Potassium-competitive Acid Blockers: Current Clinical Use and Future Developments.

PURPOSE OF THE REVIEW: Acid suppression with proton pump inhibitors (PPIs) represents the standard of care in the treatment of acid-related diseases. However, despite their effectiveness, PPIs display some intrinsic limitations, which underlie the unmet clinical needs that have been identified over the past decades. The aims of this review are to summarize the current status and future development of the new class of antisecretory drugs (potassium-competitive acid blockers, P-CABs) that have recently been introduced into medical practice. RECENT FINDINGS: Over the past decades, clinical needs unmet by the current acid suppressants have been recognized, especially in the management of patients with GERD, Helicobacter pylori infection and NSAID-related peptic ulcer. The failure to address these needs is mainly due to their inability to achieve a consistent acid suppression in all patients and, particularly, to control nighttime acidity. It was then realized that an extended duration of acid suppression would exert additional benefits. The available data with P-CABs show that they are able to address these unmet clinical needs. Four different P-CABs (vonoprazan, tegoprazan, fexuprazan and keverprazan) are currently available. However, only two of them are approved outside Asia. Vonoprazan is available in North, Central and South America while tegoprazan is marketed only in Latin American countries. Two other compounds (namely linazapran glurate and zestaprazan) are presently under clinical development. While clinical trials on GERD have been performed with all P-CABs, only vonoprazan and tegoprazan have been investigated as components of Helicobacter pylori eradication regimens. The available data show that-in the above two clinical indications-P-CABs provide similar or better efficacy in comparison with PPIs. Their safety in the short-term overlaps that of PPIs, but data from long-term treatment are needed.

Rifaximin in diverticulosis and diverticular disease: a national survey among Italian gastroenterologists and general practitioners.

The management of patients with diverticular disease remains challenging. The aim of this national survey was to assess how gastroenterologists and general practitioners use rifaximin to manage diverticulosis and diverticular disease. Members of the Italian Association of Hospital Gastroenterologists and Endoscopists (AIGO) and the Italian Federation of General Practitioners (FIMMG) were invited to complete a 39-item online survey concerning the use of rifaximin in five clinical settings: (1) diverticulosis; (2) reducing symptoms in symptomatic uncomplicated diverticular disease; (3) reducing the occurrence of diverticulitis in patients with symptomatic uncomplicated diverticular disease (primary prevention); (4) reducing the recurrence of diverticulitis in patients with previous attacks of diverticulitis (secondary prevention); (5) treatment of uncomplicated acute diverticulitis. A total of 1094 physicians completed the survey. Overall, 25.1%, 83.5%, 68%, 74.2%, and 63% of physicians prescribed rifaximin for the clinical settings 1, 2, 3, 4, and 5, respectively. In each clinical setting, the dosage of rifaximin most frequently used was 800 mg/day, the most common duration of therapy was 7 days, and the cyclic administration of treatment (expressed in months) most frequently used was > 24 months. These results highlight that a reappraisal of the use of rifaximin in patients with diverticulosis and diverticular disease is required to reduce the gap between the evidence available and the daily clinical practice, optimizing also the use of healthcare resources.

Review article: do stimulant laxatives damage the gut? A critical analysis of current knowledge.

Stimulant laxatives are well established as first- or second-line treatments for constipation and although they have a reliable therapeutic effect, alleged safety concerns still exist, particularly with long-term use. The potential harmful effects on the gastrointestinal system (including carcinogenicity) of the long-term use of diphenylmethane [bisacodyl, sodium picosulfate (SPS)] and senna stimulant laxatives were assessed in a comprehensive review of the publications identified in literature searches performed in PubMed and Embase up to and including June 2023. We identified and reviewed 43 publications of interest. While stimulant laxatives at supratherapeutic doses have been shown to cause structural alterations to surface absorptive cells in animals and humans, these effects are reversible and not considered clinically relevant. No formal long-term studies have demonstrated morphological changes in enteric neural elements or intestinal smooth muscle with bisacodyl or SPS in humans. Furthermore, there is no convincing evidence that stimulant laxatives are associated with the development of colon cancer, and in fact, chronic constipation itself has been reported to potentially increase the risk of colon cancer, therefore, the use of stimulant laxatives might reduce this risk. Many studies suggesting a possible harmful effect from laxatives were limited by their failure to consider confounding factors such as concomitant neurological disease, metabolic disorders, and age. These findings highlight the lack of evidence for the harmful effects of laxatives on the colon, and thus, the benefits of treatment with stimulant laxatives, even in the long-term, should be reconsidered for the management of patients with constipation.

Do stimulant laxatives damage the gut? Stimulant laxatives are widely used treatments for constipation that work by causing the muscles in the gut to contract and so move stool more effectively. Examples of these treatments include senna, bisacodyl and sodium picosulfate. Treatments such as these are typically available without a doctor's prescription and have a long history of helping people relieve their constipation. However, some concerns have been expressed about the safety of these treatments, particularly when they are used for a long time. We did a critical review of published studies of the safety of stimulant laxatives to try to find out whether there is any strong evidence for harm being caused by these treatments. We found 43 papers with information on the gut safety of stimulant laxatives. These studies looked at whether the treatments are associated with changes to gut structure or function and at whether there might be a link between these treatments and bowel cancer. Unfortunately, many of the studies were of poor quality. For instance, they did not look for things, in addition to the laxatives, that could have affected the results, such as the age of the patients, other medications they were taking or whether they had other health conditions that might have affected the bowel. Also, the populations in which the studies were done differed a lot, so they were hard to compare with one another. However, we did not find any strong evidence suggesting that stimulant laxatives damage the gut or cause cancer. We therefore concluded that the harms associated with stimulant laxatives are likely to have been overstated, and that patients should not be denied the benefits of stimulant laxatives for constipation, especially as they have been on the market for a very long time with no serious problems emerging.

Predictive Score for Advanced Colorectal Neoplasia Based on Cardiovascular and Colorectal Cancer Risk Factors.

Background and Aims: Cardiovascular disease and colorectal cancer (CRC) are significant health problems and share some risk factors. The aim of our study was to develop and validate a predictive score for advanced colorectal neoplasia (CRN) based on risk factors for cardiovascular disease and CRC. Materials and Methods: A cross-sectional study comprising a derivation cohort and an external validation cohort of 1049 and 308 patients, respectively. A prediction score for advanced CRN (CRNAS: Colorectal Neoplasia Advanced Score) was developed from a logistic regression model, comprising sex, age, first-degree family history for CRC, systolic and diastolic blood pressure, total cholesterol, HDL cholesterol, body mass index, diabetes, smoking, and antihypertensive treatment. Other cardiovascular risk scores (Framingham-Wilson, REGICOR, SCORE, and FRESCO) were also used to predict the risk of advanced CRN. The discriminatory capacity of each score was evaluated using the area under the curve (AUC). Results: CRN were found in 379 subjects from the derivation cohort (36%), including 228 patients (22%) with an advanced CRN. Male sex, age, diabetes, and smoking were identified as independent risk factors for advanced CRN. The newly created score (CRNAS) showed an AUC of 0.68 (95% CI: 0.64-0.73) for advanced CRN, which was better than cardiovascular risk scores (p < 0.001). In the validation cohort, the AUC of CRNAS for advanced CRN was 0.67 (95% CI: 0.57-0.76). Conclusions: The newly validated CRNAS has a better discriminatory capacity to predict advanced CRN than cardiovascular scores. It may be useful for selecting candidates for screening colonoscopy, especially in those with cardiovascular risk factors.

A translational pharmacokinetic/pharmacodynamic approach supports optimal vonoprazan dosing for erosive oesophagitis and Helicobacter pylori infection.

BACKGROUND: Treatment of acid-related disorders relies on gastric acid suppression. The percentage of time intragastric pH is >4 (pH >4 holding time ratio [HTR]) is important for healing erosive oesophagitis; and the pH >6 HTR is critical for eradication of Helicobacter pylori infection, as bacterial replication is active and antibiotic effectiveness is optimised. Vonoprazan, a potassium-competitive acid blocker approved in the USA and other countries, suppresses gastric acid secretion in a predictable, rapid and consistent manner, extended over prolonged periods. AIM: To explore the relationship between vonoprazan exposure and pH HTR through a pharmacokinetic/pharmacodynamic (PK/PD) model. METHODS: We pooled data from Phase 1 studies with intragastric pH measurements. Pharmacokinetic profiles were predicted for study participants using an existing population pharmacokinetic model. Pharmacokinetic and pharmacodynamic data were merged, and three direct-link PK/PD models were derived and used to simulate pH HTRs with between-participant variability for pH >4, >5 and >6, for vonoprazan doses of 20 mg once and twice daily. RESULTS: We used data from five Phase 1 studies to derive the PK/PD model. These included 245 participants (95.1% male, 50.6% Japanese and 49.4% non-Asian). Pre-dose, the mean pH >4 HTR was 6.4%, pH >5 3.2% and pH >6 1.2%. After 7 days of dosing, simulations predicted pH >4 HTRs of 89.7% and 98.1%, and pH >6 HTRs of 53.1% and 75.3%, for vonoprazan 20 mg once and twice daily, respectively. CONCLUSIONS: Vonoprazan 20 mg once- and twice-daily dosing demonstrated high, dose-dependent, 24-hour intragastric acid control in this PK/PD model, supporting clinical efficacy data in patients with acid-related disorders.

Tiered approach to evaluate the CYP3A victim and perpetrator drug-drug interaction potential for vonoprazan using PBPK modeling and clinical data to inform labeling.

Vonoprazan is metabolized extensively through CYP3A and is an in vitro time-dependent inhibitor of CYP3A. A tiered approach was applied to understand the CYP3A victim and perpetrator drug-drug interaction (DDI) potential for vonoprazan. Mechanistic static modeling suggested vonoprazan is a potential clinically relevant CYP3A inhibitor. Thus, a clinical study was conducted to evaluate the impact of vonoprazan on the exposure of oral midazolam, an index substrate for CYP3A. A physiologically-based pharmacokinetic (PBPK) model for vonoprazan was also developed using in vitro data, drug- and system-specific parameters, and clinical data and observations from a [14 C] human absorption, distribution, metabolism, and excretion study. The PBPK model was refined and verified using data from a clinical DDI study with the strong CYP3A inhibitor, clarithromycin, to confirm the fraction metabolized by CYP3A, and the oral midazolam clinical DDI data assessing vonoprazan as a time-dependent inhibitor of CYP3A. The verified PBPK model was applied to simulate the anticipated changes in vonoprazan exposure due to moderate and strong CYP3A inducers (efavirenz and rifampin, respectively). The clinical midazolam DDI study indicated weak inhibition of CYP3A, with a less than twofold increase in midazolam exposure. PBPK simulations projected a 50% to 80% reduction in vonoprazan exposure when administered concomitantly with moderate or strong CYP3A inducers. Based on these results, the vonoprazan label was revised and states that lower doses of sensitive CYP3A substrates with a narrow therapeutic index should be used when administered concomitantly with vonoprazan, and co-administration with moderate and strong CYP3A inducers should be avoided.

Pharmacologic treatment of GERD in adolescents: Is esophageal mucosal protection an option?

Background: Gastroesophageal reflux disease (GERD) is still a challenging and difficult to treat condition in children. Although acid suppression represents the mainstay of treatment in adolescents, it is not devoid of adverse events, especially in the long-term. Objectives: In this investigation we explored a new therapeutic avenue in GERD, that is esophageal mucosal protection. Design: To this end, we performed an investigator-initiated, retrospective study to evaluate the efficacy and safety of a short-term treatment with Esoxx™ medical device in 25 adolescents with GERD-related symptoms. This mucoadhesive formulation contains two natural mucopolysaccharides (sodium hyaluronate and chondroitin sulphate) and adheres to the esophageal mucosa, exerting a protective effect against refluxed gastric contents and allowing mucosal healing. Methods: Heartburn, epigastric burning and post-prandial regurgitation were scored with a pain VAS scale and re-evaluated after 3-week treatment with Esoxx (one stick post-prandially, three times daily). Results: All patients completed the treatment without adverse effects and with good tolerability and compliance. All the three major symptoms significantly (p<0.001) improved after treatment. No patient required additional investigation (i.e. upper Gastrointestinal endoscopy) or medication (i.e. antisecretory drugs). Conclusion: The results of this pilot study suggest that esophageal mucosal protection is a promising therapeutic avenue for GERD also in children. Provided, these data be confirmed by a large, randomized clinical trial, this medical device can enter our therapeutic armamentarium against this challenging disease.

Use of Pharmacogenetics to Optimize Immunosuppressant Therapy in Kidney-Transplanted Patients.

Immunosuppressant drugs (ISDs) are routinely used in clinical practice to maintain organ transplant survival. However, these drugs are characterized by a restricted therapeutic index, a high inter- and intra-individual pharmacokinetic variability, and a series of severe adverse effects. In particular, genetic factors have been estimated to play a role in this variability because of polymorphisms regarding genes encoding for enzymes and transporters involved in the ISDs pharmacokinetic. Several studies showed important correlations between genetic polymorphisms and ISDs blood levels in transplanted patients; therefore, this review aims to summarize the pharmacogenetics of approved ISDs. We used PubMed database to search papers on pharmacogenetics of ISDs in adults or pediatric patients of any gender and ethnicity receiving immunosuppressive therapy after kidney transplantation. We utilized as search term: "cyclosporine or tacrolimus or mycophenolic acid or sirolimus or everolimus and polymorphism and transplant". Our data showed that polymorphisms in CYP3A5, CYP3A4, ABCB1, and UGT1A9 genes could modify the pharmacokinetics of immunosuppressants, suggesting that patient genotyping could be a helpful strategy to select the ideal ISDs dose for each patient.

Review article: rethinking the "ladder" approach to reflux-like symptom management in the era of PPI "resistance" - a multidisciplinary perspective.

BACKGROUND: Despite widespread adoption of potent acid suppression treatment with proton pump inhibitors (PPI) for reflux-like symptoms, persistent symptoms are commonly reported in primary care and community studies. AIMS: This multidisciplinary review critically evaluates how the management of reflux-like symptoms could better reflect their multifactorial pathophysiology. METHODS: A panel of experts (from general practice, gastroenterology and gastropsychology) attended a series of workshops to review current management and propose a framework for the provision of more individualised care. RESULTS: It was agreed that the perceptual (as well as the physiological) causes of reflux-like symptoms should be considered at the start of management, not as a last resort when all else has failed. A short course of PPI is a pragmatic approach to address reflux-like symptoms, but equally important is counselling about the gut-brain axis and provision of symptom-specific behavioural interventions for those who show signs of somatisation, hypervigilance or co-existing disorders of gut-brain interaction. Other low-harm interventions such as lifestyle and dietary advice, should also be better integrated into care at an early stage. Multidisciplinary care management programmes (including dietary, weight loss, exercise and behavioural intervention) should be developed to promote greater self-management and take advantage of the general shift toward the use of remotely accessed health care resources. CONCLUSIONS: Management of reflux-like symptoms should be adapted to reflect the advances in knowledge about the multifactorial aetiology of these symptoms, addressing both acid-related and behavioural components early in management. The time has come to treat the patient, not the "disease".

A Population Pharmacokinetic Model of Vonoprazan: Evaluating the Effects of Race, Disease Status, and Other Covariates on Exposure.

Vonoprazan, a potassium-competitive acid blocker, is under investigation in the United States and Europe for the treatment of erosive esophagitis and Helicobacter pylori infection. Population pharmacokinetic (popPK) analysis allows the identification of factors that could affect drug exposure in population subgroups. Here, we report a popPK model based on pooled data sets of available pharmacokinetic (PK) studies in healthy volunteers and patients with gastroesophageal reflux disease, including erosive esophagitis, from Asia and Europe. This model was used to evaluate the impact of different covariates, including race and disease status, on vonoprazan exposure. We analyzed PK data from 746 patients and 410 healthy volunteers from 15 clinical trials using a nonlinear mixed-effects approach to develop the popPK model. Model development focused on characterizing and quantifying the effects of clinical covariates of race (Asian vs non-Asian) and disease status (gastroesophageal reflux disease vs healthy volunteers) on vonoprazan exposure. Identified clinical covariates included fed/fasting status, race, sex, disease status, weight, serum creatinine, and age. The impact of variations in these clinical covariates on exposure to vonoprazan was smaller than the effect of halving or doubling the dose. PK parameters were similar in Asian and non-Asian populations. Variations in weight, age, and race are not predicted to have a clinically relevant impact on vonoprazan exposure or safety and require no changes in vonoprazan dosing. The limited impact of race on exposure suggests that efficacy and safety data for vonoprazan in Asian populations are translatable to non-Asian populations.

COVID-19 and Gastrointestinal Disease: Implications for the Gastroenterologist.

BACKGROUND: COVID-19 was initially considered a respiratory disease but the SARS-CoV-2 virus can lead to serious systemic consequences affecting major organs including the digestive system. SUMMARY: This review brings new clinically important information for the gastroenterologist. This includes: the mechanisms of tissue damage seen with the SARS-CoV-2 virus; the consequences of immunosuppression in patients with inflammatory bowel disease (IBD) and chronic liver disease with the additional risks of decompensation in patients with cirrhosis; the impact of COVID-19 on gastrointestinal emergencies, on gastrointestinal endoscopy, diagnosis and treatments. These highlight the need to understand the clinical pharmacology, toxicology and therapeutic implications of drugs commonly used by gastroenterologists and their links with COVID-19. Key Messages: Any part of the digestive system may be affected by the SARS-CoV-2 virus, and those with pre-existing disease are at greatest risk of adverse outcomes. The risk for drug-drug interactions is considerable in patients seriously ill with COVID-19 who often require mechanical ventilation and life support. Some repurposed drugs used against SARS-CoV-2 can cause or aggravate some of the COVID-19-related gastrointestinal symptoms and can also induce liver injury. Ongoing clinical studies will hopefully identify effective drugs with a more favourable risk-benefit ratio than many initially tried treatments.

Combined Treatment with Polynucleotides and Hyaluronic Acid Improves Tissue Repair in Experimental Colitis.

Inflammatory bowel diseases (IBDs) are chronic conditions that can benefit from the combined treatment of adenosine receptor agonists and hyaluronic acid (HA), which, binding the CD44, has pro-survival effects. Therefore, this study investigated the effects of a mixture of polynucleotides and HA in an experimental model of dinitrobenzenesulfonic acid (DNBS)-induced colitis. A group of 40 rats received a single intra-colonic instillation of DNBS, and after 6 h, animals were randomized to receive daily: (i) saline solution; (ii) polynucleotides (Poly; 8 mg/kg); (iii) polynucleotides (8 mg/kg) plus hyaluronic acid (HA; 15 mg/kg); and (iv) hyaluronic acid (HA; 15 mg/kg). Rats in the control group (n = 10) received saline solution only. Seven days after induction, animals receiving Poly plus HA showed reduced clinical signs, weight loss and colon shortening, ameliorated macroscopic and histological damage, and apoptosis. Moreover, the combined treatment reduced the positivity in the colonic infiltrate of CD3 positive T cells, CD20 positive B cells and CD44. Furthermore, Poly plus HA reduced colonic myeloperoxidase activity and malondialdehyde, indicating a dampening of the inflammatory infiltrate and oxidation products. Our research demonstrated that a combined treatment of polynucleotides with hyaluronic acid had a protective effect in a model of ulcerative colitis, suggesting that this association deserves further attention for the treatment of IBDs.

Pharmacologic treatment of GERD: Where we are now, and where are we going?

The introduction of acid inhibition in clinical practice has revolutionized the management of acid-related diseases, leading to the virtual abolition of elective surgery for ulcer disease and relegating antireflux surgery to patients with gastroesophageal reflux disease (GERD) not adequately managed by medical therapy. Proton pump inhibitors (PPIs) are the antisecretory drugs of choice for the treatment of reflux disease. However, these drugs still leave some unmet clinical needs in GERD. PPI-refractoriness is common, and persistent symptoms are observed in up to 40-55% of daily PPI users. Potassium-competitive acid blockers (P-CABs) clearly overcome many of the drawbacks and limitations of PPIs, achieving rapid, potent, and prolonged acid suppression, offering the opportunity to address many of the unmet needs. In recent years, it has been increasingly recognized that impaired mucosal integrity is involved in the pathogenesis of GERD. As a consequence, esophageal mucosal protection has emerged as a new, promising therapeutic avenue. When P-CABS are used as add-on medications to standard treatment, a growing body of evidence suggests a significant additional benefit, especially in the relief of symptoms not responding to PPI therapy. On the contrary, reflux inhibitors are considered a promise unfulfilled, and prokinetic agents should only be used on a case-by-case basis.

Gastrointestinal pharmacology: practical tips for the esophagologist.

Gastroesophageal reflux disease (GERD) is primarily a motor disorder, and its pathogenesis is multifactorial. As a consequence, treatment should be able to address the underlying pathophysiology. Proton pump inhibitors (PPIs) are the mainstay of medical therapy for GERD, but these drugs only provide the control of symptoms and lesions without curing the disease. However, continuous acid suppression with PPIs is recommended for patients with Barrett's esophagus because of their potential chemopreventive effects. In addition to the antisecretory activity, these compounds display several pharmacological properties, often overlooked in clinical practice. PPIs can indeed affect gastric motility, exert a mucosal protective effect, and an antioxidant, anti-inflammatory, and antineoplastic activity, also protecting cancer cells from developing chemo- or radiotherapeutic resistance. Even in the third millennium, current pharmacologic approaches to address GERD are limited. Reflux inhibitors represent a promise unfulfilled, effective and safe prokinetics are lacking, and antidepressants, despite being effective in selected patients, give rise to adverse events in a large proportion of them. While waiting for new drug classes (like potassium-competitive acid blockers), reassessing old drugs (namely alginate-containing formulations), and paving the new avenue of esophageal mucosal protection are, at the present time, the only reliable alternatives to acid suppression.

Potential proton pump inhibitor-related adverse effects.

Proton pump inhibitors (PPIs) are one of the most common medications taken by patients worldwide. PPIs are used to treat acid-related disorders, including gastroesophageal reflux disease, peptic ulcer disease, Helicobacter pylori infection, and nonsteroidal anti-inflammatory drug/stress ulceration. For some of these diseases, long-term treatment is necessary. With such prolonged use, concern and investigation into potential adverse effects has increased. In addition, data are available regarding potential anticancer effects of PPIs, especially regarding solid tumors. The aim of this review is to assess the literature on PPIs with regard to common concerns, such as drug-drug interactions, the intestinal microbiome, dementia and central nervous system disease, and osteoporosis, as well as to highlight potential negative and positive impacts of the drug in cancer.

Eosinophilic esophagitis: updates on key unanswered questions.

Eosinophilic esophagitis (EoE) is a clinicopathologic disease characterized by symptoms of esophageal dysfunction and esophageal eosinophilia. In the last decade, there has been a dramatic increase in its prevalence for reasons that are not completely understood. The underlying pathophysiology involves an antigen-mediated TH 2 immune response that draws eosinophils to the esophagus, causing mucosal inflammation, esophageal remodeling, and fibrosis. This ultimately leads to esophageal dysfunction that most commonly manifests as dysphagia. In this review, we will discuss updates on key questions regarding the diagnosis and treatment of EoE.

Author Correction: Colonic diverticular disease.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Publisher Correction: Colonic diverticular disease.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.