Ondansetron compared with dexamethasone and metoclopramide as antiemetics in the chemotherapy of breast cancer with cyclophosphamide, methotrexate, and fluorouracil

A Randomized Open-Label Parallel-Group Study Comparing Ondansetron with Ondansetron plus Dexamethasone in Patients with Metastatic Breast Cancer Receiving High-Dose Epirubicin. A Hellenic Cooperative Oncology Group Study

AIMS AND BACKGROUND

The purpose of this multicenter randomized, open-label, parallel-group study was to assess whether the addition of low-dose dexamethasone to ondansetron results in improved control of chemotherapy-induced emesis in patients undergoing first-line chemotherapy with high-dose epirubicin.

METHODS & STUDY DESIGN

Patients were randomized to receive either 24 mg of ondansetron or 24 mg of ondansetron plus 8 mg of dexamethasone administered as an intravenous infusion 30 minutes prior to administration of chemotherapy. Both groups of patients received 8 mg of ondansetron given orally from day 2 to 5 two times daily. Fifty-three patients received ondansetron and 50 received ondansetron plus dexamethasone. The patients recorded nausea and the number of vomits and retches daily on diary cards.

RESULTS

Significantly more patients in the ondansetron plus dexamethasone group experienced neither vomiting nor retching during the first day of the first course of chemotherapy compared to those receiving ondansetron alone (79.6% vs 53.8%, P = 0.0062). Furthermore, there was a trend in favor of ondansetron plus dexamethasone in the control of nausea. There was no statistically significant difference between ondansetron plus dexamethasone versus ondansetron alone in protecting patients from emesis between days 2 and 5 of the first course of chemotherapy (66.7% vs 62.7%, P = 0.68). This was probably due to the small sample size. Ondansetron was well tolerated, with 15 patients (15%) reporting adverse events such as headache or constipation.

CONCLUSIONS

It appears that ondansetron given intravenously in combination with dexamethasone is more effective than ondansetron alone in the control of acute emesis in patients undergoing their first course of chemotherapy with high-dose epirubicin. No difference between the regimens was found with regard to nausea and delayed emesis control.

Antiemetics in cancer chemotherapy

Progress has been made in the prevention of chemotherapy-induced nausea and vomiting but it remains a major problem.

Use of the visual analog scale to rate and monitor severity of nausea in the emergency department

OBJECTIVES

The objective was to describe the association between verbal descriptors of nausea severity and visual analog scale (VAS) ratings in an undifferentiated emergency department (ED) population and to calculate the minimum clinically significant difference (MCSD) in VAS rating of nausea severity in this population.

METHODS

A prospective observational study was conducted at three EDs on a convenience sample of stable, consenting adult patients presenting with nausea as part of their symptom complex. Data included demographics, adjectival description of nausea severity (none, mild, moderate, or severe), and VAS rating (standard 100-mm line) at enrollment, 30 minutes, and 60 minutes. At 30 and 60 minutes they were also asked to describe any change in nausea severity from the previous rating ("a lot less,""a little less,""the same,""a little more,""a lot more"). The MCSD was defined as the average VAS change when a patient reported "a little less" or "a little more" nausea.

RESULTS

A total of 247 patients provided 693 matched adjectival ratings and VAS scores. Median age was 45 years, and 100 (40%) were male. The median VAS measures for none, mild, moderate, and severe nausea were 2, 23, 53, and 83 mm, respectively. VAS distributions in the verbal categories were statistically different from each other (Spearman rank correlation coefficient = 0.90; p < 0.0001). The MCSD was 22 mm (95% CI = 20 to 24 mm).

CONCLUSIONS

There is very good correlation between verbal descriptors of nausea and VAS ratings. The MCSD for VAS nausea ratings in an ED population is 22 mm.

[Management of chemotherapy-induced emesis: what is the standard after 20 years of clinical research]

BACKGROUND

The knowledge of the importance, the physiopathological mechanisms, and the management of the chemotherapy-induced emesis has increased exponentially during the last 20 years. High-dosage metoclopramide (MCP) therapy has been introduced in the eighties and serotonine type-3 receptor antagonists (5-HT(3) antagonists) have been used since the late eighties and early nineties. Due to both classes of substances the results of the antiemetic therapies have improved drastically. After 20 years of intensive clinical research it seems to be appropriate to come to an intermediate conclusion.

METHOD

With the aid of an overview and a new analysis of the literature published on this topic so far, the current state of research is shown (including the fields in which further improvement will be necessary), and suggestions are made, wherever it seemed possible, to attain the "gold standard" in antiemetic therapy.

RESULTS AND CONCLUSIONS

In connection with all highly or very highly emetogenic chemotherapies, an antiemetic prophylaxis should be initiated on the day of therapy, especially when using platinum or most of the cyclophosphamide-based regimes for cancer treatment. The recommended prophylaxis consists of a combination of 5-HT(3) antagonists with a corticosteroid. To combat the so-called delayed emesis on the days following therapy, all patients should undergo an oral corticoid therapy, possibly in combination with MCP (especially platinum-therapy patients), less frequently with 5-HT(3) antagonists. With these means of prophylaxis emesis can be prevented/avoided completely in most patients, and nausea can at least be reduced. It is sufficient to administer a single dose of 5-HT(3) antagonists prior to chemotherapy. For ondansetron and granisetron, the best documented substances within this class of drugs, 8 mg (ondansteron) and 3 mg (granisetron) are considered standard dosages. Among the corticoids, most data have been accumulated for dexamethasone. A standard dose of 10 to 20 mg can be administered prior to chemotherapy. Right after and especially on the days following chemotherapy higher dosages seem to be indicated.

PROSPECT

Further therapy improvements, especially concerning emesis and nausea on the days following chemotherapy, are necessary and are currently object of clinical research.

[Treatment of tumor therapy-induced nausea and vomiting]

Even today, nausea and vomiting are two of the most distressing adverse effects associated with tumor therapy. The authors give an overview of the mechanism and the trigger factors (emetogenic potential of the chemotherapies, the patient risk factors, and the used antiemetic drugs) of nausea and vomiting. A short summary will describe the antiemetic drugs focusing on metoclopramide, steroid and the currently widely used setron therapy which is effective only during the acute phase of chemotherapy-induced nausea and vomiting (CINV). In the treatment of CINV the latest improvement was the introduction of the neurokinin (NK1) receptor antagonist class. Currently the only available agent is aprepitant which is indicated to treat CINV in case of highly and moderately emetogenic chemotherapies. The pivotal phase III trials defined that aprepitant is the first drug that is able to protect against the delayed phase of CINV plus can improve the antiemetic therapy during the acute phase. Currently aprepitant is reimbursed in Hungary only after the failure of setron therapy in case of high dose (\>50 mg/m2) cisplatin protocols. The authors give a recommendation how to treat CINV based on the latest international antiemetic guidelines.The mechanism and the trigger factors of radiotherapy-induced nausea and vomiting (RINV) are different from CINV. For treatment of RINV metoclopramide (due to reimbursement regulation) and ondansetron can be used. In case of radio-chemotherapy the antiemetic treatment should follow the CINV guidelines.

Clinical Predictors of Chemotherapy-Induced Nausea and Vomiting in Breast Cancer Patients Receiving Adjuvant Doxorubicin and Cyclophosphamide

Background:

Patients with breast cancer often receive emetogenic anthracycline–based chemotherapy as part of their treatment. Chemotherapy-induced nausea and vomiting (CINV) has been commonly reported as one of the distressing adverse effects among patients with cancer. Despite the advent of newer antiemetics and better understanding of the CINV pathophysiology, total eradication of CINV has yet to be achieved.

Objective:

To assess the incidence of nausea and vomiting in patients who have breast cancer and are receiving adjuvant doxorubicin and cyclophosphamide (AC) bolus chemotherapy, ascertain patients’ risk factors affecting CINV response, and study patient adherence to delayed antiemetics.

Methods:

This was a single-institution, prospective, observational study conducted at an outpatient cancer center in Singapore from December 2006 to December 2007. Clinical events such as CINV were collated using a standardized diary. Use of rescue antiemetics and unscheduled clinic visits due to CINV were documented.

Results:

Of a total of 108 participants, 16 patients were lost to follow-up and 1 provided incomplete information; thus, 91 patients were included in the analysis. Delayed antiemetics were given according to the institution's guideline and only 9 (9.9%) patients received aprepitant. Neither acute nor delayed vomiting was reported by a majority of patients and only 4 (4.4%) experienced grade 3 vomiting. The incidence of severe nausea was highest on day 3 of chemotherapy and affected 14.3% of patients. Anxiety and history of chemotherapy-induced nausea were associated with both acute and delayed nausea, and history of motion sickness was associated with delayed vomiting. Approximately 65% of patients were adherent to their prescribed delayed antiemetics.

Conclusions:

Most of our patients adhered to their antiemetics and tolerated AC chemotherapy reasonably well, without vomiting; yet nausea persisted. To improve CINV control, clinicians must actively communicate with patients to facilitate accurate assessment of risk factors and CINV response and to encourage adherence to delayed antiemetics.

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

PURPOSE

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

UPDATE METHODOLOGY

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

RECOMMENDATIONS

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

Methodology for quality-of-life assessment: a critical appraisal

The methodology for QOL assessment covers a wide range of topics. It involves a proper choice of instruments with appropriate psychometric properties, the administration of these instruments, frequency of measurements, missing data problems, and the method of analysis. There are currently debates on the meaning and interpretation of the HRQOL domains taking the form of arguing how to define minimal clinically meaningful difference and whether this can be used in regulatory approval for drug development. From a practical point of view, the authors proposed that a disease-specific checklist or symptom domains incorporated within a HRQOL questionnaire may be a middle ground to gain general agreements among academic institutions, manufacturers, and regulatory agencies to use a specific symptom checklist or domain as the primary end point for clinical trials together with other HRQOL domains as ancillary data for the study. Antiemetic trial with HRQOL assessments is an example. Most would agree, however, that no matter what HRQOL domains or symptoms are being studied, it should be based on a patient self-administered questionnaire as shown by the lack of sensitivity in the example in this article. Missing data are a problem in the data collection and handling. The authors have examined a few commonly used approaches and performed simulation to study their properties. The subscale-mean method when one has more than 50% of the information on a subscale generally reflects the true values. In practice, one still would have missing data that cannot be handled completely by imputation. The method of analysis must be flexible enough to incorporate the nature of these data. Two approaches have been discussed, and they are both flexible in terms of using all available information being obtained in a longitudinal fashion with variable visiting schedules and potential missing data. The HRQOL response variable approach is simple and easy to understand. The growth curve models approach provides more detailed information on average trends between treatment arms. In general, these two methods agree on the results of the example. They can be used to report clinical trial results using HRQOL data as end points.

Selectivity of SSRIs: individualising patient care through rational treatment choices

Despite a common mode of action [inhibition of the 5-hydroxytryptamine (5-HT) neuronal reuptake transporter], proven antidepressant efficacy and a similar range of indications (depression and a variety of anxiety disorders), the unique secondary binding properties of each selective serotonin reuptake inhibitor (SSRI) account for clinically significant differences in tolerability and side-effect profiles, particularly in some patients. Secondary properties within the class of SSRIs include some combination of actions at noradrenergic, dopaminergic, muscarinic cholinergic, histaminergic and sigma receptors. In addition, most SSRIs inhibit at least one of the cytochrome P450 enzymes, resulting in potential pharmacokinetic interactions with co-prescribed drugs. Although secondary properties of SSRIs can be associated with side effects, sometimes these same actions can be harnessed to good therapeutic effect through rational, informed treatment choices. In this way, agents that more consistently cause central nervous system activation (such as fluoxetine and sertraline) can be used to boost energy in patients whose depression is accompanied by fatigue and apathy, while the anxiolytic, sedative properties of others (particularly paroxetine and fluvoxamine) can be beneficial in patients with insomnia and agitation. When secondary properties are experienced as undesirable side effects, agents with greater selectivity for the serotonin transporter and without significant secondary binding properties, such as citalopram and escitalopram, may be desirable. This article explains how an understanding of the secondary binding properties of the SSRIs can guide individualised treatment across the spectrum of depressive and anxious states.

Control of nausea and vomiting after chemotherapy: what is the evidence?

The control of nausea and vomiting is an important problem for patients undergoing chemotherapy. With the introduction of newer agents, including 5-HT3 antagonists, nausea and vomiting control after chemotherapy has much improved but is not always optimal. While there is an intrinsic limitation to the efficacy of anti-emetic drugs, their efficacy can be further reduced if the drugs are not used appropriately. In some circumstances newer anti-emetics may be unnecessary and better nausea and vomiting control may be established by use of older agents. This paper summarizes current evidence regarding the optimal approach to management of nausea and vomiting in patients undergoing chemotherapy.

An analysis of the antiemetic protection of metoclopramide plus dexamethasone in Chinese patients receiving moderately high emetogenic chemotherapy

This descriptive study aimed to evaluate the antiemetic protection of metoclopramide plus dexamethasone in a sample of 33 Chinese breast cancer patients who were receiving doxorubicin and cyclophosphamide. The antiemetic protection effect was not satisfactory. The results showed that the worst nausea and vomiting was experienced on the third day, with 87.9% of patients reporting nausea and 63.6% experiencing vomiting on that day. In almost one-third of the sample antiemetic medication failed to protect against either acute vomiting or delayed vomiting (i.e. patients continued to experience more than five emetic episodes). Complete protection from acute vomiting was seen in 36.4% of patients, whereas complete protection from delayed vomiting was seen in only one-third of the patients. There was an association between acute nausea/vomiting and delayed nausea/vomiting. Different types of antiemetics need to be offered to Chinese patients receiving chemotherapy (i.e. 5-HT3 receptor antagonists or a combination of antiemetics), but more research should be directed to this area.

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.

Cyclophosphamide, Methotrexate, and Fluorouracil (CMF) Regimen

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column reviews various issues related to the preparation, dispensing, and administration of cancer chemotherapy, both commercially available and investigational.

Use of 5-HT3 receptor antagonists to prevent nausea and emesis caused by chemotherapy for patients with breast carcinoma in community practice settings

BACKGROUND

Although 5-HT3 receptor antagonists are clinically more effective in controlling emesis, particularly that caused by high dose cisplatin, than previously available agents, they appear to be less effective against nausea. This report focuses on the effectiveness of these agents against nausea and emesis in patients receiving two moderately emetogenic combination chemotherapy regimens as treatment for breast carcinoma in community practice settings.

METHODS

Six hundred ninety-two breast carcinoma patients (688 female, 4 male; mean age, 51 years) enrolled in a nonrandomized study completed the Morrow Assessment of Nausea and Emesis (MANE) following 4 consecutive chemotherapy treatments. The frequency, duration, and severity of postchemotherapy nausea (PN) and postchemotherapy emesis (PE) were compared by type of antiemetic (5-HT3 receptor antagonist vs. other) and chemotherapy regimen (cyclophosphamide and doxorubicin with or without 5-fluorouracil [CA/CAF] vs. cyclophosphamide, methrotrexate, and 5-fluorouracil [CMF]).

RESULTS

Within each regimen, the mean duration of PN was significantly longer for patients who received a 5-HT3 receptor antagonist than for those who were not given an antiemetic of that type (CA: 40.3 hours vs. 29.6 hours, P < 0.05; CMF: 37.6 hours vs. 30.2 hours, P < 0.05). There were no significant differences in the frequency or severity of nausea or in the frequency, severity, or duration of emesis by type of antiemetic for patients receiving either regimen.

CONCLUSIONS

The results of this observational study suggest that 5-HT3 receptor antagonists are no more effective than other commonly used medications in controlling postchemotherapy nausea and emesis in women with breast carcinoma who are treated with moderately emetogenic chemotherapy in community practice settings. In fact, they may be associated with significant prolongation of the course of postchemotherapy nausea.

Granisetron compared with prednisolone plus metopimazine as anti-emetic prophylaxis during multiple cycles of moderately emetogenic chemotherapy

This randomized, double-blind, double-dummy parallel study compared the anti-emetic efficacy and tolerability of the serotonin antagonist granisetron with prednisolone plus the dopamine D2 antagonist metopimazine during nine cycles of moderately emetogenic chemotherapy. Chemotherapy naive women with stage I or II breast cancer scheduled to intravenous cyclophosphamide, fluorouracil and methotrexate or cyclophosphamide, epirubicin and fluorouracil every 3 weeks were included. Patients received a single intravenous dose of granisetron 3 mg or a 3-day oral treatment with prednisolone 25 mg once a day plus metopimazine 30 mg four times a day. A total of 223 women were enrolled and 218 patients (97.8%) were evaluable for efficacy. Granisetron (n = 109) was superior to prednisolone plus metopimazine (n = 109) in the prophylaxis of acute nausea and vomiting during the first cycle of chemotherapy (P < 0.001) and prednisolone plus metopimazine was superior on days 2-5 (P = 0.002). Overall, granisetron was superior on days 1-5 (P = 0.009). The median number of cycles completed with granisetron was five (95% confidence interval 4-6) compared with two (95% confidence interval 2-2) for prednisolone plus metopimazine (P = 0.0019). Constipation and rash were reported more frequently with granisetron (P < 0.001 and P = 0.043 respectively) and palpitations more frequently with prednisolone plus metopimazine (P = 0.015). In conclusion, the number of cycles completed with granisetron was significantly higher than the number completed with prednisolone plus metopimazine, but the anti-emetic efficacy of both treatments declined during multiple cycles of moderately emetogenic chemotherapy.

An audit of antiemetic use with CMF chemotherapy

A two-stage retrospective audit of the efficacy of antiemetics used with intravenous cyclophosphamide 600 mg/m2, methotrexate 40 mg/m2 and 5-fluorouracil 600 mg/m2 (CMF) chemotherapy for breast cancer has been performed in a single centre. The first audit stage examined emesis rates for 21 patients using a policy of metoclopramide and dexamethasone initially and reserving 5-HT3 antagonists for failure of this combination. Because of high failure rates, the policy was changed so that granisetron and dexamethasone were used in all patients. The second audit stage examined the effectiveness of this new policy in 28 patients. Nine of 21 patients (43%) in the first audit group changed from metoclopramide and dexamethasone because of nausea or vomiting. Emesis occurred in 15 out of 66 (23%) cycles of CMF when metoclopramide and dexmethasone were used. Only eight of 43 patients had emesis episodes with granisetron and dexamethasone (19%). Emesis occurred with only 16 of 206 CMF cycles with granisetron and dexamethasone (8%). The granisetron and dexamethasone combination is superior to metoclopramide and dexamethasone in the prophylaxis of CMF-induced nausea and vomiting, although it is more expensive. A reduced dose of granisetron, 1 mg rather than 3 mg, may allow similar control of emesis at reduced cost.

Mechanism of action of serotonin selective reuptake inhibitors. Serotonin receptors and pathways mediate therapeutic effects and side effects

Serotonin selective reuptake inhibitors (SSRIs) are currently among the most frequently prescribed therapeutic agents in all of medicine. Their therapeutic actions are diverse, ranging from efficacy in depression to obsessive-compulsive disorder, panic disorder, bulimia and other conditions as well. The plethora of biological substrates, receptors and pathways for serotonin are candidates to mediate not only the therapeutic actions of SSRIs, but also their side effects. Specifically, the immediate actions of SSRIs are mostly side effects, and may be mediated by the initiating actions of SSRIs, namely negative allosteric modulation of the serotonin transporter. A leading hypothesis to explain these immediate side effects is that serotonin is increased at specific serotonin receptor subtypes in discrete regions of the body where the relevant physiologic processes are regulated. Desensitization of post-synaptic receptors in these same discrete brain regions may explain the development of tolerance to these same side effects. The explanation for therapeutic effects characteristic of SSRIs may be found in delayed neurochemical adaptations. A leading hypothesis for this action is desensitization of somatodendritic serotonin 1A autoreceptors in the midbrain raphe. The hypothesis to explain why SSRIs have such diverse therapeutic actions is that somatodendritic 5HT1A autoreceptor desensitization increases serotonin in those critical brain regions and at those key serotonin receptor subtype(s) which may mediate the pathophysiologies of the various disorders. Understanding the topography of serotonin receptor subtypes in discrete anatomical pathways may enhance our understanding of both the therapeutic actions and side effects of these important pharmaceutical agents.

Nausea and vomiting after dexamethasone versus droperidol following outpatient laparoscopy with a propofol-based general anesthetic

BACKGROUND

The purpose of this randomized, double-blinded study was to compare the incidence and severity of postoperative nausea and vomiting (PONV) after dexamethasone versus droperidol following gynecologic laparoscopy, a group at high risk for developing PONV.

METHODS

Ninety-five patients who underwent a propofol-based general anesthetic received either dexamethasone 0.17 mg/kg i.v., or droperidol 0.02 mg/kg i.v., just prior to abdominal incision. Nausea, retching, vomiting, degree of sedation, and discharge times were assessed in the Post Anesthesia Care Unit (PACU), and the Ambulatory Care Unit (ACU). Following hospital discharge (24 h), the patients were contacted by telephone to assess any further complications.

RESULTS

PONV in the PACU (14.6% vs. 14.9%) and ACU (8.3% vs. 14.9%) was as common after dexamethasone as after droperidol. PONV following hospital discharge was, however, less common after dexamethasone than after droperidol (4.2% vs. 17.0%, P = 0.041). Postoperatively, no complications of therapy were detected.

CONCLUSIONS

We conclude that PONV is similar with dexamethasone and droperidol, but dexamethasone may have a longer duration of action in patients undergoing gynecologic laparoscopy.

Modulation of P450-dependent ifosfamide pharmacokinetics: a better understanding of drug activation in vivo

The anti-cancer prodrug ifosfamide (IF) is metabolized by liver P450 enzymes by two alternative pathways. IF is activated to 4-hydroxy IF (4-OH-IF), which ultimately yields the alkylating mustard isophosphoramide, whereas IF N-dechlororethylation inactivates the drug and produces the neurotoxic metabolite chloroacetaldehyde (CA). Both reactions are catalysed by multiple liver P450 enzymes in vitro in isolated rat liver microsomes. The present pharmacokinetic study investigates the potential for modulation of these alternative pathways of IF metabolism in vivo using the adult male Fischer 344 rat model. Rats were treated with IF alone or in conjunction with various P450 inducers and inhibitors in an effort to improve the balance between drug activation and drug inactivation. Plasma concentrations, areas under the curve (AUC) and half-lives were calculated for 4-OH-IF and CA, allowing estimations of the extent of IF activation and deactivation/toxification. Induction of liver P450 2B enzymes by 4-day high-dose phenobarbital (PB) pretreatment significantly decreased the fraction of IF undergoing 4-hydroxylation (AUC(4-OH-IF)/AUC(4-OH-IF)+AUC(CA)), from 37% to 22% of total metabolism (P < 0.05), consistent with in vitro findings that the PB-inducible P450 enzyme 2B1 plays a major role in IF N-dechloroethylation. Pretreatment with the P450 3A inducer dexamethasone proportionally decreased the AUC for both IF metabolites, without any net impact on the fraction of IF undergoing metabolic activation. By contrast, the P450 2B1 inhibitor metyrapone preferentially increased the AUC for the 4-hydroxylation pathway in 3-day low-dose PB-induced rats, thereby increasing the total fraction of IF metabolized via the activation pathway from 36% to 54% (P < 0.05), whereas the P450 inhibitors orphenadrine and troleandomycin had no significant affect on AUC values. These findings demonstrate specific roles for P450 2B and 3A enzymes in catalysing these pathways of IF metabolism in vivo, and demonstrate the potential for modulation of IF's alternative metabolic pathways in a therapeutically useful manner. These studies also highlight several clinically relevant drug interactions that may occur during concomitant administration of IF with drugs and other compounds that modulate hepatic P450 enzyme levels.

Standard treatment of chemotherapy-induced emesis

Major breakthroughs in the treatment of chemotherapy-induced emesis have come through the use of selective 5-HT3 receptor antagonists in combination with corticosteroids. This combination can be considered standard for most but not all commonly used chemotherapeutic agents. Delayed-onset emesis remains a problem, particularly for patients receiving high-dose cisplatin. There is debate over the value of using selective 5-HT3 receptor antagonists beyond the first 24 h. Clinical trials have not settled this uncertainty, although it seems likely that they add only modestly to the effect of corticosteroids. For both the acute and delayed phases, dopamine receptor antagonists may add to the effectiveness of antiemetic therapy. This article outlines a strategy for initial antiemetic therapy and the rationale for the recommendations.

An overview of randomised studies comparing 5-HT3 receptor antagonists to conventional anti-emetics in the prophylaxis of acute chemotherapy-induced vomiting

Ten years after it was demonstrated in the ferret that cisplatin-induced emesis could be blocked by the selective 5-HT3 receptor antagonist MDL 72222, 5-HT3 receptor antagonists have become routine anti-emetic agents for chemotherapy-induced emesis. However, although in association with highly emetogenic, mainly cisplatin-containing regimens, the use of these agents is well justified, the net benefit of 5-HT3 receptor antagonists in association with moderately emetogenic regimens has not been that well clarified. Here, we present an overview of 30 randomised studies comparing 5-HT3 antagonists with the conventional anti-emetics in the prophylaxis of acute vomiting induced by cytotoxic chemotherapy. A meta-analysis showed that 5-HT3 antagonists reduce the risk of acute vomiting in comparison to conventional anti-emetics both with cisplatin treatments (15 trials; odds ratio 0.60; 95% confidence interval 0.51-0.70) and with moderately emetogenic treatments (11 trials; odds ratio 0.47; 95% confidence interval 0.39-0.58). The risk of acute vomiting seems to be further reduced when 5-HT3 antagonists are combined with dexamethasone.

Comparative efficacy of oral and intravenous granisetron for the prevention of acute chemotherapy-induced emesis

Intravenous 5-hydroxytryptamine3 (5-HT3) receptor antagonists are now established antiemetics in the treatment of chemotherapy-induced emesis. For optimal convenience and acceptability, oral therapy is desirable. Retrospective comparisons indicate that oral granisetron may have an efficacy comparable with that of intravenous granisetron. Recent new data are available on the use of granisetron in the prophylaxis of acute emesis in randomized, double-masked trials. After moderately emetogenic chemotherapy, the optimal regimen appears to be 1 mg twice daily, although 2 mg once daily is equally effective. Oral granisetron is significantly superior to oral prochlorperazine. After high-dose cisplatin chemotherapy, oral granisetron is as effective as metoclopramide plus dexamethasone; the addition of dexamethasone further enhances its efficacy. Oral granisetron was well tolerated in all these trials. Headache and constipation were the most common adverse events, as has been reported for other 5-HT3 receptor antagonists. No randomized trials of oral-only tropisetron or dolasetron have yet been published.

Sleep protects against chemotherapy induced emesis

BACKGROUND

We present a clinical trial to assess the hypothesis that chemotherapy related emesis is reduced when drugs delivered while the patient is sleeping.

METHODS

Adults without previous sleep disturbances of vomit inducing conditions who were going to receive their first courses of 100 mg/m2 cisplatin were included. We reduced antiemetic prophylaxis consisting of ondansetron and dexamethasone in subsequent groups of patients.

RESULTS

Twenty-one individuals were needed to decrease the antiemetic prophylaxis to zero. Significant vomiting was observed only when prophylaxis was abolished but not in previous steps employing negligible doses of prophylaxis.

CONCLUSIONS

Our data show that when cisplatin is administered during sleep, the reduction of antiemetic prophylaxis id not followed by the expected increase in emetic toxicity. This antiemetic property of sleep is, as far as we know, unassessed in a controlled way. Further study of the clinical utility of this method in the prevention of chemotherapy related emesis is indicated.

Frequency and clinical implications of delayed nausea and delayed emesis

Studies of the adverse effects of cancer chemotherapy often do not distinguish between delayed and persistent nausea and emesis. Although persistent nausea is simply acute nausea that continues beyond the treatment day, postchemotherapy delayed nausea and delayed vomiting first develop after an initial 24 h free of these symptoms. To access its occurrence in clinical practice, we conducted a structured examination of chemotherapy-induced delayed nausea and emesis in consecutive chemotherapy patients unselected for diagnosis, chemotherapy, or antiemetic usage. Three hundred twenty-seven consecutive with histologically confirmed cancer were followed through three consecutive chemotherapy treatments at three geographically separate institutions. Patient-reported assessments of nausea and emesis were made for each 6-h period over 3 days after chemotherapy. One in three patients developed delayed nausea and one in four incurred delayed emesis. Of >950 chemotherapy treatments assessed, approximately 1 in 6 were characterized by delayed nausea and 1 in 9 by delayed vomiting. We conclude that nausea and emesis that first begin >24 h after chemotherapy are a significant clinical concern. Patients receiving cancer chemotherapy without being admitted to the hospital should be informed of the possible occurrence of delayed nausea and vomiting and be given adequate and appropriate antiemetic medication for use at home for the prevention of these delayed side effects.

Antiemetic efficacy of ondansetron and metoclopramide, both combined with corticosteroid, in malignant lymphoma patients receiving non-cisplatin chemotherapy

The aim of the present study was to compare the antiemetic efficacy of ondansetron (OND) with metoclopramide (MCP), both combined with corticosteroid (CS) in patients with malignant lymphoma. A total of 109 patients with malignant lymphoma receiving their first series of non-cisplatin chemotherapy (CT) (CHOP or MOPP) were divided into prospective, randomized, open and parallel groups and analyzed at two hematological centres at university hospitals in Copenhagen, Denmark. The patients were randomized to receive one of the two following regimens; 1) OND 8 mg/methylprednisolone 80 mg i.v. before CT and OND 8 mg p.o. after 8 h and at bedtime. OND 8 mg tid days 2-3, and 8 mg tid prn days 4-5 and prednisolone 75-100 mg qds days 2-5 and 2) MCP 30 mg/metylprednisolone 80 mg i.v. before CT and MCP 20 mg p.r. after 4 and 8 h respectively. MCP 20 mg p.r. prn days 1-5 and prednisolone 75-100 mg qds days 2-5. In the acute phase OND/CS was superior to MCP/CS in the control of nausea and emesis, resulting in no emesis in 92% of the OND/CS treated group vs. 50% treated with MCP/CS (p < 0.001), and no nausea in 79% (OND/CS) vs. 42% (MCP/CS) (p < 0.001). The ultimate aim - neither nausea nor emesis - was reached in 77% (OND/CS) vs. 35% (MCP/CS) day 1 (p < 0.001). OND/CS is significantly better than MCP/CS in the control of delayed nausea, 81% (OND/CS) vs. 58% (MCP/CS) (p < 0.026). Both the OND/CS and MCP/CS regimens are highly effective in the control of delayed emesis, 94% (OND/CS) vs. 85% (MCP/CS) (p < 0.26). Adverse events were mild and experienced in 31% of the patients. In the OND/CS group 13% had constipation vs. 8% in the MCP/CS group. Nine percent treated with OND/CS had headaches compared to none treated with MCP/CS (p < 0.08). One extrapyramidal reaction was recorded in the MCP/CS group. In malignant lymphoma patients receiving moderately emetogenic CT, the combination of OND and CS was very effective and significantly better than low dose MCP and CS in the control of acute emesis, acute nausea and delayed nausea.

Nausea, vomiting, and retching: the management of the symptom experience

OBJECTIVES

To examine the physiology of nausea, vomiting, and retching (NVR); the impact of NVR on the patient: current measures to control NVR; and selfcare interventions.

DATA SOURCES

Research studies, abstracts, and review articles relating to NVR associated with cancer treatment as well as pharmacological and nonpharmacological interventions.

CONCLUSIONS

Management of the individual symptoms of NVR require expert, ongoing assessment of the patient's symptom experience that extends beyond the clinic or hospital visit. Although a number of pharmacological antiemetic agents are currently available and additional antiemetic drugs are in phase II or II trials, nonpharmacological interventions are essential to achieve effective management.

IMPLICATIONS FOR NURSING PRACTICE

Continual assessment of the individual's symptom experience is imperative. Effective management of the symptom experience depends on the oncology nurses's ability to implement current knowledge of antiemetic, and other drugs; non-pharmacological interventions; and cost-effective and clinically useful patient outcomes.

Oral combination antiemetics in patients with small cell lung cancer receiving cisplatin or cyclophosphamide plus doxorubicin

BACKGROUND

Intravenous antiemetic combinations containing a 5-HT3 receptor antagonist (like metoclopramide, ondansetron, or granisetron) with dexamethasone have become the standard therapy for the treatment of acute chemotherapy-induced vomiting. Intravenous antiemetics, however, can be more costly and take more time to prepare and deliver, and therefore are not preferred for home, outpatient, or office use. The objective of this study was to determine the antiemetic activity and safety of the oral combination antiemetic regimen of metoclopramide, dexamethasone, and diphenhydramine in patients with small cell lung cancer receiving standard outpatient chemotherapy programs.

METHODS

Fifty-two patients receiving initial cisplatin (60 mg/m2) or cyclophosphamide (600-1500 mg/m2) plus doxorubicin (30-45 mg/m2) received an oral regimen of metoclopramide (3 mg/kg x 2 then 2 mg/kg x 2 or 4 doses), dexamethasone (20 mg) and diphenhydramine (50 mg x 2 or 3 doses) (oral MDD), beginning 30 minutes before chemotherapy.

RESULTS

Vomiting was prevented in 15 of 21 (76%) patients (95% confidence interval [CI], 53%-92%) receiving cisplatin and 21 of 31 (71%) individuals (95% CI, 52%-86%) given cyclophosphamide plus doxorubicin. Adverse effects were mild and transient and included sedation, loose stools, akathisia, and hiccoughs.

CONCLUSIONS

The oral MDD antiemetic regimen prevented acute emesis in 73% of the patients entered and was well tolerated in this population of patients with small cell lung cancer.

Beyond specificity: effects of serotonin and serotonergic treatments on psychobiological dysfunction

Serotonin is a ubiquitous neurotransmitter with widespread projections that provide for the involvement of serotonin in the regulation of many biological and psychological functions. A variety of serotonin receptor subtypes exist that mediate overlapping psychobiological functions and that are targets for a new generation of medications. Although these new generation medications appear to possess great biochemical specificity, their actions extend to many psychiatric disorders, reflecting the many interactions of serotonergic subsystems.

Pharmacological characterization of RS 25259-197, a novel and selective 5-HT3 receptor antagonist, in vivo

1. The pharmacological effects in vivo, of RS 25259-197, a selective 5-HT3 receptor antagonist, have been investigated. 2. In anaesthetized rats, RS 25259-197, administered by the intravenous, intraduodenal or transdermal route, dose-dependently inhibited the von Bezold-Jarisch reflex induced by 2-methyl 5-HT (ID50 = 0.04 micrograms kg-1, i.v., 3.2 micrograms kg-1, i.d. and 32.8 micrograms per chamber, respectively). In this regard, when administered intraduodenally, RS 25259-197 was more potent and exhibited a longer duration of action than either ondansetron or granisetron. 3. In conscious ferrets, RS 25259-197, administered intravenously or orally, dose-dependently inhibited emesis induced by cisplatin. The ID50 estimates of RS 25259-197 were 1.1 micrograms kg-1, i.v. and 3.2 micrograms kg-1, p.o. In this respect, RS 25259-197 was more potent than ondansetron and equipotent with granisetron. 4. In conscious dogs, RS 25259-197, administered intravenously or orally, dose-dependently inhibited emesis induced by cisplatin (ID50 = 1.9 micrograms kg-1, i.v. and 8.5 micrograms kg-1, p.o.), dacarbazine (ID50 = 4.1 micrograms kg-1, i.v. and 9.7 micrograms kg-1, p.o.), actinomycin D (ID50 = 4.9 micrograms kg-1, i.v. and 2.5 micrograms kg-1, p.o.) and mechlorethamine (ID50 = 4.4 micrograms kg-1, i.v. and 3.0 micrograms kg-1, p.o.). Against each of the emetogenic agents, RS 25259-197 was very much more potent than ondansetron. When tested at equi-effective intravenous doses against cisplatin-induced emesis in dogs, RS 25259-197 had a longer duration of anti-emetic activity (7 h) than ondansetron (4 h). At doses up to and including 1000 microg kg-1, p.o., neither RS25259-197 nor ondansetron was capable of inhibiting apomorphine-induced emesis.5. At doses up to 1000 microg kg-1, i.v., RS 25259-197 produced no meaningful haemodynamic changes in anaesthetized dogs.6. In summary, RS 25259-197 is a novel, highly potent and orally active 5-HT3 receptor antagonist in vivo. With respect to its anti-emetic activity, RS 25259-197 appears to be a significant improvement over ondansetron in terms of potency and duration of action.

Development of antiemetic therapy in cancer patients

Patients still consider nausea and vomiting to be severe adverse consequences of cancer chemotherapy. The physiology of chemotherapy-induced nausea is generally unknown, but the finding that high doses of metoclopramide induce the antiemetic effect by antagonizing 5-HT3 receptors, has evoked increased interest in serotonin as a possible neurotransmitter. This has led to development of more selective 5-HT3 antagonists, such as ondansetron, granisetron and tropisetron, with improvement of antiemetic therapy, especially in patients receiving cisplatin-based chemotherapy. The efficacy of serotonin antagonists is further optimized by the addition of steroids and the dopamine D2 antagonist metopimazine. Many questions in antiemetic treatment are still unanswered and future trials should focus on patients receiving multiple-day chemotherapy or multiple cycles of chemotherapy and on patients resistant to initial antiemetic therapy.

Antiemetic treatment with oral granisetron in patients receiving moderately emetogenic chemotherapy: a dose-ranging study

The antiemetic efficacy and tolerability of four different oral doses of granisetron (0.25, 0.5, 1, and 2 mg twice daily [BID]) were compared in a randomized, double-blind, parallel-group, multicenter study involving 930 patients with malignant disease receiving moderately emetogenic chemotherapy over a 7- or 14-day period. On the first day of granisetron treatment, a statistically significant association between complete response and dose was seen (P = 0.001), with the maximum response (81.1%) achieved at a dose of 1 mg BID. The 24-hour complete response rate with granisetron 1 mg BID was significantly higher than with 0.25 mg BID (61.1%) or 0.5 mg BID (70.2%) (P < 0.009). The complete response rate for days 0 to 6 was significantly higher with granisetron at 1 mg BID (58.8%) than with 0.25 mg BID (43.7%) or 0.5 mg BID (53.6%) (P < 0.009). No advantage in terms of complete response rate was shown for 2 mg BID over 1 mg BID. Granisetron was well tolerated, and few patients required additional treatment with other antiemetics.

Tropisetron (Navoban) in the prevention of chemotherapy-induced nausea and vomiting--the Nordic experience

An open, noncomparative, Nordic multicenter study was carried out during 1991-1992 to evaluate the 5-HT3 receptor antagonist tropisetron (Navoban) as an antiemetic agent for various types of cancer chemotherapy. A total of 630 patients were recruited from 15 centers in Sweden, Denmark, and Finland. Gynecological cancers (60%), breast cancer (15%), and lung cancer (10%) were the main diagnoses. Prior experience of chemotherapy was documented in 338 patients (54%). In 260 patients (41%), cisplatin was part of the cytostatic regimen. Carboplatin (23%), doxorubicin (27%), and epidoxorubicin (24%) were also frequently included. In all, 23 cytostatic agents were used in various combinations. The mean number of courses studied was 4.6 (range 1-19). Altogether, 394 of 619 evaluable patients (64%) were completely protected from acute nausea and vomiting during the first course of chemotherapy. Delayed nausea and vomiting were completely prevented in 45%-73% (days 2-6) in the complete series. Treatment efficacy remained stable (60%-79%) during ten consecutive courses of chemotherapy. With noncisplatin regimens, complete protection from acute nausea and vomiting was achieved in 72% compared with 52% for cisplatin regimens (P < 0.0001). Patients without prior experience of chemotherapy had higher control rates of acute nausea and vomiting (72%) compared to patients treated before (57%) during the first course, but not later on. There were no differences in delayed nausea and vomiting.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of chemotherapy-induced emesis in the 1990s: impact of the 5-HT3 receptor antagonists

Considerable progress has been made in the development of means to limit nausea and vomiting arising from cancer chemotherapy. A number of key conceptual advances in the last decade have been critically important. these include recognition of the value of combination antiemetic therapy, identification of important patient- and treatment-related factors predictive of emesis, and appreciation of the importance of serotonin (5-HT) in the pathophysiology of emesis and the value of selective antagonists of the type-3 serotonin receptor. Comparative trials of the 5-HT3 receptor antagonists and classic antiemetic agents have helped define optimal antiemetic approaches in a number of settings. A combination of a 5-HT3 antagonist and dexamethasone is the treatment of choice for patients receiving single- and multiple-day cisplatin. The 5-HT3 antagonists are also effective agents with noncisplatin chemotherapy. Clear-cut superiority to classic antiemetics such as dexamethasone has not been consistently demonstrated, however. Results with the 5-HT3 antagonists in cisplatin-induced delayed emesis have been disappointing to date. The results of ongoing prospective trials should define their role more clearly. At present a combination of metoclopramide and dexamethasone is the treatment of choice in this setting. Results of trials comparing 5-HT3 antagonists are beginning to emerge. Available information suggests no clinically relevant differences in antiemetic efficacy between these agents. Many questions regarding the optimal use of the 5-HT3 antagonists and their integration into clinical practice remain unanswered and are the appropriate focus for additional study.

A randomized, multicenter study comparing the efficacy and tolerability of tropisetron, a new 5-HT3 receptor antagonist, with a metoclopramide-containing antiemetic cocktail in the prevention of cisplatin-induced emesis

BACKGROUND

Chemotherapy-induced emesis is one of the most disturbing side effects in cancer therapy. Thus, antiemetic treatment is a mandatory adjunct in emetogenic chemotherapy.

METHODS

Tropisetron (Navoban, Sandoz Pharma Ltd., Basel, Switzerland), a new 5-HT3 receptor antagonist, was compared in a randomized multicenter trial with a high-dose metoclopramide-dexamethasone cocktail for the prevention of nausea and emesis during cisplatin-containing chemotherapy. Two hundred fifty-nine chemotherapy-naive patients were included and followed during two consecutive courses. The main cancer types were gynecologic tumors, followed by lung cancer, head and neck cancer, and bladder cancer. The cisplatin dose usually was in the range of 50-89 mg/m2. The efficacy and quality of life assessments and the safety recordings were done during the first 6 days of both courses of chemotherapy.

RESULTS

Acute vomiting was prevented in 63-64% of patients by both antiemetic regimens. The total rate of control of vomiting increased from 63% on day 1 to 93% on day 6 in the group receiving tropisetron. Acute nausea was prevented in 40% of the patients with tropisetron monotherapy and in 61% of patients receiving the antiemetic cocktail. With regard to delayed nausea, there were no significant differences between the two antiemetic regimens. Mild headache and constipation were more frequently associated with tropisetron, and extra-pyramidal side effects and sedation were associated with the antiemetic cocktail.

CONCLUSIONS

Tropisetron was easier to administer and better tolerated than the cocktail, and it seems to be a highly efficacious and safe new antiemetic drug.

Efficacy and tolerability of tropisetron in comparison with a combination of tropisetron and dexamethasone in the control of nausea and vomiting induced by cisplatin-containing chemotherapy

In a double-blind, randomised, multicentre study, the efficacy and tolerability of tropisetron and a combination of tropisetron and dexamethasone were compared for the control of nausea and vomiting induced by cisplatin in patients previously not entirely protected by tropisetron monotherapy. In all, 160 women with gynaecological cancers were studied during two consecutive courses of cisplatin-containing chemotherapy. During the first course (the screening course), all patients received tropisetron monotherapy [5 mg intravenous (i.v.) on day 1 and 5 mg orally on days 2-6] as antiemetic treatment. During the second course (the test course), tropisetron was compared with a combination of tropisetron and dexamethasone (20 mg i.v. on day 1 and 4.5 mg twice daily on days 2-6). This part of the study was double-blind, randomised and placebo-controlled. Candidates for randomisation were patients with partial control of nausea (< 12 h of nausea) or partial control of vomiting (1-4 episodes of vomiting) during the screening course. Patients with complete control of nausea and vomiting in the screening course continued with tropisetron monotherapy; patients with treatment failure received open rescue treatment in course 2. Total control of acute nausea was achieved in 37% of the tropisetron + placebo group and in 75% of the tropisetron + dexamethasone group (P = 0.001). Significantly more patients on tropisetron-dexamethasone than on tropisetron-placebo were also free of delayed nausea. Acute vomiting was prevented in 40% of the patients in the placebo group and in 75% in the dexamethasone group (P = 0.001). Delayed vomiting was also significantly less frequent in dexamethasone-treated patients than in placebo-treated patients. Tropisetron was well tolerated both as monotherapy and in combination with dexamethasone. The most frequent adverse events were headache (34%), constipation (12.5%) and fatigue (12.5%). Adding high doses of a corticosteroid did not induce further adverse events or disregulate concurrent diseases.

An open, randomized study to compare the efficacy and tolerability of tropisetron with that of a metoclopramide-containing antiemetic cocktail in the prevention of cisplatin-induced emesis

In a prospective randomized study comprising 66 women treated for gynecologic malignancies with cisplatin-containing chemotherapy, the new 5-hydroxytryptamine3 (5-HT3) receptor antagonist tropisetron (Navoban, Sandoz Pharma Ltd.) was compared with a metoclopramide cocktail for the prevention of nausea and emesis. All patients were chemotherapy-naive. Two consecutive courses (including the 1st week posttherapy) were studied. The cisplatin doses were in the range of 50-75 mg/m2, and the regimens also contained doxorubicin, teniposide, etoposide, vincristine, and bleomycin. Complete protection against nausea during the first 24 h (course 1) was achieved in 76% of the tropisetron group and in 85% of the metoclopramide group. Emesis was prevented in 82% of the patients in both groups. During the whole 6-day period, full emetic protection was achieved in 30% and 18% of the patients in the two groups. On days 3-4 of course 1, tropisetron was superior to metoclopramide. The overall tolerability of the tropisetron was excellent or good in 94% of patients, a rate higher than that observed for the metoclopramide regimen (75%). The most common side effects for the latter regimen were sedation (82%) and extrapyramidal reactions (21%). The only significant adverse event recorded after treatment with tropisetron was headache of slight or moderate grade.

Ondansetron. An update of its therapeutic use in chemotherapy-induced and postoperative nausea and vomiting

Ondansetron is a selective 5-HT3 receptor antagonist which has previously been reported in the Journal to be a promising new agent for use as prophylaxis against nausea and vomiting caused by chemotherapy and radiotherapy. Since the publication of this original review, further studies have been published that show ondansetron to be an effective antiemetic agent in patients receiving chemotherapy and radiotherapy. Several studies have shown ondansetron to be a more effective antiemetic agent than high-dose metoclopramide in patients with emesis induced by high- and low-dose cisplatin treatment, and noncisplatin chemotherapy-induced emesis. The drug as mono-therapy does not appear to offer any advantage over alternative therapies against delayed high-dose cisplatin-induced nausea and vomiting; however, extremely limited data suggest that ondansetron plus dexamethasone may be useful in this indication. Trials have shown combination therapy with ondansetron and dexamethasone to be significantly more effective than both ondansetron monotherapy and a standard antiemetic regimen comprising metoclopramide, dexamethasone and diphenhydramine against acute high-dose cisplatin-induced emesis. Results from a number of small scale trials suggest that ondansetron may be an effective treatment for chemotherapy-induced emesis refractory to conventional antiemetic therapy. Ondansetron also appears to be more effective against refractory emesis induced by noncisplatin chemotherapy than that induced by cisplatin chemotherapy. Several trials have shown ondansetron to be more effective than placebo as prophylaxis against postoperative nausea and vomiting; a further trial has shown single-dose ondansetron to be significantly more effective than single-dose droperidol or metoclopramide in this indication. In addition, several trials have shown ondansetron to be more effective than placebo as treatment for nausea and vomiting that has commenced postoperatively. The overall incidence of adverse events in ondansetron recipients during chemotherapy-induced emesis studies was 36%. Headache and constipation are the most common adverse events during ondansetron therapy. Thus, recent data affirms the efficacy of ondansetron in the treatment of acute chemotherapy-induced nausea and vomiting and shows it to be especially efficacious when combined with dexamethasone. It appears that the drug will also have a substantial role in the prophylaxis and treatment of postoperative nausea and vomiting.