Review article: pH, healing and symptom relief with rabeprazole treatment in acid-related disorders

Gastrointestinal and hepatic diseases during the COVID-19 pandemic: Manifestations, mechanism and management

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is considered the causative pathogen of coronavirus disease 2019 (COVID-19) and has become an international danger to human health. Although respiratory transmission and symptoms are still the essential manifestations of COVID-19, the digestive system could be an unconventional or supplementary route for COVID-19 to be transmitted and manifested, most likely due to the presence of angiotensin-converting enzyme 2 (ACE2) in the gastrointestinal tract. In addition, SARS-CoV-2 can trigger hepatic injury via direct binding to the ACE2 receptor in cholangiocytes, antibody-dependent enhancement of infection, systemic inflammatory response syndrome, inflammatory cytokine storms, ischemia/reperfusion injury, and adverse events of treatment drugs. Gastrointestinal symptoms, including anorexia, nausea, vomiting, and diarrhea, which are unusual in patients with COVID-19, and some digestive signs may occur without other respiratory symptoms. Furthermore, SARS-CoV-2 can be found in infected patients' stool, demonstrating the likelihood of transmission through the fecal-oral route. In addition, liver function should be monitored during COVID-19, particularly in more severe cases. This review summarizes the evidence for extra-pulmonary manifestations, mechanisms, and management of COVID-19, particularly those related to the gastrointestinal tract and liver.

COVID-19-associated gastrointestinal and liver injury: clinical features and potential mechanisms

Coronavirus disease-2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The infection is spreading globally and poses a huge threat to human health. Besides common respiratory symptoms, some patients with COVID-19 experience gastrointestinal symptoms, such as diarrhea, nausea, vomiting, and loss of appetite. SARS-CoV-2 might infect the gastrointestinal tract through its viral receptor angiotensin-converting enzyme 2 (ACE2) and there is increasing evidence of a possible fecal–oral transmission route. In addition, there exist multiple abnormalities in liver enzymes. COVID-19-related liver injury may be due to drug-induced liver injury, systemic inflammatory reaction, and hypoxia–ischemia reperfusion injury. The direct toxic attack of SARS-CoV-2 on the liver is still questionable. This review highlights the manifestations and potential mechanisms of gastrointestinal and hepatic injuries in COVID-19 to raise awareness of digestive system injury in COVID-19.

Modulations in extracellular calcium lead to H+-ATPase-dependent acid secretion: a clarification of PPI failure

The H⁺,K⁺-ATPase was identified as the primary proton secretory pathway in the gastric parietal cell and is the pharmacological target of agents suppressing acid secretion. Recently, we identified a second acid secretory protein expressed in the parietal cell, the vacuolar H⁺-ATPase (V-type ATPase). The aim of the present study was to further characterize H⁺-ATPase activation by modulations in extracellular calcium via the calcium sensing receptor (CaSR). Isolated gastric glands were loaded with the pH indicator dye BCECF-AM [2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester] to measure intracellular pH. Experiments were conducted in the absence of sodium and potassium to monitor H⁺-ATPase-specific transport activity. CaSR was activated with the calcimimetic R568 (400 nM) and/or by modulations in extracellular Ca²⁺. Elevation in calcium concentrations increased proton extrusion from the gastric parietal cell. Allosteric modification of the CaSR via R568 and calcium increased vacuolar H⁺-ATPase activity significantly (ΔpH/min_lowCa²⁺_(0.1mM) = 0.001 ± 0.001, ΔpH/min_normalCa²⁺_(1.0mM) = 0.033 ± 0.004, ΔpH/min_highCa²⁺_(5.0mM) = 0.051 ± 0.005). Carbachol significantly suppressed calcium-induced gastric acid secretion via the H⁺-ATPase under sodium- and potassium-free conditions. We conclude that the V-type H⁺-ATPase is tightly linked to CaSR activation. We observed that proton pump inhibitor (PPI) exposure does not modulate H⁺-ATPase activity. This elevated blood calcium activation of the H⁺-ATPase could provide an explanation for recurrent reflux symptoms while taking a PPI therapy. NEW & NOTEWORTHY This study emphasizes the role of the H⁺-ATPase in acid secretion. We further demonstrate the modification of this proton excretion pathway by extracellular calcium and the activation of the calcium sensing receptor CaSR. The novelty of this paper is based on the modulation of the H⁺-ATPase via both extracellular Ca (activation) and the classical secretagogues histamine and carbachol (inactivation). Both activation and inactivation of this proton pump are independent of PPI modulation.

Proton pump inhibitors: from CYP2C19 pharmacogenetics to precision medicine

Introduction: Proton Pump inhibitors (PPIs) are commonly used for a variety of acid related disorders. Despite the overall effectiveness and safety profile of PPIs, some patients do not respond adequately or develop treatment related adverse events. This variable response among patients is in part due to genotype variability of CYP2C19, the gene encoding the CYP450 (CYP2C19) isoenzyme responsible for PPIs metabolism.

Areas covered: This article provides an overview of the pharmacokinetics and mechanism of action of the currently available PPIs, including the magnitude of CYPC19 contribution to their metabolism. Additionally, the role of CYP2C19 genetic variability in the therapeutic effectiveness or outcomes of PPI therapy is highlighted in details, to provide supporting evidence for the potential value of CYP2C19 genotype-guided approaches to PPI drug therapy.

Expert opinion: There is a large body of evidence describing the impact of CYP2C19 variability on PPIs and its potential role in individualizing PPI therapy, yet, CYP2C19 pharmacogenetics has not been widely implemented into clinical practice. More data are needed but CYP2C19 genotype-guided dosing of PPIs is likely to become increasingly common and is expected to improve clinical outcomes, and minimize side effects related to PPIs.

Efficacy and Safety Profile of Z-215 (Azeloprazole Sodium), a Proton Pump Inhibitor, Compared with Rabeprazole Sodium in Patients with Reflux Esophagitis: A Phase II, Multicenter, Randomized, Double-Blind, Comparative Study

BACKGROUND

The metabolism of many proton pump inhibitors is influenced by CYP2C19 genotype, which is a limitation of their use.

OBJECTIVES

To determine the efficacy and safety profile of Z-215 (azeloprazole sodium) as initial treatment for reflux esophagitis (RE), dose response, and optimal dose compared with rabeprazole sodium (RPZ).

METHODS

We conducted an exploratory, multicenter, randomized, double-blind, parallel-group study in Japan. Patients with RE aged ≥20 years were enrolled and randomly assigned to receive 10, 20, or 40 mg Z-215 or 10 mg RPZ (1:1:1:1), and orally administered the respective drug for 8 weeks. The primary efficacy end point was the endoscopic healing rate after 8 weeks of treatment (at Week 8). We also assessed the effects of CYP2C19 genotype. Safety end points were the incidence of adverse events and adverse drug reactions.

RESULTS

Five hundred three patients received the study drugs (10 mg Z-215: 125 patients, 20 mg Z-215: 126 patients, 40 mg Z-215: 126 patients, and 10 mg RPZ: 126 patients). The endoscopic healing rate at Week 8 was above 95% in all groups (10 mg Z-215: 95.2%, 20 mg Z-215: 96.8%, 40 mg Z-215: 95.2%, and 10 mg RPZ: 96.8%). The endoscopic healing rate and serum gastrin levels of the Z-215 groups were not influenced by CYP2C19 genotype. In patients with Grade C/D, the endoscopic healing rate at Week 4 was slightly higher in the 40-mg Z-215 group compared with the other groups. Incidences of adverse events/adverse drug reactions did not markedly differ between the Z-215 and 10-mg RPZ groups.

CONCLUSIONS

Z-215 was as effective and well tolerated as 10 mg RPZ in the treatment of RE in this selected population. CYP2C19 genotype status may not influence the efficacy and safety of Z-215. There were no clear dose-response effects between Z-215 doses in the endoscopic healing of RE. These findings suggest that Z-215 may be 1 option for the initial treatment of RE. ClinicalTrials.gov identifier: NCT 02463643.

Rabeprazole and esomeprazole in mild-to-moderate erosive gastroesophageal reflux disease: A comparative study of efficacy and safety

Objective:

To compare the efficacy and safety of rabeprazole and esomeprazole in mild-to-moderate erosive gastroesophageal reflux disease (GERD).

Materials and Methods:

A randomized, single-blinded, outdoor-based clinical study was conducted on 60 patients of mild-to-moderate erosive GERD. After baseline clinical assessment and investigations, rabeprazole (40 mg) was prescribed to 30 patients and esomeprazole (40 mg) to another 30 patients for 4 weeks. The efficacy variables were change in GERD symptom scoring, endoscopic findings, and Quality of Life in Reflux and Dyspepsia (QOLRAD) scoring over 4 weeks.

Result:

Heartburn, acid regurgitation, and overall GERD symptom scoring (P = 0.01) were significantly decreased with rabeprazole in comparison to esomeprazole. The comparative study of all five domains of the QOLARD questionnaire including overall scoring revealed a statistically significant improvement in the rabeprazole group. Endoscopic findings in the rabeprazole group showed an absolute improvement of 30% and relative improvement of 55% over esomeprazole. Both the drugs were well tolerated having no significant difference in the incidence of adverse effects.

Conclusion:

Rabeprazole (40 mg) is a better choice for mild-to-moderate GERD compared with esomeprazole (40 mg) because of its better efficacy and safety profile.

Clinical predictors for response to proton pump inhibitor treatment in patients with globus

Background/Aims

Globus is a persistent or intermittent non-painful sensation of a lump or foreign body in the throat. Given the benign nature of the condition and the association of gastroesophageal reflux disease, empirical therapy with proton pump inhibitor seems reasonable for patients with typical globus. The aim of this study was to investigate the clinical predictors for symptom response to short-term proton pump inhibitor treatment in patients with globus symptom.

Methods

Fifty-four patients with globus symptom were enrolled prospectively. All patients were treated with pantoprazole 40 mg daily for 4 weeks. Treatment response was defined as a > 50% reduction in symptom scores between symptom assessments. Univariate and multivariate logistic regression analysis between responders and non-responders was performed to identify variables predicting response to pantoprazole treatment.

Results

Of the 54 consecutive patients considered, 13 were excluded on the basis of exclusion criteria and/or refusal to participate in the study. Finally, 41 patients were included in this study. After 4-week pantoprazole treatment, 22 patients (53.7%) were classified as responders. On multivariate analysis, the presence of reflux symptom was associated with a higher response rate to 4-week pantoprazole treatment (OR, 68.56; P = 0.043), and long symptom duration (≥ 3 months) were associated with a lower response rate to pantoprazole treatment (OR, 0.03; P = 0.034).

Conclusions

Presence of reflux symptom and short symptom duration were independent predictors of responsiveness to 4-week pantoprazole treatment in patients with globus.

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.

Endoscopic grading of gastroesophageal flap valve helps predict proton pump inhibitor response in patients with gastroesophageal reflux disease

OBJECTIVE

Limited information is available on predictors of the response to proton pump inhibitor (PPI) treatment in patients with gastroesophageal reflux disease (GERD). Endoscopic grading of gastroesophageal flap valve (GEFV) is simple and reproducible, and can provide useful information on patients with suspected reflux undergoing an endoscopy. The aim of this study was to prospectively identify predictors, including endoscopic findings such as GEFV, for PPI treatment outcomes in patients with GERD.

MATERIAL AND METHODS

One hundred and fifty consecutive patients with GERD were enrolled. All patients were treated with pantoprazole 40 mg daily for 8 weeks. Treatment response was defined as greater than 50% reduction in symptom scores between the two symptom assessments (i.e., over 4 or 8 weeks). Univariate and multivariate logistic regression analyses between responders and non-responders were performed to identify variables predicting response to pantoprazole treatment.

RESULTS

Of the 150 consecutive patients considered for this study, 31 were excluded based on exclusion criteria and/or refusal to participate, leaving 119 eligible patients. After 4-week pantoprazole treatment, 70 of 119 (58.8%) patients were classified as responders. Patients with obesity and Helicobacter pylori infection demonstrated a higher response rate to 4-week pantoprazole treatment (odds ratio (OR) 5.28, p = 0.008; OR 3.76, p = 0.023, respectively). Patients with abnormal GEFV showed a lower response rate to 4-week treatment (OR 0.17, p = 0.016). After 8-week treatment, 86 of 119 (72.3%) patients were classified as responders. Abnormal GEFV and aspirin intake were associated with a lower response rate to 8-week treatment (OR 0.17, p = 0.021; OR 0.11, p = 0.020, respectively).

CONCLUSIONS

Abnormal GEFV was a significant independent factor predicting poor response to both 4-week and 8-week pantoprazole treatment. Endoscopic grading of GEFV provides useful information for predicting the response to PPI treatment in patients with GERD.

The effect of gastroesophageal flap valve appearance on the management of patients with symptoms of gastroesophageal reflux disease

PURPOSE

To assess the effectiveness of anti-reflux treatment in gastroesophageal reflux disease patients classified according to esophagogastric junction morphology (Hill classification).

RESULTS

A symptom score and endoscopic grading of gastrooesophageal flap valve appearance were determined in 49 symptomatic patients (female 26, male 23; mean age 49 years, range 21-76 years). Patients received 8 weeks of continuous rabeprazole at a daily dose of 20 mg and, upon symptom control, continued with on-demand treatment for 3 months. The mean symptom score at 8 weeks was significantly reduced in all groups. However, at the end of the on-demand therapy, patients with Hill grade IV had used more rabeprazole tablets than those in the two other groups (II: 10.86 +/- 14.52, III: 14.73 +/- 14.58, IV: 25.78 +/- 15.85; P = 0.002).

CONCLUSIONS

Continuous treatment is effective in all groups of patients with reflux disease. Grading patients according to the gastroesophageal flap valve appearance is useful as a prognostic factor, especially when on-demand therapy is considered to be an option.

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.

Comparative efficacy of rabeprazole and pantoprazole in the control of nocturnal Acid output and intragastric acidity

BACKGROUND/AIMS

Nocturnal reflux is a largely undiagnosed and unmanaged condition predisposing to multiple esophageal complications. We evaluated the effects of rabeprazole and pantoprazole on nocturnal intragastric pH and gastric acid output during Day 1 of therapy following the consumption of standard meals.

METHODS

The study had a double-blinded, randomized, two-way crossover design, and involved 15 patients with a history of mild reflux. Following an overnight fast, patients were given either rabeprazole (20 mg) or pantoprazole (40 mg) prior to the first of three standard Western meals. They then underwent overnight continuous intragastric pH monitoring and gastric acid output measurement. The drug effect was analyzed using a two-treatment, two-period crossover mixed model.

RESULTS

The percentage of time during which the mean intragastric pH was greater than 4.0 and gastric acid output was less than 2.0 was higher for oral rabeprazole (p<0.05). The inhibition of acid output was greater for rabeprazole at almost all time points. Furthermore, the mean time-matched pH values differed significantly over the first 8.3 hours (p<0.05).

CONCLUSIONS

On day 1, oral rabeprazole inhibited acid output to a greater extent and for a longer period than pantoprazole, and the intragastric pH was significantly higher for rabeprazole than for pantoprazole over the first 8.3 hours.

Liquid chromatographic–mass spectrometry analysis and pharmacokinetic studies of a novel rabeprazole formulation, sterile powder for injection, in dogs and rats

Rabeprazole is among the most potent proton pump inhibitors (PPI) identified to date and it has been demonstrated that it is effective in such diseases as gastroesophageal reflux disease (GERD), duodenal ulcer and gastric ulcer. There is currently interest in developing a new formulation: rabeprazole sterile powder for injection (RSPI). This investigation was conducted to evaluate the preclinical pharmacokinetics of RSPI in rats and at the same time a comparative study was carried out in dogs between RSPI and Pariet tablets using liquid chromatographic-mass spectrometry analysis. The liquid chromatographic-mass spectrometry method was first conducted and validated as being specific, and having accuracy, precision, sensitivity and a satisfactory recovery. After intravenous administration of RSPI (i.v.: 2, 6 and 18 mg/kg) to rats, no significant dose-dependency was found in the CL (4.20-5.72 l/h/kg), V(area) (d) (0.94-1.32 l/kg), dose-normalized AUC (197.20-245.82 microg/l*h based on 1 mg/kg) and t(1/2) (p>0.05). In the dog, a randomized, open-label, crossover experiment was carried out to show that the mean area under the plasma concentration-time curve (AUC(0-infinity)) after i.v. administration of RSPI was at least four times larger than that following oral administration of Pariet tablet at an equivalent dose but the elimination half-life of these two formulation was similar (p>0.05). The results showed that the pharmacokinetics of RSPI was linear (r(2) = 0.98) in the dose range 2-18 mg/kg and the RSPI had a much higher AUC(0-infinity) and similar t(1/2) values compared with the enteric-coated tablet.

Effect of rabeprazole and omeprazole on the onset of gastro-oesophageal reflux disease symptom relief during the first seven days of treatment

OBJECTIVE

Gastro-oesophageal reflux disease (GORD) symptoms have a significant impact on patients' well-being. Onset of symptom relief is therefore an important consideration in GORD treatment. The primary objective was to compare the efficacy of rabeprazole (20 mg) and omeprazole (20 mg) regarding onset of heartburn control during the first 7 days of treatment in patients with erosive oesophagitis. Secondary objectives included maintenance of sustained heartburn control, control of other GORD symptoms (e.g. acid regurgitation, epigastric pain, dysphagia), effect on quality of life, patient satisfaction with treatment, and adverse events.

MATERIAL AND METHODS

In this multicentre, randomized, parallel-group, double-blind, comparative study, performed in Europe and Iceland, patients with endoscopically confirmed erosive oesophagitis were randomized to receive once-daily treatment with rabeprazole 20 mg (n=358) or omeprazole 20 mg (n=359) for 7 days. Symptoms were recorded (scored on a 5-point Likert scale) twice daily by the patients on their diary cards.

RESULTS

Median time to reach heartburn control was 1.5 days for both the rabeprazole and omeprazole groups (p<0.43). The results were similar between treatments for other study parameters. Both treatments were well tolerated.

CONCLUSIONS

Unlike previous studies, no significant differences were found between treatments with rabeprazole (20 mg) and omeprazole (20 mg) in this study. Further studies are needed to evaluate the potential benefit of fast-acting proton-pump inhibitors, such as rabeprazole, with respect to onset of symptom control in erosive GORD.

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.