A comparison of two cohort studies evaluating the safety of cisapride: Prescription-Event Monitoring and a large phase IV study

Tegaserod: What's Old Is New Again

Irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) are common gastrointestinal disorders imposing considerable impact on the quality of life and well-being of affected individuals. A paucity of evidence-based treatment options exist for CIC and IBS-C sufferers. Tegaserod, a 5-HT₄ agonist, has a substantial body of preclinical and clinical study evidence to support its beneficial role in modulating sensorimotor function of the luminal gastrointestinal tract. Tegaserod was first approved for use by the U.S. Food and Drug Administration for the management of IBS-C and CIC in 2002 and 2004, respectively. Tegaserod enjoyed a successful uptake in the management of these disorders during its first several years of availability in the United States, but was later withdrawn from the market in 2007 over concerns related to adverse cardiovascular events. Since then, additional safety data has been generated, and following a resubmission and review by the Food and Drug Administration, in April 2019, tegaserod was once again approved for use in IBS-C under a more restricted labeling, confining use to women under 65 years of age without heart disease or additional cardiovascular risk factors. This review summarizes the regulatory journey of tegaserod and details the existing pharmacokinetic, physiologic, clinical, and safety data of tegaserod generated over the last 2 decades. The discussion also examines the future of tegaserod in the treatment of these constipation disorders, as well as its potential role in other related disorders of brain-gut interaction.

Cardiovascular safety of prokinetic agents: A focus on drug-induced arrhythmias

BACKGROUND

Gastrointestinal sensorimotor dysfunction underlies a wide range of esophageal, gastric, and intestinal motility and functional disorders that collectively constitute nearly half of all referrals to gastroenterologists. As a result, substantial effort has been dedicated toward the development of prokinetic agents intended to augment or restore normal gastrointestinal motility. However, the use of several clinically efficacious gastroprokinetic agents, such as cisapride, domperidone, erythromycin, and tegaserod, is associated with unfavorable cardiovascular safety profiles, leading to restrictions in their use.

PURPOSE

The purpose of this review is to detail the cellular and molecular mechanisms that lead commonly to drug-induced cardiac arrhythmias, specifically drug-induced long QT syndrome, torsades de pointes, and ventricular fibrillation, to examine the cardiovascular safety profiles of several classes of prokinetic agents currently in clinical use, and to explore potential strategies by which the risk of drug-induced cardiac arrhythmia associated with prokinetic agents and other QT interval prolonging medications can be mitigated successfully.

Pharmacologic Treatment for Pediatric Gastroparesis: A Review of the Literature

There have been a number of agents that have been tried for treatment of gastroparesis over the past 3 decades, with varying levels of success. Guidelines exist for the management of gastroparesis in adults; however, even though the cause of gastroparesis in children is similar to that in adults, no guidelines exist for treating pediatric gastroparesis as studies on the topic are limited. With what little information we have on pediatric gastroparesis, medications used in children's studies do not seem to demonstrate the same results as in adult patients with gastroparesis; thus, future studies of whether certain medications are effective for treating pediatric gastroparesis and at what dose still need to be conducted. Pharmacological treatment options for pediatric gastroparesis do not show a clear correlation of resolving or even maintaining gastroparesis-associated symptoms or disease state. This article reviews the available studies of drugs that have shown some efficacy, with an emphasis on pediatric studies.

Systematic review: cardiovascular safety profile of 5-HT(4) agonists developed for gastrointestinal disorders

BACKGROUND

The nonselective 5-HT(4) receptor agonists, cisapride and tegaserod have been associated with cardiovascular adverse events (AEs).

AIM

To perform a systematic review of the safety profile, particularly cardiovascular, of 5-HT(4) agonists developed for gastrointestinal disorders, and a nonsystematic summary of their pharmacology and clinical efficacy.

METHODS

Articles reporting data on cisapride, clebopride, prucalopride, mosapride, renzapride, tegaserod, TD-5108 (velusetrag) and ATI-7505 (naronapride) were identified through a systematic search of the Cochrane Library, Medline, Embase and Toxfile. Abstracts from UEGW 2006-2008 and DDW 2008-2010 were searched for these drug names, and pharmaceutical companies approached to provide unpublished data.

RESULTS

Retrieved articles on pharmacokinetics, human pharmacodynamics and clinical data with these 5-HT(4) agonists, are reviewed and summarised nonsystematically. Articles relating to cardiac safety and tolerability of these agents, including any relevant case reports, are reported systematically. Two nonselective 5-HT(4) agonists had reports of cardiovascular AEs: cisapride (QT prolongation) and tegaserod (ischaemia). Interactions with, respectively, the hERG cardiac potassium channel and 5-HT(1) receptor subtypes have been suggested to account for these effects. No cardiovascular safety concerns were reported for the newer, selective 5-HT(4) agonists prucalopride, velusetrag, naronapride, or for nonselective 5-HT(4) agonists with no hERG or 5-HT(1) affinity (renzapride, clebopride, mosapride).

CONCLUSIONS

5-HT(4) agonists for GI disorders differ in chemical structure and selectivity for 5-HT(4) receptors. Selectivity for 5-HT(4) over non-5-HT(4) receptors may influence the agent's safety and overall risk-benefit profile. Based on available evidence, highly selective 5-HT(4) agonists may offer improved safety to treat patients with impaired GI motility.

Cisapride: what can we learn from the rise and fall of a prokinetic?

Cisapride, the prototype serotonergic agent, evolved from a body of research that defined the key roles of serotonergic receptors in gastrointestinal motor and sensory function. Impressed by its in vitro properties and encouraged by clinical trial data, cisapride became the drug of choice for the treatment of a wide range of motility disorders and clinicians appeared impressed by its efficacy and comfortable with its side-effect profile. Once serious cardiac events began to be reported in association with cisapride therapy, dark clouds rapidly gathered and soon enveloped the drug, leading to its widespread withdrawal from markets. What lessons can we learn from the story of cisapride? How can its brief but spectacular rise and equally sensational demise inform the development of new drugs which are so sorely needed in the management of motility and functional gastrointestinal disorders? This review explores the background to the development of cisapride, its history in clinical trials and the experience with adverse events and, in so doing, attempts to identify lessons for the future in the therapeutics of enteric neuromodulatory drugs.

Application of the Bradford Hill Criteria to Assess the Causality of Cisapride-Induced Arrhythmia

INTRODUCTION

The Bradford Hill criteria are a widely used, useful tool for the assessment of biomedical causation. We have examined their application to pharmacovigilance using the example of cisapride-induced QTc interval prolongation/arrhythmia.

METHODS

A literature search was conducted using MEDLINE, EMBASE, Reactions Weekly and regulatory websites to identify evidence for the association between cisapride and QTc interval prolongation/arrhythmia that had been published in the English language. Two hundred and five publications were identified as being potentially suitable for the study. After excluding irrelevant articles, studies on high-risk populations and review articles, 70 publications were assessed using the Bradford Hill criteria. These included 24 case reports, case series or spontaneous report summaries; eight epidemiological studies; 22 clinical studies; and 16 experimental (in vivo and in vitro) publications.

RESULTS

The most compelling evidence for an association between cisapride use and QTc interval prolongation/arrhythmia came from case/spontaneous reports and biological plausibility. Considering the rare incidence of serious cardiac events, these criteria formed the basis for the strength of the association. The number of reports from different populations showed consistency. Specificity was supported by clinical and cardiographic characterisation of the events. There were temporal relationships between the events and the initiation of cisapride treatment, increases in the dosage and the receipt of interacting medications. The relationships between the adverse events and the latter two factors exhibited biological gradients. Experimental evidence could be found from biological models, as well as reports of positive dechallenge and/or rechallenge found in individual patients. Cisapride was found to bind the human ether-a-go-go-related gene (HERG) potassium channel, which provides a plausible mechanism for QTc interval prolongation/arrhythmia. Other QTc interval-prolonging/arrhythmic drugs that also bind to HERG provided an analogy for cisapride causing QTc interval prolongation/arrhythmia via this mechanism. The evidence provided by clinical studies was inconsistent, and epidemiological studies failed to demonstrate an association. Nevertheless, this did not prevent the assessment of causation.

DISCUSSION

This study showed how different types of evidence found in pharmacovigilance can be evaluated using the Bradford Hill criteria. Further work is required to examine how the criteria can be applied to different types of adverse events and how they may be applied to pharmacovigilance.

Prolongation of the QT interval and cardiac arrhythmias associated with cisapride: limitations of the pharmacoepidemiological studies conducted and proposals for the future

Not all hazards can be identified from clinical studies prior to marketing of medicinal products. Pre-marketing large-scale trials for cisapride did not report any serious cardiac arrhythmias. After a long period of availability in several countries it was withdrawn in 2000 because of reports of serious, and in many cases fatal, cardiac events. Whilst spontaneous reporting systems for adverse drug reactions (ADRs) have limitations such as under-reporting, they are an effective system for signal generation, particularly of rare ADRs. Pharmacoepidemiological studies aim to identify and calculate the incidence of adverse reactions, with increased sensitivity to less common ADRs compared to randomised controlled trials, yet cohort sizes may be insufficient to detect very rare ADRs such as drug-induced Torsade de Pointes, with an estimated incidence of the order of 1 per 12,000 to 1 per 120,000 patients. Several pharmacoepidemiological studies investigated adverse events associated with cisapride, one of which specifically examined the association between serious cardiac arrhythmias and cisapride. These observational studies were conducted using large population databases, but each failed to identify sufficient cases to establish a causal relationship. Explanations include that the cohort sample sizes were too small, and either under-, or mis-reporting of events of interest may have occurred. To estimate the risk of very rare adverse events, pharmacoepidemiological studies require very large numbers. Furthermore, the events in question need to be clinically recognisable by doctors and adequately documented in patients' notes, computer records, or on study questionnaires. The establishment of a national registry for drug-induced QT prolongation to identify cases and correlate clinical information may help to better identify these rare ADRs earlier. Such proactive surveillance could avoid unnecessary delays for other drugs where QT prolongation and serious cardiac arrhythmias may be an issue.

Serious ventricular arrhythmias among users of cisapride and other QT-prolonging agents in the United States

PURPOSE

To evaluate the risk of serious ventricular arrhythmia (SVA) with cisapride use in the United States.

METHODS

The study population included 28,078 patients under the age of 65 years who received cisapride between 1993 and 1998 with no history of antiarrhythmia treatment. Each follow-up day was classified according to use of cisapride and other factors. Outcomes of SVAs were identified using medical claims records and National Death Index search, and confirmed by medical record review. Rates of events were calculated for time on and off cisapride. Poisson regression analysis was used to calculate adjusted rate ratios.

RESULTS

There were 23 cases of SVAs; 10 during periods of cisapride use and 13 during periods of non-use. The adjusted rate ratio comparing SVA events in cisapride use time to non-use time was 1.60 (95% CI: 0.67-3.82), and that identified for the other QT-prolonging drugs was 1.60 (95% CI: 0.65-3.98).

CONCLUSIONS

The evidence for an increased risk of SVAs associated with cisapride was equivocal after taking observation time on and off cisapride into account, and adjusting for risk factors, though we cannot exclude the possibility of a 3.8-fold increased risk. Overall, the plausible risks of cisapride were similar to those of other QT-prolonging drugs.

Efficacy and tolerability of cisapride in children

As gastro-oesophageal reflux disease (GORD) in infants and children is a motility disorder which differs in pathophysiology and clinical course from GORD in adults, prokinetics should be considered the drug of choice in certain circumstances. Indeed, cisapride may result in improvement of feeding tolerance in premature infants. Cisapride has a better tolerability profile than a 'wait-and-see-if-improvement-comes-spontaneously' policy or the other therapeutic options available. A careful and critical review of published data suggests that cisapride may have a QTc-prolonging effect. However, provided the precautions for cisapride administration are followed, the QTc-prolonging effect remains consistently without clinically relevant adverse effects. Correct dosage and avoidance of concurrent treatment with macrolides and/or azoles are the most relevant tolerability recommendations in children. Although there is a need for a prokinetic with better efficacy, cisapride is currently the prokinetic with the best benefit-to-risk ratio available. Thus, withdrawal of cisapride would result in a significantly increased risk for severe complications in infants and children with GORD or other gastrointestinal motility disorders such as chronic intestinal pseudo-obstruction, gastroparesis and feed intolerance in premature infants.

Stereoselective pharmacokinetics of cisapride in healthy volunteers and the effect of repeated administration of grapefruit juice

AIMS

To determine whether the pharmacokinetics of cisapride and its interaction with grapefruit juice are stereoselective.

METHODS

The study was a randomized, two-phase cross over design with a washout period of 2 weeks. Ten healthy volunteers were pretreated with either water or 200 ml double strength grapefruit juice three times a day for 2 days. On the 3rd each subject ingested a single 10 mg dose of rac-cisapride tablet. Double strength grapefruit juice (200 ml) or water was administered during cisapride dosing and 0.5 and 1.5 h thereafter. Blood samples were collected before and for 32 h after cisapride administration. Plasma concentrations of cisapride enantiomers were measured by a chiral h.p.l.c. method. A standard 12-lead ECG was recorded before cisapride administration (baseline) and 2, 5, 8, and 12 h later.

RESULTS

This study showed that cisapride pharmacokinetics are stereoselective. In control (water treated) subjects, the mean Cmax (30 +/- 13.6 ng ml-1; P = 0.0008) and AUC(0, infinity) (201 +/- 161 ng ml-1 h; P = 0.029) of (-)-cisapride were significantly higher than the Cmax (10.5 +/- 3.4 ng ml-1) and AUC(0, infinity) (70 +/- 51.5 ng ml-1 h) of (+)-cisapride. There was no marked difference in elimination half-life between (-)-cisapride (4.7 +/- 2.7 h) and (+)-cisapride (4.8 +/- 3 h). Compared with the water treated group, grapefruit juice significantly increased the mean Cmax of (-)-cisapride from 30 +/- 13.6-55.5 +/- 18 ng ml-1 (95% CI on mean difference, -33, -17; P = 0.00005) and of (+)-cisapride from 10.5 +/- 3.4 to 18.4 +/- 6.2 ng ml-1 (95% CI on mean difference, -11.8, -3.9, P = 0.00015). The mean AUC(0, infinity) of (-)-cisapride was increased from 201 +/- 161 to 521.6 +/- 303 ng ml-1 h (95% CI on mean difference, -439, -202; P = 0.0002) and that of (+)-cisapride from 70 +/- 51.5 to 170 +/- 91 ng ml-1 h (95% CI on mean difference, -143, -53; P = 0.0005). The tmax was also significantly increased for both enantiomers (from 1.35 to 2.8 h for (-)-cisapride and from 1.75 to 2.9 h for (+)-cisapride in the control and grapefruit juice group, respectively; P < 0.05). The t(1/2) of (-)-cisapride was significantly increased by grapefruit juice, while this change did not reach significant level for (+)-cisapride. The proportion of pharmacokinetic changes brought about by grapefruit juice was similar for both enantiomers, suggesting non-stereoselective interaction. We found no significant difference in mean QTc intervals between the water and grapefruit juice treated groups.

CONCLUSIONS

The pharmacokinetics of cisapride is stereoselective. Grapefruit juice elevates plasma concentrations of both (-)- and (+)-cisapride, probably through inhibition of CYP3A in the intestine. At present, there are no data on whether the enantiomers exhibit stereoselective pharmacodynamic actions. If they do, determination of plasma concentrations of the individual enantiomers as opposed to those of racemic cisapride may better predict the degree of drug interaction, cardiac safety and prokinetic efficacy of cisapride.

Influence of coadministration of fluoxetine on cisapride pharmacokinetics and QTc intervals in healthy volunteers

STUDY OBJECTIVE

To evaluate the effect of fluoxetine on the pharmacokinetics and cardiovascular safety of cisapride at steady state in healthy men.

DESIGN

Open-label, three-phase, sequential study.

SETTING

Clinical research center.

SUBJECTS

Twelve healthy male volunteers.

INTERVENTIONS

Each subject was treated according to the following sequence: baseline; phase 1 (days 1-6): cisapride 10 mg 4 times/day; washout (days 7-13); phase 2 (days 14-44): fluoxetine 20 mg/day; and phase 3 (days 45-52): cisapride 10 mg 4 times/day (days 45-51) plus fluoxetine 20 mg/day (days 45-52).

MEASUREMENTS AND MAIN RESULTS

Blood samples were drawn and 12-lead electrocardiograms performed at specified time points after the last morning dose of cisapride in phases 1 and 3. Blood samples also were taken before morning doses on the 3rd, 4th, and 5th days of phases 1 and 3. Electrocardiograms were done at baseline and on the last day of the washout period and phase 2. Coadministration of fluoxetine significantly decreased cisapride plasma concentrations. There were no clinically significant changes in corrected QT intervals during administration of cisapride alone or with fluoxetine. Cisapride was well tolerated when administered alone or with fluoxetine.

CONCLUSION

Cisapride can be administered safely to patients receiving low therapeutic dosages of fluoxetine.

Management of the patient with gastroparesis

Gastroparesis may be related to a variety of underlying disorders, but management options are fairly universal. Dietary measures and pharmacologic agents, primarily in the form of prokinetic medications, form the foundation of standard management. Some patients will have refractory symptoms and alternative dosing schemes or drug combinations may be used. An occasional patient will still require venting gastrostomy and/or jejunal feeding. This review addresses the standard dietary and pharmacologic approaches to gastroparesis, as well as issues pertaining to gastrostomy/jejunostomy tubes and to surgical options for refractory cases. Finally, experimental agents and techniques, such as gastric pacing, will be discussed.

Selection of drugs to treat gastro-oesophageal reflux disease: the role of drug interactions

Gastro-oesophageal reflux disease is probably the most common acid-peptic disease in Western countries, and the successful treatment of mild to moderate disease with pharmacotherapy has become commonplace. A large number of effective drugs are now available, and so the decision-making process for physicians increasingly relies on considerations other than pure efficacy. Cost, adverse effects and drug interactions have therefore become important, particularly in the most vulnerable patients - children, the elderly and patients who are ill and are taking medications that may influence the efficacy of antireflux therapy. Important drug interactions with antacids include the prevention of the absorption of antibacterials such as tetracycline, azithromycin and quinolones. H2 antagonists, proton pump inhibitors and prokinetic agents undergo metabolism by the cytochrome P450 (CYP) system present in the liver and gastrointestinal tract. Cimetidine is an inhibitor of CYP3A and it may cause significant interactions with drugs of narrow therapeutic range and low bioavailability that are metabolised by these enzymes. The gastroparietal proton pump inhibitors lansoprazole, omeprazole and pantoprazole are all primarily metabolised by a genetically polymorphic enzyme, CYP2C19, that is absent from approximately 3% of Caucasians and 20% of Asians. These drugs may also interact with CYP3A, but to a lesser extent. Interactions with prokinetic agents carry the greatest potential for harm. Metoclopramide is a dopamine antagonist that may cause extrapyramidal effects when administered alone at high concentrations, or when coadministered with antipsychotic agents such as haloperidol or phenothiazines. Cisapride is clearly able to prolong the electrocardiographic QT interval and cause lethal ventricular arrhythmias when its metabolism is slowed by interaction with inhibitors of CYP3A, such as erythromycin, ketoconazole or itraconazole.

Drug interactions with cisapride: clinical implications

Cisapride, a prokinetic agent, has been used for the treatment of a number of gastrointestinal disorders, particularly gastro-oesophageal reflux disease in adults and children. Since 1993, 341 cases of ventricular arrhythmias, including 80 deaths, have been reported to the US Food and Drug Administration. Marketing of the drug has now been discontinued in the US; however, it is still available under a limited-access protocol. Knowledge of the risk factors for cisapride-associated arrhythmias will be essential for its continued use in those patients who meet the eligibility criteria. This review summarises the published literature on the pharmacokinetic and pharmacodynamic interactions of cisapride with concomitantly administered drugs, providing clinicians with practical recommendations for avoiding these potentially fatal events. Pharmacokinetic interactions with cisapride involve inhibition of cytochrome P450 (CYP) 3A4, the primary mode of elimination of cisapride, thereby increasing plasma concentrations of the drug. The macrolide antibacterials clarithromycin, erythromycin and troleandomycin are inhibitors of CYP3A4 and should not be used in conjunction with cisapride. Azithromycin is an alternative. Similarly, azole antifungal agents such as fluconazole, itraconazole and ketoconazole are CYP3A4 inhibitors and their concomitant use with cisapride should be avoided. Of the antidepressants nefazodone and fluvoxamine should be avoided with cisapride. Data with fluoxetine is controversial, we favour the avoidance of its use. Citalopram, paroxetine and sertraline are alternatives. The HIV protease inhibitors amprenavir, indinavir, nelfinavir, ritonavir and saquinavir inhibit CYP3A4. Clinical experience with cisapride is lacking but avoidance with all protease inhibitors is recommended, although saquinavir is thought to have clinically insignificant effects on CYP3A4. Delavirdine is also a CYP3A4 inhibitor and should be avoided with cisapride. We also recommend avoiding coadministration of cisapride with amiodarone, cimetidine (alternatives are famotidine, nizatidine, ranitidine or one of the proton pump inhibitors), diltiazem and verapamil (the dihydropyridine calcium antagonists are alternatives), grapefruit juice, isoniazid, metronidazole, quinine, quinupristin/dalfopristin and zileuton (montelukast is an alternative). Pharmacodynamic interactions with cisapride involve drugs that have the potential to have additive effects on the QT interval. We do not recommend use of cisapride with class Ia and III antiarrhythmic drugs or with adenosine, bepridil, cyclobenzaprine, droperidol, haloperidol, nifedipine (immediate release), phenothiazine antipsychotics, tricyclic and tetracyclic antidepressants or vasopressin. Vigilance is advised if anthracyclines, cotrimoxazole (trimethoprim-sulfamethoxazole), enflurane, halothane, isoflurane, pentamidine or probucol are used with cisapride. In addition, uncorrected electrolyte disturbances induced by diuretics may increase the risk of torsade de pointes. Patients receiving cisapride should be promptly treated for electrolyte disturbances.

Review article: cardiac adverse effects of gastrointestinal prokinetics

Gastrointestinal prokinetics, such as metoclopramide, cisapride and levosulpiride, are widely used for the management of functional gut disorders. Recently, several studies have shown that cisapride (a partial 5-HT4 receptor agonist) can induce dose-dependent cardiac adverse effects, including lengthening of the electrocardiographic QT interval, syncopal episodes and ventricular dysrhythmias. Until recently, it was not clear whether these effects were dependent on 5-HT4 receptor activation or related to peculiar characteristics in the molecular structure of single agents within the benzamide class. Experimental evidence now favours the second hypothesis: cisapride possesses Class III antiarrhythmic properties and prolongs the action potential duration through blockade of distinct voltage-dependent K+ channels, thus delaying cardiac repolarization and prolonging the QT interval. Patients at risk of cardiac adverse effects are children, subjects with idiopathic, congenital or acquired long QT syndrome and, in particular, those receiving concomitant medication with Class III antiarrhythmic agents, some H1-receptor antagonists (e.g. terfenadine), or drugs such as azole antifungals (e.g. ketoconazole, itraconazole, miconazole and fluconazole) and macrolide antibacterials (e.g. erythromycin, clarithrod-mycin and troleandomycin), which can inhibit cisapride metabolism by interfering with the CYP3A4 isoenzyme.

The risk of serious cardiac arrhythmias among cisapride users in the United Kingdom and Canada

PURPOSE

Serious, although rare, ventricular arrhythmias and deaths have been reported in patients taking cisapride monohydrate. Without quantification of the risk involved, it is impossible to develop rational therapeutic guidelines.

SUBJECTS AND METHODS

Arrhythmic events (sudden deaths and other events compatible with serious ventricular arrhythmias) were sought among 36,743 patients prescribed cisapride in the United Kingdom and Saskatchewan, Canada. Prescriptions and cases were identified from computerized medical claims data and physicians' office records. We compared rates of events between periods of recent cisapride use and nonrecent use, using cohort analysis. Potential confounding factors, including concomitant treatment with agents that inhibit CYP3A4 metabolism or that prolong the QT interval, were assessed in a nested case-control study.

RESULTS

In the cohort analysis, the incidence of the arrhythmic events was 1.6 times greater (95% confidence interval [CI]: 0.9 to 2.9) in periods of recent use. With adjustment for clinical history, use of CYP3A4 inhibitors, and use of drugs that prolong the QT interval, the odds ratio for cisapride and cardiac outcomes was 1.0 (95% CI: 0.3 to 3.7). There was no identifiable increase in risk when cisapride was dispensed at about the same time as QT-prolonging drugs or CYP3A4 inhibitors. QT-prolonging agents were associated with a 2.5-fold increase in the risk of arrhythmic events (95% CI: 1.1 to 5.8).

CONCLUSIONS

Serious rhythm disorders were not associated with cisapride use, although the upper confidence bounds do not rule out an increase in risk.

The role of cisapride in the treatment of pediatric gastroesophageal reflux. The European Society of Paediatric Gastroenterology, Hepatology and Nutrition

BACKGROUND

Cisapride is a gastrointestinal prokinetic agent that is used worldwide in the treatment of gastrointestinal motility-related disorders in premature infants, full-term infants, and children. Efficacy data suggest that it is the most effective commercially available prokinetic drug.

METHODS

Because of recent concerns about safety, a critical and in-depth analysis of all reported adverse events was performed and resulted in the conclusions and recommendations that follow.

RESULTS

Cisapride should only be administered to patients in whom the use of prokinetics is justified according to current medical knowledge. If cisapride is given to pediatric patients who can be considered healthy except for their gastrointestinal motility disorder, and the maximum dose does not exceed 0.8 mg/kg per day in 3 to 4 administrations of 0.2 mg/kg (not exceeding 40 mg/d), no special safety procedures regarding potential cardiac adverse events are recommended. However, if cisapride is prescribed for patients who are known to be or are suspected of being at increased risk for drug-associated increases in QTc interval, certain precautions are advisable. Such patients include those:(1) with a previous history of cardiac dysrhythmias, (2) receiving drugs known to inhibit the metabolism of cisapride and/or adversely affect ventricular repolarisation, (3) with immaturity and/or disease causing reduced cytochrome P450 3A4 activity, or (4) with electrolyte disturbances. In such patients, ECG monitoring to quantitate the QTc interval should be used before initiation of therapy and after 3 days of treatment to ascertain whether a cisapride-induced cardiac adverse effect is present.

CONCLUSIONS

With rare exceptions, the total daily dose of cisapride should not exceed 0.8 mg/kg divided into 3 or 4 approximately equally spaced doses. If higher doses than this are given, the precautions above are advisable. In any patient in whom a prolonged QTc interval is found, the dose of cisapride should be reduced or the drug discontinued until the ECG normalizes. If the QTc interval returns to normal after withdrawal of cisapride, and the administration of cisapride is considered to be justified because of its efficacy and absence of alternative treatment options, cisapride can be restarted at half dose with control of the QTc interval. Unfortunately, at present, normal ranges of QTc interval in children are unknown. However, a critical analysis of the literature suggests that a duration of less than 450 milliseconds can be considered to be within the normal range and greater than 470 milliseconds as outside it.

Functional gut disorders: from motility to sensitivity disorders. A review of current and investigational drugs for their management

Functional gut disorders include several clinical entities defined on the basis of symptom patterns (e.g., functional dyspepsia, irritable bowel syndrome, functional abdominal pain, functional abdominal bloating), for which there is no established pathophysiological mechanism. Because there is no well-defined pathophysiological target, treatment should be aimed at symptom improvement. Prokinetics and antispasmodics have been widely used in the treatment of functional gut disorders on the assumption that disordered motility is the underlying cause of symptoms, and symptom improvement is indeed achievable with these compounds in some, but not all, patients with features of hypo- or hypermotility, respectively. In the first part of this review, we cover the basic pharmacology and discuss the rationale for the clinical use of prokinetics and antispasmodics. On the other hand, in the past few years, the explosive growth in the research focusing on visceral sensitivity and visceral reflexes has suggested that at least some patients with functional gut disorders have altered visceral perception. Thus, the second part of the review covers these developments and focuses on studies addressing the issue of drugs modulating visceral sensitivity.