Review article: the clinical pharmacology of proton pump inhibitors

Drug-Induced Subacute Cutaneous Lupus Erythematosus Associated with Proton Pump Inhibitors

Subacute cutaneous lupus erythematosus (SCLE) is an autoimmune disease that may be induced by proton pump inhibitors (PPIs) in at-risk populations. The US FDA does not recognize SCLE as an adverse event associated with PPIs. We queried the FDA Adverse Event Reporting System database, which contains adverse event case reports submitted by the public as well as by industry, and analyzed the data to quantify passive pharmacovigilance signals for SCLE associated with PPIs. A disproportionality analysis of the signals yielded a significant association between SCLE and PPIs. Discontinuation of PPI resulted in remission, with PPI re-challenge causing SCLE to reoccur. A follow-up analysis also yielded a significant association between SCLE and H2 receptor antagonists. We conducted a brief literature survey of published case reports and studies to discern the validity of PPI-induced SCLE signals. Healthcare prescribers and patients should be made aware that SCLE can be induced by PPIs. In such cases, PPIs should be discontinued and alternative clinical treatment sought. Regulatory bodies such as the FDA should incorporate the adverse reaction in PPI prescription labels.

Pharmacokinetics and pharmacodynamics of intravenous ilaprazole in healthy subjects after single ascending doses

1. Ilaprazole is a novel proton pump inhibitor and this is the first study to investigate the pharmacokinetics, pharmacodynamics and safety of intravenous ilaprazole in healthy volunteers. 2. In this open-label, single-dose, randomized and four-period crossover study, 16 healthy Chinese subjects received ilaprazole 5, 10 or 20 mg intravenously, or 10 mg orally. Serial blood and urine samples were collected and intragastric pH was recorded within 24 h. The percentage time of intragastric pH > 6 was the major index. Safety was assessed throughout the study. 3. Plasma exposure of intravenous ilaprazole increased proportionally over the dose of 5-20 mg. Clearance and volume of distribution were independent of dose. Ilaprazole was not eliminated through urine and the absolute bioavailability was 55.2%. For the intravenous dose of 5, 10, 20 mg, and oral dose of 10 mg, the mean percentages time of intragastric pH > 6 were 47.3%, 52.8%, 68.2% and 47.5%, respectively. 4. Ilaprazole showed linear pharmacokinetics over the dose of 5-20 mg. Intravenous ilaprazole provided rapid onset of action and the potency of effect were exhibited in a dose-dependent manner. Intravenous ilaprazole was safe and well tolerated except for elevated activated partial thromboplastin time (APTT) and prothrombin time (PT).

Is the use of esomeprazole in gastroesophageal reflux disease a cost-effective option in Poland?

OBJECTIVES

To compare the cost-effectiveness of therapy of gastroesophageal reflux disease with esomeprazole and other proton pump inhibitors (PPIs) in Poland.

MATERIALS & METHODS

Studies comparing esomeprazole with other PPIs in the treatment of erosive esophagitis, non-erosive reflux disease and gastroesophageal reflux disease maintenance therapy were systematically reviewed. 9 randomized clinical trials were selected, meta-analyses were conducted. Cost data derived from Polish Ministry of Health and Pharmacies in Wroclaw.

RESULTS

In the treatment of erosive esophagitis esomeprazole was significantly more effective than other PPIs. Both for 4- and 8-week therapy respective incremental cost-effectiveness ratio values were acceptably low. Differences in effectiveness of non-erosive reflux disease therapy were not significant. The replacement of pantoprazole 20 mg with more effective esomeprazole 20 mg in the 6-month maintenance therapy was associated with a substantially high incremental cost-effectiveness ratio.

Proton pump inhibitor associated hypomagnasaemia - a cause for concern?

AIMS

In recent years, there have been a number of case reports of severe hypomagnesaemia associated with proton pump inhibitor (PPI) use, such that both the FDA and MHRA have issued drug safety warnings. They have recommended periodic serum magnesium testing in patients prescribed PPIs but provide no guidance on timing of these measurements.

METHODS

To our knowledge, we are the first to perform a prospective study to explore specifically proton pump inhibitor associated hypomagnesaemia (PPIAH). We followed 56 patients new to PPIs prospectively as well as a further 100 patients on long term PPIs cross-sectionally to identify what factors may be influencing the development of significant hypomagnesaemia.

RESULTS

For the prospective arm of the study, we measured serum magnesium levels prior to starting a PPI and again at regular intervals for the next 8 months. For the cross-sectional arm of the study we measured serum magnesium levels on patients on PPI therapy ranging from less than 1 year to over 5 years.

CONCLUSION

We found that, although there was a significant downward trend in serum magnesium levels in patients new to PPI therapy with time, clinically relevant hypomagnesaemia was not readily identifiable on regular blood testing. We did however identify patients on concurrent diuretic therapy as being at higher risk and so would recommend regular serum magnesium testing alongside their regular renal function monitoring on a more frequent basis such as annually.

Computational insights into the interaction mechanism of triazolyl substituted tetrahydrobenzofuran derivatives with H(+),K(+)-ATPase at different pH

The interaction mechanism of triazolyl substituted tetrahydrobenzofuran derivatives (compound 1 (N, N-Dipropyl-1-(2-phenyl-4,5,6,7-tetrahydrobenzofuran-4-yl)-1H-1,2,3-triazole-4-methanamine) and 2 (1-(2-Phenyl-4,5,6,7-tetrahydrobenzofuran-4-yl)-4-(morpholin-4-ylmethyl)-1H-1,2,3-triazole)) with H(+),K(+)-ATPase at different pH were studied by induced-fit docking, QM/MM optimization and MM/GBSA binding free energy calculations of two forms (neutral and protonated form) of compounds. The inhibition activity of compound 1 is measured and almost unchanged at different pH, while the activity of compound 2 increases significantly with pH value decreased. This phenomenon could be explained by their protonated form percentages and the calculated binding free energies of protonated and neutral mixture of compounds at different pH. The binding free energy of protonated form is higher than that of neutral form of compound, and the protonated form could be a powerful inhibitor of H(+),K(+)-ATPase. By the decomposed energy comparisons of residues in binding sites, Asp137 should be the key binding site to protonated form of compound because of the hydrogen bond and electrostatic interactions. These calculation results could help for further rational design of novel H(+),K(+)-ATPase inhibitors.

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.

Pharmacogenomic testing: the case for CYP2C19 proton pump inhibitor gene-drug pairs

The use of proton pump inhibitors (PPIs) in the treatment of gastroesophageal reflux and related diseases is increasing, especially in the pediatric population. Prolonged use of PPIs has been associated with several adverse effects, including potentially life-threatening gastric and respiratory infections, which are related to dose or to the degree of gastric acid suppression. Genetic variation in the CYP2C19 gene gives rise to poor and extensive metabolizer phenotypes, which influence PPI clearance, efficacy and exposure. A recent paper linked lansoprazole-associated respiratory infections in children with the poor metabolizer phenotype. The case is made for implementing pharmacogenomic testing for the CYP2C19-PPI gene-drug pair and to dose accordingly in order to minimize PPI-associated infections.

Gastroprotective activity of chloroform extract of Muntingia calabura and Melastoma malabathricum leaves

CONTEXT

Muntingia calabura L. (family Muntingiaceae) and Melastoma malabathricum L. (family Melastomaceae) are traditionally used to treat gastric ulcer.

OBJECTIVE

The present study determines the mechanisms of gastroprotective activity of the chloroform extract of leaves obtained from both the plants using several in vitro and in vivo assays.

MATERIALS AND METHODS

Phytochemical screening, HPLC analysis, and antioxidant activity of the respective extract were carried out. Gastroprotective activity was determined using ethanol-induced gastric ulcer assay while the mechanisms of gastroprotection were determined using the pyloric ligation assay. The test solutions [8% Tween-80 (vehicle), 20 mg/kg omeprazole, and different doses of extracts (50, 250, or 500 mg/kg] were administered orally once daily for 7 consecutive days before the animals were subjected to ethanol induced gastric ulcers.

RESULTS

The chloroform-extracted M. calabura (CEMC) contains tannins, polyphenolics, triterpenes, and steroids while the chloroform-extracted M. malabathricum (CEMM) contains only triterpenes and steroids. CEMC, but not CEMM, exerted remarkably strong antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH)- (86% versus 16%) and superoxide- (73% versus 36%) radical scavenging assays. Both extracts demonstrated significant (p < 0.05) gastroprotection with the EC50 value recorded at 192.3 or 297.7 mg/kg, respectively. In the pylorus ligation assay, CEMC and CEMM significantly (p < 0.05) reduced the total and free acidity and volume; while increased the pH of gastric juice as well as the gastric wall mucus content in comparison with the vehicle-treated group.

DISCUSSION AND CONCLUSION

CEMC and CEMM exert gastroprotective effects in animals with ethanol-induced gastric ulcers via antioxidant and anti-secretory effects.

Association between use of proton pump inhibitors and non-typhoidal salmonellosis identified following investigation into an outbreak ofSalmonellaMikawasima in the UK, 2013

In November 2013, national public health agencies in England and Scotland identified an increase in laboratory-confirmedSalmonellaMikawasima. The role of proton pump inhibitors (PPIs) as a risk factor for salmonellosis is unclear; we therefore captured information on PPI usage as part of our outbreak investigation. We conducted a case-control study, comparing each case with two controls. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression. Thirty-nine of 61 eligible cases were included in the study. The median age of cases was 45 years; 56% were female. Of these, 33% were admitted to hospital and 31% reported taking PPIs. We identified an association between PPIs and non-typhoidal salmonellosis (aOR 8·8, 95% CI 2·0–38·3). There is increasing evidence supporting the existence of an association between salmonellosis and PPIs; however, biological studies are needed to understand the effect of PPIs in the pathogenesis ofSalmonella. We recommend future outbreak studies investigate PPI usage to strengthen evidence on the relevance of PPIs inSalmonellainfection. These findings should be used to support the development of guidelines for patients and prescribers on the risk of gastrointestinal infection and PPI usage.

The effect of orally administered ranitidine and once-daily or twice-daily orally administered omeprazole on intragastric pH in cats

BACKGROUND

Gastric acid suppressants frequently are used in cats with acid-related gastric disorders. However, it is not known if these drugs effectively increase intragastric pH in cats.

OBJECTIVES

To examine the effects of PO administered ranitidine and omeprazole on intragastric pH in cats and to compare the efficacy of once-daily versus twice-daily dosage regimens for omeprazole.

ANIMALS

Eight domestic shorthair cats.

METHODS

Using a randomized 4-way cross-over design, cats were given enteric-coated omeprazole granules (1.1-1.3 mg/kg q24h and q12h), ranitidine (1.5-2.3 mg/kg q12h), and placebo. Intragastric pH was monitored continuously for 96 hours using the Bravo(™) system, starting on day 4 of treatment, followed by a median washout period of 12 days. Mean percentage of time pH was ≥3 and ≥4 was compared among groups using repeated measures ANOVA.

RESULTS

Mean ± SD percentage of time intragastric pH was ≥3 and ≥4 was 67.0 ± 24.0% and 54.6 ± 26.4% for twice-daily omeprazole, 24.4 ± 22.8% and 16.8 ± 19.3% for once-daily omeprazole, 16.5 ± 9.0% and 9.6 ± 5.9% for ranitidine, and 9.4 ± 8.0% and 7.0 ± 6.6% for placebo administration. Twice-daily omeprazole treatment significantly increased intragastric pH, whereas pH after once-daily omeprazole and ranitidine treatments did not differ from that of placebo-treated cats.

CONCLUSION AND CLINICAL IMPORTANCE

Only twice-daily PO administered omeprazole significantly suppressed gastric acidity in healthy cats, whereas once-daily omeprazole and standard dosages of ranitidine were not effective acid suppressants in cats.

Repositioning proton pump inhibitors as anticancer drugs by targeting the thioesterase domain of human fatty acid synthase

Fatty acid synthase (FASN), the enzyme responsible for de novo synthesis of free fatty acids, is up-regulated in many cancers. FASN is essential for cancer cell survival and contributes to drug resistance and poor prognosis. However, it is not expressed in most nonlipogenic normal tissues. Thus, FASN is a desirable target for drug discovery. Although different FASN inhibitors have been identified, none has successfully moved into clinical use. In this study, using in silico screening of an FDA-approved drug database, we identified proton pump inhibitors (PPIs) as effective inhibitors of the thioesterase activity of human FASN. Further investigation showed that PPIs inhibited proliferation and induced apoptosis of cancer cells. Supplementation of palmitate, the end product of FASN catalysis, rescued cancer cells from PPI-induced cell death. These findings provide new evidence for the mechanism by which this FDA-approved class of compounds may be acting on cancer cells.

Analysis of the structural diversity, substitution patterns, and frequency of nitrogen heterocycles among U.S. FDA approved pharmaceuticals

Nitrogen heterocycles are among the most significant structural components of pharmaceuticals. Analysis of our database of U.S. FDA approved drugs reveals that 59% of unique small-molecule drugs contain a nitrogen heterocycle. In this review we report on the top 25 most commonly utilized nitrogen heterocycles found in pharmaceuticals. The main part of our analysis is divided into seven sections: (1) three- and four-membered heterocycles, (2) five-, (3) six-, and (4) seven- and eight-membered heterocycles, as well as (5) fused, (6) bridged bicyclic, and (7) macrocyclic nitrogen heterocycles. Each section reveals the top nitrogen heterocyclic structures and their relative impact for that ring type. For the most commonly used nitrogen heterocycles, we report detailed substitution patterns, highlight common architectural cores, and discuss unusual or rare structures.

The pharmacokinetics, pharmacodynamics and safety of oral doses of ilaprazole 10, 20 and 40 mg and esomeprazole 40 mg in healthy subjects: a randomised, open-label crossover study

BACKGROUND

Ilaprazole, a proton pump inhibitor (PPI) currently in clinical use, may provide improved acid suppression vs. other PPIs.

AIM

To compare the pharmacodynamic and pharmacokinetic profiles of ilaprazole and esomeprazole.

METHODS

A phase 1, randomised, open-label, single-centre, 4-period crossover study was conducted in 40 healthy volunteers. Ilaprazole 10, 20 or 40 mg or esomeprazole 40 mg was administered once daily for 5 days with ≥5-day washout intervals. Pharmacokinetic blood samples and intragastric pH measurements were collected at scheduled timepoints for 24 h after dosing on Days 1 and 5.

RESULTS

Esomeprazole 40 mg provided significantly better pH control during the initial hours (0-4 h) after a single dose, but ilaprazole (particularly 20 and 40 mg) provided significantly better pH control for the entire 24-h period and during evening and overnight hours after single and multiple doses. Increasing ilaprazole doses resulted in dose-proportional increases in peak plasma concentration and area under the plasma concentration vs. time curve following single and multiple doses. Ilaprazole was safe and generally well tolerated; an unexpectedly high incidence of allergic eye and skin reactions were observed but were not specific to any dosing regimen. Plasma gastrin concentrations did not increase proportionately with increasing ilaprazole dose.

CONCLUSIONS

Ilaprazole provided significantly better pH control over 24 h and during evening and overnight hours compared with esomeprazole in healthy volunteers, which may translate to greater relief of night-time heartburn in the clinical setting for patients with gastric acid-related disorders.

Rabeprazole exhibits antiproliferative effects on human gastric cancer cell lines

Intracellular proton extrusion in gastric cancer cells has been reported to promote cancer cell survival under acidic conditions via hydrogen/potassium adenosine triphosphatase (H⁺/K⁺-ATPase). Rabeprazole is a frequently used second-generation proton pump inhibitor (PPI) that irreversibly inactivates gastric H⁺/K⁺-ATPase. Therefore, we hypothesized that rabeprazole could reduce the viability of gastric cancer cells. In the present study, four human gastric cancer cell lines and one non-cancer gastric cell line were cultured. Cell viability, the α- and β-subunits of H⁺/K⁺-ATPase and cellular apoptosis were analyzed by dye exclusion assay, reverse transcription-polymerase chain reaction and annexin V-fluorescein isothiocyanate/propidium iodide staining, respectively. The expression level of total extracellular signal-regulated protein kinase 1/2 (ERK 1/2) and phosphorylated-ERK protein was detected by western blot analysis. Gastric cancer cell lines were more tolerant of the acidic culture media than non-cancer cells. Administration of rabeprazole led to a marked decrease in the viability of MKN-28 cells. Exposure to rabeprazole induced significant apoptosis in AGS cells. Rabeprazole completely inhibited the phosphorylation of ERK 1/2 in the MKN-28 cells, whereas the same effect was not observed in either the KATO III or MKN-45 cells. The ERK 1/2 inhibitor, PD98059, attenuated the viability of the AGS cells. A similar antiproliferative effect was observed in the rabeprazole treatment group. In addition, PD98059 and rabeprazole were able to efficaciously inhibit the phosphorylation of ERK 1/2 in the gastric cancer cells. Therefore, it was concluded that rabeprazole can attenuate the cell viability of human gastric cancer cells through inactivation of the ERK1/2 signaling pathway. The results of the present study demonstrate that rabeprazole inhibits the viability of gastric cancer cells in vitro and may serve as a novel antineoplastic agent.

Pharmacokinetic evaluation of esomeprazole for the treatment of gastroesophageal reflux disease

INTRODUCTION

Proton pump inhibitors (PPIs) are widely used for the treatment of acid-related diseases such as gastroesophageal reflux disease (GERD). They are recommended by the American College of Gastroenterology for healing erosive esophagitis (EO) and as long-term treatment in patients with healed EO. The available PPIs differ somewhat in their pharmacokinetics and clinical properties, but whether these differences are of clinical relevance is a matter of debate. Some safety concerns have been raised with the use of PPIs, mostly an increased incidence of infectious diseases such as community-acquired pneumonia or Clostridium difficile diarrhea.

AREAS COVERED

This article explores the results of clinical studies on the pharmacokinetics and pharmacodynamics of esomeprazole , as well as on its clinical efficacy to manage patients with GERD.

EXPERT OPINION

GERD is a public health concern as its worldwide incidence and associated complications are increasing alongside the exponentially increasing problem of obesity. PPIs are the first pharmacological option because of their efficacy and overall positive risk-to-benefit ratio. Improved efficacy with the use of stereospecific isomers of PPIs, such as esomeprazole, has not yet been convincingly demonstrated. Nevertheless, because of individual experience with former treatment, some patients may report better symptom control when treated with a specific PPI rather than with others.

Eosinophilic esophagitis: interactions with gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) and eosinophilic esophagitis (EoE) are not mutually exclusive. The notion that GERD and EoE can be distinguished by the response to proton pump inhibitor (PPI) treatment is based on the mistaken assumption that gastric acid suppression is the only important therapeutic effect of PPIs, and therefore only GERD can respond to PPIs. We believe that a clinical or histologic response to PPIs does not rule in GERD or rule out EoE. We recommend a trial of PPI therapy for patients with symptomatic esophageal eosinophilia, even if the diagnosis of EoE seems clear-cut.

Protonated form: the potent form of potassium-competitive acid blockers

Potassium-competitive acid blockers (P-CABs) are highly safe and active drugs targeting H+,K+-ATPase to cure acid-related gastric diseases. In this study, we for the first time investigate the interaction mechanism between the protonated form of P-CABs and human H+,K+-ATPase using homology modeling, molecular docking, molecular dynamics and binding free energy calculation methods. The results explain why P-CABs have higher activities with higher pKa values or at lower pH. With positive charge, the protonated forms of P-CABs have more competitive advantage to block potassium ion into luminal channel and to bind with H+,K+-ATPase via electrostatic interactions. The binding affinity of the protonated form is more favorable than that of the neutral P-CABs. In particular, Asp139 should be a very important binding site for the protonated form of P-CABs through hydrogen bonds and electrostatic interactions. These findings could promote the rational design of novel P-CABs.

Acid peptic diseases: pharmacological approach to treatment

Acid peptic disorders are the result of distinctive, but overlapping pathogenic mechanisms leading to either excessive acid secretion or diminished mucosal defense. They are common entities present in daily clinical practice that, owing to their chronicity, represent a significant cost to healthcare. Key elements in the success of controlling these entities have been the development of potent and safe drugs based on physiological targets. The histamine-2 receptor antagonists revolutionized the treatment of acid peptic disorders owing to their safety and efficacy profile. The proton-pump inhibitors (PPIs) represent a further therapeutic advance due to more potent inhibition of acid secretion. Ample data from clinical trials and observational experience have confirmed the utility of these agents in the treatment of acid peptic diseases, with differential efficacy and safety characteristics between and within drug classes. Paradigms in their speed and duration of action have underscored the need for new chemical entities that, from a single dose, would provide reliable duration of acid control, particularly at night. Moreover, PPIs reduce, but do not eliminate, the risk of ulcers in patients taking NSAIDs, reflecting untargeted physiopathologic pathways and a breach in the ability to sustain an intragastric pH of more than 4. This review provides an assessment of the current understanding of the physiology of acid production, a discussion of medications targeting gastric acid production and a review of efficacy in specific acid peptic diseases, as well as current challenges and future directions in the treatment of acid-mediated diseases.

Relief of Night-time Symptoms Associated With Gastroesophageal Reflux Disease Following 4 Weeks of Treatment With Pantoprazole Magnesium: The Mexican Gastroesophageal Reflux Disease Working Group

BACKGROUND/AIMS

To evaluate the effectiveness of pantoprazole magnesium (pantoprazole-Mg) 40 mg in the relief of esophageal and extra-esophageal symptoms of gastroesophageal reflux disease (GERD), particularly night-time symptoms.

METHODS

Patients (aged 18-50 years) with 3-month history of heartburn and/or acid regurgitation plus at least one other symptom in the last week were enrolled in a nationwide, prospective and observational study in Mexico. Patients received pantoprazole-Mg 40 mg once daily during 4 weeks. Symptoms were assessed through a physician-administered structured interview and the patient-completed ReQuest in Practice™ questionnaire. Night-time GERD was defined as arousal from sleep during the night due to GERD-associated symptoms.

RESULTS

Out of 4,343 patients included at basal visit, 3,665 were considered for the effectiveness per protocol analysis. At baseline, patients had a median of 8 GERD related symptoms. Patients with night-time GERD symptoms (42.7%) were more likely to have extra-esophageal symptoms (P < 0.001) than other GERD patients. Pantoprazole-Mg 40 mg once daily for 4 weeks improved a broad range of GERD-associated symptoms from baseline (80% reduction on physicians assessments; 68-77% reduction on ReQuest in Practice™ dimensions), including both day- and night-time GERD symptoms; improvements were the greatest for extra-esophageal symptoms in patients with night-time symptoms. Pantoprazole-Mg was well tolerated.

CONCLUSIONS

Pantoprazole-Mg 40 mg significantly improved a broad range of esophageal and extra-esophageal GERD related symptoms including sleep disturbances, as well as well-being, in patients with daytime or night-time GERD, making it a good option for patients with GERD, especially when extra-esophageal and night-time symptoms are present.

Randomised clinical trial: daily pantoprazole magnesium 40 mg vs. esomeprazole 40 mg for gastro-oesophageal reflux disease, assessed by endoscopy and symptoms

BACKGROUND

Pantoprazole magnesium (pantoprazole-Mg) may display extended inhibition of the proton pump with the potential for improved clinical efficacy in gastro-oesophageal reflux disease (GERD).

AIM

To compare the efficacy of pantoprazole-Mg and esomeprazole in GERD.

METHODS

Gastro-oesophageal reflux disease (Los Angeles grades A-D) patients were randomised to 4 weeks of treatment with pantoprazole-Mg (n = 290) or esomeprazole (n = 288), both 40 mg once daily, in this multicentre (14 Brazilian sites in 9 cities), double-blind study, with an additional 4 weeks' treatment in nonresponding patients. Severity of oesophagitis (at endoscopy) and GERD-related symptoms (ReQuest-GI) were assessed. The primary end point was the proportion of patients in complete remission (ReQuest-GI score <1.73 plus endoscopic healing) at week 4.

RESULTS

Complete remission occurred in 61% of patients in each treatment group at 4 weeks (primary endpoint) and in 81% and 79% of patients in the pantoprazole-Mg and esomeprazole groups at 8 weeks, with no significant differences. Mucosal healing rates were high and not significantly different. At 8 weeks, symptom relief with pantoprazole-Mg was significantly greater than that with esomeprazole (91.6% vs. 86.0%, P = 0.0370) because of continued improvement in symptoms with pantoprazole-Mg from week 4 to week 8 (P = 0.0206).

CONCLUSIONS

Pantoprazole-Mg 40 mg was at least as effective as esomeprazole 40 mg for complete remission and the mucosal healing rate was high. Symptom relief with pantoprazole-Mg continued to improve from 4 to 8 weeks and was greater than that with esomeprazole at week 8, suggesting an extended period of treatment effect (ClinicalTrials.gov identifier: NCT01132638).

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

This review which is the second in this series summarises the most common synthetic routes as applied to the preparation of many modern pharmaceutical compounds categorised as containing a six-membered heterocyclic ring. The reported examples are based on the top retailing drug molecules combining synthetic information from both scientific journals and the wider patent literature. It is hoped that this compilation, in combination with the previously published review on five-membered rings, will form a comprehensive foundation and reference source for individuals interested in medicinal, synthetic and preparative chemistry.

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

This review which is the second in this series summarises the most common synthetic routes as applied to the preparation of many modern pharmaceutical compounds categorised as containing a six-membered heterocyclic ring. The reported examples are based on the top retailing drug molecules combining synthetic information from both scientific journals and the wider patent literature. It is hoped that this compilation, in combination with the previously published review on five-membered rings, will form a comprehensive foundation and reference source for individuals interested in medicinal, synthetic and preparative chemistry.

A relic or still relevant: the narrowing role for vagotomy in the treatment of peptic ulcer disease

BACKGROUND

Given the rise of medical treatment for peptic ulcer disease (PUD), surgical treatment is necessary only in select cases and emergencies. The authors assess the current relevance of surgical vagotomy to treat PUD and its complications.

DATA SOURCES

Although historically significant, selective and highly selective vagotomy is very technically challenging, and highly selective vagotomy has a relatively narrow indication and high recurrence rates. Vagotomy and gastrectomy is associated with significant side effects. Two types of vagotomy remain relevant, within a narrow scope. Truncal vagotomy and pyloroplasty is safe and efficacious through a laparoscopic approach in certain emergent cases. Vagotomy and Roux-en-Y gastrojejunostomy can be used to treat severe PUD refractory to medical management.

CONCLUSIONS

The role of vagotomy in the management of PUD has a rich history but predated pharmacologic control of acid and understanding of the role of Helicobacter pylori in the disease. Thus, the current role of vagotomy is significantly limited. Specifically, the emergent use of truncal vagotomy is warranted for patients who are either resistant or allergic to proton pump inhibitors.

In vitro characterization of acid secretion in the gilthead sea bream (Sparus aurata) stomach

The gastric acid secretion of juvenile Sparus aurata was characterized in Ussing chambers; secretion rates were determined by a pH-stat method at pH5.50 and bioelectrical parameters were measured in current-clamped tissues. The basal secretion equaled to 535±87nmol·cm(-2)·h(-1). Serosal carbachol 100μM produced an increase (ΔJH(+)) of 725±133nmol·cm(-2)·h(-1) from basal secretion, this effect being inhibited by mucosal omeprazole 100μM. Basal secretion was also sensitive to the combination of serosal forskolin (FK) 10μM+serosal isobutylmethylxanthine (IBMX) 100μM (ΔJH(+)=793±239nmol·cm(-2)·h(-1)); this effect was insensitive to mucosal omeprazole 100mM but inhibited by mucosal bafilomycin A1 100nM. The effect of carbachol proceeded within a few minutes (<10min), whereas the effect of FK+IBMX was gradual, taking 40min to reach the maximum. The addition of mucosal gadolinium (Gd(3+)) 100μM, a potent calcium-sensing receptor (CaR) agonist, stimulated the basal secretion (ΔJH(+)=340±81nmol·cm(-2)·h(-1)). The present results indicate that the acid secretion mechanism in the sea bream stomach is regulated by muscarinic and CaR-like receptors, cAMP is implicated in the signal transduction, and at least two proton pumps, a HK-ATPase and a V-ATPase contribute to acid secretion.

Proton pump inhibitors for eosinophilic oesophagitis

PURPOSE OF REVIEW

To review the significance and plausible mechanisms underlying 'proton pump inhibitor (PPI) responsive oesophageal eosinophilia' in eosinophilic oesophagitis (EoE).

RECENT FINDINGS

EoE is defined as an immune-mediated clinicopathologic condition characterized by oesophageal dysfunction and eosinophil-predominant inflammation. This new conceptual definition has been proposed partly due to a recently identified disease phenotype called 'PPI-responsive oesophageal eosinophilia'. Emerging data support the possibility that this condition represents a clinical response to anti-inflammatory properties of PPIs that are independent of effects on gastric acid.

SUMMARY

Currently, the diagnosis of EoE is reserved for patients with oesophageal eosinophilia and symptoms that do not respond to PPIs. This practice may not be appropriate, however, both because gastric acid suppression by PPIs might benefit EoE patients and because PPIs have anti-inflammatory properties that also might benefit EoE patients. More studies are sorely needed to understand the mechanisms underlying PPI-responsive oesophageal eosinophilia. Currently, a favourable response to PPI therapy should not be regarded as a proof of an underlying acid peptic disorder such as gastroesophageal reflux disease (GERD) nor should it preclude a diagnosis of EoE. Furthermore, it seems prudent to recommend a trial of PPI therapy for patients with oesophageal eosinophilia and symptoms, even when the diagnosis of EoE seems clear-cut.

The pharmacokinetics of ilaprazole for gastro-esophageal reflux treatment

INTRODUCTION

Approximately 20% of the Western population is affected by gastro-esophageal reflux disease (GERD). To date, proton pump inhibitors (PPIs) represent the mainstay of GERD medical treatment. However, despite their undoubted benefit, about 40% of GERD patients display an inadequate response to these drugs. Recently, a new PPI, ilaprazole , at oral doses of 10 mg has shown higher suppression of gastric acid secretion, more prolonged plasma half-life, and similar safety compared to 20 mg omeprazole.

AREAS COVERED

This review provides an update on the following points: pharmacokinetic profile and metabolism of ilaprazole in relation to its pharmacodynamic properties; comparative data on the pharmacokinetics and pharmacodynamics of ilaprazole with currently available PPIs; and implications for studies on the therapeutic efficacy of ilaprazole in GERD.

EXPERT OPINION

Different studies show that ilaprazole, a benzimidazole derivative, has an extended plasma half-life in comparison with all other approved PPIs. In addition, ilaprazole metabolism is not significantly influenced by CYP2C19, compared to the available PPIs. Furthermore, the pharmacological characteristics of ilaprazole confer theoretical advantages that are expected to translate into an improved acid control, particularly at night time. However, studies comparing the clinical pharmacokinetics and pharmacodynamics of ilaprazole with those of second-generation PPIs are insufficient. Moreover, further investigations assessing the efficacy of ilaprazole in the management of GERD are required. In healthy volunteers, as well as in patients with gastric or duodenal ulcers, ilaprazole has not shown clinically relevant changes in hematology and biochemistry testing, nor significant treatment-related adverse symptoms.

Use of proton pump inhibitors with lack of diagnostic indications in 22 Midwestern US skilled nursing facilities

OBJECTIVES

The primary objective of this study was to identify proton pump inhibitor (PPI) prescribing patterns in a population of older adults admitted to 22 Midwestern skilled long term care facilities (LTCF) with medical coverage provided by the US Medicare Part A program. The relationship between PPI prescribing patterns and specific ICD-9 diagnostic codes and symptoms management was examined. The long-term objective is appropriate PPI prescription guidance through the development of evidence- and regulation-based pharmacy formulary and policy practices, as well as practical prescribing guidance for practitioners who are supported by this pharmacy.

DESIGN

An observational cohort study was conducted, using prospectively collected and de-identified prescribing and diagnostic data from a convenience sample of all Medicare A skilled nursing patients admitted between January 1, 2010, and May 31, 2011, to 22 urban, suburban, and rural Midwestern US LTCFs.

SETTING AND PARTICIPANTS

A common pharmacy service de-identified and aggregated PPI prescribing data and patient diagnostic information. These secondary data were analyzed for trends and patterns related to PPI use for all Medicare A patients admitted to these 22 facilities during a 17-month period in 2010 and 2011.

MEASUREMENT AND RESULTS

Rates of PPI use were determined and were compared with diagnostic codes. Of 1381 total admissions, 1100 patients (79.7%) were prescribed PPI. There was no appropriate diagnosis for PPI use in 718 patients (65.3%). Gastroesophageal reflux disease (GERD) tended to be the blanket diagnosis that was used most frequently for PPIs, but there was usually no follow-up or symptomatic evidence documented of active GERD. When long-term (current) use of nonsteroidal anti-inflammatory drugs (NSAIDs) (including aspirin) and/or anticoagulant therapy (warfarin) was considered as appropriate indications for 382 patients, 336 (24%) of all Medicare patients were still receiving PPIs with no relevant gastrointestinal ICD-9 diagnostic code. Total cost of PPIs prescribed from January 2010 to June 2011 was $348,414.

CONCLUSIONS

The examined PPI prescribing patterns show discordance between ICD-9 diagnostic code and prescribed use of PPIs in the study population. More than half (52%) of the total number of Medicare A patients were taking the medication without an indicated diagnosis. Even when NSAIDs and anticoagulant therapy were taken into consideration as valid reasons for PPI use, 24% of all patients admitted were still prescribed PPIs without a diagnosis that indicated the need for a PPI. Considering the economic cost, potential side effects, and CMS F329 regulations, which require that an LTCF resident's drug regimen be free from unnecessary medication, it is important that prescribers in LTCFs carefully consider use of PPIs in older adults in LTCFs and monitor the continued use of PPIs to prevent both the personal cost of physical side effects and drug-drug interactions, as well as the economic cost of unnecessary medication use.

Proton pump inhibitors in pediatrics : mechanism of action, pharmacokinetics, pharmacogenetics, and pharmacodynamics

Proton pump inhibitors (PPIs) have become some of the most frequently prescribed medications for treatment of adults and children. Their effectiveness for treatment of peptic conditions in the pediatric population, including gastric ulcers, gastroesophageal reflux disease (GERD), and Helicobacter pylori infections has been established for children older than 1 year. Studies of the preverbal population of neonates and infants have identified doses that inhibit acid production, but the effectiveness of PPIs in the treatment of GERD has not been established except for the recent approval of esomeprazole treatment of erosive esophagitis in infants. Reasons that have been proposed for this are complex, ranging from GERD not occurring in this population to a lack of histologic identification of esophagitis related to GERD to questions about the validity of symptom scoring systems to identify esophagitis when it occurs in infants. The effectiveness of PPIs relates to their structures, which must undergo acidic activation within the parietal cell to allow the PPI to be ionized and form covalent disulfide bonds with cysteines of the H(+)-K(+)-adenosine triphosphatase (H(+)-K(+)-ATPase). Once the PPI binds to the proton pump, the pump is inactivated. Some PPIs, such as omeprazole and rabeprazole bind to cysteines that are exposed, and their binding can be reversed. After irreversible chemical inhibition of the proton pump, such as occurs with pantoprazole, the recovery of the protein of the pump has a half-life of around 50 h. Cytochrome P450 (CYP) 2C19 and to a lesser degree CYP3A4 clear the PPIs metabolically. These enzymes are immature at birth and reach adult levels of activity by 5-6 months after birth. This parallels studies of the maturation of CYP2C19 to adult levels by roughly the same age after birth. Specific single nucleotide polymorphisms of CYP2C19 reduce clearance proportionally and increase exposure and prolong proton pump inhibition. Prolonged treatment of pediatric patients with PPIs has not caused cancer or significant abnormalities.

The promiscuous binding of pharmaceutical drugs and their transporter-mediated uptake into cells: what we (need to) know and how we can do so

A recent paper in this journal sought to counter evidence for the role of transport proteins in effecting drug uptake into cells, and questions that transporters can recognize drug molecules in addition to their endogenous substrates. However, there is abundant evidence that both drugs and proteins are highly promiscuous. Most proteins bind to many drugs and most drugs bind to multiple proteins (on average more than six), including transporters (mutations in these can determine resistance); most drugs are known to recognise at least one transporter. In this response, we alert readers to the relevant evidence that exists or is required. This needs to be acquired in cells that contain the relevant proteins, and we highlight an experimental system for simultaneous genome-wide assessment of carrier-mediated uptake in a eukaryotic cell (yeast).

Effects of Omeprazole on Vitamin and Mineral Absorption and Metabolism

Objective:

To examine the literature surrounding the effects of omeprazole on oral iron absorption and discuss the long-term use of omeprazole and its effect on vitamins C and B12, calcium, and magnesium absorption.

Data Sources:

The PubMed and MEDLINE databases were searched for reports published in English between January 1968 and August 2012, using the terms absorption, ascorbic acid, proton pump inhibitor, omeprazole, magnesium, calcium, ferrous sulfate, iron, and drug interactions.

Study Selection and Data Extraction:

Studies and reports published in English were selected for review. In some cases, reference citations from selected review articles were evaluated as well.

Data Synthesis:

Several micronutrients require an acidic environment for optimal absorption. Iron, vitamin C, and vitamin B12absorption are dependent on the intestine's acidic environment. Several studies and case reports describe associations of omeprazole with altered calcium, magnesium, and vitamin B12absorption. To date, there have been no prospective trials evaluating the effect of proton pump inhibitors (PPIs) on iron absorption.

Conclusions:

Existing data support the conclusion that the acid-suppressing effect of omeprazole can have important clinical implications for vitamin and mineral therapy. Clinicians should be cognizant of this issue in practice. Further studies exploring the relationship of PPIs and iron deficiency are warranted, especially in high-risk populations such as the elderly.

Relative bioavailability and pharmacokinetic comparison of two different enteric formulations of omeprazole

In order to comply with the requirements for a drug listed in China, the study was developed to compare the pharmacokinetics and relative bioavailability of two different enteric formulations of omeprazole (OPZ) in healthy Chinese subjects. A total of 32 volunteers participated in the study. Plasma concentrations were analyzed by nonstereospecific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method. After administration of a single 40-mg dose of the two OPZ formulations, the comparative bioavailability was assessed by calculating individual AUC(0‒t) (the area under the concentration-time curve from time zero to the last measurable concentration), AUC(0‒∞) (the area under the concentration-time curve extrapolated to infinity), C(max) (the maximum observed concentration), and T(peak) (the time to C(max)) values of OPZ, 5-hydroxyomeprazole (OH-OPZ), and omeprazole sulfone (OPZ-SFN), respectively. The 90% confidence intervals (CIs) of AUC(0‒t), AUC(0‒∞), and C(max) were 85.4%‒99.0%/88.8%‒98.6%/87.6%‒99.4%, 85.5%‒99.2%/89.0%‒98.6%/88.5%‒101.3%, and 72.3%‒87.6%/79.6%‒91.1%/88.4%‒99.1% for OPZ/OH-OPZ/OPZ-SFN, respectively, and T(peak) values did not differ significantly. In this study, the test formulation of OPZ in fasting healthy Chinese male volunteers met the Chinese bioequivalance standard to the reference formulation based on AUC, C(max), and T(peak).

Straightforward synthesis of novel 1-(2'-α-O-D-glucopyranosyl ethyl) 2-arylbenzimidazoles

A series of novel 1-(2'-α-O-D-glucopyranosyl ethyl) 2-arylbenzimidazoles has been prepared via one-pot glycosylation of ethyl-1-(2'-hydroxyethyl)-2-arylbenzimidazole-5-carboxylate derivatives. Synthesis of the 2-arylbenzimidazole aglycones from 4-fluoro-3-nitrobenzoic acid was accomplished in four high-yielding steps. The reduction and cyclocondensation steps for the aglycone synthesis proceeded efficiently under microwave irradiation to afford the appropriate benzimidazoles in excellent yields within 2-3 min. Glycosylation of the hydroxyethyl aglycones with the perbenzylated 1-hydroxy- glucopyranose, pretreated with the Appel-Lee reagent, followed by catalytic hydrogenolysis delivered the desired 1-(2'-α-O-D-glucopyranosyl ethyl) 2-aryl-benzimidazoles in a simple and straightforward manner.

Transient Psychotic Episode Induced by Helicobacter pylori Triple Therapy Treatment

The term ‘antibiomania’ refers to manic episodes that occur after a patient starts taking antibiotics. We report the case of a 49-year-old male who developed acute psychosis secondary to initiation of triple therapy for Helicobacter pylori eradication. Unlike with proton pump inhibitors, there have been several reported cases of central nervous system side effects and psychiatric consequences due to amoxicillin, however evidence points to clarithromycin as the likely culprit. On average onset of symptoms occurred within 1–5 days of initiating therapy. In all cases, symptoms resolved upon cessation of clarithromycin, mostly within 1–3 days. Unfortunately, the mechanism through which clarithromycin causes neurotoxicity remains unclear. Clinicians should be cognizant of psychiatric side effects secondary to clarithromycin, and discontinuation should be prompt for rapid recovery of mental status.

Proton pump inhibitors: are they overutilised in clinical practice and do they pose significant risk?

Proton pump inhibitors are highly effective acid suppressants with decades of use highlighting positive outcomes in millions of patients worldwide, and they offer minimal risk of adverse events. PPIs are considered overutilised when prescribed without an appropriate indication, when patients are left on them 'indefinitely' without appropriate indications and when they are continued after being utilised for most cases of hospital SUP. While several adverse outcomes have been linked to PPI therapy, most data are from retrospective observational studies that may be subject to confounding and bias.

Clopidogrel and proton pump inhibitors - where do we stand in 2012?

Clopidogrel in association with aspirine is considered state of the art of medical treatment for acute coronary syndrome by reducing the risk of new ischemic events. Concomitant treatment with proton pump inhibitors in order to prevent gastrointestinal side effects is recommended by clinical guidelines. Clopidogrel needs metabolic activation predominantly by the hepatic cytochrome P450 isoenzyme Cytochrome 2C19 (CYP2C19) and proton pump inhibitors (PPIs) are extensively metabolized by the CYP2C19 isoenzyme as well. Several pharmacodynamic studies investigating a potential clopidogrel-PPI interaction found a significant decrease of the clopidogrel platelet antiaggregation effect for omeprazole, but not for pantoprazole. Initial clinical cohort studies in 2009 reported an increased risk for adverse cardiovascular events, when under clopidogrel and PPI treatment at the same time. These observations led the United States Food and Drug Administration and the European Medecines Agency to discourage the combination of clopidogrel and PPI (especially omeprazole) in the same year. In contrast, more recent retrospective cohort studies including propensity score matching and the only existing randomized trial have not shown any difference concerning adverse cardiovascular events when concomitantly on clopidogrel and PPI or only on clopidogrel. Three meta-analyses report an inverse correlation between clopidogrel-PPI interaction and study quality, with high and moderate quality studies not reporting any association, rising concern about unmeasured confounders biasing the low quality studies. Thus, no definite evidence exists for an effect on mortality. Because PPI induced risk reduction clearly overweighs the possible adverse cardiovascular risk in patients with high risk of gastrointestinal bleeding, combination of clopidogrel with the less CYP2C19 inhibiting pantoprazole should be recommended.

Suspected methotrexate toxicity from omeprazole: a case review of carboxypeptidase G2 use in a methotrexate-experienced patient with methotrexate toxicity and a review of the literature

We report a case of methotrexate toxicity potentially induced by a drug interaction between methotrexate and omeprazole in a 25-year-old man with osteosarcoma. The patient was placed on omeprazole after his first cycle of high-dose methotrexate for stress ulcer prophylaxis, and it was discontinued before the start of the first day of the patient's second round of high-dose methotrexate. The 24-hour methotrexate level was elevated and he continued to have sustained levels for 18 days. Side effects due to elevated serum methotrexate included seizures, mucositis, acute renal failure, and thrombocytopenia. Aggressive hydration, urinary alkalinization, and leucovorin were continued during the period of elevated methotrexate levels, with the patient receiving a course of hemodialysis and a dose of carboxypeptidase G2. The patient's symptoms resolved, and his renal function returned to baseline within 2 months. The patient was able to receive future courses of chemotherapy without methotrexate. Although use of the Naranjo adverse reaction probability scale indicated a probable relationship (score of 6) between the patient's development of methotrexate toxicity and omeprazole use, we believe this was a drug-drug interaction case consistent with previous reports in the literature.

Clinical utility of esomeprazole for treatment of gastroesophageal reflux disease in pediatric and adolescent patients

Gastroesophageal reflux is a common condition in the pediatric population, with an increasing incidence in the last few years. It can be defined as an effortless retrograde movement of gastric contents into the esophagus related to complex multifactorial pathogenesis, involving anatomical, hormonal, environmental, and genetic factors. In some cases, it may be associated with esophageal or extraesophageal symptoms (heartburn and regurgitation), and is defined as gastroesophageal reflux disease (GERD). The therapeutic approach to gastroesophageal reflux in infants and children is often conservative, including changes in lifestyle (eg, posture and thickening of meals). If these children remain symptomatic after lifestyle changes (nutrition, feeding, and positional modification), or present with clinical red flags (poor weight gain, recurrent respiratory symptoms, or hematemesis) and complications of GERD (esophagitis, bleeding, stricture, Barrett’s esophagus, or adenocarcinoma) it may be necessary to set up a proper diagnostic protocol. Proton pump inhibitors have been recommended as the most effective acid suppression therapy for adults and pediatric patients. Esomeprazole, the S-isomer of omeprazole, is the only single-isomer proton pump inhibitor available. The paper assesses the safety and tolerability of esomeprazole in pediatric and adolescent patients.

Acid inhibition effect of ilaprazole on Helicobacter pylori-negative healthy volunteers: an open randomized cross-over study

OBJECTIVE

The aim of this study was to evaluate the effects and safety of different doses of ilaprazole on healthy volunteers without a Helicobacter pylori infection.

METHODS

A total of 12 healthy Chinese volunteers were enrolled and divided into four groups randomly, with a 5-day treatment of oral ilaprazole 5mg, 10mg and 20mg or omeprazole 20mg, respectively. After an interval of a 14-day washout phase, each was switched to another dose group and eventually completed all four regimens. The percentage time of intragastric pH>4 was the major index. The polymorphisms of the metabolic enzyme CYP2C19 in these volunteers were also detected.

RESULTS

The percentage time of intragastric pH>4 in the ilaprazole 5, 10 and 20mg groups were 80.4%, 88.1% and 91.0%, respectively, during the first 24h, compared to that of the 20mg omeprazole group (76.6%, P>0.05). Ilaprazole 20mg provided a significant higher mean 24-h pH than that of the same dose of omeprazole both on Day 1 (7.78 vs 6.67, P<0.01) and Day 5 (7.95 vs 7.44, P<0.05). No CYP2C19-dependent difference or obvious adverse effect were found in any ilaprazole groups.

CONCLUSION

Low dose ilaprazole offers a gastric acid inhibition comparable to a routine dose of omeprazole, and further investigations in patients with acid-associated diseases are needed.

Pharmacokinetics and Excretion Studies on CDRI-85/92, an Antiulcer Proton Pump Inhibitor

CDRI 85/92 is an antiulcer pharmacophore and a proton pump inhibitor, which is in an advanced stage of preclinical trials. In view of its importance, pharmacokinetic and excretion were studied in Sprague Dawley rats after administering 20 mg/kg oral and intravenous doses. The compound was detectable in the serum samples as early as 5 min post-oral administration. The compound was eliminated slowly from serum with an elimination half-life of 2.1 h. Following the 20 mg/kg oral dose, maximum serum concentration (C_max) was found to be 469.28 ± 45.52 ng/ml after 1.0 h. Based on AUC values, the absolute bioavailability of the CDRI 85/92 was 70.5% after oral administration. It was found to be excreted in urine (~15% of the dose) in intravenously treated (bile duct cannulated as well as noncannulated) rats, whereas bile and feces depicted insignificant levels of the compound.