Review article: understanding the pharmacodynamic and pharmacokinetic differences between proton pump inhibitors - focus on pKa and metabolism

Deprescribing and Optimal Selection of Proton Pump Inhibitors (Contributions of the 26th United Russian Gastroenterology Week)

Aim. Presentation of the Forum “Deprescribing and optimal selection of proton pump inhibitors” held in Moscow on 29 September 2020 during the 26th United Russian Gastroenterology Week.Key points. The Forum was aimed at discussing issues associated with improving the proton pump inhibitor (PPIs) therapy in treatment and prevention of acid-related diseases and upper gastrointestinal tract (GIT) disorders induced by non-steroidal anti-inflammatory drugs (NSAIDs) and antiplatelet medications. Deprescribing is considered to be an effective strategy of a motivated reduction of the PPI dosage, duration of therapy and the patient’s transfer from a regular to on-demand intake regimen. The choice of PPI may condition an optimal therapy for acid-related diseases.Conclusion. PPIs prevail in therapies for acid-related diseases and NSAID-induced upper GIT lesions. PPI deprescribing should be a strategy of choice if medically indicated. A non-enzymatic metabolism, high acid suppression, stable antisecretory effect from day 1 of therapy and cytoprotective action justify the application of rabeprazole (Pariet®) for optimising therapies for acid-related diseases and implementing the deprescribing strategy.

Does the Use of Proton Pump Inhibitors Increase the Risk of Pancreatic Cancer? A Systematic Review and Meta-Analysis of Epidemiologic Studies

Background: One of the most frequently used medications for treating gastrointestinal disorders is proton pump inhibitor (PPI), which reportedly has potential adverse effects. Although the relationship between the use of PPIs and the risk of pancreatic cancer has been extensively investigated, the results remain inconsistent. Hence, this meta-analysis aimed to evaluate such relationship. Methods: We searched for literature and subsequently included 10 studies (seven case–control and three cohort studies; 948,782 individuals). The pooled odds ratio (OR) and 95% confidence intervals (CI) for pancreatic cancer were estimated using a random-effects model. We also conducted sensitivity analysis and subgroup analysis. Results: The pooled OR of the meta-analysis was 1.698 (95% CI: 1.200–2.402, p = 0.003), with a substantial heterogeneity (I² = 98.75%, p < 0.001). Even when studies were excluded one by one, the pooled OR remained statistically significant. According to the stratified subgroup analyses, PPI use, and pancreatic cancer incidence were positively associated, regardless of the study design, quality of study, country, and PPI type. Conclusion: PPI use may be associated with the increased risk of pancreatic cancer. Hence, caution is needed when using PPIs among patients with a high risk of pancreatic cancer.

Characterization and Comparative Performance of TiO2 Photocatalysts on 6-Mercaptopurine Degradation by Solar Heterogeneous Photocatalysis

The crystallographic properties of two titanium dioxide (TiO2) photocatalysts, P25, and commercial C1-TiO2 reactive grade, were analyzed by X-ray diffraction (XRD) and the band-gap was calculated with UV–Vis spectrometry with integration sphere. Then, their performance was tested in the degradation of 6-mercaptopurine (6-MP) by heterogeneous photocatalysis with solar radiation under different pH conditions and the addition of hydrogen peroxide (H2O2); the degradation efficiency was monitored by UV–Vis spectrophotometry. The XRD analysis showed that both photocatalysts studied have anatase phase, while only P25 contains rutile; the band gap values were lower, in both catalysts, than those reported for catalysts obtained by the sol-gel method. With both photocatalysts, degradation experiments showed efficiency greater than 98% in experiments in the presence of H2O2 regardless of pH. The properties of the photocatalysts, along with the data obtained from the experimentation, helped determine the best semiconductor for the degradation of 6-MP with these operating conditions in this work.

Pharmacokinetics of rabeprazole granules versus tablets, and the effect of food on the pharmacokinetics of rabeprazole granules in healthy adults-cross-study comparison

The primary objective was to compare the pharmacokinetics (PK) of rabeprazole granules versus rabeprazole tablets, and assess the effect of food on the PK of rabeprazole granules. Data from three phase 1, open-label, single-dose, randomized, crossover studies in healthy adult participants are presented separately and as a cross-study comparison; study 1: PK of phase 1 rabeprazole granules versus rabeprazole tablets under fasting conditions; study 2: PK of phase 3 rabeprazole granules versus phase 1 rabeprazole granules; study 3: bioequivalence of to-be-marketed rabeprazole granules (sprinkle capsules) versus phase 3 rabeprazole granules; and assessment of the food effect for the to-be-marketed rabeprazole granules. Overall, 123 of 130 participants enrolled completed the studies. The overall plasma exposure as measured by area under the plasma concentration-time curve (AUC) was comparable between rabeprazole granules and tablets; mean peak plasma concentration (Cmax ) was lower for the granules compared with tablets. The plasma elimination half-life was short and independent of formulation. Food intake prior to administration of the to-be-marketed granules delayed the absorption and reduced the estimated parameters for bioavailability by 55% (Cmax ) and 28% (AUCinf ). Rabeprazole was well-tolerated.

Proton pump inhibitors: the good, the bad, and the unwanted

Proton pump inhibitors (PPIs) are one of the most commonly prescribed classes of medications in the United States. By inhibiting gastric H/K adenosine triphosphatase via covalent binding to the cysteine residues of the proton pump, they provide the most potent acid suppression available. Long-term PPI use accounts for the majority of total PPI use. Absolute indications include peptic ulcer disease, chronic nonsteroidal anti-inflammatory drugs use, treatment of Helicobacter pylori, and erosive esophagitis. Although PPIs are generally considered safe, numerous adverse effects, particularly associated with long-term use have been reported. Many patients receiving chronic PPI therapy do not have clear indications for their use, prompting consideration for reduction or discontinuation of their use. This article reviews the indications for PPI use, the adverse effects/risks involved with their use, and conditions in which their use is controversial.

Rabeprazole for the treatment of acid-related disorders

Proton pump inhibitors are widely used for the treatment of acid-related disorders. Rabeprazole is a potent and irreversible inhibitor of H(+)/K(+)-ATPase gastric pump, and it is indicated for the treatment of gastroesophageal reflux disease, Zollinger Ellison syndrome, duodenal and gastric ulcers and for the eradication of Helicobacter pylori in combination with antibiotics. Pharmacokinetic and pharmacodynamic data show that rabeprazole achieves a pronounced acid suppression from the first administration that is maintained with repeated use; this may translate into faster onset of symptom relief for patients, particularly suitable when the indication is for the on-demand long-term maintenance of gastroesophageal reflux disease. Due to its predominantly nonenzymatic metabolism, rabeprazole has a lower potential for drug-drug interactions. The objective of this article is to update efficacy and safety data of rabeprazole in the treatment of acid-related disorders, following a previous review dated 2008.

A review of stress-related mucosal disease

OBJECTIVE

To review and summarize the human and veterinary literature regarding stress-related mucosal disease (SRMD) pathogenesis, patient risk factors, and therapeutic options for prophylaxis and treatment.

ETIOLOGY

SRMD is a common sequela of critical illness in human patients. Development of SRMD results from splanchnic hypoperfusion, reperfusion injury, and exposure of the gastric mucosa to acid, pepsin, and bile acids following breakdown of the gastric mucosal defense system. Human patients with the highest risk of stress ulceration include those with respiratory failure necessitating mechanical ventilation greater than 48 h or coagulopathy. Currently, little is known about the incidence and pathophysiology of SRMD in critically ill veterinary patients.

DIAGNOSIS

A presumptive diagnosis can be made in high-risk patient populations following detection of occult or gross blood in nasogastric tube aspirates, hematemesis, or melena. Definitive diagnosis is achieved via esophagogastroduodenoscopy. Lesions are localized to the acid-producing portions of the stomach, the fundus, and body.

THERAPY

Therapy is aimed at optimization of tissue perfusion and oxygenation. Pharmacologic interventions are instituted to increase intraluminal pH and augment natural gastric defenses. Histamine(2)-receptor antagonists, proton pump inhibitors, and sucralfate are the mainstays of therapy. In people, clinically significant bleeding may necessitate additional interventions (eg, packed red blood cell transfusions, endoscopic, or surgical hemostasis).

PROGNOSIS

Mortality is increased in people with clinically significant bleeding compared to those patients who do not bleed. Institution of prophylaxis is recommended in high-risk patients. However, no consensus exists regarding initiation of prophylaxis, preference of frontline drug class, or indication for discontinuation of therapy. The prognosis of veterinary patients with SRMD remains unknown at this time.

Body mass index and the efficacy of acid-mediating agents for GERD

In studies of the association between obesity and gastroesophageal reflux, one subject that has received very little attention is the effect excess body mass may have on the effectiveness of acid-mediating agents. The lack of systematic research may reflect the perceived high clinical efficacy of drugs like proton pump inhibitors. Both proton pump inhibitors and histamine type 2 receptor antagonists have low rates of significant adverse events; if there are differences in the side effect profiles based on BMI, it is unlikely such associations would be detected. Also, while the metabolism of many drugs can be affected by body mass, it is not clear that such a relationship exists with acid-mediating agents. Nevertheless, there is evidence that body mass index may indeed be associated with the efficacy of proton pump inhibitors and histamine type 2 receptor antagonists. This review will examine that evidence and consider some of the possible pharmacokinetic effects that might relate to body mass index.

Drug interactions between proton pump inhibitors and antiretroviral drugs

Gastroesophageal reflux disease and other related symptoms are common comorbidities for HIV-infected patients. Therefore, concurrent use of proton pump inhibitors and antiretrovirals is a common practice in the clinical setting. However, this practice may alter antiretroviral pharmacokinetics and lead to treatment failure due to inadequate drug exposure. Clinician awareness of these complex interactions is essential for optimal HIV management. This review summarizes the current knowledge on the interactions between proton pump inhibitors and antiretrovirals, and makes recommendations for the coadministration of proton pump inhibitors.