Proton-pump inhibitor therapy in patients with gastro-oesophageal reflux disease: putative mechanisms of failure

An algorithm for diagnosis and treatment of refractory GERD

Patients with gastro-esophageal reflux disease (GERD) who are not responding to proton pump inhibitors (PPIs) given once daily are very common. These therapy-resistant patients have become the new face of GERD in clinical practice in the last decade. Upper endoscopy appears to have a limited diagnostic value. In contrast, esophageal impedance with pH testing on therapy appears to provide the most insightful information about the subsequent management of these patients. Commonly, doubling the PPI dose or switching to another PPI will be offered to patients who failed PPI once daily. Failure of such therapeutic strategies is commonly followed by assessment for weakly or residual acidic reflux. There is growing information about the potential value of compounds that can reduce transient lower esophageal sphincter relaxation rate. Esophageal pain modulators are commonly offered to patients with functional heartburn although supportive clinical studies are still missing.

The effects of dose and timing of esomeprazole administration on 24-h, daytime and night-time acid inhibition in healthy volunteers

BACKGROUND

Symptoms of gastro-oesophageal reflux disease (GERD) may persist despite daily treatment with a proton pump inhibitor (PPI).

AIM

To compare the pharmacodynamic effect of various esomeprazole dosage and timing regimens in healthy volunteers.

METHODS

The effect of different esomeprazole dosage regimens [20 mg once daily (od) before breakfast or dinner; 20 mg twice daily (b.d.); 40 mg od before breakfast, dinner or at bedtime; and 40 mg b.d.] on 24-h, daytime and night-time acid inhibition was evaluated in a randomized, seven-way crossover study in healthy volunteers. Each regimen was taken for 5 days.

RESULTS

Over the 24-h period (day 5), esomeprazole 20 mg b.d. was associated with superior acid inhibition vs. all 20 mg and 40 mg od regimens (P < 0.05), but was less effective than esomeprazole 40 mg b.d. (P < 0.05). Dosing with esomeprazole 20 mg or 40 mg od before breakfast gave improved 24-h and daytime acid inhibition vs. the corresponding administration before dinner or at bedtime (all P < 0.05). Night-time acid inhibition was improved when esomeprazole 40 mg od was administered before dinner or at bedtime vs. before-breakfast dosing (P < 0.05).

CONCLUSION

Varying the dose and timing of esomeprazole administration may provide acid inhibition appropriate for the symptom pattern of individual patients with GERD.

Management of gastroesophageal reflux disease that does not respond well to proton pump inhibitors

PURPOSE OF REVIEW

Patients with gastroesophageal reflux disease (GERD) who are not responding to proton pump inhibitors (PPIs) given once daily are very common. These therapy-resistant patients have become the new face of GERD in clinical practice in the last decade and presently pose a significant therapeutic challenge to the practicing physician. We reviewed newly accumulated information about the management of PPI failure that has been published over the past 2 years.

RECENT FINDINGS

There are diverse mechanisms that contribute to the failure of PPI treatment in GERD patients and they are not limited to residual reflux. Some of the causes of PPI failure may coincide in the same patient. Upper endoscopy appears to have limited diagnostic value. In contrast, esophageal impedance with pH testing on therapy appears to provide the most insightful information about the subsequent management of these patients. Commonly, doubling the PPI dose or switching to another PPI will be offered to patients who failed PPI once daily. Failure of such therapeutic strategies is commonly followed by assessment for residual reflux. There is growing information about the potential value of compounds that can reduce transient lower esophageal sphincter relaxations. Esophageal pain modulators are commonly offered to patients with functional heartburn, although supportive clinical studies are still missing.

SUMMARY

Management of refractory GERD patients remains an important clinical challenge. Recent studies have cemented the value of impedance-pH testing in pursuing proper treatment. Presently, the most promising therapeutic development for this patient population is transient lower esophageal sphincter relaxation reducers.

Effect of lesogaberan, a novel GABA(B)-receptor agonist, on transient lower oesophageal sphincter relaxations in male subjects

BACKGROUND

Transient lower oesophageal sphincter relaxations (TLESRs) are a major mechanism behind gastro-oesophageal reflux disease (GERD).

AIM

To assess the effect of lesogaberan (AZD3355) - a novel peripherally active GABA(B) receptor agonist - on TLESRs.

METHODS

Twenty-four healthy men were enrolled in this single-blind, placebo-controlled, randomized, single-centre, three-period crossover phase 1 study. Subjects were randomized to receive single oral doses of lesogaberan (0.8 mg/kg), baclofen (40 mg) and placebo, separated by washout periods of < or = 7 days. Subjects finished a meal 1 h after the dose. Oesophageal manometry and pH-metry measurements were taken during the 3 h after the meal.

RESULTS

Twenty-one subjects completed the study. Compared with placebo, lesogaberan 0.8 mg/kg significantly reduced the number of TLESRs by 36% [geometric mean ratio (GMR): 0.64; 95% confidence interval (CI): 0.51-0.82] and significantly reduced the number of acid reflux episodes (mean reduction: 1.6; 95% CI: 0.34-2.9). Lesogaberan also significantly increased lower oesophageal sphincter (LES) pressure by 39% compared with placebo (GMR: 1.39; 95% CI: 1.18-1.64). Comparable results were observed with baclofen. Similar numbers of adverse events were reported by subjects taking lesogaberan and placebo.

CONCLUSION

Compared with placebo, lesogaberan significantly reduced TLESRs and acid reflux episodes and increased LES pressure.

The novel, peripherally restricted GABAB receptor agonist lesogaberan (AZD3355) inhibits acid reflux and reduces esophageal acid exposure as measured with 24-h pHmetry in dogs

While patients with symptoms of gastroesophageal reflux disease generally respond well to proton pump inhibitors, 20-30% continue to experience troublesome symptoms. In such cases, agents that target transient lower esophageal sphincter (LES) relaxation may be useful as add-on therapy to proton pump inhibitors. The GABAB receptor agonist baclofen inhibits transient LES relaxation but it is not an ideal agent due to central nervous system activity. Lesogaberan (AZD3355) is a peripherally restricted GABAB receptor agonist with limited central nervous system activity that inhibits transient LES relaxation in dogs. In the present study, the comparative effects of lesogaberan (7 micromol/kg) and baclofen (2.8 micromol/kg) on reflux were studied in dogs using 24-h pHmetry. Drugs (or vehicle control) were administered orally prior to the first meal of the day, and the number of reflux episodes (pH<4 for > or = 5 s) and acid exposure time were computed for the 24-h monitoring period. The mean (S.E.M.) number of reflux episodes/24 h was 4.6 (0.4) and 6.4 (0.6) for lesogaberan and baclofen, respectively, versus 10.7 (0.5) for control (P<0.0001 for both). Acid exposure time was 51.2 (4.5) min for control versus 23.6 (3.8) min for lesogaberan (P<0.0001) and 35.4 (6.5) min with baclofen (P=0.05). It is concluded that lesogaberan significantly reduces acid reflux in dogs, with comparable efficacy to baclofen.

Roles of gastro-oesophageal afferents in the mechanisms and symptoms of reflux disease

Oesophageal pain is one of the most common reasons for physician consultation and/or seeking medication. It is most often caused by acid reflux from the stomach, but can also result from contractions of the oesophageal muscle. Different forms of pain are evoked by oesophageal acid, including heartburn and non-cardiac chest pain, but the basic mechanisms and pathways by which these are generated remain to be elucidated. Both vagal and spinal afferent pathways are implicated by basic research. The sensitivity of afferent fibres within these pathways may become altered after acid-induced inflammation and damage, but the severity of symptoms in humans does not necessarily correlate with the degree of inflammation. Gastro-oesophageal reflux disease (GORD) is caused by transient relaxations of the lower oesophageal sphincter, which are triggered by activation of gastric vagal mechanoreceptors. Vagal afferents are therefore an emerging therapeutic target for GORD. Pain in the absence of excess acid reflux remains a major challenge for treatment.

Gastroesophageal reflux disease (GERD) and irritable bowel syndrome (IBS)--is it one disease or an overlap of two disorders?

Up to 79% of IBS patients report gastroesophageal reflux disease (GERD) symptoms, and up to 71% of GERD patients report irritable bowel syndrome (IBS) symptoms. There are two principal hypotheses for the common presence of IBS symptoms in GERD patients. The first theory suggests that GERD and IBS overlap in a significant number of patients. The second theory suggests that IBS-like symptoms are part of the spectrum of GERD manifestation. The first theory is supported by genetic studies and similarities in gastrointestinal sensory-motor abnormalities potentially due to general gastrointestinal disorder of smooth muscle or sensory afferents. The other theory is primarily supported by studies demonstrating improvement of IBS-like symptoms in GERD patients receiving anti-reflux treatment. The close relationship between GERD and IBS could be explained by either GERD affecting different levels of the GI tract or a high overlap rate between GERD and IBS due to similar underlying GI dysfunction.

Comparison of the degree of duodenogastroesophageal reflux and acid reflux between patients who failed to respond and those who were successfully treated with a proton pump inhibitor once daily

OBJECTIVES

The objective of this study was to compare the degree of esophageal acid exposure and duodenogastroesophageal reflux (DGER) during treatment between gastroesophageal reflux disease (GERD) patients who responded fully to proton pump inhibitor (PPI) once a day and those who failed to respond.

METHODS

Gastroesophageal reflux disease patients who continued to report symptoms 3 times a week for 3 months while on PPI once a day were assigned to the PPI failure group. GERD patients who were asymptomatic on PPI once a day for 3 months were assigned to the PPI success group. All patients underwent upper endoscopy to assess esophageal mucosal injury. Subsequently, all patients underwent simultaneous 24-h esophageal Bilitec 2000 and pH testing while on treatment. Patients recorded GERD-related symptoms during the test.

RESULTS

Twenty-four patients were enrolled in the PPI failure group and 23 patients were enrolled in the PPI success group. Endoscopy was normal in 63% of PPI failure patients and 76% of PPI success patients. Abnormal DGER was documented in 82% of PPI success patients vs. 67% of PPI failure patients (P=NS). All pH testing and Bilitec parameters in the PPI failure group were similar to those in the PPI success group (P=NS). Of the 34 GERD symptoms recorded by the PPI failure group, 64% were associated with acid reflux and 41% were associated with DGER (P<0.05).

CONCLUSIONS

There is no difference in the degree of DGER and acid exposure during treatment between patients who failed to respond and those who achieved complete symptom resolution on PPI once daily. GERD symptoms in the PPI failure group are more commonly associated with acid reflux than with DGER.

What makes individuals with gastroesophageal reflux disease dissatisfied with their treatment?

BACKGROUND & AIMS

Despite the efficacy of proton pump inhibitors (PPIs) as therapeutics for patients with gastroesophageal reflux disease (GERD) in randomized controlled trials, a number of studies have shown that a proportion of patients with GERD are not satisfied with their treatment. This article reviews the possible reasons why patients are dissatisfied with the way their disease is managed.

METHODS

Studies published between 1970 and 2007 were identified from PubMed, EMBASE, and the author's existing database. The 2708 publications were reviewed, and irrelevant ones were excluded. Eleven studies were found to be appropriate for use in this review.

RESULTS

Patients who are given prescriptions for PPIs tend to be more satisfied than those given H(2)-receptor antagonists. Partial responders are likely to be more dissatisfied than patients whose symptoms are fully resolved. A decrease in health-related quality of life is associated with greater dissatisfaction. Patients are more likely to be satisfied if they are taken seriously by their physician and if their symptoms are investigated. They are also more likely to be satisfied if the patient-physician consultation is interactive.

CONCLUSIONS

Patient satisfaction is a complex issue that depends on many factors. Patient satisfaction can be influenced by treatment regimen, general level of well-being, the bedside manner of the physician, and the quality of patient-physician communication. Improvements in recognition of GERD can improve management of the disease as well as patient satisfaction with their care and treatment.

Utility of non-endoscopic investigations in the practical management of oesophageal disorders

The current available methods for diagnosis of GORD are symptom questionnaires, catheter and wireless pH-metry, impedance-pH monitoring and Bilitec(@). Osophageal pH monitoring allows both quantitative analysis of acid reflux and assessment of reflux-symptom association. Impedance-pH monitoring detects all types of reflux (acid and non-acid) and allows assessment of proximal extent of reflux, a relevant parameter for understanding symptoms perception and extraoesophageal symptoms. Bilitec provides a quantitative assessment of duodeno-gastro-oesophageal reflux. Oesophageal motor abnormalities have been associated with GORD symptoms as well as chest pain and dysphagia. High-resolution manometry contributed to re-classify oesphageal motor disorders. However, barium swallows are still essential for evaluation of oesophageal anatomy and combined oesophageal manometry-impedance can assess oesophageal motility and bolus transit simultaneously in a non-radiological way. Still in experimental phase, high-frequency ultrasound allows monitoring of the oesophageal wall thickness and exaggerated longitudinal muscle contraction that might be associated to chest pain and dysphagia. This chapter provides a critical evaluation of the clinical application of these techniques.

Two-year results of a feasibility study on antireflux transoral incisionless fundoplication using EsophyX

BACKGROUND

A feasibility study (n = 19) evaluated the safety and initial efficacy of transoral incisionless fundoplication (TIF) for the treatment of gastroesophageal disease (GERD). The results at 1 year (n = 17) indicated that TIF was safe and had a significant effect on reducing GERD symptoms, proton pump inhibitor (PPI) usage, acid exposure, and small hiatal hernia. This study was designed to evaluate the long-term safety and durability of TIF.

METHODS

Fourteen patients (50% female; median age, 34 years) completed the 2-year follow-up assessment tests. Three patients were excluded from the study after 1 year because two of them underwent retreatment and one was lost to follow-up.

RESULTS

At 2 years, no adverse events related to TIF were reported. A >or=50% improvement in GERD-HRQL scores compared with those at baseline on PPIs was sustained by 64% of patients. TIF was effective in eliminating heartburn in 93% of patients and daily PPI therapy in 71% of patients. Significantly (p < 0.05) more patients were able to consume reflux-causing foods and maintain lifestyle activities without GERD symptoms compared with baseline on PPIs. Fundoplications were durable and maintained their geometric dimensions. TIF was effective in eliminating hiatal hernia in 60% of patients and esophagitis in 55% of patients. Global assessment of all outcomes in each patient revealed that 79% of patients experienced complete cure (29%) or remission (50%) of GERD at 2 years after TIF.

CONCLUSION

The results at 2 years supported the long-term safety and durability of TIF and its sustained effect on the elimination of heartburn, esophagitis, <or=2 cm hiatal hernia, and daily dependence on PPIs.

Proton pump inhibitor failure--what are the therapeutic options?

Proton pump inhibitor (PPI) failure is very common and may affect up to one-third of the PPI consumers. Identifying the underlying mechanisms for PPI failure in each individual patient is essential for treatment success. For residual acid reflux, increasing the PPI dose to twice daily; switching to another PPI, or adding an histamine 2 receptor antagonist could be a successful therapeutic strategy. In patients with duodenogastroesophageal reflux, weak acidic/alkaline reflux and hypersensitivity to acid reflux, therapeutic modalities that reduce transient lower esophageal sphincter relaxation or visceral pain could be entertained. Treatment of PPI failure due to delayed gastric emptying should be focused on improving gastric motor activity. Psychological management may supplement any medical or surgical approach toward PPI failure.

Pharmacokinetics and pharmacodynamics of a known active PPI with a novel Dual Delayed Release technology, dexlansoprazole MR: a combined analysis of randomized controlled clinical trials

BACKGROUND

Dexlansoprazole MR is a novel Dual Delayed Release formulation of dexlansoprazole, an enantiomer of lansoprazole, designed to prolong the plasma concentration-time profile of dexlansoprazole and extend duration of acid suppression with once-daily (QD) dosing.

OBJECTIVES

To assess the pharmacokinetics and pharmacodynamics of dexlansoprazole at different doses of dexlansoprazole MR and delineate the exposure-response relationship following oral administration of dexlansoprazole MR.

METHODS

Dexlansoprazole MR was evaluated in two prospective randomized studies in healthy subjects. In study 1 (n = 40), subjects received dexlansoprazole MR 60, 90, and 120 mg and lansoprazole 30 mg QD. In study 2 (n = 45), subjects received dexlansoprazole MR 30 and 60 mg and lansoprazole 15 mg QD. Data from these trials were pooled and analyzed to describe the relationship between intragastric pH and dexlansoprazole systemic exposure.

RESULTS

Data from 83 subjects were analyzed. The dexlansoprazole plasma concentration-time profile following administration of dexlansoprazole MR was characterized by two distinct peaks and a prolonged drug exposure during the 24-h dosing interval. Approximate dose proportionality was observed for mean peak plasma concentration and area under the plasma-concentration time curve after administration of dexlansoprazole MR. In each study, doses of dexlansoprazole MR generally produced greater gastric acid suppression than lansoprazole. Based on the exposure-response analysis using combined data from these two trials, the predicted mean 24-h intragastric pH values were 4.06 and 4.35 for the dexlansoprazole MR 30- and 90-mg doses, respectively. The percent of time pH > 4 over 24 h values were 59.2% and 66.7% for dexlansoprazole MR 30 and 90 mg, respectively. No appreciable additional gain in the pharmacodynamic response was predicted for dexlansoprazole MR 120 mg. Despite combining data from two studies to evaluate a broader dose range, this analysis provided a reasonable estimate of the pharmacodynamic parameters and a good characterization of the dexlansoprazole MR exposure-response relationship.

CONCLUSIONS

Dexlansoprazole MR, a proton pump inhibitor that uses Dual Delayed Release technology, produced a pharmacokinetic profile with a plasma concentration-time curve characterized by two distinct peaks and an extended duration of pharmacologically active dexlansoprazole concentration in plasma. Exposure-response analysis indicated a progressive increase in the pharmacodynamic response as dexlansoprazole MR doses increased from 30 to 90 mg.

Review article: gastro-oesophageal reflux disease and psychological comorbidity

BACKGROUND

A growing number of studies have shown the impact of psychological comorbidities on gastro-oesophageal reflux disease (GERD) patients' symptom reports and healthcare-seeking behaviour.

AIM

To review the reported relationship between GERD and psychological comorbidity.

METHODS

Review of the literature on GERD and psychological comorbidity.

RESULTS

Psychological comorbidity is common among GERD patients and appears to afflict all GERD phenotypes. Sexual and physical abuse is also common in GERD patients. Stress enhances perception of oesophageal acid exposure. Treatment for GERD, especially in those who are not responsive to antireflux treatment, may require further evaluation for psychological comorbidity.

CONCLUSIONS

Psychological comorbidity is very common in GERD patients and is likely to play an important role in response, or failure of response, to proton pump inhibitor treatment.

Medical management of gastroesophageal reflux disease

Antisecretory therapies that raise intragastric pH provide the best healing of the esophageal mucosal damage that occurs in gastroesophageal reflux disease. Continuous maintenance therapy is also effective to reduce the likelihood of recurrence of esophagitis and control symptoms in the long term. Proton pump inhibitor (PPI) therapy is an effective approach for healing esophagitis and controlling symptoms. Endoscopic and surgical treatments may provide an option for patients who are refractory to PPIs in whom reflux has been clearly demonstrated. Long-term antireflux medication is often needed after surgical treatment because of persisting or recurrent pathologic reflux and symptoms. An alternative approach to controlling transient lower esophageal sphincter relaxations, such as the GABA-B agonists, deserves further study.

Diagnostic options for patients with refractory GERD

Patients with refractory gastroesophageal reflux disease (GERD) are those who have persistent symptoms while being treated with proton pump inhibitors (PPIs). One third of GERD patients requiring a daily PPI are estimated to eventually experience treatment failure. These patients are usually referred for further investigation to confirm the presence of GERD or to identify other entities as the cause of symptoms. Tools that can be used in this diagnostic process include upper gastrointestinal endoscopy with analysis of esophageal biopsies, esophageal pH monitoring, impedance-pH monitoring, and esophageal bilirubin monitoring. The conventional diagnostic approach includes upper gastrointestinal endoscopy and ambulatory pH monitoring while receiving PPI therapy. New diagnostic techniques that may be useful with refractory GERD include impedance-pH monitoring, which is very sensitive in detecting persistent weakly acidic reflux, and bilirubin monitoring, which detects increased esophageal exposure to bile. Gastric pH monitoring should be reserved for patients in whom PPI resistance is suspected.

[Reasons for proton-pump-inhibitor failure in the treatment of gastroesophageal reflux disease]

The introduction of proton pump inhibitors (PPI) has facilitated the successful management of patients with gastroesophageal reflux disease (GERD). In a minor, but still relevant proportion of patients with GERD-like symptoms, PPI therapy has also proved to be ineffective. In such cases, the first question to be answered is if the symptoms and complaints are related to GERD indeed, or another disorder should be searched for. If GERD is still the most likely diagnosis, patients' compliance should be thoroughly investigated before any further diagnostic and therapeutic measure is taken. If PPI failure is not a result of inadequate management of GERD, there are several other disorders to be ruled out. In our review, we summarize the most important differential diagnostic issues of PPI failure.

Proton pump inhibitors: an update of their clinical use and pharmacokinetics

BACKGROUND

Proton pump inhibitors (PPIs) represent drugs of first choice for treating peptic ulcer, Helicobacter pylori infection, gastrooesophageal reflux disease, nonsteroidal anti-inflammatory drug (NSAID)-induced gastrointestinal lesions (complications), and Zollinger-Ellison syndrome.

RESULTS

The available agents (omeprazole/esomeprazole, lansoprazole, pantoprazole, and rabeprazole) differ somewhat in their pharmacokinetic properties (e.g., time-/dose-dependent bioavailability, metabolic pattern, interaction potential, genetic variability). For all PPIs, there is a clear relationship between drug exposure (area under the plasma concentration/time curve) and the pharmacodynamic response (inhibition of acid secretion). Furthermore, clinical outcome (e.g., healing and eradication rates) depends on maintaining intragastric pH values above certain threshold levels. Thus, any changes in drug disposition will subsequently be translated directly into clinical efficiency so that extensive metabolizers of CYP2C19 will demonstrate a higher rate of therapeutic nonresponse.

CONCLUSIONS

This update of pharmacokinetic, pharmacodynamic, and clinical data will provide the necessary guide by which to select between the various PPIs that differ-based on pharmacodynamic assessments-in their relative potencies (e.g., higher doses are needed for pantoprazole and lansoprazole compared with rabeprazole). Despite their well-documented clinical efficacy and safety, there is still a certain number of patients who are refractory to treatment with PPIs (nonresponder), which will leave sufficient space for future drug development and clinical research.