Double-blind, randomized comparison of the antiemetic efficacy of intravenous dolasetron mesylate and intravenous ondansetron in the prevention of acute cisplatin-induced emesis in patients with cancer. Dolasetron Comparative Chemotherapy-induced Emesis Prevention Group

5-hydroxytryptamine type-3 receptor antagonists for chemotherapy-induced and radiotherapy-induced nausea and emesis: can we safely reduce the dose of administered agents?

BACKGROUND

Nausea and emesis as a consequence of chemotherapy or radiotherapy can have an adverse effect on patients' quality of life during cancer treatment and may last for > 5 days after administration. Guidelines suggest that, used at appropriate doses, the 5-hydroxytryptamine type-3 (5-HT3) receptor antagonists--which are considered the antiemetic "gold standard" when they are administered in combination with corticosteroids--demonstrate equivalent efficacy and safety. However, due to financial considerations, these agents often are used at lower doses than recommended.

METHODS

A literature review of relevant publications pertaining to the control of chemotherapy-induced nausea and emesis and dosing issues of the 5-HT3 receptor antagonists was undertaken to provide a comprehensive review of dosing issues relevant to the 5-HT3 receptor antagonists.

RESULTS

The issue of "down dosing" was particularly pertinent because of the nature of the 5-HT3 receptor antagonist dose-response curve: A steep dose-response profile within a narrow dose range suggests that antiemetic control will be lost suddenly after dose deescalation. However, the array of predisposing and confounding patient factors indicates that it is unlikely that a loss of antiemetic control will be apparent across a population; rather, individuals will experience loss of control as the dose is reduced below threshold. Of the 4 5-HT3 receptor antagonists currently licensed in the United States (granisetron, ondansetron, dolasetron, and palonosetron), ondansetron is used sometimes at lower than optimal doses, and there is evidence to suggest that even the approved oral dose of dolasetron may be suboptimal.

CONCLUSIONS

Suboptimal dosing not only will be detrimental to patients' quality of life but, ultimately, will prove counterproductive in terms of hospital resources, and it will add to the already significant socioeconomic burden associated with cancer therapy. Therefore, the dose of antiemetic agent administered should be sufficiently high to ensure good emesis control across the whole patient population.

Selective serotonin 5-HT3 receptor antagonists for postoperative nausea and vomiting: are they all the same?

Selective serotonin 5-HT(3) receptor antagonists have proven safe and effective for the management of postoperative nausea and vomiting. Dolasetron, granisetron, ondansetron and tropisetron selectively and competitively bind to 5-HT(3) receptors, blocking serotonin binding at vagal afferents in the gut and in the regions of the CNS involved in emesis, including the chemoreceptor trigger zone and the nucleus tractus solitarii. Despite their shared mechanism of action, 5-HT(3) receptor antagonists have different chemical structures and exhibit differences in receptor binding affinity, dose response and duration of effect. Furthermore, although dolasetron, granisetron, ondansetron and tropisetron are all extensively metabolised by the cytochrome P450 (CYP) system, different components of this system predominate in the metabolism of each of these agents. Hence, although these agents are considered equally effective in the overall population, their pharmacokinetic and pharmacodynamic differences may explain the variability in individual responses to these drugs. This review discusses the pharmacological profiles of dolasetron, granisetron, ondansetron and tropisetron, and the clinical implications of differences in their profiles.

Granisetron vs ondansetron for prevention of nausea and vomiting in hematopoietic stem cell transplant patients: results of a prospective, double-blind, randomized trial

The serotonin type-3 (5-HT3) antagonists represent a significant advance in the prevention of acute nausea and vomiting (N/V) from highly emetogenic chemotherapy. We sought to determine if any differences in efficacy or adverse effects exist between two such agents, ondansetron and granisetron, during conditioning therapy for hematopoietic stem cell transplantation (HSCT). Patients were randomized to receive either ondansetron 0.15 mg/kg intravenously every 8 h or granisetron 10 microg/kg intravenously daily. Additionally, all patients received scheduled dexamethasone and lorazepam. Prophylaxis was continued until 24 h after completion of chemotherapy. Nausea and distress were measured subjectively with visual analog scales and emetic episodes were quantified. Of the 110 randomized patients, 96 were evaluable for efficacy and safety. No significant differences in efficacy were observed between the ondansetron- and granisetron-treated patients, evaluated by comparing the degree of nausea and distress, number of emetic episodes and overall control of emesis. The adverse effects were also comparable and no patients were removed from study because of severe toxicities. This trial demonstrates that ondansetron and granisetron are equally effective at preventing acute N/V associated with conditioning therapy frequently used for HSCT. The agent of choice should be based on drug acquisition cost or preference.

Open-label, randomized comparison of the efficacy of intravenous dolasetron mesylate and ondansetron in the prevention of acute and delayed cisplatin-induced emesis in cancer patients

PURPOSE

The aim of this study is to compare the antiemetic efficacy and tolerability of intravenous dolasetron mesylate and ondansetron in the prevention of acute and delayed emesis.

MATERIAL AND METHODS

From April 2002 through October 2002, a total of 112 patients receiving cisplatin- based combination chemotherapy were randomized to receive a single i.v. dose of dolasetron 100 mg or ondansetron 8 mg, 30 minutes before the initiation of chemotherapy. In the ondansetron group, two additional doses of ondansetron 8 mg were given at intervals of 2 to 4 hours. To prevent delayed emesis, dolasetron 200 mg p.o. daily or ondansetron 8 mg p.o. bid was administered from the 2(nd) days to a maximum of 5 days. The primary end point was the proportion of patients that experienced no emetic episodes and required no rescue medication (complete response, CR) during the 24 hours (acute period) and during Day 2 to Day 5+/-2 days (delayed period), after chemotherapy. The secondary end points included the incidence and severity of emesis.

RESULTS

105 patients were evaluable for efficacy. CR rates during the acute period were 36.0% for a single dose of dolasetron 100 mg, and 43.6% for three doses of ondansetron 8 mg. CR rates during the delayed period were 8.0% and 10.9%, respectively. There was no significant difference in the efficacy between the two groups. Adverse effects were mostly mild to moderate and not related to study medication.

CONCLUSIONS

A single i.v. dose of dolasetron 100 mg is as effective as three i.v. doses of ondansetron 8 mg in preventing acute and delayed emesis after cisplatin-based chemotherapy, with a comparable safety profile.

Consensus proposals for the prevention of acute and delayed vomiting and nausea following high-emetic-risk chemotherapy

This paper uses an evidence-based approach whenever possible to formulate recommendations, emphasizing the results of controlled trials concerning the best use of antiemetic agents. We address issues of dose, schedule, and route of administration of five selective 5-HT(3) antagonists. We conclude that for each of these five drugs, there is a plateau in therapeutic efficacy above which further dose escalation does not improve outcome. Furthermore, for all classes of antiemetic agents, a single dose is as effective as multiple doses or a continuous infusion. The oral route is as efficacious as the intravenous route of administration, even with chemotherapy of high emetic risk. Selective antagonists of the type 3 serotonin receptor (5-HT(3)) in combination with dexamethasone and aprepitant are the standard of care for the prevention of emesis following chemotherapy of high emetic risk.

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

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

5-HT3 receptor antagonists for prevention of late acute-onset emesis

OBJECTIVE

To review the currently available literature on the efficacy of the 5-HT(3) receptor antagonists in the prevention of late acute-onset chemotherapy-induced nausea and vomiting (12-24 h after cytotoxic treatment).

DATA SOURCES

Primary articles were identified by PubMed search (performed in March 2004) and through secondary sources. Search terms included granisetron, ondansetron, tropisetron, dolasetron, acute, chemotherapy, nausea, and vomiting (a further search was performed for palonosetron in March 2004).

STUDY SELECTION AND DATA EXTRACTION

All studies that performed regular assessments (every 2-6 h) of antiemetic control over the first 24 hours with 5-HT(3) receptor antagonists were evaluated.

DATA SYNTHESIS

Current guidelines recommend the use of 5-HT(3) receptor antagonists for the control of chemotherapy-induced nausea and vomiting but do not differentiate between the available agents. However, there is variability in the pharmacokinetic and pharmacodynamic profiles of these agents, and this has implications for dosing regimen, safety, efficacy, and potential drug-drug interactions. Cytotoxic agents vary in the time profile of their emetic effect; this must be considered when choosing an appropriate 5-HT(3) receptor antagonist. The optimal agent should be simple to administer and provide safe and effective antiemetic protection over the whole 24-hour period.

CONCLUSIONS

The differences between the 5-HT(3) receptor antagonists have important consequences for their dosing and efficacy in the control of late acute-onset chemotherapy-induced nausea and vomiting.

Palonosetron improves prevention of chemotherapy-induced nausea and vomiting following moderately emetogenic chemotherapy: results of a double-blind randomized phase III trial comparing single doses of palonosetron with ondansetron

BACKGROUND

Although all first-generation 5-HT(3) receptor antagonists demonstrate efficacy in preventing acute chemotherapy-induced nausea and vomiting (CINV), effective prevention of delayed CINV has not yet been achieved. This study compared the efficacy and tolerability of palonosetron, a novel, second-generation 5-HT(3) receptor antagonist, with ondansetron.

PATIENTS AND METHODS

In this multicenter, randomized, double-blind, stratified, phase III study, 570 adult cancer patients were randomized to receive a single i.v. dose of palonosetron 0.25 mg, palonosetron 0.75 mg or ondansetron 32 mg, each administered 30 min before initiation of moderately emetogenic chemotherapy. The primary end point was the proportion of patients with no emetic episodes and no rescue medication [complete response (CR)] during the 24 h after chemotherapy administration (acute period). Secondary end points included efficacy in treatment of delayed CINV (</=5 days post-chemotherapy) and overall tolerability.

RESULTS

563 patients were evaluable for efficacy. CR rates were significantly higher (P <0.01) for palonosetron 0.25 mg than ondansetron during the acute (0-24 h) (81.0% versus 68.6%, respectively), delayed (24-120 h) (74.1% versus 55.1%) and overall (0-120 h) (69.3% versus 50.3%) periods. CR rates achieved with palonosetron 0.75 mg were numerically higher but not statistically different from ondansetron during all three time intervals. Both treatments were well tolerated.

CONCLUSIONS

A single i.v. dose of palonosetron 0.25 mg was significantly superior to i.v. ondansetron 32 mg in the prevention of acute and delayed CINV.

Chemotherapy-induced nausea and vomiting: the importance of acute antiemetic control

Nausea and vomiting are two of the most feared side effects of cancer chemotherapy and radiotherapy. Chemotherapy-induced nausea and vomiting can be broadly categorized as acute (occurring within 24 hours of therapy), delayed (persisting for 6-7 days after therapy), or anticipatory (occurring prior to chemotherapy administration). Breakthrough and refractory nausea and vomiting describe the symptoms of uncontrolled emesis. Evidence suggests that good control of nausea and vomiting during the acute period correlates with the control of delayed emesis. Conversely, protection failure during the first 24 hours has a high predictive value for delayed emesis in the same cycle. The 5-HT(3)-receptor antagonists, regarded as the 'gold standard' in antiemetic therapy, are the first-line treatment for moderately and highly emetogenic chemotherapy and radiotherapy regimens in adults and children. Evidence suggests that the 5-HT(3)-receptor antagonists administered in combination with corticosteroids afford the best protection from symptoms of acute emesis and, by extrapolation, the most effective prevention of delayed emesis. Antiemetic therapeutic guidelines stress that the goal of therapy is to prevent cytostatic-induced nausea and vomiting. Therefore, the prophylactic use of the most effective antiemetic regimen-taking into consideration the emetogenicity of the chemotherapy and individual patient characteristics-must be adhered to in order to prevent acute, delayed, and anticipatory nausea and vomiting.

Electrocardiographic and cardiovascular effects of the 5-hydroxytryptamine3 receptor antagonists

OBJECTIVE

To review the electrocardiographic (ECG) and cardiovascular effects of 5-hydroxytryptamine(3) (5-HT(3)) receptor antagonists preclinically, in healthy volunteers, and in patients undergoing chemotherapy or surgery.

DATA SOURCES

A MEDLINE search was performed of clinical trials and preclinical data published between 1963 and December 2002 assessing the ECG and cardiovascular effects of 5-HT(3) receptor antagonists, supplemented with reviews and secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All of the articles identified were evaluated and all information deemed relevant was included in this review.

DATA SYNTHESIS

There are no clinically relevant differences in efficacy and safety among the available 5-HT(3) receptor antagonists for prevention and treatment of chemotherapy-induced and postoperative nausea and vomiting. As a class, they have well-defined electrophysiologic activity. Changes in ECG parameters (PR, QRS, QT, QTc, JT intervals) are small, reversible, clinically insignificant, and independent of the patient population studied, and patients are asymptomatic during these changes. ECG changes are most prominent 1-2 hours after a dose of dolasetron, ondansetron, and granisetron and return to baseline within 24 hours. Clinically important adverse cardiovascular events associated with these changes are rare. No serious cardiac events (including torsade de pointes) arising from ECG interval changes have been attributed to 5-HT(3) receptor antagonist use.

CONCLUSIONS

Clinical data demonstrate that ECG interval changes are a class effect of the 5-HT(3) receptor antagonists. Theoretical concern regarding cardiovascular adverse events with these agents is not supported by clinical experience. The significant benefits of these agents outweigh the theoretical small risk of meaningful cardiovascular events.

Measuring chemotherapy-induced nausea and emesis

BACKGROUND

Chemotherapy-induced nausea and emesis (CINE) is one of the most dreaded side effects of cancer therapy. To investigate the influence of these symptoms on a patient's quality of life (QOL), a validated tool measuring many domains is needed.

METHODS

A QOL questionnaire consisting of scales from the European Organization for Research and Treatment of Cancer QLQ-C30, the Morrow Assessment of Nausea and Emesis, the Osoba Nausea and Emesis Module, and new items specific to nausea, emesis, and retching was constructed and administered daily for 7-9 days to outpatients receiving emetogenic chemotherapy.

RESULTS

Test-retest and internal consistency reliabilities ranged from 0.44 to 0.84 and from 0.59 to 0.85, respectively. Item and scale correlations indicated good convergent and discriminant validity. Scales and items measuring similar factors (e.g., severity of emesis and severity of nausea) had strong correlations than did scales measuring dissimilar factors (e.g., cognitive functioning and physical functioning). The validity of known groups was demonstrated by significant differences (P < 0.01) in patients' QOL scores between days with no episodes of nausea, emesis, or retching, days with 1 or 2 episodes, and days with more than 3 episodes. Patients' QOL significantly decreased as the number of episodes per day increased (P < 0.001).

CONCLUSIONS

A CINE QOL questionnaire that successfully measures the short-term impact of nausea, emesis, and retching on patients receiving emetogenic chemotherapy has been developed, largely as a battery of preexisting questionnaires. The psychometric properties of the new questionnaire show adequate reliability and validity to warrant its use in clinical trials and outcomes studies. CINE adversely affects many domains within a patient's QOL.

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.

5-HT(3)-receptor antagonists for the treatment of nausea and vomiting: a reappraisal of their side-effect profile

Nausea and vomiting can cause considerable distress and discomfort to patients undergoing chemotherapy, radiotherapy, or surgery. Several classes of antiemetic agents exist to combat these side effects, though the 5-HT(3)-receptor antagonists have become the first-line treatment choice for many cancer patients and are considered the "gold standard" in antiemetic therapy. Compared with the older generation antiemetic drugs, 5-HT(3)-receptor antagonists are effective, well tolerated, and associated with few side effects. However, emerging differences among these agents suggest that the incidence and/or intensity of adverse events should not be regarded as a class effect. The side-effect profile of any supportive care therapy is particularly important in certain subgroups of patients, including pediatric patients and the elderly, as well as those suffering comorbid conditions, such as cardiovascular disease and renal or hepatic impairment. Indeed, dolasetron is associated with cardiovascular effects, and thus, should be used with extreme caution in patients who suffer from or may develop prolongation of cardiac conduction intervals. Ondansetron, on the other hand, is associated with a greater incidence of central nervous system side effects than either dolasetron or ondansetron, and pharmacokinetic parameters are affected in patients with hepatic impairment, thereby requiring dose adjustments. Clinicians are encouraged to evaluate patients on an individual basis when choosing which 5-HT(3)-receptor antagonist to prescribe.

Randomized open-label trial of dolasetron for the control of nausea and vomiting associated with high-dose chemotherapy with hematopoietic stem cell transplantation

A prospective open-label trial was performed to compare the efficacy of dolasetron with that of ondansetron or granisetron (standard therapy) for prevention of nausea and vomiting associated with high-dose chemotherapy with or without total body irradiation followed by hematopoietic stem cell transplantation (HSCT). In a university teaching hospital setting, 62 patients were randomized to receive either dolasetron 100 mg daily or standard doses of ondansetron or granisetron. In addition to objective data such as number of episodes of emesis and quantity of rescue antiemetics required, 100 mm visual analogue scales were used to rate nausea, appetite, and changes in taste. A post-hoc subgroup analysis was performed between groups of patients that were matched for conditioning regimens. Sixty-five percent of the dolasetron-treated patients and 87% of patients in the standard therapy group achieved a major or complete response (P < .05) based on emetic episodes and nausea score. Patients in the standard therapy group used fewer rescue antiemetics and also rated more favorably on selected questions of the visual analogue scale. No differences in safety parameters or adverse effects were reported. At doses prescribed in this study, dolasetron was less effective than granisetron or ondansetron in preventing nausea and vomiting associated with high-dose chemotherapy/total body irradiation followed by HSCT.

The cardiotoxic potential of the 5-HT(3) receptor antagonist antiemetics: is there cause for concern?

PURPOSE

To review and evaluate the potential cardiac effects of 5-HT(3) antiemetic treatment in patients who may be predisposed to cardiac complications resulting from malignancy, cytotoxic oncologic regimens, or preexisting comorbid conditions.

DESIGN

A literature review was conducted on the negative cardiovascular effects of chemotherapeutic agents, and, more specifically, on the cardiac interactions of the 5-HT(3) receptor antagonists commonly used to treat chemotherapy-induced nausea and vomiting.

RESULTS

Clinical studies in healthy subjects have reported electrocardiograph changes following administration of 5-HT(3) receptor antagonists. However, there are limited data on the use of 5-HT(3) antiemetics when administered with cardiotoxic chemotherapy. Nonetheless, the development of significant electrocardiograph changes with some agents may indicate a potential for significant cardiac effects in patients, particularly those who may be predisposed to cardiac complication.

CONCLUSIONS

As the predicted human life span increases, clinicians will be treating a larger, older oncology population. Because two of the most common major comorbidities are cardiovascular related, we need to be acutely aware of the toxic effects of chemotherapy, as well as the possible cardiac interaction of supportive agents, specifically the 5-HT(3) antiemetics. Until more data are made available, the best antiemetic option for patients receiving emetogenic and cardiotoxic chemotherapy may be the agent with the fewest apparent cardiac effects.

Prospective evaluation of antiemetic outcome following high-dose chemotherapy with hematopoietic stem cell support

Considerable progress has been made in improving the control of chemotherapy-induced emesis. The impact of available antiemetic options for patients receiving stem cell transplants is unclear, as few prospective data have been collected. We prospectively evaluated antiemetic outcome in patients receiving stem cell transplantation over a 7-day period following the initiation of chemotherapy. The primary endpoints were the number of emetic episodes and the extent of nausea measured on a four-point scale. Eighty-two patients were evaluated. Ninety-five percent of patients had nausea during the first week of treatment; 80% had at least one emetic episode. The percentage of patients with emesis was as follows: day 1: 13%, day 2: 21%, day 3: 30%, day 4: 38%, day 5: 44%, day 6: 39%, day 7: 18%. In multivariate analysis, gender, emesis with prior chemotherapy, history of morning or motion sickness, type of transplant (auto vs allo), use of total body irradiation, or use of dexamethasone did not effect emesis control. Most patients receiving high-dose chemotherapy experience incompletely controlled emesis. Control of nausea and emesis progressively worsened with each subsequent day following initiation of chemotherapy, reaching a nadir on day 5. New treatment approaches are needed to improve emesis control in this patient population.

Randomised comparison of ondansetron plus dexamethasone with dexamethasone alone for the control of delayed cisplatin-induced emesis

The role of 5-hydroxytryptamine(3) (HT(3)) antagonists in the treatment of delayed emesis is still controversial. To evaluate whether 5-HT(3) antagonists can add to the efficacy of corticosteroids in controlling delayed emesis, we performed a randomised, prospective, open study comparing ondansetron plus dexamethasone with dexamethasone alone in cisplatin-treated patients. 149 cisplatin-naïve patients with lung cancer received at least 60 mg/m(2) of cisplatin and were treated with dexamethasone 32 mg intravenously (i.v.) and granisetron 3 mg i.v. on day 1. Patients were randomly assigned to receive either dexamethasone 16 mg i.v. alone (arm A) or dexamethasone plus ondansetron 8 mg daily (arm B) on days 2-4. None of the efficacy variables related to control of delayed emesis differed significantly between the two arms. In conclusion, there does not appear to be sufficient evidence to support the prolonged use of 5-HT(3) receptor antagonists after 24 h of cisplatin-containing chemotherapy.

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.

Stratified administration of serotonin 5-HT3 receptor antagonists (setrons) for chemotherapy-induced emesis. Economic implications

The serotonin 5-HT3 receptor antagonists or 'setrons' have become the standard of care for the prevention of chemotherapy-induced emesis (CIE) and are first-line therapy for acute CIE in healthcare organisations worldwide. However, their superior efficacy versus standard antiemetics comes at a significant cost. Currently, 3 agents are available in the US: ondansetron, granisetron and dolasetron. The most important treatment-related factor contributing to CIE is the emetogenicity of chemotherapy. The ability to customise, or stratify, the setron dose to match the emetogenic challenge of the chemotherapy administered has potential benefits, both clinically and economically. In adults, there is an appreciable amount of clinical literature addressing stratified administration; however, the amount of 'hard' economic data is rather limited. Intuitively, if clinical outcomes are equivalent, then stratified administration should be associated with economic benefits, as it generally promotes the use of doses lower than those recommended by the manufacturer. The literature strongly substantiates this for ondansetron, but is not as favourable for granisetron or dolasetron. As the rationale and justification for dose stratification is contained in the clinical literature, the authors have reviewed the pertinent literature supporting the clinical and economic benefits of dose stratification in both adult and paediatric patients. The authors also provide a discussion of various additional strategies that can be employed to ensure the appropriate and cost-effective use of setrons in real-world practice settings. These strategies include the use of lower doses than recommended by manufacturers, use for acute versus delayed phase emesis, enhancing the antiemetic efficacy by the addition of a corticosteroid, use of oral versus injectable formulations (when appropriate) and the implementation and use of local, national and international drug use guidelines.

Tropisetron: an update of its use in the prevention of chemotherapy-induced nausea and vomiting

Tropisetron is a serotonin (5-hydroxytryptamine; 5-HT) antagonist that is primarily used in the prevention of chemotherapy-induced nausea and vomiting. Antagonism of 5-HT3 binding sites in the peripheral and central nervous system is the probable mechanism of prevention of acute nausea and vomiting. Effects on delayed nausea and vomiting are less well understood as these are probably not mediated solely by 5-HT3 receptors. Tropisetron monotherapy is effective for the control of acute, and to a lesser extent delayed, nausea and vomiting in patients receiving moderately to severely emetogenic chemotherapy. The combination of dexamethasone and tropisetron is more effective than monotherapy. Complete control of cisplatin-induced nausea and vomiting was obtained in 69 to 97% of patients receiving the combination compared with 46 to 80% receiving tropisetron monotherapy in randomised trials. There were generally no significant differences between the control of acute or delayed nausea and vomiting provided by tropisetron, ondansetron or granisetron in randomised, comparative trials. The antiemetic efficacy of tropisetron was maintained over multiple cycles of chemotherapy. Most comparative studies showed tropisetron monotherapy to be more effective than metoclopramide in controlling acute nausea and vomiting, with the exception of 1 study which showed similar efficacy. However, high dose metoclopramide plus dexamethasone provided similar control of delayed emesis to tropisetron plus dexamethasone. Tropisetron is also effective in children, including those who responded poorly to previous antiemetic treatment. Tropisetron and ondansetron generally have similar efficacies in this population. The drug enhanced patients' quality of life and was well tolerated by adults and children alike. The recommended oral and IV dosage of tropisetron is 5 mg once daily; there is no increase in efficacy with doses >5 mg.

CONCLUSIONS

Tropisetron is similar to other 5-HT3 receptor antagonists for the prevention of chemotherapy-induced nausea and vomiting in both adults and children. It is suitable as first-line therapy (combined with a corticosteroid) for the prevention of acute nausea and vomiting in patients treated with moderately to severely emetogenic chemotherapeutic agents. This combination is also moderately effective in the prevention of delayed nausea and vomiting.

Comparative review of 5-HT3 receptor antagonists in the treatment of acute chemotherapy-induced nausea and vomiting

Since their introduction, 5-HT3 receptor antagonists have become the agents of choice in the prevention of acute chemotherapy-induced nausea and vomiting and are generally superior to high-dose metoclopramide regimens. The availability of four different agents (ondansetron, granisetron, dolasetron, and tropisetron) within this class has prompted investigations into potential differences between the drugs, which appear to be few. More importantly, the results of recently conducted randomized comparative trials in patients receiving moderately or highly emetogenic chemotherapy have demonstrated similar efficacy. Although study designs and patient populations differed, seven large comparative trials in patients receiving highly emetogenic chemotherapy reported no significant differences in complete or complete plus major response rates among the agents. Similar results were generally reported in trials evaluating patients receiving moderately emetogenic chemotherapy. The safety and tolerability of these agents also appear to be similar. The most common adverse events include headache, gastrointestinal effects, lightheadedness, and sedation. All agents are available in both intravenous and oral dosage forms and may be administered as a single dose.

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Advances in use of the 5-HT3 receptor antagonists

Nausea and vomiting continue to rank as important side effects for cancer patients receiving chemotherapy. The class of drugs known as the 5-HT3 receptor antagonists have become widely used for chemotherapy-induced nausea and vomiting, and are considered a standard part of care for moderately- and highly-emetogenic chemotherapy in combination with corticosteroids. Ondansetron (Zofran, Glaxo Wellcome), granisetron (Kytril, SmithKline Beecham) and dolasetron (Anzemet, Hoechst Marion Roussel) are commercially available in the US. Intravenous forms of all three drugs have demonstrated efficacy in preventing acute (< or = 24 h following chemotherapy) nausea and emesis due to moderately- and highly-emetogenic chemotherapy. Oral forms of the drugs have been shown to be effective in prevention of nausea and emesis due to moderately-emetogenic chemotherapy. More recently, oral 5-HT3 receptor antagonists have demonstrated efficacy in the prevention of nausea and vomiting due to highly-emetogenic chemotherapy as well. Comparative trials between the three agents have shown no clinically important differences in outcome and they should be considered clinically equivalent. Optimal oral anti-emetic regimens for high-dose chemotherapy with bone marrow or stem cell transplantation remain to be determined and future oral studies should target this population. In general, the decision of which 5-HT3 receptor antagonist to select for formulary inclusion should be based on the dose of anti-emetic used and the acquisition cost of the agents being compared. The oral route should be used whenever possible.

Open-label comparison of the antiemetic efficacy of single intravenous doses of dolasetron mesylate in pediatric cancer patients receiving moderately to highly emetogenic chemotherapy

BACKGROUND

Nausea and vomiting are among the most unpleasant adverse side effects of cancer therapy.

PROCEDURE

An open-label dose-escalation study was conducted to assess the appropriate intravenous dose of dolasetron for pediatric patients undergoing chemotherapy. Patients received dolasetron in single intravenous doses of 0.6 (n = 10), 1.2 (n = 12), 1.8 (n = 12), or 2.4 (n = 12) mg/kg 30 min before receiving emetogenic chemotherapy. Pharmacokinetic parameters were evaluated at each dose level and efficacy was evaluated over the first 24 hr following the administration of dolasetron.

RESULTS

A complete response was achieved in 10% of patients given 0.6 mg/kg, 25% of patients given 1. 2 mg/kg, 67% of patients given 1.8 mg/kg, and 33% of patients given 2.4 mg/kg. Peak plasma concentrations (Cmax) were observed between 0. 33 and 0.75 hr following dolasetron infusion. Cmax and area under plasma concentration-time (AUC) increased with larger doses of dolasetron, while terminal disposition half-life (t1/2) and apparent clearance (Clapp) were not significantly changed with respect to dose. For 1.8-mg/kg dolasetron, the t1/2 was 4.98 hr and the maximum plasma concentration (tmax) 0.47 hr. Adverse events were mild to moderate. No serious events occurred. Conclusions. This study suggests that a single intravenous dose of 1.8 mg/kg is the optimum single intravenous dose for controlling chemotherapy-induced emesis in pediatric patients.

Guidelines for anti-emetic therapy: acute emesis

Anti-emetic therapy has become integral to the management of patients with cancer. Goals related to complete emesis control include providing treatment that reduces hospitalisation and time in the ambulatory setting, care that is convenient for the patient and therapy that enhances patients' quality of life. A panel of clinical, health economic and basic scientists with expertise in various oncology disciplines reviewed published literature to develop evidence-based consensus guidelines for the prevention and treatment of chemotherapy-induced emesis. Currently, serotonin receptor antagonists and corticosteroids are the two categories of anti-emetics that are most effective, have the fewest side-effects and are convenient to use. These agents are recommended in combination for highly emetogenic chemotherapy regimens and as single agents or in combination for moderately to highly emetogenic chemotherapy. When possible, these agents may be given orally in single doses; current evidence does not support dose escalation for either category of anti-emetics. In special situations, such as the use of high-dose chemotherapy combination regimens, the most emetogenic component of the regimen should dictate the choice of anti-emetic. Appropriate anti-emetic use described in these guidelines represents both good medical practice and a sensible economic approach to care.

5-HT3 receptor antagonists for the prevention of chemotherapy-induced nausea and vomiting. A comparison of their pharmacology and clinical efficacy

In the mid-1980s it was discovered that serotonin (5-hydroxytryptamine; 5-HT) was at least partially responsible for producing chemotherapy-induced nausea and vomiting. It was therefore realised that serotonin receptor blockade with serotonin 5-HT3 receptor antagonists could inhibit chemotherapy-induced nausea and vomiting. 5-HT3 antagonists have different chemical structures and receptor binding affinity. Granisetron, dolasetron and its major metabolite are pure 5-HT3 antagonists, while ondansetron and tropisetron are weak antagonists at the 5-HT4 receptor. Ondansetron has also been demonstrated to bind at other serotonin receptors and to the opioid mu receptor. The half-lives of granisetron, tropisetron and the active metabolite of dolasetron are 2 to 3 times longer than that of ondansetron. These observations initially suggested that more frequent ondansetron administration would be required; however, it has now been shown that receptor blockade does not correlate with elimination half-life and all 5-HT3 antagonists can be effectively administered once daily. Clinical trials have been conducted that directly compare the 5-HT3 antagonists. To compare these studies, it is necessary to assess trial design, including known risk factors for the development of chemotherapy-induced nausea and vomiting, and response criteria. Stratification for risk factors, use of strict efficacy criteria and randomisation to a blinded trial using an appropriate comparative regimen are essential for a well designed antiemetic trial. Comparative clinical trials using various doses, routes and regimens of administration have been conducted with 5-HT3 antagonists. Despite some trial design shortcomings, most of the studies show equal efficacy between the agents, especially in moderately emetogenic chemotherapy and mild, infrequently occurring adverse effects. The addition of steroids also appears to improve outcome. However, since many doses and regimens of ondansetron were used, further study is needed to determine the optimal regimen. The efficacy of 5-HT3 antagonists in controlling delayed nausea and vomiting from chemotherapy is less well studied. Further, there is no good scientific rationale for the use of 5-HT3 antagonists in controlling delayed nausea and vomiting since serotonin has not been shown to be released during the delayed phase. In fact, most studies show no benefit or modest benefit of 5-HT3 antagonists over placebo. Because the 5-HT3 antagonists perform similarly in the clinical setting, pharmacological differences do not seem to translate into therapeutic differences. There is also no appreciable difference in the incidence or severity of adverse effects among the 5-HT3 antagonists. Determination of clinical use may then be driven by cost.

A risk-benefit assessment of serotonin 5-HT3 receptor antagonists in antineoplastic therapy-induced emesis

Insight into the pathophysiology of antineoplastic therapy-induced nausea and vomiting led to the development of the serotonin 5-HT3 receptor antagonists as the most potent class of antiemetic agents. Among those which have been investigated are ondansetron, granisetron, tropisetron and dolasetron. A risk-benefit analysis of these drugs must not only account for the modest clinical differences in efficacy and tolerability, but also should include such issues as ease of use, route of administration, dosage considerations and patient preference. Pharmacokinetic and preclinical studies reveal distinctions among these antiemetics, but, overall, these distinctions do not translate in to clinically significant differences. In clinical trials, the most widely studied members of the 5-HT3 receptor antagonists are granisetron and ondansetron, which have been found to possess equivalent antiemetic efficacy. Dolasetron and tropisetron are also available, and some randomised trials have also documented their similar antiemetic activity, depending on the doses and schedules used. The equivalent efficacy of oral granisetron 2 mg versus intravenous ondansetron 32 mg has recently been demonstrated in prospective randomised clinical trials in patients receiving either highly emetogenic or moderately emetogenic antineoplastic therapy. The utilisation and efficacy of oral ondansetron and dolasetron in patients receiving moderately emetogenic antineoplastic therapy has also been documented. This review offers a brief overview of the pharmacokinetic and preclinical research on the 5-HT3 antagonists, a review of the comparative clinical trials of the major members of this class and a summary risk-benefit assessment that considers clinical applicability and cost, as well as efficacy and safety.

Treatment of postoperative nausea and vomiting with single intravenous doses of dolasetron mesylate: a multicenter trial. Dolasetron Mesylate PONV Treatment Study Group

This study was conducted to determine the efficacy and safety of four intravenous (I.V.) doses of dolasetron, an investigational 5-HT3 receptor antagonist, for the treatment of postoperative nausea and/or vomiting (PONV) after outpatient surgery under general anesthesia. This multicenter, randomized, double-blind trial compared the antiemetic efficacy of 12.5, 25, 50, or 100 mg I.V. dolasetron with placebo over 24 h using complete response (no emetic episodes and no rescue medication), time to first emetic episode or rescue medication, and patient nausea and satisfaction with antiemetic therapy as rated by visual analog scale (VAS). Of 1557 patients enrolled, 620 patients were eligible for treatment. Complete response rates for all dolasetron doses--12.5 mg (35%), 25 mg (28%), 50 mg (29%), and 100 mg (29%)--were significantly more effective than placebo (11%, P < 0.05). There was a significant gender interaction for complete response (P < 0.01). Of the patients in the 25-mg and 100-mg dose groups, 12% and 13%, respectively, experienced no nausea (VAS score < 5 mm) versus 5% in the placebo group (P < 0.05). There were no clinically relevant changes in vital signs or laboratory values and no trends with dose for adverse events. Dolasetron is effective for treating PONV and has an adverse event profile similar to that of placebo. The 12.5-mg dose was as effective as larger doses for complete response.

IMPLICATIONS

Nausea and vomiting are common problems for postsurgical patients. In this study of 620 patients undergoing surgery, a 12.5-mg dose of intravenous dolasetron, a new serotonin-receptor blocker, was significantly more effective than placebo in treating established postoperative nausea and vomiting. Dolasetron 12.5 mg was as safe as placebo.

Intravenous dolasetron for the prevention of postoperative nausea and vomiting after outpatient laparoscopic gynecologic surgery

The newer 5-hydroxytryptamine type 3 (5-HT3) antagonists are sometimes considered for routine prophylaxis of postoperative nausea and vomiting (PONV) in high-risk patients. This multicenter, randomized, double-blind, placebo-controlled study compared the efficacy and safety of three single intravenous (IV) doses of dolasetron mesylate salt (12.5, 25, or 50 mg) for the prevention of PONV in 635 females undergoing outpatient laparoscopic gynecologic surgery. Antiemetic efficacy was evaluated over a 24-h postoperative period by recording the number and timing of emetic episodes; effects on nausea were evaluated by a visual analog scale (VAS). The proportion of complete responders (no emetic episodes and no escape medication in 24 h) was significantly higher with each dolasetron mesylate dose (> 50% for each dose; P < or = 0.0003) than with placebo (30.6%). Fewer patients given dolasetron required or requested escape antiemetic medication compared with placebo (P < 0.0003). Dolasetron-treated patients had significantly (P < 0.0357) lower median postdose maximum nausea VAS scores compared with placebo-treated patients. Patient satisfaction with dolasetron was high and, overall, was significantly (P = 0.0131) greater than that with placebo. Dolasetron was an effective and well tolerated preventive treatment for PONV resulting from laparoscopic gynecologic surgery.