Pharmacology of antiemetics

Ameliorative effects of tropisetron on liver injury in streptozotocin-induced diabetic rats

This study aimed to evaluate the effect of tropisetron on liver injury induced by diabetes. Thirty-five male Wistar rats were assigned to five groups (n = 7): control (C), tropisetron (T), diabetic (D), diabetic + tropisetron (D + T) and diabetic + glibenclamide (D + G). Diabetic rats were treated with tropisetron (3 mg/kg body weight/day) or glibenclamide (1 mg/kg/day) for two weeks. Liver from diabetic rats exhibited a significant increase in alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cholesterol (Chol), triglycerides (TG), low-density lipoprotein (LDL), and atherogenic index, and a significant decrease in liver glycogen, serum albumin and high-density lipoprotein. Treatment with tropisetron significantly abrogated diabetes-induced perturbation in these parameters. These effects were equipotent with glibenclamide, suggesting that tropisetron treatment is associated with a hepatoprotective effect against diabetic injury. Therefore, the results of this study manifested the significance of using tropisetron as a promising remedial agent to improve diabetic complications.

Fifty-eight-year-old female with abdominal migraine: A rare cause of episodic gastrointestinal disturbance in adults

Abdominal migraine (AM) is a predominantly pediatric condition characterized by erratic episodes of abdominal pain, nausea, and vomiting with spontaneous periodic relief. It should be considered as a differential diagnosis in symptomatic adults.

Comparison of the Effects of Metoclopramide and Ondansetron on Emergency Service Observation Times in Acute Gastroenteritis-Related Nausea and Vomiting Cases

Objectives:

The aim of the present study was to compare the effect of metoclopramide and ondansetron treatments on the emergency department observation time in acute gastroenteritis-related nausea and vomiting (NV).

Methods:

The study was conducted retrospectively on 297 patients diagnosed with acute gastroenteritis in a training and research hospital’s emergency service observation unit within 6 months. Patients with gastroenteritis who were diagnosed with NV were divided into two groups according to the treatment they received in the observation unit. Patients who received 4 mg ondansetron slow infusion therapy were classified as Group 1, and patients who received 10 mg metoclopramide slow infusion therapy were classified as Group 2.

Results:

The average age of the patients was 39.57±18.75 years. Of the 297 participants, 56.6% (168) were female. Among them, 51.5% (153) received ondansetron (Group 1), and 48.5% (144) received metoclopramide (Group 2). 6.9% weakness–numbness and 4.9% akathisia were detected due to metoclopramide use. There were no adverse effects related to ondansetron use. The duration of observation ranged from 19 to 75 min in Group 1 and from 42 to 122 min in Group 2. Nineteen (13.2%) patients in Group 2 and 5 (3.3%) patients in Group 1 revisited the emergency department within 24 h due to ongoing complaints.

Conclusion:

In conclusion, side effects of weakness and akathisia due to metoclopramide use were observed. However, no side effects were observed due to ondansetron use. Additionally, the use of ondansetron showed a shorter observation time and less recurrent admission to the emergency department. Therefore, ondansetron is a more effective drug in the treatment of NV associated with acute gastroenteritis.

Modulatory effect of tropisetron in the liver of streptozotocin-induced diabetes in rats: biochemical and histological evidence

Objectives There is an association between diabetes and liver disorders. Oxidative stress plays a crucial role in the pathology of hepatic abnormalities in diabetes. In this study, the effect of Tropisetron on the oxidative damage and histological alterations in the liver of type 1 diabetes mellitus (DM) were evaluated. Methods Thiry-five male Wistar rats were randomly divided into five experimental groups (n = 7): control (C), tropisetron (T), diabetes (D), diabetes + tropisetron (D + T) and diabetes + glibenclamide (D + G). A single injection of streptozotocin (STZ, 50 mg/kg; i.p) was used to induce diabetes. Tropisetron (3 mg/kg; i.p), as a 5-HT3 receptor antagonist and glibenclamide (1 mg/kg; i.p), as a positive control were given once daily for 2 weeks. Finally, animals were euthanized and liver samples were obtained for histopathological examination and biochemical measurements including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx) levels. Results There is a significant increase in MDA (p < 0.001) level and a significant decrease (p < 0.001) in SOD and GPx contents in diabetic animals. Tropisetron attenuated MDA levels (p < 0.001) and enhanced SOD (p < 0.05) and GPx (p < 0.01) activities accompanied by histopathological improvement in the diabetes liver. Similar results were achieved in the rats treated with the standard drug, namely: glibenclamide. Conclusions Our findings indicate that tropisetron mitigates liver damage in the diabetes rats in part by attenuation of oxidative stress.

Tropisetron inhibits high glucose-induced calcineurin/NFAT hypertrophic pathway in H9c2 myocardial cells

OBJECTIVES

Cardiomyocyte hypertrophy is an important structural feature of diabetic cardiomyopathy. Calcineurin/nuclear factor of activated T-cell (NFAT) pathway plays a central role in the pathogenesis of cardiac hypertrophy. The purpose of this study was to investigate the effects of tropisetron, a novel calcineurin inhibitor, on high glucose (HG)-induced cardiomyocyte hypertrophy and its underlying mechanism.

METHODS

H9c2 myocardial cells were treated with tropisetron or cyclosporine A 1 h before exposure to HG for 48 h.

KEY FINDINGS

Exposure to HG resulted in enhanced cell size, protein content and atrial natriuretic peptide (ANP) protein expression. HG significantly increased Ca(2+) level, calcineurin expression and nuclear translocation of NFATc4. Both tropisetron and cyclosporine A markedly prevented the hypertrophic characteristic features, calcineurin overexpression and nuclear localization of NFATc4 while intracellular Ca(2+) was not affected.

CONCLUSION

Our results showed that tropisetron may have protective effects against HG-induced cardiomyocyte hypertrophy. The mechanism responsible for this beneficial effect seems to be, at least in part, blockade of calcineurin/NFAT signalling pathway.

Tropisetron ameliorates early diabetic nephropathy in streptozotocin-induced diabetic rats

It has been well established that oxidative stress and inflammation are involved in the pathogenesis of diabetic nephropathy. It has been shown that tropisetron exerts anti-inflammatory and immunomodulatory properties. The current study was designed to investigate protective effects of tropisetron on early diabetic nephropathy in streptozotocin-induced diabetic rats. Rats were divided into six groups: (i) untreated diabetic (streptozotocin group); (ii) untreated control; (iii) diabetic rats treated with tropisetron (3 mg/kg); (iv) normal rats treated with tropisetron (3 mg/kg); (v) diabetic rats treated with granisetron (3 mg/kg); and (vi) normal rats treated with granisetron (3 mg/kg); rats began receiving treatment at the time of diabetes induction for 2 weeks. At the termination of the experiments, bodyweight, kidney index, urinary albumin excretion, and glomerular filtration rate were measured. The levels of oxidative stress markers and tumour necrosis factor-α were also determined. Streptozotocin-treated animals showed significant loss of bodyweight and renal enlargement and dysfunction. Diabetic rats also exhibited an increase in malondialdehyde along with a significant decrease in glutathione, superoxide dismutase activity, and catalase activity. Furthermore, the diabetic animals demonstrated a significant rise in renal cortical, urinary tumour necrosis factor-α, and urinary albumin excretion. Both granisetron and tropisetron decreased blood glucose in diabetic animals, but this decrease was not significant for granisetron. Treatment with tropisetron, but not granisetron, prevented increases in oxidative stress and tumour necrosis factor-α, decreased urinary cytokine excretion and albuminuria, and improved renal morphological damage. In conclusion, the present study suggests that tropisetron may be a protective agent in early diabetic nephropathy, and its action is mediated, at least in part, by anti-oxidative and anti-inflammatory mechanisms that appear to be independent of the 5-HT3 receptor.

Postoperative nausea and vomiting

Postoperative nausea and vomiting (PONV) is a long-standing issue, not a new concept in anesthesiology. Despite many studies over the last several decades, PONV remains a significant problem due to its complex mechanism. This review presents a summary of the mechanism underlying the pathogenesis of PONV, focusing on preventive treatment, particularly the use of new drugs. In addition, we discuss the latest meta-analysis results regarding correct clinical use of classic drugs. I also summarize the latest trends of postdischarge nausea and vomiting and the pharmacogenetics, which is attracting a great deal of attention from other medical fields in PONV-related studies. Finally, we discuss the drawbacks of existing studies on PONV and suggest a focus for future investigations.

A prospective, randomized, double-blind, multicenter trial to evaluate the therapeutic efficacy and safety of palonosetron in the treatment of postoperative nausea and vomiting over a 72-h period

PURPOSE

We performed a multicenter, randomized, double-blind trial to assess the efficacy and safety of a single, fixed, intravenous dose of palonosetron (0.075 mg) in the treatment of established postoperative nausea and vomiting (PONV).

METHODS

Three hundred and eighty-four patients who had at least one risk factors of PONV and underwent surgery under general anesthesia were screened. Those who developed PONV were randomized to receive either 0.075 mg intravenous palonosetron or a placebo. The incidence of nausea and vomiting, severity of nausea, requirements for rescue anti-emetics, and adverse effects at 2, 24, and 72 h after drug administration were evaluated. Complete response (CR) and complete control (CC) rate were compared for 24 and 72 h.

RESULTS

Among the 384 patients, 152 (39.6 %) developed PONV and were randomized to either the palonosetron (n = 75) or placebo (n = 77) group. The number of patients with CR at 24 and 72 h was higher in the palonosetron group than the placebo group [0-24 h: n = 49 (68.1 %) vs. n = 30 (40.5 %), p < 0.001; 0-72 h: n = 47 (65.3 %) vs. n = 28 (37.8 %), p < 0.001]. The incidence of PONV at 2, 24, and 72 h periods was lower in the palonosetron group than the placebo group (29.2, 45.8, and 50.0 % in the palonosetron group vs. 50.0, 62.2, and 66.2 % in the placebo group, p = 0.010, 0.048, 0.047, respectively). The incidence of adverse events was not different between the groups.

CONCLUSION

A single 0.075 mg IV dose of palonosetron effectively increased the CR rates at 24 and 72 h in these moderate-risk patients with established PONV.

The cellular mechanisms of the antiemetic action of dexamethasone and related glucocorticoids against vomiting

Glucocorticoids, used primarily as anti-allergic and anti-inflammatory drugs, are also effective, alone or combined with other antiemetics, for preventing nausea and vomiting. Dexamethasone, one of the glucocorticoids, has been suggested as a first-line drug for preventing low-level emetogenic chemotherapy- and radiotherapy-induced nausea and vomiting, and in patients with only one or two risks for postoperative nausea and vomiting (PONV). Dexamethasone combined with 5-HT3 or tachykinin NK1 antagonists is also suggested for higher-level emetogenic chemotherapy and radiotherapy and for patients at high risk for PONV. Glucocorticoids may act via the following mechanisms: (1) anti-inflammatory effect; (2) direct central action at the solitary tract nucleus, (3) interaction with the neurotransmitter serotonin, and receptor proteins tachykinin NK1 and NK2, alpha-adrenaline, etc.; (4) maintaining the normal physiological functions of organs and systems; (5) regulation of the hypothalamic-pituitary-adrenal axis; and (6) reducing pain and the concomitant use of opioids, which in turn reduces opioid-related nausea and vomiting.

The management of postoperative nausea and vomiting: current thoughts and protocols

The postoperative course of surgical patients can have a tremendous impact on the surgical outcome and on patient satisfaction. One of the most significant issues is postoperative nausea and vomiting (PONV) which, despite being a common side effect of general anesthesia, has received little attention in the plastic surgery literature. The incidence and potential consequences of PONV are frequently underestimated and consequently the need for prophylaxis is often overlooked. There are significant consequences to this seemingly minor morbidity that extend beyond patient discomfort and dissatisfaction. In addition to being considered a significant undesirable outcome by patients, severe cases of PONV may result in postoperative complications and unplanned hospital admissions. In this article we overview the mechanism, pathophysiology, and risk factors for PONV and provide a comprehensive algorithmic approach to its management.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Emergency department use of oral ondansetron for acute gastroenteritis-related vomiting in infants and children

Acute gastroenteritis is one of the most common causes of emergency room visits. Although it is usually a self-limited infection, vomiting related to this illness can cause various degrees of dehydration, leading to intravenous insertion, electrolyte abnormalities and/or hospital admission. Ondansetron is a highly potent antiemetic drug that is effective in preventing chemotherapy-and radiation-induced nausea and vomiting with a very low risk of adverse effects. Recently, ondansetron has been used to control vomiting related to acute gastroenteritis. The present article examines evidence for the use of oral ondansetron for acute gastroenteritis-related vomiting in infants and children, and provides a recommendation for treatment based on the evidence-based review.

Anti-emetic effect of ondansetron and palonosetron in thyroidectomy: a prospective, randomized, double-blind study

BACKGROUND

Palonosetron is a new potent 5-hydroxytryptamine 3 antagonist. Although this drug is thought to be more effective in patients receiving opioid-based patient-controlled analgesia (PCA), clinical data are lacking. This study compared the effects of i.v. ondansetron and palonosetron administered at the end of surgery in preventing postoperative nausea and vomiting (PONV) in high-risk patients receiving i.v. PCA after thyroidectomy.

METHODS

A total of 100 female non-smoking subjects were randomly assigned into a palonosetron group or an ondansetron group. Ondansetron was given as an 8 mg bolus and 16 mg was added to the i.v. PCA mixture. In the palonosetron group, 0.075 mg was injected as a bolus only. Fentanyl-based PCA was provided for 24 h after operation. The incidence of nausea and vomiting, severity of nausea, requirement for rescue anti-emetics, and adverse effects were evaluated during 0-2 and 2-24 h.

RESULTS

The incidence of PONV during the 24 h postoperative period was lower in the palonosetron group than in the ondansetron group (42% vs 62%, P=0.045). No differences were observed between the groups during the first 2 h. However, the incidence of nausea and vomiting and nausea severity were significantly lower in the palonosetron group than in the ondansetron group during 2-24 h. The only difference in the use of rescue anti-emetics was at 2-24 h (10% with palonosetron compared with 28% with ondansetron, P=0.02).

CONCLUSIONS

Palonosetron is more effective than ondansetron for high-risk patients receiving fentanyl-based PCA after thyroidectomy, especially 2-24 h after surgery.

Pharmacologic management of postoperative nausea and vomiting

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Therapeutics of 5-HT3 receptor antagonists: current uses and future directions

The 5-Hydroxytryptamine3 (5-HT3) receptor is a member of the cys-loop family of ligand gated ion channels, of which the nicotinic acetylcholine receptor is the prototype. All other 5-HT receptors identified to date are metabotropic receptors. The 5-HT3 receptor is present in the central and peripheral nervous systems, as well as a number of non-nervous tissues. As an ion channel that is permeable to the cations, Na(+), K(+), and Ca(2+), the 5-HT3 receptor mediates fast depolarizing responses in pre- and post-synaptic neurons. As such, 5-HT3 receptor antagonists that are used clinically block afferent and efferent synaptic transmission. The most well established physiological roles of the 5-HT3 receptor are to coordinate emesis and regulate gastrointestinal motility. Currently marketed 5-HT3 receptor antagonists are indicated for the treatment of chemotherapy, radiation, and anesthesia-induced nausea and vomiting, as well as irritable bowel syndrome. Other therapeutic uses that have been explored include pain and drug addiction. The 5-HT3 receptor is one of a number of receptors that play a role in mediating nausea and vomiting, and as such, 5-HT3 receptor antagonists demonstrate the greatest anti-emetic efficacy when administered in combination with other drug classes.

In vivo assessment of antiemetic drugs and mechanism of lycorine-induced nausea and emesis

Lycorine is the main alkaloid of many Amaryllidaceae and known to cause poisoning with still unknown mechanisms. Longer lasting toxicological core symptoms of nausea and emesis may become a burden for human and animal patients and may result in substantial loss of water and electrolytes. To optimise the only empirical symptomatic antiemetic drug treatment at present, it is important to elucidate the causative involved targets of lycorine-induced emesis. Therefore, in the current study, we have tested the actions of a various antiemetic drugs with selective receptor affinities on lycorine-induced nausea and emesis in vivo in dogs. Beagle dogs were pre-treated in a saline vehicle-controlled crossover and random design with diphenhydramine, maropitant, metoclopramide, ondansetron or scopolamine prior lycorine administration (2 mg/kg subcutaneously). In vivo effects were assessed by a scoring system for nausea and emesis as well as by the number and lag time of emetic events for at least 3 h. Moreover, plasma pharmacokinetic analysis was carried out for ondansetron before and after lycorine injection. The data show that histaminergic (H₁), muscarinic and dopaminergic (D₂) receptors are presumably not involved in lycorine-induced emetic effects. While ondansetron significantly reduced the number of emetic events, lycorine-induced emesis was completely blocked by maropitant. Only ondansetron also significantly decreased the level of nausea and was able to prolong the lag time until onset of emesis suggesting a preferential participation of 5-HT₃ receptors in lycorine-induced nausea. Thus, it is the first in vivo report evidencing that predominantly neurokinin-1 (NK₁) and to a lesser extent 5-hydroxytryptamine 3 (5-HT₃) receptors are involved in lycorine-induced emesis facilitating a target-oriented therapy.

General anesthesia and altered states of arousal: a systems neuroscience analysis

Placing a patient in a state of general anesthesia is crucial for safely and humanely performing most surgical and many nonsurgical procedures. How anesthetic drugs create the state of general anesthesia is considered a major mystery of modern medicine. Unconsciousness, induced by altered arousal and/or cognition, is perhaps the most fascinating behavioral state of general anesthesia. We perform a systems neuroscience analysis of the altered arousal states induced by five classes of intravenous anesthetics by relating their behavioral and physiological features to the molecular targets and neural circuits at which these drugs are purported to act. The altered states of arousal are sedation-unconsciousness, sedation-analgesia, dissociative anesthesia, pharmacologic non-REM sleep, and neuroleptic anesthesia. Each altered arousal state results from the anesthetic drugs acting at multiple targets in the central nervous system. Our analysis shows that general anesthesia is less mysterious than currently believed.

Acute gastroenteritis: from guidelines to real life

Acute gastroenteritis is a very common disease. It causes significant mortality in developing countries and significant economic burden to developed countries. Viruses are responsible for approximately 70% of episodes of acute gastroenteritis in children and rotavirus is one of the best studied of these viruses. Oral rehydration therapy is as effective as intravenous therapy in treating mild to moderate dehydration in acute gastroenteritis and is strongly recommended as the first line therapy. However, the oral rehydration solution is described as an underused simple solution. Vomiting is one of the main reasons to explain the underuse of oral rehydration therapy. Antiemetics are not routinely recommended in treating acute gastroenteritis, though they are still commonly prescribed. Ondansetron is one of the best studied antiemetics and its role in enhancing the compliance of oral rehydration therapy and decreasing the rate of hospitalization has been proved recently. The guidelines regarding the recommendation on antiemetics have been changed according to the evidence of these recent studies.

Update on the management of postoperative nausea and vomiting and postdischarge nausea and vomiting in ambulatory surgery

Postoperative nausea and vomiting (PONV) continues to be one of the most common complaints following surgery, occurring in more than 30% of surgeries, or as high as 70% to 80% in certain high-risk populations without prophylaxis. The 5-hydroxytryptamine type 3 (5-HT(3)) receptor antagonists continue to be the mainstay of antiemetic therapy, but newer approaches, such as neurokinin-1 antagonists, a longer-acting serotonin receptor antagonist, multimodal management, and novel techniques for managing high-risk patients are gaining prominence. The related problem of postdischarge nausea and vomiting (PDNV) has received increasing attention from health care providers. The issues of PONV and PDNV are especially significant in the context of ambulatory surgeries, which comprise more than 60% of the combined 56.4 million ambulatory and inpatient surgery visits in the United States. Because of the relatively brief period that ambulatory patients spend in health care facilities, it is particularly important to prevent and treat PONV and PDNV swiftly and effectively.

Anti-inflammatory effects of 5-HT receptor antagonist, tropisetron on experimental colitis in rats

BACKGROUND

There is a pressing need for research that will lead to the development of new therapeutic approaches for treating inflammatory bowel disease (IBD). The aim of this study was to investigate the effects of tropisetron, a 5-Hydroxytryptamine (5-HT)-3 receptor antagonist with anti-inflammatory properties in a model of experimental colitis in rat.

MATERIALS AND METHODS

Acetic acid model of colitis in rats was used. Colitis was induced by intracolonal instillation of 4% (v/v) acetic acid. One hour after induction of colitis, intraperitoneal (IP) or intrarectal (IR) tropisetron (2 mg kg(-1), either route) or dexamethasone (1 mg kg(-1), either route) was administered. The severity of colitis was assessed 24 h later using macroscopic and microscopic changes of damaged colon, measurement of inflammatory cytokines interleukin-1beta, interleukin-6 and tumour necrosis factor-alpha levels and oxidative stress markers myeloperoxidase (MPO) and malondialdehyde (MDA) in colonic tissues.

RESULTS

Tropisetron decreased colonic macroscopic and microscopic damage scores. This was associated with significant reduction in both neutrophil infiltration indicated by decreased colonic MPO activity and lipid peroxidation measured by MDA content, as well as a decreased colonic inflammatory cytokines. IR tropisetron decreased colonic damage that was associated with decreased neutrophil infiltration, lipid peroxidation and colonic inflammatory cytokines. Beneficial effects of tropisetron were lower than those of dexamethasone. No significant differences were observed between IP and IR administration with the exception of MDA level more diminished by IP tropisetron and dexamethasone.

CONCLUSIONS

Tropisetron exert beneficial effects in experimental rat colitis and therefore might be useful in the treatment of IBD.

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

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

Time course of effect of piperazine citrate on the electrocardiogram of the rat

The acute electrocardiographic (ECG) changes induced by 4 different doses of piperazine citrate (15, 30, 60, and 100 mg/kg) were determined in the anesthetized Wistar rat. A dose-dependent reduction in heart rate occurred, from 9.03%+/-2.97% at a dose of 15 mg/kg to 30.84%+/-3.4% at 100 mg/kg body weight. The P-R interval showed dose-dependent increases over values at equilibration, increasing from 10.69% +/-2.82% at 15 mg/kg to 24.79%+/-2.71% at 100 mg/kg. Similarly, the Q-T interval corrected for heart rate (Q-Tc) showed dose-dependent increases, from 4.7%+/-1.89% at 15 mg/kg to 29.40%+/-6.09% at 100 mg/kg. In comparison with values for controls, all these changes except those associated with 15 mg/kg were statistically significant (P<0.05). Piperazine did not have any effect on the duration of the QRS complex except at 100 mg/kg, the dose at which marked widening occurred in 3 of the 7 rats. Dysrhythmic phenomena, including various forms of atrioventricular (AV) block, sometimes with idioventricular rhythms, were also evident in the 3 rats. Severe bradycardia from sino-atrial depression and AV block was also observed. At this concentration (100 mg/kg), 3 of 7 rats died of complete heart block within 30 minutes of drug administration. It was concluded that piperazine citrate at the suggested antiarrhythmic dose (15 mg/kg intravenously) and even at four times that dose was associated with no ECG abnormality suggestive of cardiotoxicity. However, at 100 mg/kg very serious ECG aberrations can occur, with severe heart block and death.

Acute gastroenteritis in children: role of anti-emetic medication for gastroenteritis-related vomiting

Acute gastroenteritis is associated with significant morbidity in developed countries and each year is the cause of death of several million children in developing countries. Acute gastroenteritis is usually self-limiting. Oral rehydration therapy (ORT) is effective and successful in the majority of patients. Vomiting is common at the outset of viral gastroenteritis and can limit the effectiveness of ORT. Treatment with newer anti-emetic medications has been reported to facilitate ORT and to minimize the risk of dehydration and the need for intravenous hydration and hospitalization. The role of anti-emetic medications in the treatment of gastroenteritis-related vomiting is not clear. Some physicians agree with the use of anti-emetic medications because vomiting is unpleasant and distressing for the child and parents alike, and because vomiting can increase the likelihood of dehydration, electrolyte imbalance, and the need for intravenous hydration or hospitalization. Several surveys have shown that anti-emetic medications are commonly prescribed in the treatment of pediatric gastroenteritis and that adverse events are uncommon. Efficacy studies of the newer anti-emetic medications are now available and reveal that some are effective and help facilitate ORT. Other physicians disagree with the use of anti-emetic medications because acute gastroenteritis is a self-limiting condition, vomiting might help rid the body of toxic substances, there was previously a relative lack of published evidence of clinical benefit, and there are potential adverse events associated with the use of an anti-emetic medication. Anti-emetic medications that are currently available include ondansetron, granisetron, tropisetron, dolasetron, ramosetron, promethazine, dimenhydrinate, metoclopramide, domperidone, droperidol, prochlorperazine, and trimethobenzamide. Randomized, placebo-controlled trials suggest that ondansetron is efficacious and superior to other anti-emetic medications in the treatment of gastroenteritis-related vomiting. A recent double-blind clinical trial showed that a single oral dose of ondansetron reduces gastroenteritis-related vomiting and facilitates ORT without significant adverse events. Ondansetron shows promise as a first-line anti-emetic, and judicious use of this agent might increase the success of ORT, minimize the need for intravenous therapy and hospitalization, and reduce healthcare costs. Ondansetron should be considered in situations where vomiting hinders ORT, but a larger randomized, placebo-controlled trial is necessary before the medication can be routinely recommended for the treatment of gastroenteritis-related vomiting in children.