Are there unmet needs in acid suppression?

P-CAB versus PPI in the eradication of Helicobacter pylori: a systematic review and network meta-analysis

Background

The efficacy and safety of potassium-competitive acid blockers (P-CABs) in the eradication of Helicobacter pylori (Hp) remains controversial when compared with proton pump inhibitors (PPIs).

Objectives

The current study set out to compare the differences in the eradication rate and adverse reactions between eradication regimens based on P-CAB or PPI drugs and the differences between the vonoprazan-based and the tegoprazan-based regimens to explore the efficacy and safety of different Hp eradication regimens.

Data sources and methods

Databases including PubMed, EMBASE, Cochrane Library, and WOS were searched from the inception of these databases up to July 2023, and eligible randomized controlled trials (RCTs) were included. The outcome measures were the eradication rate and the incidence of adverse reactions of different regimens in treating Hp. The results were estimated as relative risk (RR) and its 95% confidence interval (CI), and R 4.2.1 software was used to perform the network meta-analysis (NMA).

Results

A total of 20 studies were included in the analysis, involving 5815 patients with Hp. In terms of eradication rate, the 2-week vonoprazan-based triple regimen (V-Tri-2w) was the best, which was superior to the 2-week PPI-based quadruple regimen [P-Qua-2w, RR = 0.9, 95% CI: (0.85-0.95)] and the 1-week tegoprazan-based triple regimen [T-Tri-1w, RR = 0.79, 95% CI: (0.64-0.97)]; the 2-week tegoprazan-based quadruple regimen (T-Qua-2w) was superior to the 1-week PPI-based triple regimen [P-Tri-1w, RR = 0.82, 95% CI: (0.67-0.99)], and there was no difference between the remaining tegoprazan-based regimens and the PPI-based or vonoprazan-based regimens. In terms of the incidence of adverse reactions, the 2-week vonoprazan-based binary regimen (V-Bi-2w) was lower than that of the 2-week PPI-based quadruple regimen [P-Qua-2w, RR = 1.98, 95% CI: (1.57-2.52)]; there was no significant difference between 1 and 2 weeks for each regimen, such as the vonoprazan-based triple regimen [RR = 1.11, 95% CI: (0.82-1.52)].

Conclusion

In the eradication treatment of Hp, the efficacy and safety of vonoprazan-based regimens are generally better than those of PPI-based regimens. Among them, the V-Tri-2w regimen has the highest eradication rate and may be the preferred choice for Hp eradication.

Comparison of Pharmacodynamics between Tegoprazan and Dexlansoprazole Regarding Nocturnal Acid Breakthrough: A Randomized Crossover Study

Background/Aims

Tegoprazan, a novel potassium-competitive acid blocker, is expected to overcome the limitations of proton pump inhibitors and effectively control nocturnal acid breakthrough. To evaluate the pharmacodynamics of tegoprazan versus dexlansoprazole regarding nocturnal acid breakthrough in healthy subjects.

Methods

In a randomized, open-label, single-dose, balanced incomplete block crossover study, 24 healthy male volunteers were enrolled and randomized to receive oral tegoprazan (50, 100, or 200 mg) or dexlansoprazole (60 mg) during each of two administration periods, separated by a 7- to 10-day washout period. Blood samples were collected for pharmacokinetic parameter analysis; gastric monitoring was performed for pharmacodynamic parameter evaluation.

Results

All 24 subjects completed the study. Average maximum plasma concentration, area under the plasma concentration-time curve, and mean time with gastric pH >4 and pH >6 for tegoprazan demonstrated dose-dependent incremental increases. All the tegoprazan groups reached mean pH ≥4 within 2 hours, whereas the dexlansoprazole group required 7 hours after drug administration. Based on pharmacodynamic parameters up to 12 hours after evening dosing, 50, 100, and 200 mg of tegoprazan presented a stronger acid-suppressive effect than 60 mg of dexlansoprazole. Moreover, the dexlansoprazole group presented a comparable acid-suppressive effect with the tegoprazan groups 12 hours after dosing.

Conclusions

All the tegoprazan groups demonstrated a significantly faster onset of gastric pH increase and longer holding times above pH >4 and pH >6 up to 12 hours after evening dosing than the dexlansoprazole group.

The Physiology of the Gastric Parietal Cell

Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria. However, a fine balance of activators and inhibitors of parietal cell-mediated acid secretion is required to ensure proper digestion of food, while preventing damage to the gastric and duodenal mucosa. As a result, parietal cell secretion is highly regulated through numerous mechanisms including the vagus nerve, gastrin, histamine, ghrelin, somatostatin, glucagon-like peptide 1, and other agonists and antagonists. The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl. Inhibition of the H+-K+-ATPase is the most efficacious method of preventing harmful gastric acid secretion. Proton pump inhibitors and potassium competitive acid blockers are widely used therapeutically to inhibit acid secretion. Stimulated delivery of the H+-K+-ATPase to the parietal cell apical surface requires the fusion of intracellular tubulovesicles with the overlying secretory canaliculus, a process that represents the most prominent example of apical membrane recycling. In addition to their unique ability to secrete gastric acid, parietal cells also play an important role in gastric mucosal homeostasis through the secretion of multiple growth factor molecules. The gastric parietal cell therefore plays multiple roles in gastric secretion and protection as well as coordination of physiological repair.

Long-term outcomes of patients with symptomatic gastroesophageal reflux disease treated with vonoprazan

OBJECTIVE

The novel potassium-competitive acid blocker, vonoprazan, provides rapid and effective acid suppression. The aim of this study is to evaluate the long-term outcomes of patients with symptomatic gastroesophageal reflux disease (GERD) treated with vonoprazan.

METHODS

This retrospective cohort study included 55 patients with symptomatic GERD treated with vonoprazan who have been followed for more than one year. The effectiveness of vonoprazan on gastrointestinal symptoms was evaluated using the Izumo scale, a self-reported questionnaire reflecting quality of life related to various abdominal symptoms.

RESULTS

These 55 patients with symptomatic GERD had non-erosive reflux disease (n = 30) or erosive esophagitis (n = 25). Vonoprazan (10 mg) for one month improved GERD symptoms in 89% (responders) and the improvement was maintained at one year in 82% without additional treatment. One-year maintenance therapy resulted in sustained resolution of GERD symptoms in 47%. Of the 49 responders, nine patients had relapse of GERD symptoms and dose escalation of vonoprazan improved the symptoms in six patients. Postprandial distress and the presence of erosive esophagitis before starting vonoprazan were identified as significant negative and positive predictors of sustained resolution of GERD symptoms for one year, respectively. Epigastric pain, postprandial distress, constipation and diarrhea were significantly improved at one-month and maintained at one year. After one-year of treatment, the endoscopic healing rate of erosive esophagitis was 95%.

CONCLUSION

One-year treatment with vonoprazan significantly improves GERD symptoms and endoscopic healing of erosive esophagitis is satisfactory. The long-term use of vonoprazan is effective and useful to control GERD.

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.

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.

Potassium-Competitive Acid Blockers (P-CABs): Are They Finally Ready for Prime Time in Acid-Related Disease?

The need for new acid suppressing agents with improved pharmacology and superior antisecretory effects to address unmet clinical needs in acid-related disorders has been evident for over a decade. Recent new antisecretory drugs (IR-omeprazole and MR-dexlansoprazole) only provide a small incremental advance in control of acid secretion over the delayed-release proton pump inhibitors. Vonoprazan (a new potassium-competitive acid blocker) displays more potent and extended 24 h acid suppression and preliminary Japanese trials translate this into meaningful clinical benefits in gastro-esophageal reflux disease and Helicobacter pylori eradication. We review the vonoprazan information to date and the indications, benefits, and concerns of more effective therapeutic control of acid secretion.

Gastric acid secretion: changes during a century

The advances in knowledge of gastric physiology within the past century have been the most exciting and important in this area of interest for many decades. The aim of this presentation consists of a comprehensive review of the extensive recent literature on this topic in order to highlight milestones in the field of gastric physiology, in particular in gastric acid secretion, gastric pathophysiology, acid-related diseases and use of acid regulatory drugs. Moreover, in the 21st century there have been many epidemiologic changes as well as a decrease of Helicobacter pylori infection and gastric cancer together with an increase of gastroesophageal reflux disease and the related increase of pomp proton inhibitor wide use.

Poor effectiveness of proton pump inhibitors in non-erosive reflux disease: the truth in the end!

Despite acid secretion being normal in the majority of patients with gastro-esophageal reflux disease (GERD) or Barrett's esophagus, acid inhibition represents the mainstay of treatment for both these conditions, with the aim of reducing the aggressive nature of the refluxate toward the esophageal mucosa. Proton pump inhibitors (PPIs) represent, therefore, the first choice medical treatment for GERD, in that they are able to provide an 80-85% healing rate for esophageal lesions, a 56-76% symptom relief and also reduce the incidence of complications, such as strictures as well as dysplasia and adenocarcinoma in Barrett's esophagus. According to a widely quoted systematic review, compared to patients with erosive esophagitis, patients with non-erosive reflux disease (i.e., NERD) display a reduced symptom relief with PPIs, with about 20% reduction of therapeutic gain. In this issue of NeuroGastroenterology & Motility, Weijenborg et al. address for the first time the PPI efficacy in subpopulations of patients with NERD. The study shows clearly that, when the diagnosis is accurately made by including a functional test, NERD patients respond to PPI therapy in a similar way to those with erosive disease. Although not as frequent as previously suggested, however, PPI-refractory heartburn does exist. Some 20% (range: 15-27%) of correctly diagnosed and appropriately treated patients do not respond to PPI treatment at standard doses. Although the pathophysiology underlying PPI failure in GERD is complex and likely multifactorial, acid (be it the sole component of refluxate or not) still remains a major causative factor. A better and more predictable form of acid suppression should therefore be pursued.

Evolving issues in the management of reflux disease?

PURPOSE OF REVIEW

Gastroesophageal reflux disease (GERD) is a common chronic disorder often successfully treated, although there are several evolving issues in management. We reviewed the issues related to unmet needs over the past 12 months.

RECENT FINDINGS

A substantial number of patients fail to respond adequately to once or even twice daily proton pump inhibitor (PPI). There is no standard definition of PPI failure in GERD; a universally accepted definition for treatment success is also not available. Differentiation between erosive esophagitis and nonerosive reflux disease can be made but requires endoscopy; but studies still confuse functional heartburn and nonerosive reflux disease, which impacts management. Acid reflux plays an important role in GERD pathogenesis and the precise role of acid requires more studies of differences between erosive esophagitis and nonerosive reflux disease symptom generation and the implication of nocturnal acidification. Several possible mechanisms may explain GERD refractory to PPIs.

SUMMARY

Management of PPI nonresponders remains a challenge. Objective and precise evaluation of symptoms and treatment response requires study in high-quality trials. New therapeutic approaches are under investigation to answer unmet needs and improve erosive esophagitis healing rates and symptom control.

A comparison of the effects of gastrin, somatostatin and dopamine receptor ligands on rat gastric enterochromaffin-like cell secretion and proliferation

Gastrin regulates ECL cell histamine release and is a critical determinant of acid secretion. ECL cell secretion and proliferation is inhibited by gastrin antagonists and somatostatin but little is known about the role of dopamine agonists in this process. Since the ECL cell exhibits all three classes of receptor we evaluated and compared the effects of the gastrin receptor antagonist, (YF476), lanreotide (SST agonist) and novel dopaminergic agents (BIM53061 and BIM27A760) on ECL cell histamine secretion and proliferation. Highly enriched (>98%) ECL cell preparations prepared from rat gastric mucosa using a FACS approach were studied. Real-time PCR confirmed presence of the CCK2, SS2 and SS5 and D1 receptors on ECL cells. YF476 inhibited histamine secretion and proliferation with IC(50)s of 1.25 nM and 1.3 x 10(-11) M respectively, values 10-1000x more potent than L365,260. Lanreotide inhibited secretion and proliferation (2.2 nM, 1.9 x 10(-10) M) and increased YF476-inhibited proliferation a further 5-fold. The dopamine agonist, BIM53061, inhibited gastrin-mediated ECL cell secretion and proliferation (17 nM, 6 x 10(-10) M) as did the novel dopamine/somatostatin chimera BIM23A760 (22 nM, 4.9 x 10(-10) M). Our studies demonstrate that the gastrin receptor antagonist, YF476, is the most potent inhibitor of ECL cell histamine secretion and proliferation. Lanreotide, a dopamine agonist and a dopamine/somatostatin chimera inhibited ECL cell function but were 10-1000x less potent than YF476. Agents that selectively target the CCK2 receptor may provide alternative therapeutic strategies for gastrin-mediated gastrointestinal cell secretion and proliferation such as evident in the hypergastrinemic gastric carcinoids associated with low acid states.

Review article: the opportunities and benefits of extended acid suppression

Acid suppression therapy with proton pump inhibitors is associated with well-established benefits in the management of gastro-oesophageal reflux (GERD) and other acid-related disorders. However, a number of issues still remain unsettled. Despite their clinical efficacy, when given once daily, currently available proton pump inhibitors may not adequately control intragastric acidity during the night in a significant proportion of both healthy subjects and GERD patients, in whom symptom relief remains suboptimal. Although some novel proton pump inhibitors have been synthesized, only few reached clinical testing. Amongst them, tenatoprazole represents a true advance displaying a long half-life (five to seven times longer than that of currently available drugs) and extended acid suppression covering both day and night. All the available clinical studies suggest both pharmacokinetic and pharmacodynamic advantages of tenatoprazole over esomeprazole. As this last compound provides - amongst the members of the class - the most effective control of intragastric pH whatever the parameter considered, it is conceivable that tenatoprazole could similarly be better than the other existing proton pump inhibitors. Tenatoprazole appears to be a promising proton pump inhibitor for the treatment of acid-related diseases, where it has the potential to address unmet clinical needs.