Combined analysis of three crossover clinical pharmacology studies of effects of rabeprazole and esomeprazole on 24-h intragastric pH in healthy volunteers

Efficacy of long-term maintenance therapy with 10-mg vonoprazan for proton pump inhibitor-resistant reflux esophagitis

BACKGROUND

To investigate the efficacy of long-term (52 weeks) maintenance therapy by 10-mg vonoprazan administration for proton pump inhibitor-resistant reflux esophagitis continued from the preceding study.

METHODS

Sixteen patients with proton pump inhibitor-resistant reflux esophagitis (mean age 70.9 years, eight males) in whom endoscopic healing was achieved by 20-mg vonoprazan administration for 4 weeks and maintenance of remission was maintained by 10-mg vonoprazan administration for 8 weeks were enrolled. Endoscopy was performed at 52 weeks after the initiation of maintenance therapy with 10-mg vonoprazan to evaluate whether there was any recurrence of reflux esophagitis. Changes in the gastric mucosa were investigated at 52 weeks. Symptoms were assessed using the frequency scale for the symptoms of gastroesophageal reflux disease and the fast gastrin level at 8 and 52 weeks following the maintenance therapy.

RESULTS

Endoscopic remission was maintained at 52 weeks in 15 (93.8%) of the 16 patients with proton pump inhibitor-resistant reflux esophagitis. One patient relapsed with grade C of reflux esophagitis. There were no significant differences in the symptom score at 8 and 52 weeks, nor the gastrin level at 8 and 52 weeks. There was no change in the stomach on endoscopy at 52 weeks.

CONCLUSION

Long-term maintenance therapy by 10-mg vonoprazan administration is very effective for proton pump inhibitor-resistant reflux esophagitis patients in whom endoscopic healing was maintained by 8 weeks maintenance therapy with 10-mg vonoprazan administration.

Efficacy of on-demand therapy using 20-mg vonoprazan for non-erosive reflux disease

BACKGROUND

To evaluate the efficacy of on-demand therapy using 20-mg vonoprazan for non-erosive reflux disease.

METHODS

On-demand therapy by taking one 20-mg tablet of vonoprazan only when reflux symptoms occurred was performed for 8 weeks by 30 patients (11 men, mean age: 67.8) with non-erosive reflux disease who responded well to maintenance therapy using proton pump inhibitor and answered "very satisfied" or "satisfied" to an overall satisfaction survey (5-grade scale). The degree of overall satisfaction with the treatment, score of symptoms, and fasting gastrin levels before breakfast was examined before and after on-demand therapy. The number of vonoprazan tablets taken and the frequency (regular, temporary, rare) of its administration were also investigated.

RESULTS

All patients completed 8-week on-demand therapy with 20-mg vonoprazan. Comparisons of patient satisfaction levels before and after therapy revealed no significant differences in the number of patients who were very satisfied and satisfied with the therapy. Furthermore, there were no significant differences in score of symptoms or gastrin levels before and after therapy. During 8-week on-demand therapy, patients took 11 tablets (median) (7.0-18.0 tablets: 25-75 percentiles), and 30.0% of patients (n = 9) took vonoprazan on a regular basis (at least 2 tablets a week).

CONCLUSION

On-demand therapy with 20-mg vonoprazan exerted equivalent effects to continuous PPI maintenance therapy for patients with non-erosive reflux disease.

Pathophysiology of Potassium-competitive Acid Blocker-refractory Gastroesophageal Reflux and the Potential of Potassium-competitive Acid Blocker Test

BACKGROUND/AIMS

Potassium-competitive acid blockers are expected to be the next generation of drugs for the treatment of diseases caused by gastric acid. In 2015, vonoprazan fumarate, a novel potassium-competitive acid blocker, was approved by the Japanese health insurance system. Since its approval, patients refractory to vonoprazan can be encountered in clinical settings. We designed this study to clarify the pathophysiology of gastroesophageal reflux disease refractory to vonoprazan.

METHODS

In this retrospective study, we involved patients who had refractory symptoms after administration of standard-dose proton pump inhibitors or vonoprazan and underwent diagnostic testing with esophageal high-resolution manometry and 24-hour multichannel intraluminal impedance and pH monitoring while using proton pump inhibitors or vonoprazan. Patients were diagnosed based on the Rome IV criteria for functional gastrointestinal disorders and diagnostic test results.

RESULTS

Twenty-seven patients were analyzed during this study. Gastric pH ≥ 4 was sustained for a longer period of time, and the esophageal acid exposure time and number of acid reflux events were shorter in the vonoprazan group than in the proton pump inhibitor group. The percentage of patients diagnosed with acidic gastroesophageal reflux disease in the vonoprazan group was lower than that in the proton pump inhibitor group.

CONCLUSIONS

Intra-gastric pH and acid reflux were strongly suppressed by 20-mg vonoprazan. When patients with gastroesophageal reflux disease present symptoms after administration of 20-mg vonoprazan, the possibility of pathophysiologies other than acid reflux should be considered.

Efficacy of On-Demand Therapy Using 20-mg Vonoprazan for Mild Reflux Esophagitis

BACKGROUND

The study aimed to evaluate the efficacy of on-demand therapy using 20-mg vonoprazan for mild reflux esophagitis (RE).

METHODS

On-demand therapy by taking one 20-mg tablet of vonoprazan only when reflux symptoms occurred was performed for 24 weeks using 30 patients with mild RE who were receiving maintenance therapy with proton pomp inhibitors (PPIs). The presence or absence of RE, degree of overall satisfaction with the treatment, score of symptoms, and fasting gastrin level before breakfast were examined before and after on-demand therapy. The number of tablets taken during the 24-week period was also noted.

RESULTS

One of the 30 patients dropped out of on-demand therapy 1 week after its initiation. Remission was maintained in 25 (86.2%) of the 29 patients (all 10 [100%] Los Angeles classification grade A patients and 15 (78.9%) of the 19 grade B patients). However, 4 grade B patients exhibited grade B relapse. There were no differences in the degree of overall satisfaction, score of symptoms or the gastrin level between PPI and on-demand therapies. The number of vonoprazan tablets taken during the observation period was 33 tablets (median)/24 weeks.

CONCLUSION

On-demand therapy using 20-mg vonoprazan tablets is an effective alternative maintenance therapy for mild RE.

Vonoprazan is Superior to Rabeprazole for Healing Endoscopic Submucosal Dissection: Induced Ulcers

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) is a well-established minimally invasive treatment for early gastric cancer. To heal ESD-induced ulcers, we commonly prescribe proton pump inhibitors (PPIs). Vonoprazan is our new choice, which is reported to have a stronger and longer acid inhibitory effect than existing PPIs. Here, we aimed to evaluate the efficacy of vonoprazan for healing ESD-induced ulcers compared with rabeprazole.

METHODS

We reviewed 190 patients who underwent ESD before and after we switched the acid secretion inhibitor from rabeprazole to vonoprazan. We evaluated scarring and reduction rates at 4 weeks after ESD.

RESULTS

Scarring rates were not different between vonoprazan and rabeprazole (31.7 vs. 18.9%; p = 0.07). However, for ulcers ≤35 mm, vonoprazan was superior to rabeprazole (42.2 vs. 19.2%; p < 0.05). Reduction rates were superior for vonoprazan compared with rabeprazole (93.0 vs. 90.4%; p < 0.05). In multivariate analysis, vonoprazan was superior to rabeprazole for ulcer scarring (OR 2.21; p < 0.05), and ulcer location in the lower-third of the stomach had higher risk of incomplete scarring (OR 0.37; p < 0.05).

CONCLUSION

Vonoprazan was superior to rabeprazole for healing ESD-induced ulcers.

Interchangeable Use of Proton Pump Inhibitors Based on Relative Potency

Although proton pump inhibitors (PPIs) are widely used, their relative potency and ideal dosing regimens remain unclear. We analyzed data from randomized clinical trials that performed pH testing in patients receiving solid-dose PPI formulations (omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole) for a minimum of 5 days. We used omeprazole equivalency and the surrogate biomarker, percentage time pH > 4 over a 24-hour period (pH4time), to compare PPI effectiveness for different PPIs given once, twice, or 3 times daily. We found that increasing strength of once-daily PPIs (9-64 mg omeprazole equivalents) increased pH4time linearly from approximately 10.0 to 15.6 hours; higher doses produced no further increase in pH4time. Increasing the frequency to twice-daily PPI increased pH4time linearly, from approximately 15.8 to 21.0 hours. Three-times daily PPIs performed similarly to twice-daily PPIs. The costs of PPIs varied greatly, but the cost variation was not directly related to potency. We conclude that PPIs can be used interchangeably based on potency. Using twice-daily PPIs is more effective in increasing efficacy increasing once-daily PPI dosage. Omeprazole and lansoprazole (30 mg) and 20 mg of esomeprazole rabeprazole are functionally equivalent.

Efficacy of vonoprazan for 24-week maintenance therapy of patients with healed reflux esophagitis refractory to proton pump inhibitors

The aim of the present study was to evaluate the efficacy of a potassium-competitive acid blocker (P-CAB), vonoprazan, for the maintenance therapy of healed reflux esophagitis (RE). A total of 60 patients were enrolled in this open-label, single-center, prospective study. All patients were diagnosed with RE with a frequency scale for the symptoms of gastroesophageal reflux disease (FSSG) total score ≥8 following treatment with standard proton pump inhibitors (PPIs) for a minimum of 8 weeks. Standard PPI treatment was switched to vonoprazan 20 mg once daily for 4 weeks. A total of 52 patients, who had no endoscopic evidence of erosive esophagitis following vonoprazan treatment, received maintenance therapy with vonoprazan 10 mg once daily for 24 weeks. Symptoms were evaluated using the FSSG and Gastrointestinal Symptom Rating Scale (GSRS). Upper gastrointestinal endoscopies were performed following 24 weeks of maintenance therapy. The primary endpoint was to determine the proportion of patients who exhibited maintenance of healed RE refractory to PPIs following 24 weeks of maintenance therapy with vonoprazan 10 mg once daily. Secondary endpoints included evaluation of the proportion of patients with symptomatic non-relapse at 24 weeks. Maintenance therapy with vonoprazan 10 mg once daily prevented relapse of esophageal mucosal breaks in 37/43 (86.0%) patients at 24 weeks. However, the number of patients with symptomatic relapse was 1 (1.9%) and 4 (7.7%) at 4 and 8 weeks, respectively. A total of 4 patients were withdrawn due to loss to follow-up. At the end of the 24-week maintenance period, the symptomatic non-relapse rate for acid reflux-associated and dysmotility symptom FSSG scores were 86.5 and 80.8%, respectively. Furthermore, the symptomatic non-relapse rate for reflux, abdominal pain, indigestion, diarrhea, and constipation GSRS scores at 24 weeks were 86.5, 80.8, 75.0, 71.2 and 76.9%, respectively. No serious adverse events were reported during the study. The mean gastrin level was 1,059 pg/ml. In conclusion, the results of the present study indicate that vonoprazan 10 mg once daily is effective for 24-week maintenance therapy of healed RE refractory to PPIs.

A novel K+ competitive acid blocker, YH4808, sustains inhibition of gastric acid secretion with a faster onset than esomeprazole: randomised clinical study in healthy volunteers

BACKGROUND

YH4808, a K⁺ -competitive acid blocker, is under clinical development for the treatment of acid-related disorders, such as gastroesophageal reflux disease.

AIMS

To determine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of YH4808, compared to placebo and esomeprazole.

METHODS

This double-blind, randomised, placebo- and active comparator (esomeprazole)-controlled study was conducted with 123 healthy male volunteers. We evaluated YH4808 (30-800 mg) properties, administered in single (N=55) and multiple (N=24) oral doses, and recorded the effects on 24-hour intragastric acidity. Results were compared to placebo (N=20) and esomeprazole 40 mg (N=24).

RESULTS

Plasma YH4808 exposure increased dose-proportionally and declined in a multi-phasic manner. YH4808 ≥200 mg/d maintained intragastric acidity at pH >4 for longer times than esomeprazole during both day and night (%Time at pH >4: >70% vs 58% of a 24-hour period, respectively; and >50% vs 33% of a 9-hour night respectively). A twice-daily regimen of YH4808 more effectively controlled intragastric pH at night than a once-daily regimen. In evaluating the mean areas under the intragastric pH-time curves in 15-minute intervals for 2 hours after dosing, we found that YH4808 had a faster onset than esomeprazole. Moreover, unlike esomeprazole, YH4808 PK and PD were not significantly affected by the CYP2C19 genotype of the subjects. YH4808 was well-tolerated at all doses administered.

CONCLUSION

This study showed that YH4808 produced a rapid, sustained suppression of gastric secretion with good tolerability. The results at YH4808 ≥200 mg/d provide a rationale for further clinical investigations in populations with acid-related diseases.

Efficacy of Vonoprazan for Proton Pump Inhibitor-Resistant Reflux Esophagitis

BACKGROUND

Vonoprazan (VPZ) is a novel potassium-competitive acid blocker that may be clinically beneficial for proton pump inhibitor (PPI)-resistant reflux esophagitis (RE). The aim of this study was to investigate the efficacies of VPZ therapy at 20 mg for 4 weeks in patients with PPI-resistant RE and VPZ maintenance therapy at 10 mg for 8 weeks in patients who have been successfully treated.

METHODS

Subjects comprised 24 patients with PPI-resistant RE (Los Angeles classification grade A/B/C/D: 3/7/11/3). After confirming PPI-resistant RE by endoscopy, 20 mg VPZ was administered. Endoscopy was performed 4 weeks after the initiation of VPZ. Symptoms were evaluated using the frequency scale for the symptoms of gastroesophageal reflux disease (FSSG). Maintenance therapy with 10 mg VPZ was performed and endoscopy was conducted after 8 weeks.

RESULTS

In 21 (87.5%) out of 24 patients, esophageal mucosal breaks were successfully treated by 20 mg VPZ. The median FSSG score was significantly lower on days 1-7, 14, and 28 after the initiation of VPZ than before its administration. Maintenance therapy with 10 mg VPZ prevented the relapse of esophageal mucosal breaks in 16 (76.2%) out of 21 patients.

CONCLUSION

VPZ was effective for most patients with PPI-resistant RE.

Pharmacokinetic and Pharmacodynamic Modeling Analysis of Intravenous Esomeprazole in Healthy Volunteers

Esomeprazole is one of the most commonly used drugs to treat gastroesophageal reflux disease and peptic ulcers, but the quantitative relationships among the pharmacokinetics (PK), pharmacodynamics (PD), and pharmacogenomics (PG) of the drug are not fully understood in special patient populations. A clinical PK/PD/PG study of intravenous (IV) esomeprazole in 5 dosing regimens was conducted in 20 healthy Chinese volunteers, who were categorized into Helicobacter pylori (HP)-negative and HP-positive subgroups. Plasma esomeprazole concentration and intragastric H(+) concentration were monitored for 24 hours postdosing. Population PK (PopPK) models were tested based on elimination characteristics and other data. For a single-dose IV esomeprazole regimen, a 2-compartment model with nonlinear elimination characteristics fitted the PK data well. The elimination of esomeprazole was found to be significantly linked to CYP2C19 genotype by 11% to 29%. A mechanism-based PD model was first tested to mimic the irreversible inhibition of H(+) /K(+) -ATPase by esomeprazole using a cell-killing mechanism and models of gastric H(+) secretion that included the effects of an asymmetric circadian rhythm and food effects. Results from this PD model showed that the turnover rate of H(+) /K(+) -ATPase was significantly different between HP-negative and HP-positive subgroups. In conclusion, the PopPK model quantitatively identified the effects of the CYP2C19 genotype on esomeprazole elimination in healthy subjects for the first time. In addition, the effects of HP status on drug effect, H(+) /K(+) -ATPase turnover, and circadian rhythm amplitude were preliminarily explored using a mechanism-based PD model.

Prevalence of gastroesophageal reflux disease symptoms and effects of esomeprazole on the quality of life related to reflux and dyspepsia in patients on maintenance hemodialysis

BACKGROUND

The prevalence of gastroesophageal reflux disease (GERD) symptoms has not been investigated in patients on maintenance hemodialysis in Japan, and few studies have reported the effect of proton pump inhibitors (PPIs) in hemodialysis patients with GERD symptoms. Here, we investigated the prevalence of GERD symptoms and the effects of the PPI esomeprazole on the quality of life related to reflux and dyspepsia in patients on maintenance hemodialysis.

METHODS

This was a cross-sectional/cohort study of hemodialysis outpatients implemented in 10 Japanese medical facilities from October 2012 to March 2014. The trial was registered in the UMIN Clinical Trial Registry (UMIN000009124).

RESULTS

Forty-one of 385 patients (11%) reported GERD symptoms on the Global Overall Symptom (GOS) questionnaire. Multivariate logistic regression analysis identified the independent prognostic factors for GERD symptoms as a history of gastric ulcer and use of sevelamer hydrochloride or calcium polystyrene sulfonate. Participants with GERD symptoms completed the Quality of Life in Reflux and Dyspepsia, Japanese version (QOLRAD-J) questionnaire and were assigned to receive 4-week esomeprazole treatment (20 mg/day). This PPI therapy significantly improved all QOLRAD-J domains in the full analysis set (n = 28) and improved the GERD symptoms listed in the GOS questionnaire. Significantly impaired disease-specific quality of life (QOL) in the QOLRAD-J domains was observed in 44.4-74.1% of patients who had symptoms before treatment. The mean GOS and QOLRAD-J scores correlated significantly.

CONCLUSION

Therapy with 20 mg/day esomeprazole appears to be efficacious for improving disease-specific QOL and GERD symptoms in Japanese patients on maintenance hemodialysis.

Intra-gastric pH following single oral administrations of rabeprazole and esomeprazole: double-blind cross-over comparison

Comparisons between the acid inhibitory effects of rabeprazole and esomeprazole after single oral administration with standard doses have not been previously presented. We examined intra-gastric pH after oral administrations of these two proton pump inhibitors using 24-h pH monitoring. Fifty-four normal volunteers not infected by Helicobacter pylori were investigated. Using a cross-over design, we administered 10 mg of rabeprazole or 20 mg of esomeprazole in 27 at 30 min after supper and in the remaining 27 subjects at 15 min before supper, and performed 24-h pH monitoring. Intra-gastric pH data were nearly identical when the proton pump inhibitors were taken after meals. Even if the data were compared in different CYP2C19 genotypes, rabeprazole and esomeprazole did not show the difference. In poor metabolizer, both of the drugs showed stronger acid inhibition. When taken before meals, intra-gastric pH after esomeprazole administration was slightly but not significantly higher than that observed after rabeprazole administration not only in daytime but also in nighttime period. In conclusion, rabeprazole and esomeprazole were similarly effective when administered after a meal.

Effects of Esomeprazole on the Pharmacokinetics of Lapatinib in Breast Cancer Patients

The aqueous solubility of lapatinib declines significantly at pH >4, suggesting that its bioavailability might be lowered by acid-reducing drugs. A study was therefore conducted to assess the effects of esomeprazole on lapatinib pharmacokinetics (PK). Women with metastatic human epidermal growth factor receptor 2 positive (HER2(+) ) breast cancer were enrolled. Patients received 1,250 mg lapatinib once daily (QD) in the morning on Days 1-7 (Period 1) and Days 8-14 (Period 2) with 40 mg esomeprazole QD at bedtime 3 hours after dinner on Days 8-14. Lapatinib PK sampling occurred during the 24-hour steady-state dosing intervals on Day 7 (lapatinib alone) and Day 14 (lapatinib with esomeprazole). Esomeprazole treatment resulted in decreased lapatinib bioavailability (mean 26%, range 6-49%) that was inversely associated with patient age as a significant covariate.

A comparison of the acid-inhibitory effects of esomeprazole and rabeprazole in relation to pharmacokinetics and CYP2C19 polymorphism

BACKGROUND

Esomeprazole and rabeprazole are metabolised in the liver by means of the CYP2C19 enzyme, which has several functional genetic polymorphisms. Among Caucasians, 70% of the population has a fast metaboliser phenotype, 25-30% an intermediate and 2-5% a slow metaboliser phenotype. It is unknown whether different PPIs are affected to the same extent by these phenotypic differences.

AIM

To compare the acid-inhibitory effects of esomeprazole 40 mg and rabeprazole 20 mg in relation to CYP2C19 genotype and pharmacokinetics.

METHODS

Eighteen healthy Helicobacter pylori-negative Caucasian subjects with CYP2C19*2-*6 and *17 genotype were included in a randomised investigator-blinded crossover study with esomeprazole 40 mg and rabeprazole 20 mg. Intragastric 24-h pH-monitoring was performed on days 0, 1 and 5 of oral dosing.

RESULTS

Onset of acid inhibition during the first 4 h after administration did not differ significantly between PPIs. During the upright period, the proportion of time with pH >4 was significantly higher with esomeprazole compared to rabeprazole (52.2 vs. 40.3%, P = 0.003). At day 1 and 5, acid inhibition was significantly greater with esomeprazole than with rabeprazole (median intragastric pH: day 1: 3.7 vs. 3.0, P = 0.008; day 5: 4.7 vs. 3.8, P < 0.001; percentage of time pH >4: day 1: 45 vs. 39%, P = 0.054; day 5: 65 vs. 48%, P < 0.001). Differences in acid inhibition between wt/wt and wt/*2 genotype were significant for both PPIs.

CONCLUSIONS

Once-daily dosing with esomeprazole 40 mg provides a more effective and faster acid-inhibitory effect than rabeprazole 20 mg. The acid-inhibitory effect of esomeprazole and rabeprazole are both influenced by CYP2C19 polymorphism.

Systematic review: the use of proton pump inhibitors and increased susceptibility to enteric infection

The use of proton pump inhibitors (PPIs) is increasing worldwide. Suppression of gastric acid alters the susceptibility to enteric bacterial pathogens. AIM  This systematic review was undertaken to examine the relationship between PPI use and susceptibility to enteric infections by a specific pathogen based on published literature and to discuss the potential mechanisms of PPI enhanced pathogenesis of enteric infections. METHODS  PubMed, OVID Medline Databases were searched. Search terms included proton pump inhibitors and mechanisms of, actions of, gastric acid, enteric infections, diarrhoea, Clostridium difficile, Salmonella, Shigella and Campylobacter. RESULTS The use of PPIs increases gastric pH, encourages growth of the gut microflora, increases bacterial translocation and alters various immunomodulatory and anti-inflammatory effects. Enteric pathogens show variable gastric acid pH susceptibility and acid tolerance levels. By multiple mechanisms, PPIs appear to increase susceptibility to the following bacterial enteropathogens: Salmonella, Campylobacter jejuni, invasive strains of Escherichia coli, vegetative cells of Clostridium difficile, Vibrio cholerae and Listeria. We describe the available evidence for enhanced susceptibility to enteric infection caused by Salmonella, Campylobacter and C. difficile by PPI use, with adjusted relative risk ranges of 4.2-8.3 (two studies); 3.5-11.7 (four studies); and 1.2-5.0 (17 of 27 studies) for the three respective organisms. CONCLUSIONS Severe hypochlorhydria generated by PPI use leads to bacterial colonisation and increased susceptibility to enteric bacterial infection. The clinical implication of chronic PPI use among hospitalized patients placed on antibiotics and travellers departing for areas with high incidence of diarrhoea should be considered by their physicians.

Clinical trial: the treatment of gastro-oesophageal reflux disease in primary care--prospective randomized comparison of rabeprazole 20 mg with esomeprazole 20 and 40 mg

BACKGROUND

A trial of empirical PPI therapy is usual practice for most patients with symptoms of gastro-oesophageal reflux disease (GERD) in primary care.

AIM

To determine if the 4-week efficacy of rabeprazole 20 mg for resolving heartburn and regurgitation symptoms is non-inferior to esomeprazole 40 mg or 20 mg.

METHODS

In all, 1392 patients were randomized to rabeprazole 20 mg, esomeprazole 20 mg or 40 mg once daily. Patients, doctors and assessors were blinded. Symptom resolution data were collected on days 0-7 and day-28 using the Patient Assessment of Upper Gastrointestinal Disorders Symptom Severity Index with a shortened version used on days 8-27.

RESULTS

Rabeprazole 20 mg was non-inferior to esomeprazole 40 mg for complete resolution of regurgitation and satisfactory resolution of heartburn and regurgitation. For complete heartburn resolution, the efficacy of rabeprazole 20 mg and esomeprazole 40 mg was statistically indistinguishable, although the non-inferiority test was inconclusive. Rabeprazole 20 mg was non-inferior to esomeprazole 20 mg for all outcomes.

CONCLUSIONS

In uninvestigated GERD patients, rabeprazole 20 mg was non-inferior to esomeprazole 40 mg for complete and satisfactory relief of regurgitation and satisfactory relief of heartburn, and not different for complete resolution of heartburn.

Relative potency of proton-pump inhibitors-comparison of effects on intragastric pH

AIM

Comparative potency of proton-pump inhibitors (PPIs) is an important clinical issue. Most available trials have compared the different PPIs at one or a few selected specific dosages, making it difficult to derive quantitative equivalence dosages. Here we derived PPI dose equivalents based on a comprehensive assessment of dose-dependent effects on intragastric pH.

METHODS

All available clinical studies reporting the effects of PPIs on mean 24-h intragastric pH were sought from electronic databases including Medline. Studies included were restricted to those targeting the Caucasian population, and healthy volunteers or gastroesophageal reflux disease (GERD) patients. The dose-effect relationships for mean 24-h intragastric pH and for percentage of time with pH > 4 in 24 h were analyzed for each PPI using pharmacodynamic modeling with NONMEM and a model integrating all available data.

RESULTS

Fifty-seven studies fulfilled the inclusion criteria. Based on the mean 24-h gastric pH, the relative potencies of the five PPIs compared to omeprazole were 0.23, 0.90, 1.00, 1.60, and 1.82 for pantoprazole, lansoprazole, omeprazole, esomeprazole, and rabeprazole, respectively. Compared with healthy volunteers, patients with GERD needed a 1.9-fold higher dose and Helicobacter pylori-positive individuals needed only about 20% of the dose to achieve a given increase in mean 24-h intragastric pH.

CONCLUSION

The present meta-analysis provides quantitative estimates on clinical potency of individual PPIs that may be helpful when switching between PPIs and for assessing the cost-effectiveness of specific PPIs. However, our estimates must be viewed with caution because only a limited dose range has been tested and not exactly the same study conditions were applied for the different substances.

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.

Rabeprazole: a second-generation proton pump inhibitor in the treatment of acid-related disease

Rabeprazole is a proton pump inhibitor (PPI) presenting a very advantageous pharmacodynamic and pharmacokinetic profile over older PPIs. In particular, this drug has a very fast onset of action, due to a short activation time and a very high pKa, and may therefore be defined as a 'second generation' PPI. The aim of this article is to provide an update on the pharmacology and clinical profile of rabeprazole and its use in acid-related disorders, with a particular focus on its role in gastroesophageal reflux disease; in the treatment and prevention of duodenal and gastric ulcers and Zollinger-Ellison syndrome; in the therapy of the extraesophageal manifestations of gastroesophageal reflux disease (in particular the respiratory and ear, nose and throat ones); and in the eradication of Helicobacter pylori.

Comparison of esomeprazole enteric-coated capsules vs esomeprazole magnesium in the treatment of active duodenal ulcer: A randomized, double-blind, controlled study

AIM: To evaluate the efficacy and tolerability of two different preparations of esomeprazole in healing duodenal ulcers.

METHODS: A total of 60 patients with active duodenal ulcers were enrolled and randomized to receive esomeprazole enteric-coated capsules (40 mg) or esomeprazole magnesium (40 mg), once daily, for 4 consecutive wk, with ulcer healing being monitored by endoscopy. Safety and tolerability were also assessed.

RESULTS: Fifty seven patients completed the whole trial. The ulcer healing rates at the end of wk 2 were 86.7% and 85.2% in the esomeprazole enteric-coated capsules and esomeprazole magnesium groups, respectively (P = 0.8410), and reached 100% at the end of wk 4 in both groups. Symptom relief at the end of wk 2 was 90.8% in the esomeprazole enteric-coated capsules group and 86.7% in the esomeprazole magnesium group (P = 0.5406); at the end of wk 4 symptom relief was 95.2% and 93.2%, respectively (P = 0.5786). Adverse events occurred in 16.7% of the esomeprazole enteric-coated capsules group and 14.8% of the esomeprazole magnesium group (P = 1.0000).

CONCLUSION: The efficacies of esomeprazole enteric-coated capsules and esomeprazole magnesium in healing duodenal ulcer lesions and relieving gastrointestinal symptoms are equivalent. The tolerability and safety of both drugs were comparable.