Inhibiting the proton pump: mechanisms, benefits, harms, and questions

Wood calamint ameliorates ethanol-induced stomach injury in rats by augmentation of hsp/bax and inflammatory mechanisms

Clinopodium menthifolium (wood calamint) is a folkloric medicinal plant ingested as a treatment for many human disorders including gastric disorders. Our study evaluates the anti-ulcer potentials of Clinopodium menthifolium ethanol extracts (CMEE) in induced gastric ulcers in rats. Thirty Dawley male rats were divided into 5 groups: normal and ulcer controls, treated orally with Tween 20%; reference rats treated with Omeprazole 20 mg/kg, and the remaining two groups received 250 and 500 mg/kg CMEE for 2 weeks. After that, food was taken away for 24 h, and then, rats received ethanol-induced gastric ulceration (except normal control), 80% (1 ml/rat). After anesthetization and sacrificing, the ulcer index, mucus content, and other ulcer measurements were obtained from dissected rat stomachs. Stomach tissues were also analyzed by different histology procedures and homogenized stomach tissues were assessed for their antioxidant contents. The toxicity trial showed the absence of any toxic signs in rats supplemented with 2 and 5 g/kg of CMEE. The gastroprotective results showed a significantly lower ulcer index and higher gastric mucin content in CMEE-ingested rats compared to ulcer controls. Furthermore, CMEE treatments significantly increased the intensity of periodic acid Schiff stained (PAS), HSP 70 protein, and down-regulation of Bax protein expression in the stomach epithelium. Rats supplemented with 500 mg/kg revealed noticeable changes in their serum inflammatory cytokines along with positive regulations of antioxidant enzymes. The outcomes provide a scientific backup behind the gastroprotective potential effect of CMEE that could serve as a natural resource against peptic ulcers.

Safety, Tolerability, and Pharmacokinetics of Anaprazole, a Novel Proton Pump Inhibitor, in Healthy Chinese Subjects

Anaprazole, a newly developed oral proton pump inhibitor, was evaluated for safety, tolerability, and pharmacokinetics in healthy Chinese subjects. This study involved administering either anaprazole sodium enteric-coated tablet or placebo, followed by monitoring the incidence and severity of any adverse events (AEs). The pharmacokinetic parameters of anaprazole, its isomer, and main metabolisms were determined. The results showed that both single-dose (2.5-120 mg) and multiple-dose (20 mg once daily, 40 mg once daily, or 20 mg twice daily) oral administration of anaprazole sodium enteric-coated tablet were safe and well tolerated. Following single-dose administration, the median time to reach maximum plasma concentration of anaprazole was between 3.50 and 5.25 hours, with mean elimination half-life of 1.22-3.79 hours. The absorption and elimination of anaprazole in the human body appeared to basically follow linear kinetics. After repeated dosing, steady-state concentrations of anaprazole, its isomer, and primary metabolites were achieved, with a median time to reach maximum plasma concentration of 3-3.75 hours and a mean elimination half-life of 1.61-2.27 hours for anaprazole. There was no significant drug accumulation after multiple-dose oral administration. In conclusion, anaprazole sodium enteric-coated tablets were found to be safe and well tolerated in healthy Chinese individuals. Anaprazole is absorbed and metabolized consistently in the human body without any accumulation.

Unimolecular Helix-Based Transmembrane Nanochannel with a Smallest Luminal Cavity of 1 Å Expressing High Proton Selectivity and Transport Activity

Natural protein channels have evolved with exquisite structures to transport ions selectively and rapidly. Learning from nature to construct biomimetic artificial channels is always challenging. Herein we present a unimolecular transmembrane proton channel by quinoline-derived helix, which exhibited highly selective and ultrafast proton transport behaviors. This helix-based channel possesses a small luminal cavity of 1 Å in diameter, which could efficiently reject the permeation of cations, anions or water molecules but only permits the translocation of protons owing to the size effect. The proton flow rate exceeded 10⁷ H⁺ s^-1 channel^-1 and reached the same magnitude with gramicidin A. Mechanism investigation revealed that the directionally arrayed NH-chain inside the synthetic channel played a pivotal role during the proton flux. This work not only presented a helix-based channel with the smallest observable nanopore, but also unveiled an unexplored pathway for realizing efficient transport of protons via the consecutive NH-chain.

The pharmacotherapeutic management of duodenal and gastric ulcers

INTRODUCTION

Although the incidence and prevalence of duodenal and gastric ulcers have been declining, it remains challenging for health care systems. Based on the underlying cause, history, and characteristics of ulcers, management is generally provided by administering proton pump inhibitors (PPIs) or antibiotics.

AREAS COVERED

This article is based on global guidelines and English language literature from the past decade obtained through searches using PubMed, Clinicaltrials.gov, the US FDA, and the Cochrane library. Using a stepwise approach, dose and duration of treatment, drug interactions, warnings and contraindications, adverse effects, and administration points were specified. New drug candidates that may get American and European approvals were also introduced.

EXPERT OPINION

Despite the wide use of PPIs, their development lags behind the clinical need. There is an absolute requirement to develop third-generation PPIs with higher potency and improved pharmacokinetic and safety profiles. Regarding the antibiotic resistance crisis, including those used against H. pylori, conducting more clinical trials and investigating regional antibiotic resistance are warranted. Potassium competitive acid blockers, ilaprazole, and an H. pylori vaccine all show promise for the future.

Impact of interventions targeting the inappropriate use of proton-pump inhibitors by clinical pharmacists in a hepatobiliary surgery department

WHAT IS KNOWN AND OBJECTIVE

At present, studies on the usage of proton-pump inhibitors (PPIs) have universal significance. In clinical practice, PPIs are widely used to treat a variety of acid-related diseases, but they can be inappropriately prescribed, leading to increased medical costs and patient harm. The study comprehensively evaluated the clinical effects of a clinical pharmacist intervention on inappropriate PPI prescriptions in a tertiary general hospital hepatobiliary surgery ward.

METHODS

A retrospective, single-centre intervention study covering the periods of July-December 2018 and July-December 2019 was conducted. In the intervention group, clinical pharmaceutical care was initiated by a clinical pharmacist in the hepatobiliary surgery ward. Outcomes, including the clinical pattern of PPI utilization, the rate of inappropriate PPI use and safety outcomes, were compared between the two periods.

RESULTS AND DISCUSSION

In total, 1150 patients were admitted to the hepatobiliary surgery ward in our hospital in the study periods. Of these, 717 patients met the inclusion criteria for this study, and 420 and 297 patients were included in the preintervention and post-intervention groups, respectively. The PPI utilization rates before and after the intervention were 82.0% and 55.0%, respectively. The rates of inappropriate PPI use before and after the intervention were 48.9 and 22.7 per 100 patient-days, respectively. Clinical safety outcomes were nearly identical between before and after the intervention, but patients treated with PPIs were more likely to experience nosocomial pneumonia (2.4% vs. 0.6%).

WHAT IS NEW AND CONCLUSION

The implementation of a clinical pharmacist intervention for PPI use decreased inappropriate PPI use during hospitalization without sacrificing clinical safety outcomes.

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

Personalized therapy for Helicobacter pylori: CYP2C19 genotype effect on first-line triple therapy

BACKGROUND

Triple therapy efficacy against Helicobacter pylori is low worldwide, and thus, alternatives must be sought to improve eradication. The aim of the present study was to determine CYP2C19 genetic polymorphism effect on H pylori eradication.

METHODS

A randomized, single-blinded clinical trial including 133 participants was carried out. H pylori infection was confirmed by histologic and microbiologic test. Antibiotic susceptibility to amoxicillin and clarithromycin was performed. CYP2C19 polymorphisms *1, *2, and *3 were analyzed by real-time PCR (Roche ®), and nested PCR for CYP2C19*17 polymorphisms. Participants were randomized into two groups for different H pylori therapies, one with standard omeprazole doses and another with omeprazole doses depending on CYP2C19 polymorphism. H pylori eradication was verified by stool antigen tests (Meridian ®).

RESULTS

The most common CYP2C19 polymorphism was *1/*1 in 54.9% of the participants followed by *17/*17 in 21.1%. Triple therapy efficacy with standard omeprazole doses versus personalized therapy based on CYP2C19 polymorphism by ITT analysis was 84% (95% CI: 0.73-0.91) vs 92.2% (95% CI: 0.82-0.97) (P = 0. 14), respectively. The efficacy by PP analysis was 92.1% (95% CI: 0.82-0.97) vs 100% (95% CI: 0.92-0.01) (P = 0.027), respectively.

CONCLUSIONS

The most frequent polymorphism was extensive PPI metabolizers (62.4%). Effectiveness of guided therapies by susceptibility test was good, yet they can be further improved by customized therapy based on CYP genotype. Therefore, high PPI (80 mg/d) doses are recommended for H pylori eradication therapies in Colombia. ClinicalTrials.gov ID: NCT03650543.

The relationship between proton pump inhibitors and renal disease

Proton pump inhibitors (PPIs) bind to enzyme H⁺/K⁺-ATPase and inhibit its activity in the stomach, thus decreasing the secretion of gastric acid. PPIs may trigger acute interstitial nephritis, a potentially severe adverse event commonly associated with acute kidney injury. Studies have found that prolonged use of PPIs may increase the risk of chronic kidney disease (CKD). The increase in prescription and inadequate use of this class of medication calls for studies on the effects of prolonged PPI therapy on renal function. Therefore, this review aimed to analyze recent studies on the matter and discuss the possible consequences of the long-term use of PPIs on renal function.

Physiologic, pathophysiologic, and pharmacologic regulation of gastric acid secretion

PURPOSE OF REVIEW

The present review summarizes the past year's literature, both clinical and basic science, regarding physiologic and pharmacologic regulation of gastric acid secretion in health and disease.

RECENT FINDINGS

Gastric acid kills microorganisms, assists digestion, and facilitates absorption of iron, calcium, and vitamin B12. The main stimulants of acid secretion are the hormone gastrin, released from antral G cells; paracrine agent histamine, released from oxyntic enterochromaffin-like cells; and neuropeptide acetylcholine, released from antral and oxyntic intramural neurons. Gastrin is also a trophic hormone that participates in carcinogenesis. Helicobacter pylori may increase or decrease acid secretion depending upon the acuity and predominant anatomic focus of infection; most patients manifest hypochlorhydria. Despite the fact that proton pump inhibitors (PPIs) are amongst the most widely prescribed drugs, they are underutilized in patients at high risk for UGI bleeding. Although generally considered well tolerated, concerns have been raised regarding associations between PPI use and dementia, kidney disease, myocardial infarction, pneumonia, osteoporosis, dysbiosis, small bowel injury, micronutrient deficiency, and fundic gland polyps.

SUMMARY

Our understanding of the physiologic, pathophysiologic, and pharmacologic regulation of gastric secretion continues to advance. Such knowledge is crucial for improved and safe management of acid-peptic disorders.

Tumour acidosis: from the passenger to the driver's seat

The high metabolic demand of cancer cells leads to an accumulation of H⁺ ions in the tumour microenvironment. The disorganized tumour vasculature prevents an efficient wash-out of H⁺ ions released into the extracellular medium but also favours the development of tumour hypoxic regions associated with a shift towards glycolytic metabolism. Under hypoxia, the final balance of glycolysis, including breakdown of generated ATP, is the production of lactate and a stoichiometric amount of H⁺ ions. Another major source of H⁺ ions results from hydration of CO₂ produced in the more oxidative tumour areas. All of these events occur at high rates in tumours to fulfil bioenergetic and biosynthetic needs. This Review summarizes the current understanding of how H⁺-generating metabolic processes segregate within tumours according to the distance from blood vessels and inversely how ambient acidosis influences tumour metabolism, reducing glycolysis while promoting mitochondrial activity. The Review also presents novel insights supporting the participation of acidosis in cancer progression via stimulation of autophagy and immunosuppression. Finally, recent advances in the different therapeutic modalities aiming to either block pH-regulatory systems or exploit acidosis will be discussed.

KFP-H008 blocks gastric acid secretion through inhibiting H+-K+-ATPase

1-(5-(1H-indol-5-yl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl)-N-methylmethanamine (KFP-H008)，a novel and potent potassium-competitive acid blocker for the treatment of acid secretion related diseases, has not been reported previously. In this study, we demonstrated that KFP-H008 inhibits basal acid secretion, 2-deoxy-D-glucose- (2DG-) stimulated gastric acid secretion in rats. KFP-H008 blocked histamine-stimulated acid secretion in rats and heidenhain pouch dogs and reversed acid output in isolated gastric perfusion under histamine stimulation. In all the animal experiments, KFP-H008 exerted a more effective, potent and longer-lasting inhibitory action in comparison with lansoprazole, a proton pump inhibitor (PPI) commonly used in clinic. KFP-H008 inhibited H⁺-K⁺-ATPase activity both at pH 6.5 and pH 7.5, and was unaffected by pH. The inhibitory action was reversible and was achieved in a K⁺-competitive manner. Furthermore, KFP-H008 did not affect Na⁺-K⁺-ATPase activity, thus exhibiting high selectivity, which is different from PPIs. In all, KFP-H008, a novel potassium-competitive acid blocker, may provide new option for the patients with acid-related diseases and provide longer-lasting inhibitory action than drugs commonly used in clinical treatment.

Gastrin and Gastric Cancer

Gastric cancer although occurring in reduced frequency is still an important disease, partly because of the bad prognosis when occurring in western countries. This decline in occurrence may mainly be due to the reduced prevalence of Helicobacter pylori (Hp) infection, which is the most important cause of gastric cancer. There exist many different pathological classifications of gastric carcinomas, but the most useful seems to be the one by Lauren into intestinal and diffuse types since these types seldom transform into the other and also have different epidemiology. During the nearly 30 years that have passed since the groundbreaking description of Hp as the cause of gastritis and gastric cancer, a continuous search for the mechanism by which Hp infection causes gastric cancer has been done. Interestingly, it is mainly atrophic gastritis of the oxyntic mucosa that predisposes to gastric cancer possibly by inducing hypoacidity and hypergastrinemia. There are many arguments in favor of an important role of gastrin and its target cell, the enterochromaffin-like cell, in gastric carcinogenesis. The role of gastrin in gastric carcinogenesis implies caution in the long-term treatment with inhibitors of gastric acid secretion inducing secondary hypergastrinemia, in a common disease like gastroesophageal reflux disease.