoms was low and appeared to be unrelated to the patient's Apfel risk score.

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.

Mechanisms underlying postoperative nausea and vomiting and neurotransmitter receptor antagonist-based pharmacotherapy

Postoperative nausea and vomiting (PONV) is one of the most common and distressing complications following surgery, and understanding the mechanism(s) underlying PONV is essential to providing optimal prophylaxis and/or treatment of PONV. The knowledge base of PONV physiology has significantly expanded over the past decade. This article reviews the risk factors for the development of PONV and the mechanisms of action of pharmacological agents (including antagonists of serotonin 5-HT(3), dopaminergic D(2), histamine H(1), muscarinic cholinergic, opioid and neurokinin NK(1) receptors) for the management (i.e. prophylaxis and treatment) of PONV. NK(1) receptor antagonists, with their unique mechanism of action, are a particularly promising area of research as they appear to be efficacious in preventing PONV during both the early and the late postoperative periods. A successful PONV management strategy includes: (i) identifying patients at risk; (ii) keeping the baseline risk low; and (iii) using a combination of antiemetics acting on different receptors in moderate- to high-risk patients.

Risk factors for prolonged stay after ambulatory surgery: economic considerations

The risk factors that prolong length of stay of ambulatory patients can be classified as preoperative, intraoperative, and postoperative. Preoperative factors include the type of surgery, ear, nose and throat and strabismus surgery, old age and pre-existing congestive heart failure. Intraoperative factors include increasing length of surgery, and general anesthesia, while postoperative factors include postoperative nausea and vomiting, excessive pain and adverse cardiovascular events. The factors that anesthesiologists can address to reduce length of stay are postoperative nausea and vomiting and excessive pain. Multimodal management of postoperative nausea and vomiting and pain can minimize adverse events and thereby reduce length of stay in the postanesthetic care unit, but will not necessarily lead to a reduction in staffing levels. As personnel costs contribute the majority of postanesthetic care unit costs, more than 95%, direct financial savings may not be possible from eliminating adverse events alone. Optimizing the use of the postanesthetic care unit and reducing total hours in the unit with higher operating room turnover may lead to indirect financial benefits.

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.

Metabolism and excretion of CP-122,721, a non-peptide antagonist of the neurokinin NK1 receptor, in dogs: identification of the novel cleaved product 5-trifluoromethoxy salicylic acid in plasma

The metabolism and excretion of a potent and selective substance P receptor antagonist, CP-122,721, have been studied in beagle dogs following oral administration of a single 5 mg kg(-1) dose of [(14)C]CP-122,721. Total recovery of the administered dose was on average 89% for male dogs and 95% for female dogs. Approximately 94% of the radioactivity recovered in urine and feces was excreted in the first 72 h. Male bile duct-cannulated dogs excreted a mean of approximately 56% of the dose in bile, approximately 11% in feces, and approximately 25% in urine. The sum of radioactivity in bile and urine indicates >80% of the [(14)C]CP-122,721-derived radioactivity was absorbed by the gastrointestinal tract. CP-122,721 was extensively metabolized in dogs, and only a small amount of parent CP-122,721 was excreted as unchanged drug. There were no significant gender-related quantitative/qualitative differences in the excretion of metabolites in urine or feces. The major metabolic pathways of CP-122,721 were O-demethylation, aromatic hydroxylation, and indirect glucuronidation. The minor metabolic pathways included: Aliphatic oxidation at the piperidine moiety, O-dealkylation of the trifluoromethoxy group, and N-dealkylation with subsequent sulfation and/or oxidative deamination. In addition, the novel cleaved product 5-trifluoromethoxy salicylic acid (TFMSA) was identified in plasma. These results suggest that dog is the most relevant animal species in which the metabolism of CP-122,721 can be studied for extrapolating the results to humans.

Prophylaxis of postoperative nausea and vomiting: controversies in the use of serotonin 5-hydroxytryptamine subtype 3 receptor antagonists

Postoperative nausea and vomiting (PONV) continues to be a "big little problem" despite recent advances in anesthesia. Because of an increased interest in, and the abundant publications on this topic, guidelines for the management of PONV were published in 2003. Several key but controversial issues regarding PONV prophylaxis were left unaddressed, however. These included whether clinical differences exist between the 5-hydroxytryptamine subtype 3 (5-HT3) receptor antagonists, concern over optimal dosage and timing of administration, optimal 5-HT3 receptor antagonist combination therapy, and whether rescue therapy is effective after prior administration of the same or a different 5-HT3 receptor antagonist. The application of these antiemetics in clinical practice has raised questions regarding the role of the 5-HT3 receptor antagonists in the treatment of postdischarge nausea and vomiting and opioid-induced nausea and vomiting. A brief overview of the incidence, risk factors and current management recommendations for PONV and current controversies with special emphasis on the 5-HT3 receptor antagonists, is discussed.

How can we best prevent or treat postoperative nausea and vomiting?

In pursuit of preventing or rapidly rescuing patients from postoperative nausea and vomiting, new clinical studies provide revised postoperative nausea and vomiting risk prediction tools, risk stratification formulae, comparative trials to identify the most appropriate cost-effective anti-emetics, and several trials recommending the addition of steroids in anti-emetic prophylactic multimodal approaches. Common variables that identify high-risk postoperative nausea and vomiting patients include female sex, a history of postoperative nausea and vomiting or motion sickness, young age, volatile anesthetic agents, nitrous oxide, and the administration of opioids. The most successful approach to the prevention of postoperative nausea and vomiting is multimodal, with combination anti-emetics, dexamethasone, aggressive hydration, the avoidance of opioids, and aggressive pain control.

Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

Postoperative Nausea and Vomiting

Despite many medical advances, the incidence of postoperative nausea and vomiting (PONV) and postdischarge nausea and vomit-ing (PDNV) remains high. Sequelae such as dehydration, wound dehiscence, bleeding and others, contributed to increased healthcare costs and patient dissatisfaction. This article reviews the literature regarding the anatomy of emesis, the predictors of PONV and various treatments.

Action of ondansetron and CP-99,994 to modify behavior and antagonize cisplatin-induced emesis in the ferret

The action of ondansetron (1 mg/kg, i.p.) and (+)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine (CP-99,994; 10 mg/kg, i.p.) on spontaneous behavior and the emesis induced by cisplatin (10 mg/kg, i.p.) was studied in the ferret. Ondansetron was inactive to modify behavior, but CP-99,994 reduced spontaneous locomotor activity and lip licking by 48% (P<0.01) and 79% (P<0.01), respectively; CP-99,994 also abolished spontaneous burrowing activity (P<0.05). Treatment of animals with cisplatin induced an emetic response that was abolished by both ondansetron and CP-99,994 (P<0.01). However, cisplatin did not significantly modify other behavioral measures although animals that received CP-99,994, cisplatin, or CP-99,994 in combination with cisplatin exhibited more episodes of defecation than animals that received ondansetron (P<0.05). The action of CP-99,994 to modify behavior in this species is discussed in relation to animal models of nausea.

Evidence-based management of postoperative nausea and vomiting: a review

PURPOSE

To provide evidence-based guidelines for the prophylaxis and treatment of postoperative nausea and vomiting (PONV).

SOURCE

Literature from randomized controlled trials, systematic reviews, logistic regression analyses and expert opinion in the management of PONV.

PRINCIPAL FINDINGS

The etiology of PONV is multifactorial. Patient, anesthesia, and surgery related risk factors have been identified. Universal PONV prophylaxis is not cost-effective. Identification of patients at high-risk of PONV allows targeting prophylaxis to those who will benefit most from it. No prophylaxis is needed for patients at low risk for PONV. For patients at moderate risk for PONV, prophylaxis using a single antiemetic or a combination of two agents should be considered. Double and triple antiemetic combinations should be considered for patients at high risk for PONV. Furthermore, a multimodal approach should be adopted incorporating steps to keep the baseline risk of PONV low. The optimum cost-effective approach to the management of PONV will differ between an ambulatory centre and an inpatient hospital setting. For the treatment of established PONV in patients who failed prophylaxis, patients should not receive a repeat dose of the prophylactic antiemetic. Rather, a drug acting at a different receptor should be used. Beyond six hours after surgery, patients can be treated with any of the agents used for prophylaxis, except dexamethasone and transdermal scopolamine.

CONCLUSION

PONV are common after anesthesia and surgery. We provided evidence-based guidelines for the management of this problem based on the available literature.

Identification of single-nucleotide polymorphisms of the human neurokinin 1 receptor gene and pharmacological characterization of a Y192H variant

Neurokinin receptors in the central nervous system are involved in the neural circuitry of anxiety, depression and emesis. This has led to the development of nonpeptidic NK1 receptor antagonists as therapeutic agents. Clinical trials have shown that NK1 receptor antagonists have efficacy in chemotherapy-induced emesis and depression. Sequence polymorphisms can potentially influence the efficacy of drugs in patient populations and are an important consideration in the drug development process. To identify DNA sequence variants in the NK1 receptor, comparative DNA sequencing was performed on a population of 93 individuals. In total, 19 single-nucleotide polymorphisms (SNPs) were identified with one SNP (g.78351T>C) resulting in a tyrosine to histidine substitution at residue 192 (Y192H). The Y192H variant was expressed using site-directed mutagenesis and was characterized with respect to affinity, receptor kinetics, functional calcium response and receptor internalization. In all cases the Y192H variant was found to display properties similar to those of the wild-type receptor.