Review article: the pharmacology of rabeprazole

Identification of Inhibitors of the Disease-Associated Protein Phosphatase Scp1 Using Antibody Mimetic Molecules

Protein phosphorylation is a prevalent translational modification, and its dysregulation has been implicated in various diseases, including cancer. Despite its significance, there is a lack of specific inhibitors of the FCP/SCP-type Ser/Thr protein phosphatase Scp1, characterized by high specificity and affinity. In this study, we focused on adnectin, an antibody-mimetic protein, aiming to identify Scp1-specific binding molecules with a broad binding surface that target the substrate-recognition site of Scp1. Biopanning of Scp1 was performed using an adnectin-presenting phage library with a randomized FG loop. We succeeded in identifying FG-1Adn, which showed high affinity and specificity for Scp1. Ala scanning analysis of the Scp1-binding sequence in relation to the FG-1 peptide revealed that hydrophobic residues, including aromatic amino acids, play important roles in Scp1 recognition. Furthermore, FG-1Adn was found to co-localize with Scp1 in cells, especially on the plasma membrane. In addition, Western blotting analysis showed that FG-1Adn increased the phosphorylation level of the target protein of Scp1 in cells, indicating that FG-1Adn can inhibit the function of Scp1. These results suggest that FG-1Adn can be used as a specific inhibitor of Scp1.

Improved quantitative determination of (R)- and (S)-rabeprazole sodium and its metabolites in rat plasma by LC-MS/MS and its application to a toxicokinetic study

There exist two enantiomers: (R)- and (S)-rabeprazole. (R)-rabeprazole offers specific pharmacokinetic advantages and enhanced therapeutic efficacy, warranting further investigation and development. Here, we developed a simple and rapid chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to simultaneously quantify rabeprazole enantiomers and their metabolites (rabeprazole sulfoxide and desmethyl rabeprazole enantiomers) and a LC-MS to quantify rabeprazole thioether. As for the chiral LC-MS/MS method, Chiral-AGP column (150 × 4 mm, 5 μm) was used and its mobile phase was acetonitrile (mobile phase A) and 10 mmol/L ammonium acetate (mobile phase B) (linear gradient profile: 0 min, 10 % B; 5 min, 15 % B; 9 min, 15 % B; 9.01 min, 10 % B; 13 min, 10 % B). The multiple reactions monitoring transitions of m/z 360.3 → 242.1, 376.2 → 240.1, 346.2 → 228.2 and 368.2 → 190.2 were opted for quantifying rabeprazole enantiomers, rabeprazole sulfoxide, desmethyl rabeprazole enantiomers and internal standard omeprazole. The analyte samples were prepared by a simple liquid-liquid extraction method. As for the LC-MS method, analytes were separated on a Inertsil® ODS-3 column (4.6 × 150 mm, 5 μm). The mobile phase was acetonitrile-5 mmol/L ammonium acetate water solution (65:35, v/v). ESI+ was used and ion peaks with m/z 344.2 (rabeprazole thioether) and 285.1 (internal standard diazepam) were monitored. Both these 2 methods were validated for specificity, linearity, precision, accuracy, matrix effect and extraction recovery, and, particularly, the stability of analytes under various conditions. We successfully applied these methods to a 13-week toxicokinetic study of rabeprazole in rats after intravenous administration of (R)- (80, 20, 5 mg/kg/d) and racemic (80 mg/kg/d) rabeprazole sodium. The results showed that rabeprazole and its metabolites did not accumulate in rats. However, desmethyl rabeprazole and rabeprazole thioether showed higher exposure and lower clearance rate in the last administration than in the first one. (R)-rabeprazole showed a higher exposure and a slower elimination rate than (S)-rabeprazole in rats. These findings offer experimental evidence and a theoretical foundation for further preclinical investigations and clinical applications of (R)-rabeprazole.

Identification of novel and potential PPARγ stimulators as repurposed drugs for MCAO associated brain degeneration

Peroxisome proliferator-activated receptor-gamma (PPARγ) has been shown to have therapeutic promise in the treatment of ischemic stroke and is supported by several studies. To identify possible PPARγ activators, the current study used an in silico technique in conjunction with molecular simulations and in vivo validation. FDA-approved drugs were evaluated using molecular docking to determine their affinity for PPARγ. The findings of molecular simulations support the repurposing of rabeprazole and ethambutol for the treatment of ischemic stroke. Adult Sprague Dawley rats were subjected to transient middle cerebral artery occlusion (t-MCAO). Five groups were made as a sham-operated, t-MCAO group, rabeprazole +t-MCAO, ethambutol +t-MCAO, and pioglitazone +t-MCAO. The neuroprotective effects of these drugs were evaluated using the neurological deficit score and the infarct area. The inflammatory mediators and signaling transduction proteins were quantified using Western blotting, ELISA, and immunohistochemistry. The repurposed drugs mitigated cerebral ischemic injury by PPARγ mediated downregulation of nods like receptor protein 3 inflammasomes (NLRP3), tumor necrosis factor-alpha (TNF-α), cyclooxygenase 2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-kB), and c-Jun N-terminal kinase (p-JNK). Our data demonstrated that rabeprazole and ethambutol have neuroprotective potential via modulating the cytoprotective stress response, increasing cellular survival, and balancing homeostatic processes, and so may be suitable for future research in stroke therapy.

Quality by Design Applied Development of Immediate-Release Rabeprazole Sodium Dry-Coated Tablet

The aim of this study was to develop immediate-release oral rabeprazole sodium tablets with rapid efficacy and gastric stability for the treatment of gastroesophageal reflux disease. Rabeprazole sodium is a commonly prescribed proton pump inhibitor; however, it is extremely unstable and degrades in acidic environments. Hence, it has been manufactured and supplied only in enteric-coated tablet form, while immediate-release (IR) formulations for this drug are very limited. In this study, we applied the quality by design (QbD) approach to formulate and optimize an IR dry-coated tablet containing rabeprazole sodium as an inner core with an outer sodium bicarbonate layer to stabilize the active pharmaceutical ingredient at gastric pH. We also investigated the stability of the pharmaceutical dosage form and its pharmacokinetic profile. The results show that the developed tablets are stable for approximately 12 months and have a high dissolution rate, greater than or equal to 90% at 30 min. Further, in vivo beagle pharmacokinetics confirmed that the newly developed IR tablet had an AUC_t which is bioequivalent to the existing delayed-release rabeprazole tablet; however, its T_max was 0.5 h, which is up to seven times faster than that of the existing tablet. Moreover, the IR tablet was found to immediately absorb in the stomach. Hence, the development of IR tablets can be used as a platform to overcome the technical and commercial limitations currently associated with various proton pump inhibitors used to treat patients with gastroesophageal reflux disease that require immediate therapeutic relief.

Identification of a Specific Inhibitor of Human Scp1 Phosphatase Using the Phosphorylation Mimic Phage Display Method

Protein phosphatases are divided into tyrosine (Tyr) phosphatases and serine/threonine (Ser/Thr) phosphatases. While substrate trapping mutants are frequently used to identify substrates of Tyr phosphatases, a rapid and simple method to identify Ser/Thr phosphatase substrates is yet to be developed. The TFIIF-associating component of RNA polymerase II C-terminal domain (CTD) phosphatase/small CTD phosphatase (FCP/SCP) phosphatase family is one of the three types of Ser/Thr protein phosphatases. Defects in these phosphatases are correlated with the occurrence of various diseases such as cancer and neuropathy. Recently, we developed phosphorylation mimic phage display (PMPD) method with AlF4−, a methodology to identify substrates for FCP/SCP type Ser/Thr phosphatase Scp1. Here, we report a PMPD method using BeF3− to identify novel substrate peptides bound to Scp1. After screening peptide phages, we identified peptides that bound to Scp1 in a BeF3−-dependent manner. Synthetic phosphopeptide BeM12-1, the sequence of which was isolated at the highest frequency, directly bound to Scp1. The binding was inhibited by adding BeF3−, indicating that the peptide binds to the active center of catalytic site in Scp1. The phosphorylated BeM12-1 worked as a competitive inhibitor of Scp1. Thus, PMPD method may be applicable for the identification of novel substrates and inhibitors of the FCP/SCP phosphatase family.

Proton Pump Inhibitors: More Indigestion than Relief?

Proton pump inhibitors (PPIs) are widely prescribed to treat a number of gastrointestinal (GI) disorders due to excessive acid production. While effective and safe, adverse renal effects have been increasingly described in epidemiological literature. The most well-documented adverse renal outcome is acute interstitial nephritis; however, association with overall acute kidney injury has also been recently reported. Recently, two observational studies have linked PPI use with chronic kidney disease. Finally, hypomagnesemia is another reported complication and is thought to be resulting from GI loss of magnesium. This study will critically review literature on the effect of PPIs on the kidney.

25 Years of Proton Pump Inhibitors: A Comprehensive Review

Proton pump inhibitors (PPIs) were clinically introduced more than 25 years ago and have since proven to be invaluable, safe, and effective agents for the management of a variety of acid-related disorders. Although all members in this class act in a similar fashion, inhibiting active parietal cell acid secretion, there are slight differences among PPIs relating to their pharmacokinetic properties, metabolism, and Food and Drug Administration (FDA)-approved clinical indications. Nevertheless, each is effective in managing gastroesophageal reflux disease and uncomplicated or complicated peptic ulcer disease. Despite their overall efficacy, PPIs do have some limitations related to their short plasma half-lives and requirement for meal-associated dosing, which can lead to breakthrough symptoms in some individuals, especially at night. Longer-acting PPIs and technology to prolong conventional PPI activity have been developed to specifically address these limitations and may improve clinical outcomes.

Identification and characterization of stressed degradation products of rabeprazole using LC-ESI/MS/MS and 1H-NMR experiments: in vitro toxicity evaluation of major degradation products

Rabeprazole, an antiulcer drug in the class of proton pump inhibitors was subjected to force degradation studies as per ICH guidelines Q1A (R2).

Proton pump inhibitors drastically modify triosephosphate isomerase from Giardia lamblia at functional and structural levels, providing molecular leads in the design of new antigiardiasic drugs

BACKGROUND

Proton pump inhibitors (PPIs) are extensively used in clinical practice because of their effectiveness and safety. Omeprazole is one of the best-selling drugs worldwide and, with other PPIs, has been proposed to be potential drugs for the treatment of several diseases. We demonstrated that omeprazole shows cytotoxic effects in Giardia and concomitantly inactivates giardial triosephosphate isomerase (GlTIM). Therefore, we evaluated the efficiency of commercially available PPIs to inactivate this enzyme.

METHODS

We assayed the effect of PPIs on the GlTIM WT, single Cys mutants, and the human counterpart, following enzyme activity, thermal stability, exposure of hydrophobic regions, and susceptibility to limited proteolysis.

RESULTS

PPIs efficiently inactivated GlTIM; however, rabeprazole was the best inactivating drug and was nearly ten times more effective. The mechanism of inactivation by PPIs was through the modification of the Cys 222 residue. Moreover, there are important changes at the structural level, the thermal stability of inactivated-GlTIM was drastically diminished and the structural rigidity was lost, as observed by the exposure of hydrophobic regions and their susceptibility to limited proteolysis.

CONCLUSIONS

Our results demonstrate that rabeprazole is the most potent PPI for GlTIM inactivation and that all PPIs tested have substantial abilities to alter GITIM at the structural level, causing serious damage.

GENERAL SIGNIFICANCE

This is the first report demonstrating the effectiveness of commercial PPIs on a glycolytic parasitic enzyme, with structural features well known. This study is a step forward in the use and understanding the implicated mechanisms of new antigiardiasic drugs safe in humans.

CYP2C19 polymorphism influences Helicobacter pylori eradication

The known factors that have contributed to the decline of Helicobacter pylori (H. pylori) eradication rate include antibiotic resistance, poor compliance, high gastric acidity, high bacterial load, and cytochrome P450 2C19 (CYP2C19) polymorphism. Proton pump inhibitor (PPI) is important in the eradication regimen. The principal enzyme implicated in the metabolism of PPIs is CYP2C19. The effects of PPI depend on metabolic enzyme, cytochrome P450 enzymes, and CYP2C19 with genetic differences in the activity of this enzyme (the homozygous EM, heterozygous EM (HetEM), and poor metabolizer). The frequency of the CYP2C19 polymorphism is highly varied among different ethnic populations. The CYP2C19 genotype is a cardinal factor of H. pylori eradication in patients taking omeprazole- based or lansoprazole-based triple therapies. In contrast, the CYP2C19 polymorphism has no significant effect on the rabeprazole-based or esomeprazole-based triple therapies. The efficacy of levofloxacin-based rescue triple therapy might be also affected by the CYP2C19 polymorphism, but CYP2C19 genotypes did not show obvious impact on other levofloxacin-based rescue therapies. Choice of different PPIs and/or increasing doses of PPIs should be individualized based on the pharmacogenetics background of each patient and pharmacological profile of each drug. Other possible factors influencing gastric acid secretion (e.g., IL-1β- 511 polymorphism) would be also under consideration.

Formulation and evaluation of sustained release matrix tablet of rabeprazole using wet granulation technique

Introduction:

Rabeprazole, a member of substituted benzimidazoles, inhibits the final step in gastric acid secretions. This drug claims to cause fastest acid separation (due to higher pKa), and more rapidly converts to the active species to aid gastric mucin synthesis. The most significant pharmacological action of Rabeprazole is dose dependent suppression of gastric acid secretion; without anticholinergic or H2-blocking action. It completely abolishes the hydrochloric acid secretion as it is powerful inhibitor of gastric acid. Rabeprazole is acid labile and hence commonly formulated as an enteric coated tablet. The absorption of rabeprazole occurs rapidly as soon as tablet leaves the stomach.

Aim:

In the present study an attempt was made to formulate and evaluate Rabeprazole sustained release matrix tablet using wet granulation technique incorporating various polymers like HPMC-E15, Carbopol934, and sodium carboxymethyl cellulose (CMC).

Materials and Methods:

The Formulated tablets were evaluated for different physicochemical properties like rheological properties, weight variation, thickness, hardness, % friability, in vitro release studies and drug content.

Results:

Studies revealed that all the physicochemical parameters comply with the official standards. The in vitro release studies exhibits the release up to 90%, over a prolonged period of time which confirms the extended release profile of formulation, having better bioavailability as well as decreased dosing frequency with reduced doses.

Conclusion:

The sustained release matrix tablets of rabiprazole shown better bioavailability, efficacy and potency, when compared with official standards.

Comparison of five-day Helicobacter pylori eradication regimens: rabeprazole-based and omeprazole-based regimens with and without omeprazole pretreatment

BACKGROUND

The onset of antisecretory activity of rabeprazole is faster than that of omeprazole.

OBJECTIVE

This study was performed to compare the efficacy of short-term rabeprazole-based triple therapy with that of omeprazole-based triple therapy and to determine the influence of omeprazole pretreatment in omeprazole-based short-term triple therapy.

METHODS

This was a 2-center, open-label, prospective, randomized study. Patients who tested positive for Helicobacter (formerly Campylobacter) pylori were randomized to one of three 5-day regimens: (1) rabeprazole 20 mg BID, amoxicillin 500 mg TID, and clarithromycin 400 mg BID (RAC group); (2) omeprazole 20 mg BID, amoxicillin 500 mg TID, and clarithromycin 400 mg BID without omeprazole pretreatment (OAC1 group); and (3) omeprazole 20 mg BID, amoxicillin 500 mg TID, and clarithromycin 400 mg BID with 5 days of omeprazole pretreatment 20 mg BID (OAC2 group). Eradication was assessed by (13)C-urea breath test and rapid urease test ∼1 month after completion of treatment. All patients who entered this study were included in the intent-to-treat (ITT) analysis, patients who completed the study were included in the per-protocol (PP) analysis, and patients who did not undergo the (13)C-urea breath test and rapid urease test were included in the all-patients-treated (APT) analysis.

RESULTS

A total of 120 patients (86 men, 34 women; mean [SD] age, 55.8 [14.3] years; range, 19-86 years) were assigned to the RAC, OAC1, or OAC2 group (40 patients in each group). ITT, PP, and APT eradication rates in the RAC group were 90%, 92%, and 90%, respectively; in the OAC1 group, 75%, 83%, and 75%; and in the OAC2 group, 85%, 90%, and 87%. These eradication rates were not significantly different between groups.

CONCLUSIONS

Eradication rates did not differ significantly between the three 5-day proton pump inhibitor-based triple therapies in this study population. However, 5-day rabeprazole-based triple therapy tends to be more effective than 5-day omeprazole-based triple therapy in the eradication of H pylori, and treatment with omeprazole before eradication therapy may improve the eradication rates of 5-day omeprazole-based therapy.

Rabeprazole: the role of proton pump inhibitors inHelicobacter pylorieradication

Proton pump inhibitors have become one of the cornerstones in the treatment of Helicobacter pylori infection. Rabeprazole (Pariet) is a substituted benzimidazole proton pump inhibitor with potent gastric acid suppression properties. Its high acid-base dissociation constant allows activation over a broader pH range, resulting in quick, irreversible binding to the H+/K+-ATPase pump, and a more rapid onset of action compared with omeprazole, lansoprazole and pantoprazole. Unlike other proton pump inhibitors, the metabolism of rabeprazole is primarily via a nonenzymatic reduction to the thioether derivative, and the cytochrome P450 isoenzyme 2C19 is only partly involved in its metabolism. The effect of genetic polymorphism in cytochrome P450 isoenzyme 2C19 on the pharmacokinetics and pharmacodynamics of rabeprazole is therefore limited. In humans, once-daily dosing of 5-40 mg of rabeprazole inhibits gastric acid secretion in a dose-dependent manner. In vitro studies have shown that rabeprazole possesses more potent antibacterial properties against the growth of H. pylori than other proton pump inhibitors. Furthermore, its thioether derivative has more potent inhibitory in vitro activity against the growth and motility of clarithromycin-resistant H. pylori than other proton pump inhibitors or commonly used antimicrobials. Despite these inherent favorable characteristics of rabeprazole, randomized controlled trials have largely shown equivalence amongst proton pump inhibitors when used with two antibiotics in the eradication of H. pylori, with cure rates of 75-89% on an intent-to-treat basis. However, rabeprazole appears to consistently achieve such comparable eradication rates even when used at reduced doses (10 mg twice daily) as part of clarithromycin-based triple therapy.

Development and Validation of a Stability-Indicating RP-HPLC Method for the Determination of Process-Related Impurities and Degradation Products of Rabeprazole Sodium in Pharmaceutical Formulation

The objective of the current study was to develop and validate a reversed-phase high-performance liquid chromatographic method for the quantitative determination of process-related impurities and degradation products of rabeprazole sodium in pharmaceutical formulation. Chromatographic separation was achieved on the Waters Symmetry Shield RP18 (250 mm × 4.6 mm) 5 μm column with a mobile phase containing a gradient mixture of solvent A (mixture of 0.025 M KH₂PO₄ buffer and 0.1% triethylamine in water, pH 6.4 and acetonitrile in the ratio of 90:10 v/v, respectively) and solvent B (mixture of acetonitrile and water in the ratio of 90:10 v/v, respectively). The mobile phase was delivered at a flow rate of 1.0 mL/min and with UV detection at 280 nm. Rabeprazole sodium was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Rabeprazole sodium was found to degrade significantly under acid hydrolysis, base hydrolysis, oxidative, and thermal degradation conditions. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The mass balance was found to be in the range of 97.3–101.3% in all of the stressed conditions, thus proving the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, and robustness.

Proton pump inhibitor-induced hypomagnesemia: A new challenge

Proton pump inhibitors (PPIs) are commonly used in clinical practice for the prevention and treatment of peptic ulcer, gastritis, esophagitis and gastroesophageal reflux. Hypomagnesemia has recently been recognized as a side effect of PPIs. Low magnesium levels may cause symptoms from several systems, some of which being potentially serious, such as tetany, seizures and arrhythmias. It seems that PPIs affect the gastrointestinal absorption of magnesium. Clinicians should be vigilant in order to timely consider and prevent or reverse hypomagnesemia in patients who take PPIs, especially if they are prone to this electrolyte disorder.

A comparison of the acid-inhibitory effects of esomeprazole and rabeprazole in relation to pharmacokinetics and CYP2C19 polymorphism

BACKGROUND

Esomeprazole and rabeprazole are metabolised in the liver by means of the CYP2C19 enzyme, which has several functional genetic polymorphisms. Among Caucasians, 70% of the population has a fast metaboliser phenotype, 25-30% an intermediate and 2-5% a slow metaboliser phenotype. It is unknown whether different PPIs are affected to the same extent by these phenotypic differences.

AIM

To compare the acid-inhibitory effects of esomeprazole 40 mg and rabeprazole 20 mg in relation to CYP2C19 genotype and pharmacokinetics.

METHODS

Eighteen healthy Helicobacter pylori-negative Caucasian subjects with CYP2C19*2-*6 and *17 genotype were included in a randomised investigator-blinded crossover study with esomeprazole 40 mg and rabeprazole 20 mg. Intragastric 24-h pH-monitoring was performed on days 0, 1 and 5 of oral dosing.

RESULTS

Onset of acid inhibition during the first 4 h after administration did not differ significantly between PPIs. During the upright period, the proportion of time with pH >4 was significantly higher with esomeprazole compared to rabeprazole (52.2 vs. 40.3%, P = 0.003). At day 1 and 5, acid inhibition was significantly greater with esomeprazole than with rabeprazole (median intragastric pH: day 1: 3.7 vs. 3.0, P = 0.008; day 5: 4.7 vs. 3.8, P < 0.001; percentage of time pH >4: day 1: 45 vs. 39%, P = 0.054; day 5: 65 vs. 48%, P < 0.001). Differences in acid inhibition between wt/wt and wt/*2 genotype were significant for both PPIs.

CONCLUSIONS

Once-daily dosing with esomeprazole 40 mg provides a more effective and faster acid-inhibitory effect than rabeprazole 20 mg. The acid-inhibitory effect of esomeprazole and rabeprazole are both influenced by CYP2C19 polymorphism.

Ureases as a target for the treatment of gastric and urinary infections

Urease is known to be a major contributor to pathologies induced by Helicobacter pylori and Proteus species. In H pylori, urease allows the bacteria to survive in an acidic gastric environment during colonisation, playing an important role in the pathogenesis of gastric and peptic ulcers. Ureolytic activity also results in the production of ammonia in close proximity to the gastric epithelium, causing cell damage and inflammation. In the case of Proteus species (notably Proteus mirabilis) infection, stones are formed due to the presence of ammonia and carbon dioxide released by urease action. In addition, the ammonia released is able to damage the glycosaminoglycan layer, which protects the urothelial surface against bacterial infection. In this context, the administration of urease inhibitors may be an effective therapy for urease-dependent pathogenic bacteria. This is a review of the role of ureases in H pylori and Proteus species infections, focussing on the biochemical and clinical aspects of the most promising and/or potent urease inhibitors for the treatment of gastric and urinary tract infections.

Rabeprazole can overcome the impact of CYP2C19 polymorphism on quadruple therapy

OBJECTIVES

The prospective study was designed to clarify the impact of CYP2C19 on quadruple therapies and survey the efficacies of rabeprazole-based quadruple therapy for Helicobacter pylori infection after failure of standard triple therapies.

PATIENTS AND METHODS

From January 2007 to March 2009, 1055 H. pylori-infected patients received standard triple regimens (proton-pump inhibitor (PPI), clarithromycin, and amoxicillin). Helicobacter pylori eradication was achieved in 865 (81.9%) subjects. One hundred ninety eradication-failure patients were enrolled and randomly assigned to receive a 7-day eradication therapy. Ninety-six patients were treated with esomeprazole-based quadruple rescue therapies (EB), while 94 patients were treated with rabeprazole-based quadruple rescue therapies (RB). Follow-up endoscopy was done 16 weeks later to assess the treatment response. Patients' responses, CYP2C19 genotypes, and antibiotics resistances were also examined.

RESULTS

Intention-to-treat analysis revealed that RB had better eradication rates than EB (EB: 72.9%; 95% CI: 64.9-80.9% and RB: 78.7%; 95% CI 72.5-84.9%) (p value = .543). Per-protocol results were EB = 75.3%; 95% CI: 70.3-80.3% and RB = 85.1%; 95% CI: 80.6-89.6% (p value = .0401). Both regimens had similar compliance (p value = 0.155) and adverse events (p value = 0.219). We also surveyed those patients without resistance of any antibiotics. RB still showed better outcome than EB. Our data showed that esomeprazole-based regimen and CYP2C19 Hom EM genotype were important predictors for eradication failure.

CONCLUSIONS

In quadruple therapy, rabeprazole-based regimens had better efficacy than esomeprazole-based regimens. CYP2C19 polymorphism also played an important role in quadruple therapy. It seems advisable to change PPI to rabeprazole in second-line quadruple therapy.

The modified sequential treatment regimen containing levofloxacin for Helicobacter pylori eradication in Turkey

BACKGROUND

Eradication rates of Helicobacter pylori have declined to unacceptable levels in recent years. New and effective treatment options are warranted both as a first and second line treatment.

AIM

To test an effectiveness of modified sequential therapy with levofloxacin for H. pylori eradication in Turkey.

MATERIAL AND METHODS

Helicobacter pylori infected dyspeptic patients were included to the study. Subjects were treated with modified sequential therapy consisting of rabeprazole 20 mg b.i.d. and amoxicillin 1 g b.i.d., for 7 days followed by rabeprazole 20 mg b.i.d, levofloxacin 500 mg q.d. and metronidazole 500 mg b.i.d for the remaining 7 days.

RESULTS

Sixty-three treatment naive patients and 37 previous treatment failures were enrolled to the study (59 F, 41 M, age: 21-80 years). There was five drop out. Helicobacter pylori eradication was achieved in 80 patients, intention-to-treat (ITT): 80% (95% CI: 71-87%) and per-protocol (PP): 84.2% (95% CI: 75-91%), totally. In treatment naive patients ITT and PP eradication rates were 82.5% (95% CI: 71-91%), and 86.7% (95% CI: 75-94%), respectively. As a second line treatment eradication was successful in ITT 75.7%.(95% CI: 59-88%), and PP 80% (95% CI: 63-92%).Mild side effects were reported by 8 patients (8.4%).

CONCLUSIONS

Sequential therapy using "rabeprazole and amoxicillin 7 days followed by rabeprazole, metronidazole and levofloxacin for 7 days" is a new regimen with acceptable eradication rates in naïve patients in Turkey. Further modifications in the dose or duration of this new sequential therapy might increase its effectiveness as both first and second line treatment.

Rabeprazole: a review of its use in the management of gastric acid-related diseases in adults

Rabeprazole (Aciphex, Alfence, Pariet) is a proton pump inhibitor (PPI) used for the treatment of adults with conditions requiring a reduction of gastric acid secretion such as erosive or ulcerative gastro-oesophageal reflux disease (GORD), non-erosive reflux disease (NERD), duodenal and gastric ulcers, and pathological hypersecretory conditions including Zollinger-Ellison syndrome (ZES). It is also used as part of combination therapy for the eradication of Helicobacter pylori, a pathogen frequently implicated in the development of gastric and duodenal ulcers. Rabeprazole has a well established efficacy and safety profile in the treatment of gastric acid-related diseases. Rabeprazole is a useful, well tolerated and cost-effective option for the treatment of GORD, NERD, peptic ulcer and other gastric acid-related diseases (including ZES), and provides an appropriate alternative to other currently available PPIs, with the added benefits of having a consistent efficacy profile and low drug interaction potential due to its predominantly nonenzymatic metabolism.

Comparative study of omeprazole, lansoprazole, pantoprazole and esomeprazole for symptom relief in patients with reflux esophagitis

AIM: To clarify whether there is any difference in the symptom relief in patients with reflux esophagitis following the administration of four Proton pump inhibitors (PPIs).

METHODS: Two hundred and seventy-four patients with erosive reflux esophagitis were randomized to receive 8 wk of 20 mg omeprazole (n = 68), 30 mg of lansoprazole (n = 69), 40 mg of pantoprazole (n = 69), 40 mg of esomeprazole (n = 68) once a day in the morning. Daily changes in heartburn and acid reflux symptoms in the first 7 d of administration were assessed using a six-point scale (0: none; 1: mild; 2: mild-moderate; 3: moderate; 4: moderate-severe; 5: severe).

RESULTS: The mean heartburn score in patients treated with esomeprazole more rapidly decreased than those receiving other PPI. Complete resolution of heartburn was also more rapid in patients treated with esomeprazole for 5 d compared with omeprazole (P = 0.0018, P = 0.0098, P = 0.0027, P = 0.0137, P = 0.0069, respectively), lansoprazole (P = 0.0020, P = 0.0046, P = 0.0037, P = 0.0016, P = 0.0076, respectively), and pantoprazole (P = 0.0006, P = 0.0005, P = 0.0009, P = 0.0031, P = 0.0119, respectively). There were no significant differences between the four groups in the rate of endoscopic healing of reflux esophagitis at week 8.

CONCLUSION: Esomeprazole may be more effective than omeprazole, lansoprazole, and pantoprazole for the rapid relief of heartburn symptoms and acid reflux symptoms in patients with reflux esophagitis.

Pharmacokinetic- pharmacodynamic analysis of the role of CYP2C19 genotypes in short-term rabeprazole-based triple therapy against Helicobacter pylori

AIMS

The aim was to explore the role of CYP2C19 polymorphism in short-term rabeprazole-based triple therapy against Helicobacter pylori infection.

METHODS

Patients with H. pylori infection were tested for CYP2C19 genotype as poor metabolizers (PMs) or extensive metabolizers (EMs, homozygous EM or heterozygous EM) and given rabeprazole for 7 days. Antibiotics (clarithromycin and amoxicillin) were given on days 1-4, days 4-7, or days 1-7. A direct link model with an effect compartment was used in the population pharmacokinetic-pharmacodynamic analysis. The status of H. pylori infection was evaluated.

RESULTS

Rabeprazole clearance was lower in CYP2C19 PMs than in EMs (with average values of 10.7 vs. 16.8 l h(-1) in PMs and EMs, respectively), resulting in higher plasma levels in the former group. The values of EC(50) and k(eo) of gastrin response increased with multiple doses of rabeprazole. The k(eo) values were lower in CYP2C19 PMs than in EMs on day 1 (0.012 vs. 0.017 x 10(-4) l min(-1)), and higher than in EMs on day 4 (0.804 vs. 0.169 x 10(-4) l min(-1)) of rabeprazole treatment. The predicted gastrin-time profile showed a higher response in CYP2C19 PMs than in EMs on days 4 and 7. Helicobacter pylori was eradicated in all CYP2C19 PMs except in one patient infected by a resistant strain. In contrast, in CYP2C19 EMs the eradication rates ranged from 58 to 85%.

CONCLUSIONS

CYP2C19 genotypes play a role in H. pylori eradication therapy. Rabeprazole-based short-term triple therapy may be applicable in CYP2C19 PMs for H. pylori eradication.

Rabeprazole- versus esomeprazole-based eradication regimens for H. pylori infection

BACKGROUND

Different kinds of proton pump inhibitor-based triple therapies could result in different Helicobacter pylori eradication rates.

AIM

The aims of this study were to compare the efficacy and safety of rabeprazole- and esomeprazole-based triple therapy in primary treatment of H. pylori infection in Taiwan.

PATIENTS AND METHODS

From June 2005 to March 2007, 420 H. pylori-infected patients were randomly assigned to receive a 7-day eradication therapy with either esomeprazole 40 mg daily (EAC group, n = 209) or rabeprazole 20 mg b.i.d. (RAC group, n = 211) in combination with amoxicillin 1 g b.i.d. and clarithromycin 500 mg b.i.d.. Follow-up endoscopy with biopsy was done 12-16 weeks after completion of eradication therapy. Those who refused endoscopic exams underwent (13)C-urea breath test to assess the treatment response.

RESULTS

Intention-to-treat analysis revealed that the eradication rate was 89.4% in the EAC group and 90.5% in RAC groups (p-value = .72). All of the subjects returned for assessment of compliance (100% in EAC group vs. 99.5% in RAC group, p-value = .32) and adverse events (3.83% in EAC group vs. 6.16% in RAC group, p-value = .27). Sixty (28.7%) and 37 (17.6%) patients in EAC and RAC group, respectively, refused endoscopy and underwent a (13)C-urea breath test to determine the treatment effect.

CONCLUSION

In conclusion, rabeprazole- and esomeprazole-based primary therapies for H. pylori infection are comparable in efficacy and safety.

Medical management of gastroesophageal reflux disease

Gastroesophageal reflux disease is a common worldwide disorder. Most patients have typical symptoms of heartburn, regurgitation and exacerbation of symptoms with large meal volumes, fatty meals, recumbency or bending forward. Patients who show typical symptoms for under 10 years may be treated empirically with lifestyle and dietary modifications plus acid-suppressing medications. The recent decrease in cost, established safety and wide availability of proton pump inhibitors make them the best choice for monotherapy. Other medical therapies include antacids, H(2) receptor antagonists and prokinetic agents. Patients who have alarm symptoms or long-standing symptoms should have an esophagoscopy to evaluate for complications of reflux. Patients who do not respond to therapy should have a test to confirm the diagnosis of gastroesophageal reflux disease.

Liquid chromatographic–mass spectrometry analysis and pharmacokinetic studies of a novel rabeprazole formulation, sterile powder for injection, in dogs and rats

Rabeprazole is among the most potent proton pump inhibitors (PPI) identified to date and it has been demonstrated that it is effective in such diseases as gastroesophageal reflux disease (GERD), duodenal ulcer and gastric ulcer. There is currently interest in developing a new formulation: rabeprazole sterile powder for injection (RSPI). This investigation was conducted to evaluate the preclinical pharmacokinetics of RSPI in rats and at the same time a comparative study was carried out in dogs between RSPI and Pariet tablets using liquid chromatographic-mass spectrometry analysis. The liquid chromatographic-mass spectrometry method was first conducted and validated as being specific, and having accuracy, precision, sensitivity and a satisfactory recovery. After intravenous administration of RSPI (i.v.: 2, 6 and 18 mg/kg) to rats, no significant dose-dependency was found in the CL (4.20-5.72 l/h/kg), V(area) (d) (0.94-1.32 l/kg), dose-normalized AUC (197.20-245.82 microg/l*h based on 1 mg/kg) and t(1/2) (p>0.05). In the dog, a randomized, open-label, crossover experiment was carried out to show that the mean area under the plasma concentration-time curve (AUC(0-infinity)) after i.v. administration of RSPI was at least four times larger than that following oral administration of Pariet tablet at an equivalent dose but the elimination half-life of these two formulation was similar (p>0.05). The results showed that the pharmacokinetics of RSPI was linear (r(2) = 0.98) in the dose range 2-18 mg/kg and the RSPI had a much higher AUC(0-infinity) and similar t(1/2) values compared with the enteric-coated tablet.

Different effects of fluvoxamine on rabeprazole pharmacokinetics in relation to CYP2C19 genotype status

AIMS

Rabeprazole is known to be a substrate of CYP2C19. Our objective was to evaluate the possible effect of an inhibitor of CYP2C19, fluvoxamine, and compare the inhibitory effect of fluvoxamine on the metabolism of rabeprazole between CYP2C19 genotypes.

METHODS

A two-way randomized double-blind, placebo-controlled crossover study was performed. Twenty-one volunteers, of whom seven were homozygous extensive metabolizers (EMs), eight were heterozygous EMs and six were poor metabolizers (PMs) for CYP2C19, received two 6-day courses of either fluvoxamine 50 mg or placebo daily in a randomized fashion with a single oral dose of rabeprazole 20 mg on day 6 in all cases. Plasma concentrations of rabeprazole and its metabolite rabeprazole thioether were monitored up to 24 h after dosing.

RESULTS

During placebo administration, the mean AUCs(0,infinity) of rabeprazole in homozygous EMs, heterozygous EMs and PMs were 882 (95% CI, 602, 1162) ng ml-1h , 1214 (975, 1453) ng ml-1 h and 2762 (2482, 3042) ng ml-1 h (P<0.001), respectively. Fluvoxamine treatment increased AUC(0,infinity) of rabeprazole and rabeprazole thioether by 2.8-fold (P<0.001) and 5.1-fold (P<0.01) in homozygous EMs, and by 1.7-fold (P<0.01) and 2.6-fold (P<0.01) in heterozygous EMs, and significantly prolonged the elimination half-life of rabeprazole and rabeprazole thioether in homozygous EMs and in heterozygous EMs, whereas no difference in any pharmacokinetic parameters was found in PMs. There was a significant difference in fluvoxamine-mediated percentage increase in AUC(0,infinity) of rabeprazole and rabeprazole thioether between CYP2C19 genotypes.

CONCLUSIONS

The present study indicates that there are significant drug interactions between rabeprazole and fluvoxamine in EMs of CYP2C19. It is predominantly involved in rabeprazole and rabeprazole thioether metabolism in EMs. Therefore, CYP2C19 is the key determinant of rabeprazole disposition in EMs.

Effects of clarithromycin and verapamil on rabeprazole pharmacokinetics between CYP2C19 genotypes

OBJECTIVE

Rabeprazole as a proton pump inhibitor (PPI) is mainly reduced to rabeprazole thioether via a nonenzymatic pathway, with minor CYP2C19 and CYP3A4 involvement. The aim of this study was to compare possible effects of clarithromycin and verapamil as inhibitors of CYP3A4 on the pharmacokinetics of rabeprazole among CYP2C19 genotypes.

METHODS

A three-way randomized, double-blind, placebo-controlled crossover study was performed. Nineteen volunteers, of whom six were homozygous extensive metabolizers (EMs), eight were heterozygous EMs, and five were poor metabolizers (PMs) for CYP2C19, received three 6-day courses of either daily 800 mg clarithromycin, 240 mg verapamil, or placebo in a randomized fashion, with a single oral dose of 20 mg rabeprazole on day 6 in all cases. Plasma concentrations of rabeprazole and rabeprazole thioether were monitored up to 24 h after the dosing.

RESULTS

In the control phase, the AUC(0-infinity) values for rabeprazole and rabeprazole thioether were 1,005+/-366 and 412+/-149 ng.h/ml in homozygous EMs, 1,108+/-340 and 491+/-245 ng.h/ml in heterozygous EMs, and 2,697+/-364 and 2,116+/-373 ng.h/ml in PMs, respectively. There were significant differences (p<0.001) in the AUC(0-infinity) of rabeprazole and rabeprazole thioether among three different CYP2C19 genotypes. In the clarithromycin and verapamil phases, no significant differences were found in the pharmacokinetic parameters of rabeprazole compared with those in the control phase irrespective of CYP2C19 genotypes, whereas the AUC(0-infinity) of rabeprazole thioether was significantly increased 2.8-fold and 2.3-fold in homozygous EMs (p<0.01), 2.0-fold and 2.0-fold in heterozygous EMs (p<0.05), and 1.6-fold and 1.9-fold in PMs (p<0.05), respectively. In each genotype group for CYP2C19, there were no statistical differences in the percent increase in those pharmacokinetic parameters between the clarithromycin and verapamil pretreatment phases.

CONCLUSION

The pharmacokinetic parameters of rabeprazole were not altered by clarithromycin or verapamil irrespective of the CYP2C19 genotypes. However, this result shows that both clarithromycin and verapamil significantly influence the disposition of rabeprazole by inhibiting the oxidation of the thioether, since the AUC(0-infinity) of rabeprazole thioether that has no effect on acid secretion increased. Therefore, the pharmacokinetic interactions between rabeprazole and CYP3A4 or P-glycoprotein inhibitors have limited clinical significance.

Influence of antisecretory treatment with proton pump inhibitors on serum pepsinogen I levels

It has been reported in literature that serum pepsinogen levels rise during omeprazole and lansoprazole administration. However, the influence of pantoprazole and esomeprazole on serum pepsinogens levels is still to be assessed. The aim of this study was to evaluate the influence of proton pump inhibitor (PPI) therapy on pepsinogen I (PGI) levels. PGI and gastrin (G17) levels (EIA; Biohit, Helsinki, Finland) in 126 consecutive patients (M 57; F 69, mean age 53, range 15-91), with upper gastrointestinal symptoms at baseline condition and after 2 months of PPI treatment, were evaluated. Patients underwent a therapy schedule based on: omeprazole 20 mg b.i.d. (20 patients), pantoprazole 40 mg b.i.d. (27 patients), esomeprazole 40 mg b.i.d. (29 patients), lansoprazole 30 mg b.i.d. (21 patients) and rabeprazole 20 mg b.i.d. (26 patients) for 2 months. A significant increase in serum PGI (sPGI) levels was found after a 2-month treatment for all five different PPIs: omeprazole, pantoprazole, esomeprazole, lansoprazole and rabeprazole (P < 0.05). The effect of rabeprazole on sPGI was less pronounced as compared with other PPIs, whereas esomeprazole achieved superior sPGI levels, with no overall statistically significant difference among the five groups (P > 0.05). However, a comparison within a single group of PPIs showed a statistical significance when the esomeprazole group was compared with the rabeprazole group (P = 0.007). sPGI levels are significantly influenced by antisecretory therapy, rising under PPI treatment. Moreover, a statistically significant difference in sPGI levels between the rabeprazole and esomeprazole groups has been demonstrated.

Low-dose rabeprazole, amoxicillin and metronidazole triple therapy for the treatment of Helicobacter pylori infection in Chinese patients

BACKGROUND

Rabeprazole in combination with amoxicillin and metronidazole (RAM) has been shown to be an effective second-line treatment of Helicobacter pylori infection. The effects were compared of 7-day low-dose and high dose rabeprazole in RAM for the primary treatment of H. pylori infection in Chinese patients.

METHODS

Helicobacter pylori-positive dyspeptic patients were randomized to receive either (i) rabeprazole 10 mg, amoxicillin 1000 mg and metronidazole 400 mg (RAM-10) or (ii) high-dose rabeprazole 20 mg, amoxicillin 1000 mg and metronidazole 400 mg (RAM-20), each given twice daily for 7 days. Helicobacter pylori eradication was confirmed by (13)c-urea breath test 5 weeks after stopping medications. side-effects of treatments were documented.

RESULTS

A total of 120 patients were eligible for analysis. By intention-to-treat and per-protocol analysis, the eradication rates were 83% and 86% in the RAM-10 group and 75% and 76% in the RAM-20 group, respectively (P = 0.26 and P = 0.17). Both regimens were well-tolerated and compliance was >98% in both groups.

CONCLUSIONS

Low-dose rabeprazole in combination with amoxicillin and metronidazole is an effective, economical and well-tolerated therapy for the treatment of H. pylori infection in Chinese population.

Potent Gastric Acid Inhibition in Helicobacter pylori Eradication

At present, antisecretory drugs--foremost among them the proton pump inhibitors (PPIs)--represent a keystone in Helicobacter pylori eradication therapy. The present article shall first compare the role of PPIs as compared with histamine H2 receptor antagonists, both of them in the role of antibiotic-associated antisecretory therapy, and shall then address the contribution of each of the various PPIs that have been developed until the present time to the H. pylori eradication therapies. In summary, it may be concluded that PPIs are more effective overall than H2 receptor antagonists when the two groups of antisecretory drugs are given at the usual standard doses together with antibiotics with the intention of eradicating H. pylori infection. However, all PPIs (omeprazole, lansoprazole, pantoprazole, rabeprazole, and esomeprazole) are equivalent when given together with two antibiotics to cure the infection.

Review article: treatment for gastro-oesophageal reflux disease--lifestyle advice and medication

Management of gastro-oesophageal reflux disease (GERD) is aimed at reducing oesophageal acid exposure to achieve symptom relief. Therapy has traditionally included advice to the patient on diet and lifestyle management. Recent evidence suggests, however, that some specific dietary modifications may be applicable to the Japanese patient. For example, ingestion of Japanese sweet cakes or rice cakes should be avoided by the Japanese patient with GERD as these foods may provoke heartburn. Pharmacological therapy is, however, usually also required for effective symptom relief. While antacids and histamine H(2)-receptor antagonists have a role in treating mild GERD, effective relief of many cases of oesophagitis is usually only achieved by using proton-pump inhibitors such as lansoprazole, omeprazole and rabeprazole. In the Japanese population, variation in the genetic polymorphism of CYP2C19 (a cytochrome P450 isoenzyme) leads to considerable inter-individual unpredictability in the activity of lansoprazole and omeprazole due to inter-individual differences in the extent to which these agents are metabolized. Consequently, rabeprazole, which does not undergo hepatic biotransformation by CYP2C19, offers significant advantages over the other PPIs as a result of its more predictable activity. This, coupled with its more rapid onset of action, leads to a more efficient and less variable acid-suppressing effect.

Review article: relief of symptoms in gastric acid-related diseases--correlation with acid suppression in rabeprazole treatment

Symptom relief is one of the key goals in the management of gastric acid-related disorders such as gastro-oesophageal reflux disease (GERD), including nonerosive reflux disease (NERD), and duodenal and gastric ulcer. Whereas heartburn and regurgitation are classic symptoms of GERD, duodenal and gastric ulcers are associated with epigastric pain. The relationship between gastric acid and the presence of symptoms correlates well in GERD and duodenal ulcer, but not in gastric ulcer and NERD. Nevertheless, in all these disorders, gastric acid is considered a key pathogenic element, and acid suppression remains central to therapy. With their profound, prolonged effect on acid inhibition, proton pump inhibitors are considered the first-choice therapy for these disorders. Rabeprazole is a newer generation proton pump inhibitor that suppresses the gastric proton pump and acid secretion more rapidly than does omeprazole, lansoprazole or pantoprazole. In clinical trial settings, rabeprazole provided fast and sustained symptom relief, which can help ensure patient acceptance of therapy and aid in patient compliance.

Review article: the pharmacodynamics and pharmacokinetics of proton pump inhibitors--overview and clinical implications

During the past two decades, enormous changes occurred in the management of gastric acid-related diseases. First, the histamine2-receptor antagonists were introduced, offering patients the first single-agent therapy that effectively reduced gastric acid secretion. Proton pump inhibitors became widely available in the early 1990s, and they generally appeared to be superior to the histamine2-receptor antagonists in acid-suppressing activity, symptom control and healing. Most physicians now use proton pump inhibitors as first-line treatment for many patients with acid-peptic disorders, including erosive gastro-oesophageal reflux disease (GERD), nonerosive reflux disease (NERD) and duodenal and gastric ulcers. Although proton pump inhibitors are often thought to be interchangeable, some differences have emerged in their pharmacological properties, which may be reflected in some aspects of clinical efficacy. Such differences include potency, speed of onset and duration of pH 'holding times'. Helicobacter pylori has now been recognized as an important factor in the pathogenesis of acid-peptic disorders. It is clear that H. pylori eradication can dramatically reduce the chronicity of gastric and duodenal ulcers, and accepted therapeutic regimens for H. pylori eradication now include proton pump inhibitors and two or more antibiotics. Although all accepted proton pump inhibitor-based 'triple therapies' are roughly equivalent in efficacy, there is now a shortened regimen available that will potentially enhance compliance and decrease cost. This review examines the relative advantages of proton pump inhibitors vs. histamine2-receptor antagonists in the context of acid suppression and in various gastric acid-related diseases. A brief overview presents the pharmacodynamics and pharmacokinetics of the proton pump inhibitors with particular attention paid to rabeprazole, one of the newer drugs in its class.

Review article: pH, healing and symptom relief with rabeprazole treatment in acid-related disorders

Control of gastric acid secretion by antisecretory agents has been the cornerstone of therapy in the successful management of all acid-related disorders, including gastro-oesophageal reflux disease (GERD), and duodenal and gastric ulcer. Treatment efficacy has been strongly correlated with degree and duration of acid suppression within the 24-h period and with total duration of therapy. All proton pump inhibitors are highly effective for the healing of ulcers and erosive oesophagitis. All have closely similar mechanisms of action, yet important pharmacological differences exist, which can significantly impact certain aspects of their clinical efficacy. Rabeprazole's rapid activation over a wide pH range may be the explanation for its early onset of effective acid inhibition compared with other proton pump inhibitors such as omeprazole, lansoprazole and pantoprazole. Like rabeprazole, esomeprazole is also a potent inhibitor of gastric acid at steady state, although it is thought that rabeprazole may provide enhanced first-day acid suppression compared with esomeprazole. First-day antisecretory efficacy should produce faster symptom relief, a hypothesis supported by clinical data. Moreover, drugs with pharmacological profiles that include both rapid onset and potent antisecretory effects should help control healthcare costs by reducing the need for otherwise commonly used twice-daily proton pump inhibitor administration.

The choice of proton pump inhibitor: does it matter?

Proton pump inhibitors are used at different dosages for the treatment of acid-related gastrointestinal disorders, such as gastro-oesophaeal reflux and peptic ulcer disease. Comparisons of four different proton pump inhibitors: lansoprazole, omeprazole, pantoprazole, and rabeprazole show that they all have similar potency and efficacy. Rabeprazole, however, displays a slightly more rapid onset of acid inhibition than the others; the clinical advantage of this seems limited. The S-isomer of omeprazole, esomeprazole, exhibits a somewhat higher potency than the other proton pump inhibitors. Reports supporting a clinical advantage of this property are not convincing. To conclude, all inhibitors seem comparable as regards inhibition of gastric acid secretion.

Symptom relief in patients with reflux esophagitis: comparative study of omeprazole, lansoprazole, and rabeprazole

BACKGROUND AND AIM

Rabeprazole has a faster onset of antisecretory activity than omeprazole and lansoprazole. The aim of the present study was to clarify whether there is any difference in the speed of symptom relief in patients with reflux esophagitis following the administration of these three proton pump inhibitors (PPI).

METHODS

Eighty-five patients with erosive reflux esophagitis were randomized to receive 8 weeks of 20 mg of omeprazole (n = 30), 30 mg of lansoprazole (n = 25), or 20 mg of rabeprazole (n = 30) once a morning. Daily changes in heartburn and acid reflux symptoms in the first 7 days of administration were assessed using a six-point scale (0: none, 1: mild, 2: mild-moderate, 3: moderate, 4: moderate-severe, 5: severe).

RESULTS

The mean heartburn score in patients administered rabeprazole decreased more rapidly than those given the other PPI. Complete heartburn remission also occurred more rapidly in patients administered rabeprazole (compared with omeprazole: P = 0.035, compared with lansoprazole: P = 0.038 by log-rank test). No differences were seen in the rate of endoscopic healing of reflux esophagitis at 8 weeks between the three treatment regimens.

CONCLUSION

Rabeprazole may be more effective than omeprazole and lansoprazole for the rapid relief of heartburn symptoms in patients with reflux esophagitis.

Effect of a single oral dose of rabeprazole on nocturnal acid breakthrough and nocturnal alkaline amplitude

AIM: To study the effect of rabeprazole (RAB) on nocturnal acid breakthrough (NAB) and nocturnal alkaline amplitude (NAKA) and to compare it with omeprazole (OME) and pantoprazole (PAN).

METHODS: By an open comparative study, forty patients with active peptic ulcer were randomly assigned to receive one of the three PPIs (proton pump inhibitor) with a single oral dose. They were divided into RAB group (10 mg), OME group (20 mg) and PAN group (40 mg). Twenty healthy volunteers were enrolled to the control group (without taking any drug). Intragastric pH monitoring was then performed 1 h before and 24 h after the dose was given.

RESULTS: No clinically undesirable signs and symptoms possibly attributed to the administration of RAB or OME and PAN were recognizable throughout the study period. All subjects completed the study according to the protocol. All data were processed by a computer using the Student t test or t’ test followed by an analysis of covariance. P < 0.05 was considered to have statistical significance. The intragastric pH of NAB was significantly higher in RAB group (1.84 ± 0.55) than in either OME group (1.15 ± 0.31) or PAN group (1.10 ± 0.30) (both P < 0.01). RAB produced a longer sustaining time (4.65 ± 1.22 h) on NAKA than OME (3.22 ± 1.89 h) (P < 0.05), PAN (3.15 ± 1.92 h) (P < 0.05), and the sustaining time of NAKA in RAB group was longer than that in the healthy control group (P < 0.01) too. In addition, RAB produced a much higher pH on NAKA (6.41 ± 0.45) in comparison with PAN (6.01 ± 0.92) (P < 0.05).

CONCLUSION: A single oral dose of 10 mg RAB may increase the pH of NAB and shorten the sustaining time of NAB, and it may increase the pH of NAKA as well as prolong the sustaining time of NAKA.

Randomized study of different 'second-line' therapies for Helicobacter pylori infection after failure of the standard 'Maastricht triple therapy'

BACKGROUND

Triple therapy with proton pump inhibitor, clarithromycin and amoxicillin and, in the event of eradication failure, quadruple therapy with proton pump inhibitor, bismuth, tetracycline and metronidazole have been proposed in Maastricht as the optimal sequential treatment of Helicobacter pylori infection.

AIM

To compare two second-line regimens with quadruple therapy.

METHODS

One hundred and eighty patients with a previous failed course of standard therapy were randomly given one of the following 7-day treatments: ranitidine bismuth citrate 400 mg b.d. plus amoxicillin 1 g b.d. and tinidazole 500 mg b.d. (RBCAT), pantoprazole 40 mg b.d. plus amoxicillin 1 g b.d. and levofloxacin 500 mg/day (PAL) and pantoprazole 40 mg b.d., bismuth citrate 240 mg b.d., tetracycline 500 mg q.d.s. and metronidazole 500 mg b.d. (PBTM). The eradication rate was assessed by 13C-urea breath test. Side-effects and compliance were evaluated by a standardized questionnaire and by counting returned medication.

RESULTS

The RBCAT, PAL and PBTM groups achieved mean intention-to-treat eradication rates of 85%, 63% and 83%, respectively (P<0.05 for PAL vs. either RBCAT or PBTM). Compliance was optimal in all patients, although side-effects were more commonly observed in the PBTM group than in the other two patient groups (P<0.0001).

CONCLUSIONS

Both RBCAT and PBTM can be used as second-line therapies. Conversely, PAL did not achieve satisfactory eradication rates.

High-dose rabeprazole-amoxicillin versus rabeprazole-amoxicillin-metronidazole as second-line treatment after failure of the Japanese standard regimen for Helicobacter pylori infection

BACKGROUND

There is currently no optimal second-line treatment after failure of Helicobacter pylori triple therapy.

AIM

To determine effective salvage therapy after failure of lansoprazole-amoxicillin-clarithromycin.

METHODS

After failure of lansoprazole-amoxicillin-clarithromycin 123 out-patients were randomized to receive either 2-week rabeprazole (20 mg b.d.) + amoxicillin (1000 mg b.d.) (RA group) or 1-week rabeprazole (10 mg b.d.) + amoxicillin (750 mg twice b.d.) + metronidazole (250 mg b.d.) (RAM group). Eradication was assessed by the 13C-urea breath test. We also evaluated cytochrome p450 (CYP) 2C19 genotype status, determined by polymerase chain reaction - restriction fragment length polymorphism, and susceptibility to clarithromycin and metronidazole.

RESULTS

On an intention-to-treat basis, H. pylori infection cure was achieved in 37 of 63 (59%) patients in the RA group and in 49 of 60 (82%) patients in the RAM group. Per protocol-based eradication rates in the RA and RAM groups were 66% (37/56) and 88% (49/56), respectively. In both analytic sets there were significant differences between the treatment groups (P < 0.01 in each). Mild adverse events were observed in eight and five patients from the RA and RAM groups, respectively. Genetic predisposition of CYP2C19 and antibiotic resistance did not influence the treatment outcome either regimen.

CONCLUSIONS

The rabeprazole + amoxicillin + metronidazole therapy yielded satisfactory results. In contrast, the cure rate in high-dose rabeprazole + amoxicillin was below an acceptable level.

Rabeprazole is superior to omeprazole for the inhibition of peptone meal-stimulated gastric acid secretion in Helicobacter pylori-negative subjects

BACKGROUND

Peptone meal-stimulated gastric acid output is considered to be a reliable means to evaluate drug-mediated inhibition of stimulated gastric acid output, an important measure of the efficacy of the agents--such as proton pump inhibitors--used to treat acid-related disorders.

AIM

To compare the initial and overall inhibitory effects on peptone meal-stimulated gastric acid secretion of rabeprazole and omeprazole, 20 mg, in Helicobacter pylori-negative subjects on the first and eighth days of treatment.

METHODS

Healthy volunteers (n = 27) were randomized in a single-centre, double-blind, double-dummy, 2 x 2 cross-over study. Subjects received an oral dose of rabeprazole or omeprazole, 20 mg once daily, for 8 days. After a 2-4-week washout period, subjects were crossed over to receive the other medication for 8 days. Peptone meal-stimulated gastric acid secretion was measured at hours 11 and 23 at baseline and on days 1 and 8 of treatment.

RESULTS

On days 1 and 8, rabeprazole demonstrated a significantly greater inhibition of peptone meal-stimulated gastric acid secretion compared with omeprazole at all time points (P < 0.03). Median values of steady-state inhibition on day 1 were statistically significant at hour 23 (rabeprazole 100% vs. omeprazole 74%, P < 0.02).

CONCLUSIONS

Rabeprazole, 20 mg, demonstrated superior control of peptone meal-stimulated gastric acid secretion compared with omeprazole, 20 mg, after the first dose and after the eighth daily dose. Rabeprazole achieved a more rapid onset of acid inhibition and a greater steady-state reduction in peptone meal-stimulated gastric acid secretion.

Lafutidine, a novel histamine H2-receptor antagonist, vs lansoprazole in combination with amoxicillin and clarithromycin for eradication of Helicobacter pylori

BACKGROUND

In contrast to the growing amount of data concerning proton pump inhibitor-based triple therapy for Helicobacter pylori infection, it is still controversial whether proton pump inhibitor can be replaced by H2 receptor antagonist without compromising efficacy. Lafutidine is a novel potent H2 receptor antagonist with gastroprotective activities such as enhancement of gastric mucosal blood flow.

METHODS

122 outpatients with positive cultures and subsequent successful cultivation of H. pylori for antimicrobial susceptibility tests were randomized to receive a 7-day course of either lafutidine (20 mg twice daily) or lansoprazole (30 mg twice daily), plus clarithromycin (200 mg twice daily) and amoxicillin (750 mg twice daily). Eradication was considered successful if the rapid urease test, culture, histology and [13]C-urea breath test were all negative at least 4 weeks after cessation of therapy. Cytochrome p450 2C19 genotype status using polymerase chain reaction-restriction fragment length polymorphism was also studied.

RESULTS

On intention-to-treat basis, H. pylori cure was achieved in 52 of 61 (85.2%) patients and 49 of 61 (80.3%) patients for the lafutidine- and lansoprazole-based therapies, respectively. The predicted 95% confidential intervals for the 4.9% of the difference were -1.8-11.6%. Using per protocol analysis, the eradication rates were 88.2% (52/59) and 84.5% (49/58), respectively. The predicted 95% confidential intervals for the 3.7% of the difference were -2.6-10.0%. Adverse events were observed in five and six patients, from the lafutidine and lansoprazole groups, respectively, but they were generally mild. Genetic predisposition of cytochrome p450 2C19 had no significant influence on treatment outcome in both regimens.

CONCLUSIONS

The lafutidine-clarithromycin-amoxicillin therapy yielded satisfactory results for eradicating H. pylori, which was comparable with those of the lansoprazole-based regimen with the same drug combination.

Pharmacological control of gastric acid secretion for the treatment of acid-related peptic disease: past, present, and future

Pharmacological agents, such as histamine H(2) receptor antagonists and acid pump inhibitors, are now the most frequently used treatment for such acid-related diseases as gastroduodenal ulcers and reflux esophagitis. Based on increased understanding of the precise mechanisms of gastric acid secretion at the level of receptors, enzymes, and cytoplasmic signal transduction systems, further possibilities exist for the development of effective antisecretory pharmacotherapy. Gastrin CCK(2) receptor antagonists and locally active agents appear to represent promising therapies for the future. Development of gene targeting techniques has allowed production of genetically engineered transgenic and knockout mice. Such genetic technology has increased the investigative power for pharmacotherapy for not only antisecretory agents, but also treatment of mucosal diseases, such as atrophy, hyperplasia, and cancer. Elucidation of the origin of gastric parietal cells also represents an interesting investigative target that should allow a better understanding of not only acid-related diseases, but also the evolution of the stomach as an acid-secreting organ.

Systematic review: Rabeprazole-based therapies in Helicobacter pylori eradication

AIM

To perform a systematic review of the efficacy of rabeprazole-based therapies in Helicobacter pylori eradication, and to conduct a meta-analysis comparing the efficacy of rabeprazole and other proton pump inhibitors when co-prescribed with antibiotics.

METHODS

Studies evaluating rabeprazole plus antibiotics were considered. Only randomized trials comparing rabeprazole and other proton pump inhibitors with antibiotics, and differing only in the proton pump inhibitor, were included in the meta-analysis. Electronic and manual bibliographic searches were conducted. The percentage (weighted mean) of successful eradication was calculated. Meta-analysis was performed by combining the odds ratios (OR) of the individual studies.

RESULTS

The eradication rates were as follows: 14-day rabeprazole-amoxicillin, 73%; rabeprazole-amoxicillin-clarithromycin for 3, 5, 7 and 10 days, 44%, 72%, 78% and 75%, respectively; low-dose rabeprazole (20 mg/day), amoxicillin and clarithromycin for 7 days, 81%; high-dose rabeprazole (40 mg/day), amoxicillin and clarithromycin for 7 days, 75%; 7-day rabeprazole-clarithromycin-nitroimidazole, 85%. Twelve comparative studies were included in the meta-analysis. The eradication rate with rabeprazole plus antibiotics was 79%; it was 77% with other proton pump inhibitors (OR = 1.15; 95% confidence interval, 0.93-1.42). Sub-analysis comparing rabeprazole at low doses (10 mg b.d.) with other proton pump inhibitors at standard doses (omeprazole 20 mg b.d. or lansoprazole 30 mg b.d.) showed no differences.

CONCLUSIONS

Rabeprazole achieves similar H. pylori eradication rates to omeprazole and lansoprazole when co-prescribed with antibiotics. Low doses of rabeprazole (10 mg b.d.), when administered with two antibiotics, may be sufficient to eradicate H. pylori infection.

Randomized controlled study of rabeprazole, levofloxacin and rifabutin triple therapy vs. quadruple therapy as second-line treatment for Helicobacter pylori infection

AIM

To test the efficacy of rabeprazole, levofloxacin and rifabutin triple therapy vs. quadruple therapy for the second-line treatment of Helicobacter pylori infection.

METHODS

One hundred and nine patients who had failed previous H. pylori eradication were randomized to receive: (i) rabeprazole, 20 mg b.d., rifabutin, 300 mg once daily, and levofloxacin, 500 mg once daily, for 7 days (triple therapy); or (ii) rabeprazole, 20 mg b.d., metronidazole, 400 mg t.d.s., bismuth subcitrate, 120 mg q.d.s., and tetracycline, 500 mg q.d.s., for 7 days (quadruple therapy). Endoscopy and culture were performed before treatment.

RESULTS

The clarithromycin (79% vs. 21%, P < 0.001) and metronidazole (89% vs. 40%, P < 0.001) resistance rates were significantly higher in patients with previous exposure than in those with no previous exposure. The intention-to-treat and per protocol eradication rates were 91%/91% for the triple therapy group and 91%/92% for the quadruple therapy group. For patients with double resistance to metronidazole and clarithromycin, the eradication rates were 85% (17/20) in the triple therapy group and 87% (13/15) in the quadruple therapy group. Compliance was greater than 95% for both regimens.

CONCLUSION

Rabeprazole, levofloxacin and rifabutin-based triple therapy and quadruple therapy were equally effective as second-line treatments for H. pylori infection.

Randomized open trial for comparison of proton pump inhibitors in triple therapy for Helicobacter pylori infection in relation to CYP2C19 genotype

BACKGROUND AND AIMS

Genetic polymorphism of cytochrome P450 (CYP) 2C19 influences the efficacy of Helicobacter pylori eradication therapy with a proton pump inhibitor (PPI) and amoxicillin. However, in triple therapy (PPI plus amoxicillin and clarithromycin), little is known about the impact of CYP2C19 polymorphism, or the use of rabeprazole, which is not well metabolized by CYP2C19. The efficacy of three PPI (omeprazole, lansoprazole, and rabeprazole) in a 1-week triple regimen were compared in relation to CYP2C19 polymorphism.

METHOD

One hundred and eighty-three patients were randomized to receive one of the following regimens: amoxicillin 500 mg t.i.d., clarithromycin 200 mg t.i.d., and PPI (omeprazole 20 mg, lansoprazole 30 mg, or rabeprazole 10 mg) b.i.d. CYP2C19 polymorphism was analyzed by PCR restriction fragment length polymorphism.

RESULTS

Intention-to-treat-based overall cure rates for omeprazole, lansoprazole or rabeprazole regimens were 83.1% (95% confidence interval (CI): 69-89%), 86.7% (CI: 75-93%), and 76.6% (CI: 64-85%), respectively, without significant difference. The cure rate of the rabeprazole regimen (but not the lansoprazole or omeprazole regimens) tended to be correlated with CYP2C19 genotypes (P = 0.076). In patients with a homozygous extensive metabolizer genotype, the per protocol-based cure rate with rabeprazole (62.5%) was significantly lower than that with lansoprazole (90.0%; P = 0.038).

CONCLUSION

The overall cure rate of 1-week triple therapy for H. pylori eradication was not significantly different between regimens with omeprazole, lansoprazole or rabeprazole, but the impact of CYP2C19 genetic polymorphism on the cure rate appeared to differ between these PPI.

Comparison of lansoprazole and famotidine for gastric acid inhibition during the daytime and night-time in different CYP2C19 genotype groups

BACKGROUND

The acid inhibitory effect of lansoprazole depends on the S-mephenytoin 4'-hydroxylase (CYP2C19) genotype status. The effect of famotidine is independent of this genotype.

AIM

To investigate the acid inhibitory effects of lansoprazole vs. famotidine during the daytime and night-time with reference to different CYP2C19 genotypes.

METHODS

Fifteen healthy volunteers were given 20 mg famotidine twice a day or 30 mg lansoprazole once a day for 8 days. On post-dose day 8, 24-h intragastric pH monitoring was performed.

RESULTS

During the daytime, the intragastric pH with lansoprazole was significantly higher than that with famotidine in the heterozygous extensive metabolizer group, whereas no significant difference was observed in the homozygous extensive metabolizer group. During the night-time, the intragastric pH with famotidine was quite similar to that with lansoprazole in the heterozygous extensive metabolizer and poor metabolizer groups. However, during the night-time, the intragastric pH with famotidine was significantly higher than that with lansoprazole in the homozygous extensive metabolizer group.

CONCLUSIONS

An insufficient acid inhibition by lansoprazole during the night-time in the homozygous extensive metabolizer group could be compensated for by famotidine. CYP2C19 genotype testing appears to be useful for predicting the optimal acid inhibitory drug treatment collated with circadian intragastric pH change.

Rabeprazole-based 3-day and 7-day triple therapy vs. omeprazole-based 7-day triple therapy for the treatment of Helicobacter pylori infection

BACKGROUND

Rabeprazole is a new proton pump inhibitor with more potent acid suppressive and anti-Helicobacter effects.

AIM

To compare two different regimens of rabeprazole-based triple therapy vs. 7-day omeprazole-based triple therapy for the eradication of Helicobacter pylori infection.

METHOD

Patients with proven H. pylori infection were randomized to receive: (i) 7-day rabeprazole, 10 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily; (ii) 3-day rabeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily; or (iii) 7-day omeprazole, 20 mg, amoxicillin, 1000 mg, and clarithromycin, 500 mg, all twice daily. Endoscopy (CLO test, histology) was performed before randomization and 6 weeks after drug treatment.

RESULTS

One hundred and seventy-three patients were randomized. H. pylori eradication rates (intention-to-treat, n=173/per protocol, n=167) were 88%/91% for 7-day rabeprazole-based therapy, 72%/72% for 3-day rabeprazole-based therapy and 82%/89% for 7-day omeprazole-based therapy, respectively. The per protocol eradication rate was significantly better in the 7-day rabeprazole-based therapy and 7-day omeprazole-based therapy groups when compared to the 3-day rabeprazole-based therapy group (P=0.01 and P=0.04, respectively). Compliance was excellent and all three regimens were well tolerated.

CONCLUSIONS

The efficacy of seven-day rabeprazole-based triple therapy is similar to 7-day omeprazole-based triple therapy for the eradication of H. pylori infection.