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

Alcohol-medical drug interactions

Concomitant use of alcohol and medications may lead to potentially serious medical conditions. Increasing prescription medication abuse in today's society necessitates a deeper understanding of the mechanisms involved in alcohol-medication interactions in order to help prevent adverse events. Interactions of medications with alcohol result in altered bioavailability of the medication or alcohol (pharmacokinetic interactions) or modification of the effects at receptor or ion channel sites to alter behavioral or physical outcome (pharmacodynamic interactions). The nature of pharmacokinetic or pharmacodynamic interactions involved in alcohol-medication interactions may differ between acute and chronic alcohol use and be influenced by race, gender, or environmental or genetic factors. This review focuses on the mechanisms underlying pharmacokinetic and pharmacodynamic interactions between alcohol and medications and provides examples for such interactions from replicated research studies. In conclusion, further translational research is needed to address several gaps in our current knowledge of alcohol-medication interactions, including those under various pathologic conditions.

Tegaserod mimics the neurostimulatory glycan polysialic acid and promotes nervous system repair

Glycans attached to the cell surface via proteins or lipids or exposed in the extracellular matrix affect many cellular processes, including neuritogenesis, cell survival and migration, as well as synaptic activity and plasticity. These functions make glycans attractive molecules for stimulating repair of the injured nervous system. Yet, glycans are often difficult to synthesize or isolate and have the disadvantage to be unstable in a complex tissue environment. To circumvent these issues, we have screened a library of small organic compounds to search for structural and functional mimetics of the neurostimulatory glycan polysialic acid (PSA) and identified the 5-HT₄ receptor agonist tegaserod as a PSA mimetic. The PSA mimicking activity of tegaserod was shown in cultures of central and peripheral nervous system cells of the mouse and found to be independent of its described function as a serotonin (5-HT₄) receptor agonist. In an in vivo model for peripheral nerve regeneration, mice receiving tegaserod at the site of injury showed enhanced recovery compared to control mice receiving vehicle control as evidenced by functional measurements and histology. These data indicate that tegaserod could be repurposed for treatment of nervous system injuries and underscores the potential of using small molecules as mimetics of neurostimulatory glycans.

Drug-induced acute myocardial infarction: identifying 'prime suspects' from electronic healthcare records-based surveillance system

BACKGROUND

Drug-related adverse events remain an important cause of morbidity and mortality and impose huge burden on healthcare costs. Routinely collected electronic healthcare data give a good snapshot of how drugs are being used in 'real-world' settings.

OBJECTIVE

To describe a strategy that identifies potentially drug-induced acute myocardial infarction (AMI) from a large international healthcare data network.

METHODS

Post-marketing safety surveillance was conducted in seven population-based healthcare databases in three countries (Denmark, Italy, and the Netherlands) using anonymised demographic, clinical, and prescription/dispensing data representing 21,171,291 individuals with 154,474,063 person-years of follow-up in the period 1996-2010. Primary care physicians' medical records and administrative claims containing reimbursements for filled prescriptions, laboratory tests, and hospitalisations were evaluated using a three-tier triage system of detection, filtering, and substantiation that generated a list of drugs potentially associated with AMI. Outcome of interest was statistically significant increased risk of AMI during drug exposure that has not been previously described in current literature and is biologically plausible.

RESULTS

Overall, 163 drugs were identified to be associated with increased risk of AMI during preliminary screening. Of these, 124 drugs were eliminated after adjustment for possible bias and confounding. With subsequent application of criteria for novelty and biological plausibility, association with AMI remained for nine drugs ('prime suspects'): azithromycin; erythromycin; roxithromycin; metoclopramide; cisapride; domperidone; betamethasone; fluconazole; and megestrol acetate.

LIMITATIONS

Although global health status, co-morbidities, and time-invariant factors were adjusted for, residual confounding cannot be ruled out.

CONCLUSION

A strategy to identify potentially drug-induced AMI from electronic healthcare data has been proposed that takes into account not only statistical association, but also public health relevance, novelty, and biological plausibility. Although this strategy needs to be further evaluated using other healthcare data sources, the list of 'prime suspects' makes a good starting point for further clinical, laboratory, and epidemiologic investigation.

Emerging treatments for chronic constipation

INTRODUCTION

Chronic constipation (CC) is a common problem worldwide and, for some sufferers, a cause of considerable morbidity. Recent definitions of CC have moved from the former emphasis on stool frequency alone to a broader concept that strives to encompass the various symptoms that may bother afflicted individuals. Accordingly, new therapies attempt to not only increase frequency of defecation but also to address such symptoms as satisfaction with bowel action, straining, bloating, and distension.

AREAS COVERED

To provide context the relative merits and problems related to conventional laxative-based approaches to constipation are first reviewed and then more recent novel pharmacological approaches to the management of constipation assessed. The focus is on two classes of compounds, selective prokinetics and prosecretory agents, and studies on their efficacy and safety in chronic idiopathic constipation were retrieved and evaluated.

EXPERT OPINION

While undoubtedly effective, high-quality evidence to support laxatives, the traditional remedies for constipation, is remarkably scarce due, in large part, to the absence, until very recently, of high-quality randomized controlled clinical trials. The selective prokinetic agent prucalopride and the prosecretory agents lubiprostone and linaclotide have shown efficacy and been associated with a good safety record in large well-conducted clinical studies. Other novel approaches, such as the inhibition of ileal bile salt absorption, offer particular promise.

Overlap of functional dyspepsia and GERD--diagnostic and treatment implications

GERD and functional dyspepsia are the two most prevalent upper gastrointestinal disorders. Gastro-oesophageal reflux is most commonly diagnosed using the cardinal symptoms of heartburn and regurgitation. Patients might also be diagnosed using a questionnaire, after empiric treatment with an acid suppressant, after upper endoscopy or by pH testing. Functional dyspepsia is best diagnosed using symptoms outlined by the Rome committee in conjunction with a normal upper endoscopy. Theoretically, distinguishing these two populations should be easy for all health-care providers. In reality, however, carefully separating out these two populations can be quite difficult, as substantial overlap exists epidemiologically, symptomatically and even diagnostically. This overlap renders precise diagnosis a challenge; given the limited treatment options, the primary goal is to identify those patients who will respond to acid suppressive therapy. Despite the frequency with which functional dyspepsia and GERD overlap, remarkably few studies have investigated this overlap. Most recommendations are based on data derived from separate studies of functional dyspepsia and GERD. A further limitation of existing studies is their failure to differentiate between the various diagnostic categories into which the individual presenting with heartburn might belong.

Current status of drug screening and disease modelling in human pluripotent stem cells

The emphasis in human pluripotent stem cell (hPSC) technologies has shifted from cell therapy to in vitro disease modelling and drug screening. This review examines why this shift has occurred, and how current technological limitations might be overcome to fully realise the potential of hPSCs. Details are provided for all disease-specific human induced pluripotent stem cell lines spanning a dozen dysfunctional organ systems. Phenotype and pharmacology have been examined in only 17 of 63 lines, primarily those that model neurological and cardiac conditions. Drug screening is most advanced in hPSC-cardiomyocytes. Responses for almost 60 agents include examples of how careful tests in hPSC-cardiomyocytes have improved on existing in vitro assays, and how these cells have been integrated into high throughput imaging and electrophysiology industrial platforms. Such successes will provide an incentive to overcome bottlenecks in hPSC technology such as improving cell maturity and industrial scalability whilst reducing cost.

Evolving pharmacological approaches in gastroesophageal reflux disease

INTRODUCTION

Proton pump inhibitors (PPIs) have considerably improved quality of life in patients with gastroesophageal reflux disease (GERD). However, many patients remain symptomatic despite standard PPI therapy.

AREAS COVERED

This review focuses on evolving therapeutic strategies related to the pathophysiological processes of GERD and insufficient response to PPIs. Several clinical trials evaluated new PPI formulations and newer types of acid-suppressive drugs. These studies have evaluated traditional end points in GERD, but have not shown clinical superiority to current PPIs. Novel therapeutic strategies targeting underlying mechanisms of GERD, such as transient lower esophageal sphincter relaxations (TLESRs) and esophageal hypersensitivity, are being developed for add-on therapy to PPIs. Prokinetic drugs may also have some potential in the add-on treatment of GERD with insufficient response to PPIs. Add-on studies are hampered by insufficient information on optimal patient selection and lack of established end points.

EXPERT OPINION

Newer drugs for symptomatic control in GERD have largely focused on improved acid suppression, without evidence of clinical superiority. Drugs targeting esophageal motility and sensitivity to be used as add-onc therapy in PPI insufficient responders have not reached Phase III trials to date, due to difficulties with patient selection, tolerability and end points.

Effects of domperidone on QTc interval in infants

AIM

To prospectively evaluate the effects of oral domperidone on the QTc interval in infants.

METHODS

Infants (0-1 year) with a diagnosis of gastro-oesophageal reflux (GOR) disease were included. A 12-lead electrocardiography (ECG) was performed in all infants at baseline and 1 h after the intake of domperidone after 7-14 days; the corrected QTc interval was calculated by one investigator (MV) according to Bazett's formula.

RESULTS

Forty-five infants were enrolled in this study. The mean gestational age was of 38.6 weeks (35.5-42.0), and the mean age at the start of domperidone was 75.3 days (19-218 days). No statistically significant difference in corrected QTc was observed between baseline and the second ECG (0.389 ± 0.02 vs. 0.397 ± 0.31; p 0.130)). A trend was observed regarding gender: Although there was no difference in QTc change in girls (p 0.622), there was a strong trend in boys (p 0.051). Two infants (both boys) had a clinically significant QTc prolongation (> 460 msec) without symptoms. The Spearman correlation test showed no relation between the QTc change and age (r: -0.05822; p 0.7284). There was no relation between domperidone dosage and QTc change.

CONCLUSION

Overall, the group-analysis showed no statistical significant difference in QTc duration induced by domperidone. However, 2/45 (4.4%) infants had a prolonged QTc interval (> 460 msec) induced by domperidone. As a consequence, QTc measurement should be recommended in routine in infants when domperidone is started.

Ghrelin prevents levodopa-induced inhibition of gastric emptying and increases circulating levodopa in fasted rats

BACKGROUND

Levodopa (L-dopa) is the most commonly used treatment for alleviating symptoms of Parkinson's disease. However, L-dopa delays gastric emptying, which dampens its absorption. We investigated whether ghrelin prevents L-dopa action on gastric emptying and enhances circulating L-dopa in rats.

METHODS

Gastric emptying of non-nutrient methylcellulose/phenol red viscous solution was determined in fasted rats treated with orogastric or intraperitoneal (i.p.) L-dopa, or intravenous (i.v.) ghrelin 10 min before orogastric L-dopa. Plasma L-dopa and dopamine levels were determined by high pressure liquid chromatography. Plasma acyl ghrelin levels were assessed by radioimmunoassay. Fos expression in the brain was immunostained after i.v. ghrelin (30 μg kg(-1)) 10 min before i.p. L-dopa.

KEY RESULTS

Levodopa (5 and 15 mg kg(-1)) decreased significantly gastric emptying by 32% and 62%, respectively, when administered orally, and by 91% and 83% when injected i.p. Ghrelin (30 or 100 μg kg(-1), i.v.) completely prevented L-dopa's (15 mg kg(-1), orogastrically) inhibitory action on gastric emptying and enhanced plasma L-dopa and dopamine levels compared with vehicle 15 min after orogastric L-dopa. Levodopa (5 mg kg(-1)) did not modify plasma acyl ghrelin levels at 30 min, 1, and 2 h after i.v. injection. Levodopa (15 mg kg(-1), i.p.) induced Fos in brain autonomic centers, which was not modified by i.v. ghrelin.

CONCLUSIONS & INFERENCES

Ghrelin counteracts L-dopa-induced delayed gastric emptying but not Fos induction in the brain and enhances circulating L-dopa levels. Potential therapeutic benefits of ghrelin agonists in Parkinson's disease patients treated with L-dopa remain to be investigated.

Prucalopride: safety, efficacy and potential applications

Chronic constipation is a very common functional gastrointestinal disorder which can be associated with significant impairments in quality of life for some people with the condition. Its management has, traditionally, been based on dietary and lifestyle changes and the use of a variety of laxative agents. The evidence base for the efficacy of the latter is, in many cases, slim. Not surprisingly, many patients remain dissatisfied with laxatives thus leading to the development of more pharmacological approaches. Among these approaches is the use of prokinetic agents; while prior molecules have been troubled by lack of selectivity and cardiac side effects, the new agent, prucalopride, appears to be highly selective for the serotonin 5-HT4 receptor and is, therefore, a potent stimulator of gut motility. In three large pivotal randomized controlled trials, prucalopride has been effective in relieving the cardinal symptoms of chronic constipation; these effects have been sustained in open-label follow up for as long as 18 months. The safety profile has been encouraging and, especially so, the absence of arrhythmogenic potential. Studies in men, in constipation-predominant irritable bowel syndrome and in other motor disorders are eagerly awaited.

Motility disorders in the patient with neurologic disease

Gastrointestinal symptoms are common in the patient with chronic neurologic disease and may loom large in terms of impact on quality of life and on nutrition and mobility. A knowledge of the range of gastrointestinal disorders associated with a given neurologic disease, together with an understanding of the risks and benefits of various therapeutic options and approaches, should aid gastroenterologists in their efforts to contribute to the care of these patients. In most instances a multidisciplinary team (neurologist/neurosurgeon, gastroenterologist, nutritionist, therapist, specialist nurse) aware of the wishes and needs of the family and their carers and mindful of the nature and the natural history of the underlying disease process are best placed to assess and manage these problems.