Effects of ABT-229, a motilin agonist, on acid reflux, oesophageal motility and gastric emptying in patients with gastro-oesophageal reflux disease

Esophageal contractility increases and gastroesophageal reflux does not worsen after lung transplantation

Gastroesophageal reflux and esophageal dysmotility are common in patients with advanced lung disease and are associated with allograft dysfunction after lung transplantation. The effect of transplantation on reflux and esophageal motility is unclear. The aim of this study was to describe the changes in esophageal function occurring after lung transplantation. A retrospective cohort study was performed on lung transplant candidates evaluated at a tertiary care center between 2015 and 2016. A total of 76 patients who underwent lung transplantation had high-resolution manometry and ambulatory pH-metry before and after transplant. Demographic data, esophageal function testing results, and clinical outcomes such as pulmonary function testing were collected and analyzed using appropriate statistical tests and multivariable regression. Of the 76 patients, 59 (78%) received a bilateral transplant. There was a significant increase in esophageal contractility posttransplant, with an increase in median distal contractile integral from 1470 to 2549 mmHg cm s (P < 0.01). There were 19 patients with Jackhammer esophagus posttransplant, including 15 patients with normal motility pretransplant. Nine patients with ineffective or fragmented peristalsis pretransplant had normal manometry posttransplant. Abnormal pH-metry was observed in 35 (46%) patients pretransplant and 29 (38%) patients posttransplant (P = 0.33). Patients with gastroesophageal reflux disease posttransplant had less improvement in pulmonary function at one year, as measured by forced expiratory volume (P = 0.04). These results demonstrate that esophageal contractility increases significantly after lung transplantation, with an associated change in motility classification. In comparison, gastroesophageal reflux does not worsen, but is associated with worse pulmonary function, posttransplant.

Ghrelin and Motilin Control Systems in GI Physiology and Therapeutics

Ghrelin and motilin are released from gastrointestinal endocrine cells during hunger, to act through G protein-coupled receptors that have closely related amino acid sequences. The actions of ghrelin are more complex than motilin because ghrelin also exists outside the GI tract, it is processed to des-acyl ghrelin which has activity, ghrelin can exist in truncated forms and retain activity, the ghrelin receptor can have constitutive activity and is subject to biased agonism and finally additional ghrelin-like and des-acyl ghrelin receptors are proposed. Both ghrelin and motilin can stimulate gastric emptying, acting via different pathways, perhaps influenced by biased agonism at the receptors, but research is revealing additional pathways of activity. For example, it is becoming apparent that reduction of nausea may be a key therapeutic target for ghrelin receptor agonists and perhaps for compounds that modulate the constitutive activity of the ghrelin receptor. Reduction of nausea may be the mechanism through which gastroparesis symptoms are reduced. Intriguingly, a potential ability of motilin to influence nausea is also becoming apparent. Ghrelin interacts with digestive function through its effects on appetite, and ghrelin antagonists may have a place in treating Prader-Willi syndrome. Unlike motilin, ghrelin receptor agonists also have the potential to treat constipation by acting at the lumbosacral defecation centres. In conclusion, agonists of both ghrelin and motilin receptors hold potential as treatments for specific subsets of digestive system disorders.

Regionally dependent neuromuscular functions of motilin and 5-HT₄ receptors in human isolated esophageal body and gastric fundus

BACKGROUND

Motilin agonists promote human gastric motility and cholinergic activity, but excitatory and inhibitory actions are reported in the esophagus. The effect of 5-HT₄ agonists in esophagus is also unclear. Perhaps the use of drugs with additional actions explains the variation. The aim, therefore, was to examine how motilin and prucalopride, selective motilin and 5-HT₄ receptor agonists, modulate neuromuscular functions in human esophagus and gastric fundus.

METHODS

Electrical field stimulation (EFS) evoked nerve-mediated contractions of circular and longitudinal muscle from human esophageal body and circular muscle from gastric fundus.

KEY RESULTS

In esophageal circular muscle EFS evoked brief contraction, followed by another contraction on termination of EFS, each prevented by atropine. Nitric oxide synthase inhibition facilitated contraction during EFS and the overall contraction became monophasic. In esophagus longitudinal muscle and gastric fundus, EFS evoked cholinergically mediated, monophasic contractions, attenuated by simultaneous nitrergic activation. Motilin (100-300 nM) reduced esophagus circular muscle contractions during EFS, unaffected by L-NAME or apamin. Motilin 300 nM also reduced EFS-evoked contractions of longitudinal muscle. Similar concentrations of motilin facilitated cholinergic activity in the fundus and increased baseline muscle tension. Prucalopride facilitated EFS-evoked contractions in esophagus (tested at 30 μM) and fundus (0.1-30 μM).

CONCLUSIONS & INFERENCES

Selective motilin and 5-HT₄ agonists have different, region-dependent abilities to modulate human esophageal and stomach neuromuscular activity, exemplified by weak inhibition (motilin) or excitation (5-HT₄) in esophageal body and excitation for both in stomach. In different patients with motility dysfunctions, motilin and 5-HT₄ agonists may reduce gastro-esophageal reflux in different ways.

Pharmacological therapy of feed intolerance in the critically ills

Feed intolerance in the setting of critical illness is associated with higher morbidity and mortality, and thus requires promptly and effective treatment. Prokinetic agents are currently considered as the first-line therapy given issues relating to parenteral nutrition and post-pyloric placement. Currently, the agents of choice are erythromycin and metoclopramide, either alone or in combination, which are highly effective with relatively low incidence of cardiac, hemodynamic or neurological adverse effects. Diarrhea, however, can occur in up to 49% of patients who are treated with the dual prokinetic therapy, which is not associated with Clostridium difficile infection and settled soon after the cessation of the drugs. Hence, the use of prokinetic therapy over a long period or for prophylactic purpose must be avoided, and the indication for ongoing use of the drug(s) must be reviewed frequently. Second line therapy, such as total parenteral nutrition and post-pyloric feeding, must be considered once adverse effects relating the prokinetic therapy develop.

Current issues on safety of prokinetics in critically ill patients with feed intolerance

Feed intolerance in the setting of critical illness should be treated promptly given its adverse impact on morbidity and mortality. The technical difficulty of postpyloric feeding tube placement and the morbidities associated with parenteral nutrition prevent these approaches being considered as first-line nutrition. Prokinetic agents are currently the mainstay of therapy for feed intolerance in the critically ill. Current information is limited but suggests that erythromycin or metoclopramide (alone or in combination) are effective in the management of feed intolerance in the critically ill and not associated with significant cardiac, haemodynamic or neurological adverse effects. However, diarrhoea is a very common gastrointestinal side effect, and can occur in up to 49% of patients who receive both erythromycin and metoclopramide. Fortunately, the diarrhoea associated with prokinetic treatments has not been linked to Clostridium difficile infection and settles soon after the drugs are ceased. Therefore, prolonged or prophylactic use of prokinetics should be avoided. If diarrhoea occurs, the drugs should be stopped immediately. To minimize avoidable adverse effects the ongoing need for prokinetic drugs in these patient should be reviewed daily.

Gastric acid pocket and gastroesophageal reflux disease

Gastric acid pocket is an area of highly acid that escapes the neutralization of food in the proximal stomach after meals and has been noticed in healthy individuals and gastroesophageal reflux disease (GERD) patients. It was first found by Fletcher et al, who carried out a series of experiments in 2001. After that, other researchers have carried out in-depth studies on it. Hiatus hernia, gastric motility, gastric anatomy and physiology seem to be important elements for the genesis of postprandial proximal gastric acid pocket (PPGAP). Because PPGAP may play an important role in the pathogenesis of GERD, treatments for suppressing the production of gastric acid, antacid agents, prokinetic agents, surgery and other treatments may be used to alter the presence of PPGAP to achieve the purpose of treating GERD. Therefore, the discovery of gastric acid pocket may provide a new idea for the treatment of GERD.

New pharmacologic approaches in gastroesophageal reflux disease

This article highlights current and emerging pharmacological treatments for gastroesophageal reflux disease (GERD), opportunities for improving medical treatment, the extent to which improvements may be achieved with current therapy, and where new therapies may be required. These issues are discussed in the context of current thinking on the pathogenesis of GERD and its various manifestations and on the pharmacologic basis of current treatments.

Relevance of GERD in lung transplant patients

Lung transplantation has become a valuable treatment for end-stage pulmonary disorders in an attempt to improve quality of life and extend survival. Development of chronic rejection, also known as bronchiolitis obliterans syndrome (BOS), is responsible for the vast majority of deaths after lung transplantation. Up to 50% of lung transplant patients develop BOS within the first 5 years after transplantation. A high prevalence of gastroesophageal reflux and aspiration of gastric components has been described after lung transplantation. Reflux and aspiration have been implicated in the development of BOS and antireflux surgery has been proposed; however, the causal relationship with BOS and the impact of reflux in lung transplantation survival needs to be further elucidated.

Beyond acid suppression: new pharmacologic approaches for treatment of GERD

Proton pump inhibitors are highly successful in treating gastroesophageal reflux disease, but a significant proportion of patients have persistent symptoms from weakly or nonacidic reflux. Transient lower esophageal sphincter relaxation (TLESR) represents the dominant mechanism of gastroesophageal reflux and has therefore become the most intensely investigated therapeutic target. The triggering of TLESR involve the vagal pathways and the gamma-aminobutyric type B (GABA(B)) and metabotropic glutamate type 5 (mGluR5) receptors. Baclofen is a GABA(B) receptor agonist that is effective in inhibiting TLESR and reducing the number of reflux episodes, but is associated with significant central nervous system (CNS) side effects. The newer GABA(B) agonists, such as AZD9343 and AZD3355, and mGluR5 antagonists, such as 2-methyl-6-(phenylethynyl)-pyridine (MPEP), have been shown in small, randomized, controlled trials to have comparable efficacy to baclofen, but possibly a more favorable CNS side effect profile. Cannibinoid agonists, such as Delta(9)-THC, have also been demonstrated to reduce TLESRs and reflux events respectively. Macrolide antibiotics (eg, erythromycin) show early promise in a select group of patients with possible reflux associated post-lung transplant problems.

New pharmacologic approaches in gastroesophageal reflux disease

This article highlights current and emerging pharmacological treatments for gastroesophageal reflux disease (GERD), opportunities for improving medical treatment, the extent to which improvements may be achieved with current therapy, and where new therapies may be required. These issues are discussed in the context of current thinking on the pathogenesis of GERD and its various manifestations and on the pharmacologic basis of current treatments.

Effect of atilmotin, a motilin receptor agonist, on esophageal, lower esophageal sphincter, and gastric pressures

BACKGROUND

Motilin, an endogenous gastrointestinal (GI) hormone, increases upper gastrointestinal tract motility and is associated with phase III of the gastric migrating motor complex. The motilin receptor agonist, atilmotin, at doses of 6, 30 or 60 microg intravenously (IV), increases the early phase of gastric emptying. Prior studies at higher doses of 100-450 microg IV demonstrated that some subjects developed noncardiac chest pain.

AIMS

The aim of this study is to determine the effects of atilmotin on esophageal, lower esophageal sphincter (LES), and gastric contractility and the development of esophageal-related symptoms.

METHODS

Ten healthy volunteers underwent esophageal manometry to study the effects of atilmotin on upper GI motility. Five subjects were studied on three separate days following administration of saline placebo and subsequent IV bolus dose of atilmotin (6, 30 or 150 microg). Another five subjects were studied at the highest dose (150 microg).

RESULTS

Atilmotin at 150 microg increased proximal gastric pressure by 6.5 mmHg (P = 0.001 compared with placebo). Atilmotin increased LES pressure at all studied doses; LES pressure increased from 24 +/- 2 mmHg following placebo injection to 34 +/- 4 mmHg following a 30 microg dose of atilmotin (P = 0.007). In the esophagus, atilmotin increased the percentage of failed swallows at the highest dose studied. Failed swallows increased from 17 +/- 7% following placebo injection to 36 +/- 7% following a 150 microg dose of atilmotin (P = 0.016). Atilmotin decreased distal esophageal contractile amplitude only at the highest dose studied, from 69 +/- 8 mmHg (placebo) to 50 +/- 5 mmHg following 150 microg atilmotin (P = 0.018). There were no serious adverse effects or episodes of chest pain with atilmotin.

CONCLUSIONS

Atilmotin affects esophageal, LES, and gastric motility. LES and gastric pressures were increased, whereas there was disruption of esophageal peristalsis characterized by lower amplitude and failed contractions.

Motilin concentrations in relation to gastro intestinal dysmotility in diabetes mellitus

AIM

Dysmotility in the upper gastro intestinal (GI) tract are common problems in diabetics. Many peptides are involved in the regulation of the motility. The aim of this study was to examine whether plasma levels of motilin were related to dysfunction in the oesophagus and stomach in a well-defined diabetic patient group.

METHODS

Nineteen patients with symptoms from the GI tract who had been examined with oesophageal manometry, gastric emptying scintigraphy and deep-breathing test were included. They received a fat-rich meal, after which blood samples were collected and analysed for motilin concentrations.

RESULTS

Symptoms of abdominal fullness and gastro oesophageal reflux significantly associated with delayed gastric emptying, whereas no symptom correlated to oesophageal dysmotility. Plasma levels of motilin were increased after the fat-rich meal (p=0.000), with no difference between the groups. Abnormal manometry was characterized by aperistalsis and/or simultaneous contractions. The percentage of simultaneous contractions correlated to basic and peak motilin values (r(s)=0.898, p=0.006 and r(s)=0.842, p=0.017, respectively). Gastric emptying did not influence motilin concentrations.

CONCLUSION

Plasma motilin concentrations vary with abnormalities of oesophageal motility in diabetics, but not with abnormalities of gastric emptying.

Azithromycin reduces gastroesophageal reflux and aspiration in lung transplant recipients

Azithromycin (AZI) is a macrolide antibiotic that improves lung function in lung transplant recipients (LTx). Gastroesophageal reflux (GER) has been implicated in the pathogenesis of chronic rejection after LTx. Macrolide antibiotics may affect GER by modifying esophageal and gastric motility. The purpose of this study was to evaluate the effect of AZI on GER and gastric aspiration after LTx. Acid and weakly acidic GER was measured with 24-h pH-impedance monitoring in 47 LTx patients (12 patients "on" AZI). Gastric aspiration was assessed in a separate group of 30 LTx patients before and after AZI by measurements of pepsin and bile acid in bronchoalveolar lavage fluid (BALF). Patients "on" AZI had a significant lower total number of reflux events [41 (30-61) vs. 22.5 (7-37.5)], number of acid reflux events [24 (16-41) vs. 8 (4-18)], esophageal acid exposure [2.9% (0.7-7.3) vs. 0.2% (0.1-2.0)], bolus exposure [0.73% (0.5-1.4) vs. 0.21% (0.12-0.92)], and proximal extent of reflux [14 (9-24) vs. 5 (2-7)]. AZI reduced the concentration of bile acids in BALF without affecting levels of pepsin. LTx patients "on" AZI have less GER and bile acids aspiration. This effect might be due to enhanced esophageal motility and accelerated gastric emptying.

Advances in roles of prokinetic agents in the treatment of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is characterized by the reflux of gastric content into esophagus with or without histological changes. Pathogenesis of GERD is lower esophageal sphincter (LES) dysfunction, abnormal clearing capacity of refluxed materials, delayed gastric emptying and abnormal resistance of esophageal mucosa to gastric acid, but the primary upper gastrointestinal motility dysfunction is regarded as the most important factor in general. Therefore, prokinetic agents which can restore gastric motility with increasing of LES and esophageal motility have been developed and used frequently in the treatment of GERD. There are several prokinetic agents such as metoclopramide, domperidone, cisapride and mosapride that facilitate acetylcholine release from the enteric cholinergic neurons through a selective 5-HT₄ receptor agonistic action. It is considered that prokinetic agents have the same effect as H2 blocker in the treatment of patients with mild GERD. Additionally, it was reported that a combination therapy with prokinetic agents and proton pump inhibitors (PPI) or H2 receptor antagonists (H2RAs) is more effective than monotherapy in patients with severe GERD. This article reviews the recent advances in the role of prokinetic agents in the treatment of gastroesophageal reflux disease.

Therapeutic strategies for the management of delayed gastric emptying after pancreatic resection

BACKGROUND

Delayed gastric emptying (DGE) is one of the most troublesome postoperative complications following pancreatic resection. Not only does it contribute considerably to prolonged hospitalization, but it is also associated with increased postoperative morbidity and mortality.

METHODS

We performed an electronic and manual search of the international literature for studies dealing with the treatment of DGE following pancreatic resection using the Medline database. The search items used were "delayed gastric emptying," "pancreaticoduodenectomy," "Whipple procedure," "pylorus-preserving pancreaticoduodenectomy," and "complications following pancreatic resection" in various combinations.

RESULTS

A number of studies were identified regarding possible therapeutic alternatives for the treatment of DGE. From the class of prokinetic regimens, most studies seem to support the use of erythromycin. However, its use has not gained wide acceptance. Regarding the operative technique, both standard Whipple and pylorus-preserving pancreatic resection carry similar rates of DGE. Billroth II type-like gastrointestinal reconstruction is the most widely accepted method and is associated with lower rates of DGE. Reoperations for managing severe DGE were very rarely reported.

CONCLUSIONS

The incidence of DGE in high-volume centers specialized in pancreatic surgery is well below 20%, thus following the improved rates that have been reported in the last decade regarding mortality and length of hospital stay after pancreatic surgery. DGE mandates a uniform definition and method of evaluation to achieve homogeneity among studies. Standardization of the operative technique, as well as "centralizing" pancreatic resections in high-volume centers, should aid to improve the occurrence of this bothersome postoperative complication.

Synthesis and SAR of 1,3-disubstituted cyclohexylmethyl urea and amide derivatives as non-peptidic motilin receptor antagonists

A series of 1,3-disubstituted cyclohexylmethyl urea and amide derivatives were synthesized as motilin receptor antagonists. Starting from known motilin antagonists, 1a and 1b, the cyclopentene scaffold was replaced and the four recognition elements optimized to arrive at a potent novel series.

Pharmacological targets in gastro-oesophageal reflux disease

Although proton pump inhibitors have become the mainstay of treatment in gastro-oesophageal reflux disease (GORD), there are still unmet needs in the management of this very common disorder. For example, all current proton pump inhibitors have a relatively slow onset of action and their activity is limited mainly to the post-prandial period with far less effective inhibition of nocturnal acid secretion. In order to achieve more potent, rapid and sustained acid inhibition several compounds are currently under development, such as new proton pump inhibitors with a prolonged plasma half-life, potassium competitive ATPase blockers (PCABs), histamine H3 agonists, and gastrin antagonists. Acid suppression does not, however, cure the disease and relapses are frequently observed after discontinuation of proton pump inhibitor therapy. Among the different abnormalities involved in the pathophysiology of this multifactorial disease, transient lower oesophageal sphincter relaxations represent the major mechanism responsible for episodes of reflux. Baclofen, the prototype GABA(B) receptor agonist, is one of the most potent inhibitors of transient lower oesophageal sphincter relaxations identified. To date the transfer of these relaxation-controlling pharmacological agents into clinical practice has however been hampered by the occurrence of unacceptable side effects. Beside "anti-relaxation therapy", the potential of novel prokinetics such as motilin agonists has been explored, especially since the motilin receptor has been cloned. Thus far the broad therapeutic value of prokinetics in GORD does, however, seem very limited in terms of efficacy with respect to oesophageal motility and acid exposure. Lastly, further research is necessary to better understand the complex mechanisms involved in oesophageal sensitivity and mucosal defence.

Promotility medications--now and in the future

Gastrointestinal promotility drugs stimulate smooth muscle contractions to enhance gastric emptying and small and large bowel transit. Currently available drug classes with prokinetic properties include antidopaminergic agents, serotonergic agents, and motilin-receptor agonists. Due to moderate prokinetic effects, poor symptomatic responses and the presence of adverse effects, there is a clear need for new classes of prokinetics. Several newer prokinetic drugs and drug classes are currently under evaluation. Selecting candidate agents and designing the appropriate therapeutic trials is hampered by the lack of insight in the pathophysiology of motility-related symptoms. As gastrointestinal motor disorders are chronic, relapsing, and remitting disorders, it seems desirable that studies with candidate prokinetic drugs establish a long-term efficacy and not only short-term effects on gastrointestinal functions.

Effect of atilmotin on gastrointestinal transit in healthy subjects: a randomized, placebo-controlled study

We studied effects of i.v. atilmotin (BAX-ACC-1638, a novel motilin agonist, circulating t(1/2) < 10 min) on gastrointestinal transit in humans using a randomized, parallel-group, dose-response double-blind study of i.v. atilmotin, 6, 30, 60 microg or vehicle (placebo) given 2 min after standardized breakfast, lunch and dinner. The breakfast meal contained (99m)Tc-eggs and (111)In-milk. Full gastrointestinal transit was measured by scintigraphy. Primary endpoints were % gastric emptying (GE) at 30 min, GE t(1/2), colonic filling (CF) at 6 h, and geometric centre of colonic transit at 24 h. Analysis included adjustment for age, gender and body mass index, with Bonferroni correction applied for multiple comparisons. A significant treatment effect of atilmotin was detected for GE (%) at 30 min for solids and liquids (P < 0.01 for both). There were no significant effects on CF or CT and no significant adverse clinical events. Thus, atilmotin accelerates GE of solids and liquids in healthy humans. These data suggest that, at the doses tested, atilmotin should be considered for treatment of stomach motility disorders.

Characterization of agonist-induced motilin receptor trafficking and its implications for tachyphylaxis

The motilin receptor (MR) is a member of the seven-transmembrane receptor family and is expressed throughout the gastrointestinal tract of humans and other species. Motilin, the natural MR peptide ligand, has profound stimulatory effects on gastrointestinal contractility, indicating a therapeutic potential for MR modulators. However, long-term clinical use of certain MR agonists is limited by tachyphylaxis, a reduced responsiveness to repeated compound exposure. This study was meant to characterize the ligand-induced endocytosis of MR and to test whether receptor trafficking contributes to tachyphylaxis. A cell-based assay was developed by fusing a green fluorescent protein (GFP) moiety to the motilin receptor, and high-content biology instrumentation was used to quantify time and dose dependence of MR-GFP endocytosis. Maximal internalization of MR-GFP was induced after 45 min of constant exposure to 80 nM motilin. This process was disrupted by nocodazole, suggesting an essential role for microtubules. Internalized MR-GFP vesicles disappeared within 15 to 45 min of motilin withdrawal but did not overlap with the lysosomal compartment, indicating that MR-GFP escaped degradation and was recycled back to the plasma membrane. It is noteworthy that the kinetics of MR-GFP redistribution varied substantially when stimulated with motilin, erythromycin, 6,9-hemiacetal 8,9-anhydro-4''-deoxy-3'-N-desmethyl-3'-N-ethylerythromycin B (ABT-229), or N-[(1S)-1-[[[(1S)-1-(aminocarbonyl)-3-phenylpropyl]amino]carbonyl]-3-phenylpropyl]-2'-(1,3-benzodioxol-5-ylmethyl)tetrahydro-1',3'-dioxo-spiro[piperidine-4,5'(6'H)-[1H][1,2,4]triazolo[1,2-a]pyridazine]-8'-carboxamide (BMS-591348) at equipotent doses for Ca(2+)-mobilization. Retardation of the intracellular MR-GFP sorting cycle seemed to correlate with the tachyphylaxis-inducing properties of each compound, but not its EC(50). These results indicate that MR internalization, desensitization, and resensitization are ligand-dependent and that appropriate screening strategies may enable the development of small molecule agonists with ideal combinations of these distinct properties.

Progress with novel pharmacological strategies for gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GORD) is a chronic disorder characterised by an increased exposure of the oesophagus to intragastric contents. Currently, GORD symptoms are maintained under control with antisecretory agents, mainly gastric proton pump inhibitors (PPIs). Although impaired oesophageal motility may partly underlie the pathophysiology of GORD, the use of prokinetic agents has been found to be unsatisfactory. To date, novel pharmacological approaches for GORD are mainly related to the control of transient lower oesophageal sphincter (LOS) relaxations (TLOSRs). The majority of patients with GORD have reflux episodes during TLOSRs, which are evoked by gastric distension, mainly occurring after ingestion of a meal. Patients with reflux disease with normal peristalsis and without or with mild erosive disease could potentially benefit from anti-TLOSR therapy. This therapy might also be of value to treat some severe forms of esophagitis in combination with PPIs. GABA-B-receptor agonists are the most promising class of agents identified so far for TLOSR control. The GABA-B-receptor agonist, baclofen, is the most effective compound in inhibiting TLOSRs in humans. Since baclofen has several CNS adverse effects, novel orally available GABA-B agonists are needed for effective and well tolerated treatment of GORD. Endogenous or exogenous cholecystokinin (CCK) causes a reduction in LOS pressure, an increase in TLOSR frequency and a reduction in gastric emptying. In healthy volunteers and patients with GORD, loxiglumide, a selective CCK1-receptor antagonist, was found to reduce the rate of TLOSRs, although its effect on postprandial acid reflux may be modest. Orally effective CCK antagonists are not marketed to date. The anticholinergic agent atropine, given to healthy volunteers and patients with GORD, markedly reduced the rate of TLOSRs. Because of severe gastrointestinal (and other) adverse effects of anticholinergics, including worsening of supine acid clearance and constipation, it is unlikely that this class of drugs will have a future as anti-TLOSR agents on a routine basis. In spite of their effectiveness in reducing TLOSR rate, untoward adverse effects, such as addiction and severe constipation, currently limit the use of morphine and other opioid mu-receptor agonists. The same applies to nitric oxide synthase inhibitors, which are associated with marked gastrointestinal, cardiovascular, urinary and respiratory adverse effects. Animal studies provide promising evidence for the use of cannabinoid receptor 1 agonists, by showing potent inhibition of TLOSRs in the dog, thus opening a new route for clinical investigation in humans. A better understanding of TLOSR pathophysiology is a necessary step for the further development of novel drugs effective for anti-reflux therapy.

Gastroesophageal reflux disease

Globally, gastroesophageal reflux disease (GERD) remains a common and important clinical disorder. This review summarizes the major advances in the understanding and treatment of GERD that have been made in the past 12 months. Epidemiologic studies have yielded additional data on the clinical presentation and natural history of GERD in the East. Further insights have been presented on the pathogenesis of GERD, including the immunoregulatory environment of GERD, the neurophysiology of transient lower esophageal sphincter relaxation (TLESR), the mechanics of the esophagogastric junction as well as the influence of Helicobacter pylori. Diagnostically, a new acid exposure sensor may be a helpful cost-effective tool. Developments have been made in pharmacotherapy for TLESR. There is ongoing interest in endoscopic therapy and further developments have been made in laparoscopic fundoplication. The cost-effectiveness of several management strategies has been evaluated, aiming to reduce the cost impact of GERD on the health care system.