Effects of genotypic differences in CYP2C19 status on cure rates for Helicobacter pylori infection by dual therapy with rabeprazole plus amoxicillin

Modeled Hepatic/Plasma Exposures of Fluvastatin Prescribed Alone in Subjects with Impaired Cytochrome P450 2C9*3 as One of Possible Determinant Factors Likely Associated with Hepatic Toxicity Reported in a Japanese Adverse Event Database

Fluvastatin is a 3-hydroxy-3-methylglutaryl CoA reductase inhibitor that competitively inhibits human cytochrome P450 (P450) 2C9 in vitro. Drug interactions between a variety of P450 2C9 substrates/inhibitors and fluvastatin can increase the incidence of fluvastatin-related hepatic or skeletal muscle toxicity in vivo. In this survey, the prescribed dosage of fluvastatin was reduced or discontinued in 133 of 164 patients receiving fluvastatin alone, as recorded in the Japanese Adverse Drug Event Report database of spontaneously reported events. The median days to onset of fluvastatin-related disorders were in the range 30-35 d in the 87 patients. Therefore, we aimed to focus on fluvastatin and, using the pharmacokinetic modeling technique, estimated the virtual plasma and hepatic exposures in subjects harboring the impaired CYP2C9*3 allele. The plasma concentrations of fluvastatin modeled after a virtual oral 20-mg dose increased in homozygotes with CYP2C9*3; the area under the plasma concentration curve was 4.9-fold higher than that in Japanese homozygotes for wild-type CYP2C9*1. The modeled hepatic concentrations of fluvastatin in patients with CYP2C9*3/*3 after virtual daily 20-mg doses for 7 d were 31-fold higher than those in subjects with CYP2C9*1/*1. However, heterozygous Chinese patients with CYP2C9*1/*3 reportedly have a limited elevation (1.2-fold) in plasma maximum concentrations. Virtual hepatic/plasma exposures in subjects harboring the impaired CYP2C9*3 allele estimated using pharmacokinetic modeling indicate that such exposure could be a causal factor for hepatic disorders induced by fluvastatin prescribed alone in a manner similar to that for interactions with a variety of co-administered drugs.

The Efficacy and Safety of 14-day Rabeprazole Plus Amoxicillin High Dose Dual Therapy by Comparing to 14-day Rabeprazole-Containing Hybrid Therapy for the Naïve Helicobacter pylori Infection in Taiwan: A Randomized Controlled Trial

INTRODUCTION

High-dose dual therapy (HDDT) can attain acceptable eradication rates provided that the optimal doses, timing and treatment duration are applied. The existing evidence still shows inconsistent reports (< 90%) on HDDT therapy except in some Asian countries. We aimed to assess and compare the efficacy of 14-day HDDT by comparing it to 14-day rabeprazole-containing hybrid therapy (HT) and to investigate the host and bacterial factors predicting the treatment outcomes of eradication therapies.

METHODS

In this open-label, randomized controlled trial, we recruited 243 naïve Helicobacter pylori-infected patients from September 1, 2018, to November 30, 2021. They were randomly allocated (1:1) to the HDDT group (rabeprazole 20 mg and amoxicillin 750 mg q.i.d for 14 days, n = 122) and the HT group (rabeprazole 20 mg and amoxicillin 1 g b.i.d. for 7 days, followed by rabeprazole 20 mg, amoxicillin 1 g, clarithromycin 500 mg and metronidazole 500 mg b.i.d. for 7 days, n = 121). Twelve patients were absent during follow-up in the HDDT group and 4 in the HT group, resulting in 110 for the HDDT group and 117 for HT group in the per protocol (PP) study. The outcome was determined by urea breath tests 8 weeks later.

RESULTS

The eradication rates for the HDDT and HT groups were 77.0% (95% confidence interval [CI]: 68.5% to 84.1%) and 94.2% (95% CI: 88.4% to 97.6%) (P < 0.001) in intention-to-treat analysis; 85.5% (95% CI: 77.5% to 91.5%) and 97.4% [95% CI: 92.6% to 99.5%] (P = 0.001) in per protocol analysis. The adverse event rates were 7.3% in the HDDT group and 14.5% in the HT group (P = 0.081). The habit of coffee drinking was the dependent factor for eradication failure in the HDDT group (88.2% vs. 68.8%, P = 0.040), but had no influence in the HT group (97.9% versus 95.0%, P = 0.449) in the univariate analysis.

CONCLUSION

This study demonstrated that 14-day rabeprazole-containing HDDT did not achieve > 90% eradication rates for first-line H. pylori eradication as 14-day rabeprazole-containing HT did. HDDT is a potentially beneficial combination, which involves only two drugs with mild adverse effects; more precise studies are urged to find answers regarding these failures. This clinical trial was registered retrospectively on 28 November, 2021, as ClinicalTrials.gov identifier: NCT05152004.

Therapeutic eradication choices in Helicobacter pylori infection in children

Current recommendations on Helicobacter pylori (H. pylori) eradication in children differ from adults. In H. pylori-infected adults, the eradication is always recommended because of the risk to develop gastrointestinal and non-gastrointestinal associated diseases. Instead, before treating infected children, we should consider all the possible causes and not merely focus on H. pylori infection. Indeed, pediatric international guidelines do not recommend the test and treat strategy in children. Therefore, gastroscopy with antimicrobial susceptibility testing by culture on gastric biopsies should be performed before starting the eradication therapy in children to better evaluate all the possible causes of the symptomatology and to increase the eradication rate. Whether antibiotic susceptibility testing is not available, gastroscopy is anyway recommended to better set any possible cause of symptoms and not simply focus on the presence of H. pylori. In children the lower antibiotics availability compared to adults forces to treat based on antimicrobial susceptibility testing to minimize the unsuccessful rates. The main antibiotics used in children are amoxicillin, clarithromycin, and metronidazole in various combinations. In empirical treatment, triple therapy for 14 days based either on local antimicrobial susceptibility or on personal antibiotic history is generally recommended. Triple therapy with high dose of amoxicillin is a valid alternative choice, either in double resistance or in second-line treatment. Moving from therapeutic regimens used in adults, we could also select quadruple therapy with or without bismuth salts. However, all the treatment regimens often entail unpleasant side effects and lower compliance in children. In this review, the alternative and not yet commonly used therapeutic choices in children were also analyzed.

Expectations for the Dual Therapy with Vonoprazan and Amoxicillin for the Eradication of H. pylori

Vonoprazan (VPZ) inhibits gastric acid secretion more potently than proton pump inhibitors. Recently, attention has been focused on the dual therapy with VPZ and amoxicillin (AMOX) for the eradication of H. pylori. The dual VPZ/AMOX therapy attains the sufficient eradication rate with lowering the risk of adverse events in comparison with the triple therapy and quadruple therapy. Therefore, the dual VPZ/AMOX therapy is considered a useful eradication regimen for H. pylori infection.

Influence of Cytochrome P450 2C19 Genotype on Helicobacter pylori Proton Pump Inhibitor-Amoxicillin-Clarithromycin Eradication Therapy: A Meta-Analysis

Background: Proton pump inhibitors (PPIs) are the first-line treatment for acid-related diseases. The pharmacokinetics and therapeutic efficacy of PPIs, however, are influenced by genetic factors such as variants in genes encoding drug-metabolizing enzymes (e.g., cytochrome P450 2C19 [CYP2C19]) and drug transporters. We performed a meta-analysis to evaluate the influence of CYP2C19 genotype and PPI class, PPI dose, treatment duration and clarithromycin dose on the cure rate of PPI-containing Helicobacter pylori eradication therapy.

Methods: Randomized control trials (RCTs) investigating cure rates using a PPI-amoxicillin-clarithromycin regimen among different CYP2C19 genotypes through May 2021 were included.

Results: A total of 25 studies (5,318 patients) were included. The overall eradication rate in the intention-to-treat analysis was 79.0% (3,689/4,669, 95% confidence interval [CI]: 77.8–80.2%), and that in CYP2C19 extensive metabolizers (EMs), intermediate metabolizer (IMs) and poor metabolizers (PMs) was 77.7% (1,137/1,464, 95% CI: 75.3–79.6%), 81.2% (1,498/1,844, 95% CI: 79.3–83.0%) and 86.8% (644/742, 95% CI: 83.9–88.9%), respectively. Meta-analysis showed that the relaTakashitive risk of failed eradication in CYP2C19 EMs compared with IMs and PMs was 1.21 (95% CI: 1.06–1.39, P = 0.006) and 1.57 (95% CI: 1.27–1.94, P < 0.001), respectively, in the fixed-effects model. The cure rate of omeprazole and lansoprazole-containing eradication regimens differed among CYP2C19 genotypes (P < 0.05), while that of rabeprazole and esomeprazole-containing regimens was similar.

Conclusion: The cure rates of PPI-amoxicillin-clarithromycin H. pylori eradication regimen, especially those containing omeprazole and lansoprazole, differ among CYP2C19 genotypes. Therefore, selection of a second-generation PPI or tailored treatment may achieve higher eradication rates than first-generation PPI-amoxicillin-clarithromycin triple regimen.

High-dose dual therapy is effective as first-line treatment for Helicobacter pylori infection

BACKGROUND/AIMS

Although many regimens, including quadruple, sequential, and concomitant treatment, are used and recommended as first-line or rescue therapies for Helicobacter pylori infection, eradication rates are still below 90% in intention-to-treat analyses. Treatment protocols with substantially high eradication rates and low antibiotic resistance are needed. In this study, we investigated the efficacy of high-dose dual therapy as first-line treatment in a Turkish population.

MATERIALS AND METHODS

All patients underwent upper gastrointestinal endoscopy for the initial H. pylori status because of dyspeptic symptoms. All patients received a 14-day, high-dose dual therapy comprising rabeprazole (20 mg t.i.d.) and amoxicillin (1 g t.i.d.) for H. pylori eradication. H. pylori stool antigen tests of eradication were administered to all participants at least 4 weeks after the completion of the treatment.

RESULTS

The high-dose dual therapy demonstrated a 91.3% rate of successful eradication of H. pylori infection. Per-protocol success was 94.4% among female patients (n=51) and 89.6% among male patients (n=86); in terms of gender, the differences were not significant (p=0.310). No side effects were observed during the study in any patient. Six other patients did not take adequate doses of the treatment protocol.

CONCLUSION

High-dose dual therapy with rabeprazole and amoxicillin was highly effective and well tolerated as a first-line therapy for H. pylori eradication.

The effect of CYP2C19 gene polymorphism on the eradication rate of Helicobacter pylori by proton pump inhibitors-containing regimens in Asian populations: a meta-analysis

Premise: The effects of proton pump inhibitors (PPI) depend on metabolic enzyme CYP2C19 that has different activity due to gene polymorphism. The purpose of this meta-analysis is to determine the potential effects of CYP2C19 polymorphism on the efficiency of PPI-based treatment. Materials & methods: The PubMed, EMBASE, Cochrane Library, etc. were searched for relevant articles published in English or Chinese from inception to 31 May 2020. Finally, 26 randomized controlled trials and 15 cohort studies met the inclusion criteria and used for the meta-analysis via STATA version 15. Results: Poor metabolizer (PM) genotype Helicobacter pylori eradication rates were highest for Asian individuals receiving triple or quadruple first-line therapy based on PPIs (p < 0.05). CYP2C19 polymorphism could influence H. pylori eradication rate only in Mainland China and Japan (p < 0.05). Conclusion: PM genotype facilitates the elimination of H. pylori in Asian populations. Rabeprazole-, esomeprazole- and pantoprazole-based eradication program was less affected by the CYP2C19 polymorphism.

High-dose dual therapy versus bismuth-containing quadruple therapy for the treatment of Helicobacter pylori infection – A review of the strengths, weaknesses, and proposed solutions

Helicobacter pylori is the principal cause of peptic ulcers, gastric cancer, and mucosa-associated lymphoid tissue lymphoma. The first treatment to H. pylori infection is dual therapy (a bismuth compound plus metronidazole). On the launch of omeprazole in 1988, dual therapy became omeprazole and amoxicillin (low dose). The poor H. pylori eradication rates by either bismuth-based or low-dose dual therapy drove more combinations of antibiotics were needed. Antibiotic resistance, especially clarithromycin and metronidazole, has made bismuth-containing quadruple therapy (BCQT) a savior for first-line and second-line treatments. However, its complicated dosing regimen commonly causes more adverse events and poor drug compliance. Thus, high-dose dual therapy (HDDT) has been re-arising. This article reviews the strengths and weaknesses of HDDT versus BCQT with proposed solutions.

Review - Treatment of Helicobacter pylori infection 2020

This review summarizes important studies regarding Helicobacter pylori therapy published from April 2019 to April 2020. The main themes that emerge involve studies assessing antibiotic resistance, and there is also growing momentum behind the utility of vonoprazan as an alternative to proton pump inhibitor (PPI) therapy and also bismuth-based regimens as a first-line regimen. Antibiotic resistance is rising wherever it is being assessed, and clarithromycin resistance in particular has reached a point where it may no longer be a viable therapy without previous testing in many regions of the world. The evidence for the efficacy of a bismuth-based quadruple therapy as a first-line therapy is now very clearly established, and there is substantial evidence that it is the best performing first-line therapy. The utility of vonoprazan as an alternative to PPI therapy, especially in resistant and difficult-to-treat groups, has also been considered in great detail this year, and it may offer an opportunity in the near future to reduce the problem of antibiotic resistance.

Clarithromycin Versus Metronidazole in First-Line Helicobacter Pylori Triple Eradication Therapy Based on Resistance to Antimicrobial Agents: Meta-Analysis

Background: International treatment guidelines for Helicobacter pylori infection recommend a proton pump inhibitor (PPI)/amoxicillin/clarithromycin (CAM) regimen (PAC) or PPI/amoxicillin/metronidazole (MNZ) regimen (PAM) as first-line therapy based on culture and sensitivity testing. As incidence rates of antimicrobial agent-resistant strains are changing year by year, it is important to reevaluate the efficacy of eradication regimens. We performed a meta-analysis to evaluate the efficacy and safety of PAC and PAM based on different locations categorized by the reported incidence of CAM- and MNZ-resistant strains. Methods: Randomized control trials (RCTs) comparing eradication rates between PAC and PAM first-line treatment up to December 2018 were included. We divided RCTs into four groups based on resistance to CAM (< 15% or ≥ 15%) and MNZ (< 15% or ≥ 15%). Results: A total of 27 studies (4825 patients) were included. Overall eradication rates between PAC and PAM were similar (74.8% and 72.5%, relative risk (RR): 1.13, 95% confidence interval (CI): 0.91–1.39, P = 0.27) in the intention-to-treat analysis. In areas with low MNZ- and high CAM-resistance rates, PAM had a significantly higher eradication rate than PAC (92.5% vs. 70.8%, RR: 0.29, 95% CI: 0.13–0.68). In areas with high MNZ- and low CAM-resistance rates, the eradication rate with PAC was only 72.9%. Conclusions: Overall eradication rates with PAC and PAM were equivalent worldwide. In low MNZ-resistance areas, PAM may be recommended as first-line therapy. However, the efficacy of PAC may be insufficient, irrespective of susceptibility to CAM.

13C Breath Tests in Infections and Beyond

Stable isotope labeled compounds are widely used as diagnostic probes in medicine. These diagnostic stable isotope probes are now being expanded in their scope, to provide precise indications of the presence or absence of etiologically significant change in metabolism due to a specific disease. This concept exploits a labeled tracer probe that is a specifically designed substrate of a “gateway” enzyme in a discrete metabolic pathway, whose turnover can be measured by monitoring unidirectional precursor product mass flow. An example of such a probe is the 13C-urea breath test, where labeled urea is given to patients with H. pylori infection. Another example of this kind of probe is used to study the tripeptide glutathione (glu-cys-gly, GSH), which is the most abundant cellular thiol, and protects cells from the toxic effects of reactive oxygen species. Within the gamma glutamyl cycle, 5-oxoproline (L-pyroglutamic acid) is a metabolite generated during GSH catabolism, and is metabolized to glutamic acid by 5-oxoprolinase. This enzyme can also utilize the substrate L-2-oxothiazolidone-4-carboxylate (OTC), to generate intracellular cysteine, which is beneficial to the cell. Thus, labeled (13C) OTC would, under enzymatic attack yield cysteine and 13CO2, and can thus track the state and capacity of glutathione metabolism. Similarly, stable isotope labeled probes can be used to track the activity of the rate of homocysteine clearance, lymphocyte CD26, and liver CYP (cytochrome P450) enzyme activity. In the future, these applications should be able to titrate, in vivo, the characteristics of various specific enzyme systems in the body and their response to stress or infection as well as to treatment regimes.

Four-times-daily Dosing of Rabeprazole with Sitafloxacin, High-Dose Amoxicillin, or Both for Metronidazole-Resistant Infection with Helicobacter pylori in Japan

BACKGROUND

The bacterial resistance of Helicobacter pylori to antimicrobial agents such as clarithromycin and metronidazole has been increasing worldwide, leading to the failure of eradication treatment. Here, we present an eradication regimen consisting of four-times-daily dosing (q.i.d.) of rabeprazole with potent acid inhibition.

AIM

To investigate the efficacy of eradication therapy with rabeprazole q.i.d. and amoxicillin or sitafloxacin in Japanese infected with a metronidazole-resistant strain.

METHODS

We retrospectively investigated the efficacy of eradication regimens with rabeprazole q.i.d. for 7 days in 111 Japanese pooled patients infected with a metronidazole-resistant strain of H. pylori at Hamamatsu University School of Medicine Hospital or the Shiga University of Medical Science Hospital: 1, with sitafloxacin 100 mg twice daily (b.i.d.) (n = 82); 2, with amoxicillin 500 mg q.i.d. (n = 15); and 3, with amoxicillin q.i.d. and sitafloxacin b.i.d.-combined regimen (n = 14). Eradication status was assessed at 8 weeks via a ¹³ C-urea breath test.

RESULTS

Eradication rate on intention-to-treat analysis was 93.7% (95% confidence interval: 87.4-97.4%, 104/111), irrespective of the high prevalence of strains resistant to clarithromycin (81.1%, 90/111) and levofloxacin (42.3%, 47/111). No significant differences in eradication rates were observed among the different treatment regimens (p = .408), eradication history (p = .096) and different CYP2C19 genotypes (p = .789). On multivariate analysis, no significant risk factor for eradication failure by therapy with potent acid inhibition was seen.

CONCLUSION

In Japanese patients infected with metronidazole-resistant strains of H. pylori, eradication rates exceeding 90% can be achieved using appropriate dosing of antibiotic agents with strain susceptibility (amoxicillin q.i.d. and/or sitafloxacin b.i.d.) together with acid inhibition for a full 24 h and rabeprazole 10 mg q.i.d. These findings may be further evidence for dual therapy with rabeprazole q.i.d. and an antibiotic agent (amoxicillin q.i.d. or sitafloxacin b.i.d.) in Japanese patients with metronidazole-resistant strains.

One-day front-loading with four doses of rabeprazole followed by a standard twice-daily regimen provides sufficient acid inhibition in extensive metabolizers of CYP2C19

BACKGROUND

Four times daily dosing (qid) with a proton pump inhibitor can cause rapid increase in intragastric pH. We investigated the efficacy of the front-loading with rabeprazole 10 mg qid on a subsequent regimen with rabeprazole 10 mg twice daily (bid) for 7 days in extensive metabolizers (EMs) of CYP2C19.

METHODS

Five EMs received three different 1-week regimens in a crossover manner as follows: (1) rabeprazole 10 mg bid for 7 days; (2) a front-loading regimen of rabeprazole (rabeprazole 10 mg qid on day 0 and bid on days 1 to 7); and (3) rabeprazole 10 mg qid for 7 days. Five intermediate metabolizers (IMs) and four poor metabolizers (PMs) received rabeprazole 10 mg bid regimen only. Twenty-four-hour intragastric pH-monitorings were performed on days 1, 4, and 7. Area under the intragastric pH-time curves (AUCs) from days 1 to 7 was calculated using 24-h median intragastric pHs on days 1, 4, and 7.

RESULTS

Twenty-four-hour intragastric pHs in the front-loading group on days 1, 4, and 7 were 5.1, 4.9, and 5.1, respectively. The median AUC with front-loading in EMs (34.4, pH·day) was significantly higher than that in EMs with rabeprazole 10 mg bid (30.74, p = 0.043). No statistically significant differences in median AUCs were noted among front-loading in EMs, rabeprazole 10 mg qid in EMs (37.2), rabeprazole 10 mg bid in IMs (37.3), and PMs (39.4).

CONCLUSIONS

The one-day front-loading regimen of rabeprazole 10 mg qid provided sufficient acid inhibition for 7 days, even in CYP2C19 EMs.

The frequency of CYP2C19 genetic polymorphisms in Russian patients with peptic ulcers treated with proton pump inhibitors

Introduction

Proton pump inhibitors, which are widely used as acid-inhibitory agents for the treatment of peptic ulcers, are mainly metabolized by 2C19 isoenzyme of cytochrome P450 (CYP2C19). CYP2C19 has genetic polymorphisms, associated with extensive, poor, intermediate or ultra-rapid metabolism of proton pump inhibitors. Genetic polymorphisms of CYP2C19 could be of clinical concern in the treatment of peptic ulcers with proton pump inhibitors.

Aim

To investigate the frequencies of CYP2C19*2, CYP2C19*3, and CYP2C19*17 alleles and genotypes in Russian patients with peptic ulcers.

Methods

We retrospectively reviewed the cases of 971 patients of Caucasian origin with Russian nationality from Moscow region with endoscopically and histologically proven ulcers, 428 males (44%) and 543 females (56%). The mean age was 44.6±11.9 years (range: 15–88 years). DNA was extracted from ethylenediaminetetraacetic acid whole blood samples (10 mL). The polymorphisms CYP2C19 681G.A (CYP2C19*2, rs4244285), CYP2C19 636 G.A (CYP2C19*3, rs4986893) and CYP2C19 -806 C.T (CYP2C19*17, rs12248560) were evaluated using real-time polymerase chain reaction.

Results

Regarding CYP2C19 genotype, 317 patients (32.65%) out of 971 were CYP2C19*1/*1 carriers classified as extensive metabolizers. Three hundred and eighty-six (39.75%) with CYP2C19*1/*17 or CYP2C19*17/*17 genotype were ultra-rapid metabolizers. Two hundred and fifty-one people (25.85%) were intermediate metabolizers with CYP2C19*1/*2, CYP2C19*2/*17, CYP2C19*1/*3, CYP2C19*3/*17 genotypes. Seventeen patients (1.75%) with CYP2C19*2/*2, CYP2C19*3/*3, CYP2C19*2/*3 genotypes were poor metabolizers. The allele frequencies were the following: CYP2C19*2 – 0.140, CYP2C19*3 – 0.006, CYP2C19*17 – 0.274.

Conclusion

There is a high frequency of CYP2C19 genotypes associated with modified response to proton pump inhibitors in Russian patients with peptic ulcers. Genotyping for CYP2C19 polymorphisms is suggested to be a useful tool for personalized dosing of proton pump inhibitors.

High-dose dual therapy is superior to standard first-line or rescue therapy for Helicobacter pylori infection

BACKGROUND & AIMS

The efficacy of treatment of Helicobacter pylori infection has decreased steadily because of increasing resistance to clarithromycin, metronidazole, and levofloxacin. Resistance to amoxicillin is generally low, and high intragastric pH increases the efficacy of amoxicillin, so we investigated whether a combination of a high-dose proton pump inhibitor and amoxicillin (dual therapy) was more effective than standard first-line or rescue therapies in eradicating H pylori.

METHODS

We performed a large-scale multihospital trial to compare the efficacy of a high-dose dual therapy (HDDT) with that of standard therapies in treatment-naive (n = 450) or treatment-experienced (n = 168) patients with H pylori infection. Treatment-naive patients were randomly assigned to groups given HDDT (rabeprazole 20 mg and amoxicillin 750 mg, 4 times/day for 14 days, group A1), sequential therapy for 10 days (group B1), or clarithromycin-containing triple therapy for 7 days (group C1). Treatment-experienced patients were randomly assigned to groups given HDDT for 14 days (group A2), sequential therapy for 10 days (B2), or levofloxacin-containing triple therapy for 7 days (C2). H pylori infection was detected by using the (13)C-urea breath test. We evaluated factors associated with treatment outcomes.

RESULTS

In the intention-to-treat analysis, H pylori was eradicated in 95.3% of patients in group A1 (95% confidence interval [CI], 91.9%-98.8%), 85.3% in B1 (95% CI, 79.6%-91.1%), and 80.7% in group C1 (95% CI, 74.3%-87.1%). Infection was eradicated in 89.3% of patients in group A2 (95% CI, 80.9%-97.6%), 51.8% in group B2 (95% CI, 38.3%-65.3%), and 78.6% (95% CI, 67.5%-89.7%) in group C2. The efficacy of HDDT was significantly higher than that of currently recommended regimens, irrespective of CYP2C19 genotype. Bacterial resistance to drugs was associated with treatment failure. There were no significant differences between groups in adverse events or patient adherence.

CONCLUSIONS

HDDT is superior to standard regimens as empirical first-line or rescue therapy for H pylori infection, with similar safety profiles and tolerability. ClinicalTrials.gov number: NCT01163435.

Efficacy of Levofloxacin Based Triple and High-Dose PPI-Amoxicillin Dual Eradication Therapy for Helicobacter pylori after Failures of First- and Second-Line Therapies

Objectives. The aim of this study was to investigate and compare the eradication rate of Helicobacter pylori as the third-line triple therapy with rabeprazole (RPZ) + amoxicillin (AMPC) + levofloxacin (LVFX) and high-dose RPZ + AMPC. Methods. 51 patients who failed Japanese first-line (proton pump inhibitor (PPI) + AMPC + clarithromycin) and second-line (PPI + AMPC + metronidazole) eradication therapy were randomly assigned at a 1 : 1 ratio to one of the following third-line eradication groups: (1) RAL group: RPZ 10 mg (b.i.d.), AMPC 750 mg (b.i.d.), and LVFX 500 mg (o.d.) for 10 days; (2) RA group: RPZ 10 mg (q.i.d.) and AMPC 500 mg (q.i.d.) for 14 days. Patients who failed to respond to third-line eradication therapy received salvage therapy. Results. The rates of eradication success, based on intention to treat (ITT) analysis, were 45.8% in the RAL group and 40.7% in the RA group. The overall eradication rates were 73.9% in the RAL group and 64.0% in the RA group. There was no significant difference between the two groups. Conclusions. The third-line triple therapy with RPZ, AMPC, and LVFX was as effective as that with high-dose RPZ and AMPC.

Efficacy of tailored Helicobacter pylori eradication treatment based on clarithromycin susceptibility and maintenance of acid secretion

BACKGROUND

Insufficient acid inhibition during Helicobacter pylori eradication treatment and bacterial resistance to antibiotics often causes eradication failure. Four times daily dosing (q.i.d.) of a proton-pump inhibitor (PPI) achieves potent acid inhibition, suggesting its potential usefulness as a regimen for eradicating H. pylori infection. Therefore, a tailored eradication regimen based on antibiotic susceptibility and maintenance of acid inhibition should have a high success rate. We investigated the efficacy of such treatment based on clarithromycin (CAM) susceptibility.

METHODS

Using 153 H. pylori-positive Japanese patients, we investigated the efficacy of tailored eradication strategy: (1) Patients infected with CAM-sensitive H. pylori were treated with a PPI (rabeprazole 10 mg q.i.d.), amoxicillin 500 mg q.i.d., and CAM 200 mg b.i.d. (n = 89), and (2) patients infected with CAM-resistant were given the same doses of rabeprazole and amoxicillin and metronidazole 250 mg b.i.d. (n = 64) for 1 week.

RESULTS

In the tailored regimen group, the overall eradication rate was 96.7% (95% CI: 92.5-98.9%, 148/153) in the intention-to-treat (ITT) analysis and 97.4% (93.4-99.3%, 148/152) in the PP analysis. The eradication rates for the CAM- and metronidazole-based treatments were similar (95.5% and 98.4%, respectively, p = .400). The tailored treatment achieved a high eradication rate in CYP2C19 rapid metabolizers who were a resistance genotype for PPI treatment (94.3% (86.0-98.4%, 66/70)).

DISCUSSION

A tailored H. pylori eradication regimen based on CAM susceptibility and maintaining acid secretion (rabeprazole 10 mg q.i.d.) is useful because it can achieve an eradication rate exceeding 95%, irrespective of eradication history, thus overcoming differences among CYP2C19 genotypes.

High-dose extended-release lansoprazole (dexlansoprazole) and amoxicillin dual therapy for Helicobacter pylori infections

BACKGROUND

Helicobacter pylori infections have become increasingly difficult to treat.

AIM

To examine whether amoxicillin and high-dose dexlansoprazole would reliably achieve an H. pylori eradication rate of ≥90%.

METHODS

An open-label prospective pilot study of H. pylori eradication in treatment-naïve subjects with active H. pylori infection (positive by two tests).

THERAPY

amoxicillin 1 g and dexlansoprazole 120 mg each twice a day at approximately 12-hour intervals for 14 days. Success was accessed by urea breath test. An effective therapy was defined as a per-protocol treatment success of 90% or greater; treatment success of 80% or less was prespecified as an unacceptable result.

RESULTS

After 13 subjects were entered (12 men, one woman; average age of 54 years), the prespecified stopping rule of six treatment failures was achieved (i.e., the 95% confidence interval excluded achieving the required 90% success rate even if the proposed study of 50 completed patients were entered) and enrollment was stopped. Per-protocol and intention-to-treat treatment success were both 53.8%; (7/13); 95% CI = 25-80%. Compliance was 100%. Three patients (23%) reported side effects, all of which were mild and none interrupted therapy.

CONCLUSION

Theoretically, dual PPI plus amoxicillin should reliably eradicate H. pylori provided nearly neutral intragastric pH can be maintained. Clearly, dexlansoprazole, despite being administered at high dose and twice a day (i.e., total daily dose 240 mg), failed to achieve an intragastric milieu consistent with dual PPI plus amoxicillin therapy being an effective anti-H. pylori regimen.

Comparison of acid inhibition with standard dosages of proton pump inhibitors in relation to CYP2C19 genotype in Japanese

INTRODUCTION

The aim of therapeutic regimens using proton pump inhibitors (PPIs) in patients with acid-related diseases is to potently inhibit acid secretion for the full 24 h. However, optimum treatment is still unclear because the pharmacodynamics of PPIs differ among CYP2C19 genotypes and most of the previous studies have had loss of sample power.

METHODS

Using pH monitoring, we compared acid inhibition at standard dosage of omeprazole (20 mg, 50 times), lansoprazole (30 mg, 68 times), and rabeprazole (10 mg, 65 times) in Helicobacter pylori-negative healthy young Japanese volunteers.

RESULTS

Median pH with rabeprazole was 5.4 (3.3-7.5), which was significantly greater than with either omeprazole [4.4 (2.1-7.3)] or lansoprazole [4.8 (3.5-6.4)] (both P < 0.05). Median 24-h pH differed among the different CYP2C19 genotypes in all three PPIs. In CYP2C19 extensive metabolizers (EMs), the genotype that is refractory to PPI treatment, median pH with omeprazole, lansoprazole, and rabeprazole was 3.8 (2.1-4.4), 4.5 (3.5-5.3) and 4.8 (3.3-7.5), respectively.

DISCUSSION

Treatment with the selected PPIs at their standard dosages had difficulty maintaining acid inhibition for a full 24 h, especially in CYP2C19 EM. However, rabeprazole has the merit of less influence of CYP2C19 genotype compared with the other PPIs.

Efficacy of tailored Helicobacter pylori eradication therapy based on antibiotic susceptibility and CYP2C19 genotype

The cure rates of Helicobacter pylori (H. pylori) eradication therapy using a proton pump inhibitor (PPI) and antimicrobial agents such as amoxicillin, clarithromycin, and metronidazole are mainly influenced by bacterial susceptibility to antimicrobial agents and the magnitude of the inhibition of acid secretion. Annual cure rates have gradually decreased because of the increased prevalence of H. pylori strains resistant to antimicrobial agents, especially to clarithromycin. Alternative regimens have therefore been developed incorporating different antimicrobial agents. Further, standard PPI therapy (twice-daily dosing) often fails to induce a long-term increase in intragastric pH > 4.0. Increasing the eradication rate requires more frequent and higher doses of PPIs. Therapeutic efficacy related to acid secretion is influenced by genetic factors such as variants of the genes encoding drug-metabolizing enzymes (e.g., cytochrome P450 2C19, CYP2C19), drug transporters (e.g., multidrug resistance protein-1; ABCB1), and inflammatory cytokines (e.g., interleukin-1β). For example, quadruple daily administration of PPI therapy potently inhibits acid secretion within 24 h, irrespective of CYP2C19 genotype. Therefore, tailored H. pylori eradication regimens that address acid secretion and employ optimal antimicrobial agents based on results of antimicrobial agent-susceptibility testing may prove effective in attaining higher eradication rates.

Treatment of Helicobacter pylori infection: current status and future concepts

Helicobacter pylori (H. pylori) infection is highly associated with the occurrence of gastrointestinal diseases, including gastric inflammation, peptic ulcer, gastric cancer, and gastric mucosa-associated lymphoid-tissue lymphoma. Although alternative therapies, including phytomedicines and probiotics, have been used to improve eradication, current treatment still relies on a combination of antimicrobial agents, such as amoxicillin, clarithromycin, metronidazole, and levofloxacin, and antisecretory agents, such as proton pump inhibitors (PPIs). A standard triple therapy consisting of a PPI and two antibiotics (clarithromycin and amoxicillin/metronidazole) is widely used as the first-line regimen for treatment of infection, but the increased resistance of H. pylori to clarithromycin and metronidazole has significantly reduced the eradication rate using this therapy and bismuth-containing therapy or 10-d sequential therapy has therefore been proposed to replace standard triple therapy. Alternatively, levofloxacin-based triple therapy can be used as rescue therapy for H. pylori infection after failure of first-line therapy. The increase in resistance to antibiotics, including levofloxacin, may limit the applicability of such regimens. However, since resistance of H. pylori to amoxicillin is generally low, an optimized high dose dual therapy consisting of a PPI and amoxicillin can be an effective first-line or rescue therapy. In addition, the concomitant use of alternative medicine has the potential to provide additive or synergistic effects against H. pylori infection, though its efficacy needs to be verified in clinical studies.

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.

Twice-daily dosing of esomeprazole effectively inhibits acid secretion in CYP2C19 rapid metabolisers compared with twice-daily omeprazole, rabeprazole or lansoprazole

BACKGROUND

Twice-daily dosing of proton pump inhibitors (PPIs) is used to treat Helicobacter pylori or acid-related diseases, such as gastro-oesophageal reflux disease (GERD) refractory to standard dose of a PPI. Genetic polymorphisms of CYP2C19 are involved to different extents in the metabolism of four kinds of PPIs (omeprazole, lansoprazole, rabeprazole and esomeprazole) available in Japan.

AIM

To compare acid-inhibitory effects of the four PPIs dosed twice daily in relation to CYP2C19 genotype.

METHODS

We performed 24-h pH monitoring studies on Day 7 of PPI treatment for 40 Japanese H. pylori-negative volunteers [15 CYP2C19 rapid metabolisers (RMs), 15 intermediate metabolisers (IMs) and 10 poor metabolisers (PMs)] using a randomised four-way crossover design: omeprazole 20 mg, esomeprazole 20 mg, lansoprazole 30 mg and rabeprazole 10 mg twice daily.

RESULTS

Although median pH values with esomeprazole, omeprazole, lansoprazole and rabeprazole were 5.7 (3.5-7.2), 5.5 (2.4-7.2), 5.5 (3.7-7.3) and 5.2 (2.5-7.3), respectively (no statistically significant differences), CYP2C19 genotype-dependent differences were smaller for esomeprazole and rabeprazole compared with values for omeprazole and lansoprazole. In CYP2C19 RMs, the median pH with esomeprazole [5.4 (3.5-6.8)] was significantly higher than those with omeprazole [5.0 (2.4-5.9), P = 0.018], lansoprazole [4.7 (3.7-5.5), P = 0.017] or rabeprazole [4.8 (2.5-6.4), P = 0.002]. In IMs and PMs, the median pH was >5.0 independent of the PPI.

CONCLUSIONS

In intermediate and rapid metabolisers of CYP2C19, PPIs dosed twice daily could attain sufficient acid suppression, while in CYP2C19 RMs, esomeprazole 20 mg twice daily caused the strongest inhibition of the four PPIs. Therefore, esomeprazole may be effective in Japanese population when dosed twice daily.

Individualized therapy for gastroesophageal reflux disease: potential impact of pharmacogenetic testing based on CYP2C19

The main therapeutic agent for gastroesophageal reflux disease (GERD) is a proton pump inhibitor (PPI). Plasma levels and the acid inhibitory effect of PPIs depend on the activity of cytochrome P450 (CYP) 2C19, which is polymorphic. Genotypes of CYP2C19 are classified into three groups: rapid metabolizers (RMs: *1/*1), intermediate metabolizers (IMs: *1/*X), and poor metabolizers (PMs: *X/*X), where *1 and X represent the wild type and the mutant allele, respectively. RMs include ultra-rapid metabolizers, who possess the CYP2C19*17 allele. The pharmacokinetics and pharmacodynamics of PPIs differ among different CYP2C19 genotype groups. Plasma PPI levels and intragastric pH values during PPI treatment are lowest in the RM group, intermediate in the IM group, and highest in the PM group. These CYP2C19-genotype-dependent differences in the pharmacokinetics and pharmacodynamics of PPIs influence the healing and recurrence of GERD during PPI treatment, suggesting the need for CYP2C19 genotype-based tailored therapy for GERD. CYP2C19 pharmacogenetics should be taken into consideration for the personalization of PPI-based therapy. However, the clinical usefulness of CYP2C19 genotype testing in GERD therapy should be verified in clinical studies.

Individualized therapy for gastroesophageal reflux disease: potential impact of pharmacogenetic testing based on CYP2C19

The main therapeutic agent for gastroesophageal reflux disease (GERD) is a proton pump inhibitor (PPI). Plasma levels and the acid inhibitory effect of PPIs depend on the activity of cytochrome P450 (CYP) 2C19, which is polymorphic. Genotypes of CYP2C19 are classified into three groups: rapid metabolizers (RMs: *1/*1), intermediate metabolizers (IMs: *1/*X), and poor metabolizers (PMs: *X/*X), where *1 and X represent the wild type and the mutant allele, respectively. RMs include ultra-rapid metabolizers, who possess the CYP2C19*17 allele. The pharmacokinetics and pharmacodynamics of PPIs differ among different CYP2C19 genotype groups. Plasma PPI levels and intragastric pH values during PPI treatment are lowest in the RM group, intermediate in the IM group, and highest in the PM group. These CYP2C19-genotype-dependent differences in the pharmacokinetics and pharmacodynamics of PPIs influence the healing and recurrence of GERD during PPI treatment, suggesting the need for CYP2C19 genotype-based tailored therapy for GERD. CYP2C19 pharmacogenetics should be taken into consideration for the personalization of PPI-based therapy. However, the clinical usefulness of CYP2C19 genotype testing in GERD therapy should be verified in clinical studies.

Rabeprazole 10 mg q.d.s. decreases 24-h intragastric acidity significantly more than rabeprazole 20 mg b.d. or 40 mg o.m., overcoming CYP2C19 genotype

BACKGROUND

Standard dosing (i.e. once daily) of proton pump inhibitors (PPIs) cannot inhibit acid secretion for a full 24 h. Better therapeutic regimens using PPIs are required to sustain potent acid inhibition for the full 24 h in all patients with acid-related diseases.

AIM

To evaluate acid inhibitory effects by different dosing times of a PPI at the same daily dosage, in a study involving 70 rounds of pH monitoring.

METHODS

Using pH monitoring, we evaluated the efficacy of different divided treatment regimens with the same total daily dose of rabeprazole (40 mg o.m., 15 rounds; 20 mg b.d., 20 rounds; 10 mg q.d.s., 35 rounds) on day 7 or 8 of PPI dosing.

RESULTS

In the study of divided treatment, the median pH (when administered once, twice or four times to achieve a daily dose of 40 mg) was 4.8 (3.6-6.4), 5.7 (4.1-7.4), 6.6 (4.9-8.4), respectively. When comparing the median pHs at the same CYP2C19 genotype among different dosing times of rabeprazole, the median pH attained with 10 mg q.d.s. was significantly higher than that in 40 mg o.m. or 20 mg b.d. Increase in the frequency of dosing effectively increased pH [median percent time of pH > 4.0 with q.d.s. therapy: 95.5% (63.2-100.0%)], irrespective to CYP2C19 genotype.

CONCLUSION

Four times daily dosing with rabeprazole 10 mg achieved potent acid inhibition, including during the night-time, suggesting its potential usefulness as a regimen for patients who are refractory to standard once daily PPI treatment.

Clinical Application of Pharmacogenomics

The purpose of this review is to discuss the clinical application of pharmacogenomics for select drug therapies (eg, proton pump inhibitors [PPIs], codeine, and carbamazepine) and to highlight limitations and challenges that preclude implementation of pharmacogenomics into clinical practice. Genetic polymorphisms of cytochrome P450 (CYP) enzymes and the presence of the human leukocyte antigen ( HLA) -B*1502 allele influence drug disposition and/or response. A portion of PPI pharmacokinetic and pharmacodynamic variability can be explained by CYP2C19 genotype. However, conflicting evidence exists related to Helicobacter pylori cure rates based on CYP2C19 genotype. For codeine, adverse drug reactions in neonates through breast-feeding from CYP2D6 ultra-rapid metabolizers have been reported. However, there is lack of conclusive evidence regarding the overall influence of CYP2D6 polymorphisms on codeine efficacy and toxicity. Although CYP2C19 and CYP2D6 genotyping tests are available, clinical utility remains low. The presence of the HLA-B*1502 allele is associated with carbamazepine-induced Stevens-Johnson syndrome (SJS) and/or toxic epidermal necrolysis (TEN). Pharmacogenomic testing is required prior to initiating carbamazepine in high-risk patients. Lack of sufficient resources, provider knowledge, and ethical, legal, and social issues are several limitations and challenges to implementing pharmacogenomic testing in clinical practice.

High-dose rabeprazole-amoxicillin dual therapy and rabeprazole triple therapy with amoxicillin and levofloxacin for 2 weeks as first and second line rescue therapies for Helicobacter pylori treatment failures

BACKGROUND

H. pylori eradication failures are difficult to treat and rescue therapies often consist of complex treatment regimens.

AIM

To determine an effective and practical rescue therapeutic strategy for H. pylori treatment failures using two consecutive regimens: first rescue therapy - rabeprazole 20 mg t.d.s. and amoxicillin 1 g t.d.s. for 2 weeks and for failures a further second rescue therapy - rabeprazole 20 mg b.d., levofloxacin 500 mg b.d., amoxicillin 1 g b.d. for a further 2 weeks.

METHODS

Consecutive patients who failed the proton pump inhibitor (PPI) 1-week triple therapy were recruited for the study. H. pylori status was determined by a C(13) urea breath test.

RESULTS

One hundred and forty-nine patients received the first rescue therapy. Seven were not compliant to medication/defaulted follow-up. Eradication success- first rescue therapy: per protocol (PP) analysis-107/142 (75.4%) (95% CI (68.3-82.4%) and intention to treat (ITT) analysis-107/149 (71.8%) 95% CI (64.6-79.0%). Thirty-one of 35 patients who failed the first rescue therapy received the second rescue therapy. All were compliant with medications. Eradication success- PP and ITT was 28/31 (90.3%) 95% CI (74.2-98.0%). The cumulative eradication rate using both rescue therapies: PP analysis- 135/138 (97.8%) 95% CI: (93.8-99.6%), ITT analysis- 135/149 (90.6%) 95% CI: (84.7-94.8%).

CONCLUSIONS

A 2-week high dose PPI-amoxicillin dual therapy followed by a PPI-amoxicillin-levofloxacin triple therapy were highly successful in achieving eradication in H. pylori treatment failures.

Effectiveness of three times daily lansoprazole/amoxicillin dual therapy for Helicobacter pylori infection in Korea

AIM

We compared three times daily dual therapy with standard triple therapy for effectiveness and safety in H. pylori infection.

METHODS

Two hundred and four H. pylori positive patients with peptic ulcer were randomly assigned to one of two regimens: (i) triple therapy with amoxicillin, clarithromycin and lansoprazole twice daily for 2 weeks or (ii) dual therapy with amoxicillin and lansoprazole three times daily for 2 weeks. The success of eradication was evaluated 4 to 5 weeks after completing treatment.

RESULTS

The eradication rate was 82.8% in the triple therapy group and 78.4% in the dual therapy group by per protocol analysis. This difference was not significant (P= 0.573). Adverse events were more frequent in the triple therapy group than in the dual therapy group (P= 0.002).

CONCLUSIONS

Because dual therapy had fewer side effects than triple therapy and a similar eradication rate, dual therapy may provide an acceptable alternative first line therapy for H. pylori eradication in Korea.

Effectiveness of three times daily lansoprazole/amoxicillin dual therapy for Helicobacter pylori infection in Korea

AIM

We compared three times daily dual therapy with standard triple therapy for effectiveness and safety in H. pylori infection.

METHODS

Two hundred and four H. pylori positive patients with peptic ulcer were randomly assigned to one of two regimens: (i) triple therapy with amoxicillin, clarithromycin and lansoprazole twice daily for 2 weeks or (ii) dual therapy with amoxicillin and lansoprazole three times daily for 2 weeks. The success of eradication was evaluated 4 to 5 weeks after completing treatment.

RESULTS

The eradication rate was 82.8% in the triple therapy group and 78.4% in the dual therapy group by per protocol analysis. This difference was not significant (P= 0.573). Adverse events were more frequent in the triple therapy group than in the dual therapy group (P= 0.002).

CONCLUSIONS

Because dual therapy had fewer side effects than triple therapy and a similar eradication rate, dual therapy may provide an acceptable alternative first line therapy for H. pylori eradication in Korea.

Proton Pump Inhibitor Therapy before and after Endoscopic Submucosal Dissection: A Review

Endoscopic submucosal dissection (ESD) is a novel endoscopic procedure first developed in the 1990s which enables en bloc resection of gastric neoplastic lesions that are difficult to resect via conventional endoscopic mucosal resection. However, given that ESD increases the risk of intra- and post-ESD delayed bleeding and that platelet aggregation and coagulation in artificial ulcers after ESD strongly depend on intragastric pH, faster and stronger acid inhibition via proton pump inhibitors (PPIs) and histamine 2-receptor antagonists (H(2)RAs) as well as endoscopic hemostasis by thermocoagulation during ESD have been used to prevent ESD-related bleeding. Because PPIs more potently inhibit acid secretion than H(2)RAs, they are often the first-line drugs employed in ESD treatment. However, acid inhibition after the initial infusion of a PPI is weaker in the early phase than that achievable with H(2)RAs; further, PPI effectiveness can vary depending on genetic differences in CYP2C19. Therefore, optimal acid inhibition may require tailored treatment based on CYP2C19 genotype when ESD is performed, with a concomitant infusion of PPI and H(2)RA possibly most effective for patients with the rapid metabolizer CYP2C19 genotype, while PPI alone may be sufficient for those with the intermediate or poor metabolizer genotypes.

[Helicobacter pylori eradication therapy in Korea]

Helicobacter pylori (H. pylori) is known to be associated with many gastrointestinal diseases including peptic ulcer. In Korea, eradication of H. pylori is recommended for peptic ulcer disease, low grade gastric mucosa-associated lymphoid tissue lymphoma, and early gastric cancer. Standard triple therapy using proton pump inhibitor, clarithromycin, and amoxicillin and bismuth-containing quadruple therapy have been the main first-line and second-line therapy for H. pylori in Korea. Although eradication rate of second-line quadruple therapy remains similar to that of the past, the success rate of eradication with triple therapy has decreased with increasing antimicrobial resistance to H. pylori. There is no standard third-line therapy, and some regimens that incorporate levofloxacin, moxifloxacin, and rifabutin can be used. New regimens such as sequential or concomitant therapy are suggested as alternative treatment for H. pylori. We need more well designed randomized controlled studies to choose proper treatment for H. pylori infection.

Update on the pharmacogenomics of proton pump inhibitors

Proton pump inhibitors (PPIs) are widely used for the treatment of gastroesophageal reflux disease as well as other acid-related disorders. PPIs are metabolized primarily via the CYP2C19 and CYP3A4 isoenzymes; their activity is influenced both by exogenous and endogenous (pharmacogenetic) factors. The CYP2C19 polymorphism affects the metabolism of PPIs, causing large individual pharmacokinetic variations. Differences in the CYP2C19-mediated metabolism can produce marked interpatient variability in acid suppression, in drug-interaction potential and in clinical efficacy. Understanding the pharmacokinetic properties of PPIs and examining the pharmacogenetic alterations may help clinicians optimize PPI therapy and administer individual treatment, especially to nonresponder patients with gastroesophageal reflux disease or ulcer or after failed eradication therapy.

Role of cytochrome P450 genotype in the steps toward personalized drug therapy

Genetic polymorphism for cytochrome 450 (P450) enzymes leads to interindividual variability in the plasma concentrations of many drugs. In some cases, P450 genotype results in decreased enzyme activity and an increased risk for adverse drug effects. For example, individuals with the CYP2D6 loss-of-function genotype are at increased risk for ventricular arrhythmia if treated with usual does of thioridazine. In other cases, P450 genotype may influence the dose of a drug required to achieve a desired effect. This is the case with warfarin, with lower doses often necessary in carriers of a variant CYP2C9*2 or *3 allele to avoid supratherapeutic anticoagulation. When a prodrug, such as clopidogrel or codeine, must undergo hepatic biotransformation to its active form, a loss-of-function P450 genotype leads to reduced concentrations of the active drug and decreased drug efficacy. In contrast, patients with multiple CYP2D6 gene copies are at risk for opioid-related toxicity if treated with usual doses of codeine-containing analgesics. At least 25 drugs contain information in their US Food and Drug Administration-approved labeling regarding P450 genotype. The CYP2C9, CYP2C19, and CYP2D6 genes are the P450 genes most often cited. To date, integration of P450 genetic information into clinical decision making is limited. However, some institutions are beginning to embrace routine P450 genotyping to assist in the treatment of their patients. Genotyping for P450 variants may carry less risk for discrimination compared with genotyping for disease-associated variants. As such, P450 genotyping is likely to lead the way in the clinical implementation of pharmacogenomics. This review discusses variability in the CYP2C9, CYP2C19, and CYP2D6 genes and the implications of this for drug efficacy and safety.

Role of omeprazole dosage and cytochrome P450 2C19 genotype in patients receiving omeprazole-amoxicillin dual therapy for Helicobacter pylori eradication

STUDY OBJECTIVE

To determine the factors that may influence Helicobacter pylori eradication in patients receiving omeprazole-amoxicillin dual therapy.

DESIGN

Prospective, randomized study.

SETTING

University-affiliated hospital in Taiwan.

PATIENTS

A total of 128 adults (age range 20-75 yrs) with H. pylori-positive duodenal ulcer were enrolled; 121 completed the final evaluation.

INTERVENTION

Patients were randomly assigned to one of four omeprazole-amoxicillin treatment groups, with each treatment administered for 2 weeks: O2A2 group (33 patients)--omeprazole 20 mg twice/day plus amoxicillin 500 mg 4 times/day; O2A1 group (32 patients)--omeprazole 20 mg twice/day plus amoxicillin 250 mg 4 times/day; O1A2 group (32 patients)--omeprazole 20 mg once/day plus amoxicillin 500 mg 4 times/day; and O1A1 group (31 patients)--omeprazole 20 mg once/day plus amoxicillin 250 mg 4 times/day.

MEASUREMENTS AND MAIN RESULTS

Data were collected on H. pylori status, histologic parameters, antibiotic resistance, intragastric pH, cytochrome P450 (CYP) 2C19 genotype, and adverse reactions. The intent-to-treat cure rates (95% confidence interval [CI]) in groups O2A2, O2A1, O1A2, and O1A1 were 76% (95% CI 59-87%), 72% (95% CI 54-84%), 50% (95% CI 34-66%) and 52% (95% CI 35-68%), respectively. Eradication of H. pylori infection was statistically significantly dependent on omeprazole dosage, CYP2C19 genotype, age, gastritis status, and H. pylori density. All CYP2C19 poor metabolizers were cured, whereas the H. pylori cure rate in CYP2C19 extensive metabolizers varied from 44-76% in the different treatment groups. Eradication of H. pylori was favored in the omeprazole higher dose groups versus the lower dose groups (79% vs 53%, p=0.004). No secondary antibiotic resistance was found. Thirty-seven (95%) of 39 patients who failed with the initial treatment were cured by subsequent antibiotic susceptibility-driven proton pump inhibitor-based triple therapy.

CONCLUSION

Provided a maintenance dose of amoxicillin is given every 6 hours, eradication of H. pylori infection was significantly dependent on omeprazole dosage, CYP2C19 genotype, age, gastritis status, and H. pylori density.

Triple therapy with ecabet sodium, amoxicillin and lansoprazole for 2 weeks as the rescue regimen for H. pylori infection

BACKGROUND/AIM

Ecabet sodium has an anti-H. pylori effect. We assessed the efficacy of ecabet sodium in the rescue therapy for the eradication of H. pylori.

METHODS

A total of 74 patients with failed eradication of H. pylori after triple therapy with lansoprazole 30 mg bid, amoxicillin 750 mg bid and clarithromycin 200 mg bid were enrolled. They were randomly assigned to the three treatment groups as follows: LAC, lansoprazole 30 mg + amoxicillin 750 mg + clarithromycin 200 mg bid for 1 week; LAC2E, lansoprazole 30 mg bid + amoxicillin 750 mg bid + clarithromycin 200 mg bid + ecabet sodium 2 g bid for 1 week; and LA2E, lansoprazole 30 mg bid + amoxicillin 750 mg bid + ecabet sodium 2 g bid for 2 weeks. Eradication of H. pylori was assessed by the 13C-urea breath test after treatment.

RESULTS

Eradication rates in intention-to-treat and per-protocol analyses were 20.0% (95% CI: 6.8-40.7) and 20.0% (6.8-40.7) with LAC, respectively, and 16.0% (4.5-36.1) and 17.4% (5.0-38.8) with LAC2E. In contrast, respective rates with LA2E were 75% (53.3-90.2) and 85.7% (63.7-97.0), which were significantly higher than those with LAC (p<0.001 for both ITT and PP) and LAC2E (p<0.001 for both ITT and PP).

CONCLUSION

Triple therapy with ecabet sodium, lansoprazole and amoxicillin for 2 weeks was effective as the rescue therapy after failure of the standard clarithromycin-based regimen.

Pharmacologic aspects of eradication therapy for Helicobacter pylori Infection

The commonly used regimens for the eradication of Helicobacter pylori infection consist of administration of proton pump inhibitors (PPIs) and 1 to 3 antimicrobial agents, such as amoxicillin, clarithromycin, metronidazole, fluoroquinolone, or tetracycline. Each agent has its own pharmacologic characteristics. PPIs are metabolized by cytochrome P450 2C19 (CYP2C19), which is polymorphic. CYP2C19 genotypic differences in the pharmacokinetics and pharmacodynamics of PPIs influence the eradication rates of H pylori infection by PPI-containing regimens. Amoxicillin is a time-dependent antibiotic, whereas clarithromycin, metronidazole, tetracycline, and fluoroquinolone are not. The plasma half-life of antimicrobial agents also differs among these antibiotics. To achieve consistently high eradication rates, the eradication regimens must be designed based on a good understanding of the resistance patterns of the bacteria and the pharmacologic characteristics of the agents used for H pylori eradication therapy.

Dual proton pump inhibitor plus amoxicillin as an empiric anti-H. pylori therapy: studies from the United States

BACKGROUND

Studies with CYP2C19 slow metabolizers have shown that the combination of a proton pump inhibitor (PPI) plus amoxicillin (dual therapy) can reliably cure more than 90% of Helicobacter pylori infections. Theoretically, the use of a PPI dose that provides equivalent acid suppression with fast metabolizers and slow metabolizers would achieve high cure rates irrespective of the CYP2C19 genotype.

AIM

To evaluate high-dose PPI plus amoxicillin dual therapy for H. pylori eradication.

METHODS

H. pylori-infected individuals (positive by 2 tests) received esomeprazole 40 mg plus amoxicillin 750 mg every 8 h for 14 days. The protocol was planned based on the "efficient identification strategy" requiring more than 90% success, with stop criteria of 6 or more failures within 50 patients or a cure rate of less than 80%.

RESULTS

Thirty-six patients (5 women, 31 men), average age 58 years, were enrolled before achieving stop criteria. All were first H. pylori treatments. The intention-to-treat cure was achieved in 26/36 [72.2%; 95% confidence interval (CI) = 56-84%] and in 26/35 per protocol (74.2%; 95% CI = 56-87%). There were no significant side effects. Compliance was 85% or greater in all (100% in 91.6%).

CONCLUSIONS

If the hypothesis that consistently high intragastric pH is required to reliably achieve more than 90% H. pylori eradication, our regimen was not sufficient. Success may require more than every 8 h dosing, the concomitant administration of sodium bicarbonate, or the use of a long-acting PPI. However, the result was positive in that dual therapy with the doses tested here was at least as successful as empiric triple therapy.

Changes in 12-Year First-Line Eradication Rate of Helicobacter pylori Based on Triple Therapy with Proton Pump Inhibitor, Amoxicillin and Clarithromycin

A triple therapy based on a proton pump inhibitor (PPI), amoxicillin (AMPC), and clarithromycin (CAM) is recommended as a first-line therapy for Helicobacter pylori (H. pylori) eradication and is widely used in Japan. However, a decline in eradication rate associated with an increase in prevalence of CAM resistance is viewed as a problem. We investigated CAM resistance and eradication rates over time retrospectively in 750 patients who had undergone the triple therapy as first-line eradication therapy at Nagoya City University Hospital from 1995 to 2008, divided into four terms (Term 1: 1997-2000, Term 2: 2001-2003, Term 3: 2004-2006, Term 4: 2007-2008). Primary resistance to CAM rose significantly over time from 8.7% to 23.5%, 26.7% and 34.5% while the eradication rate decreased significantly from 90.6% to 80.2%, 76.0% and 74.8%. Based on the PPI type, significant declines in eradication rates were observed with omeprazole or lansoprazole, but not with rabeprazole. A decrease in the H. pylori eradication rate after triple therapy using a PPI + AMPC + CAM has been acknowledged, and an increase in CAM resistance is considered to be a factor. From now on, a first-line eradication regimen that results in a higher eradication rate ought to be investigated.

CYP2C19 genotypes in the pharmacokinetics/pharmacodynamics of proton pump inhibitor-based therapy of Helicobacter pylori infection

IMPORTANCE OF THE FIELD

Proton pump inhibitors (PPIs) are potent gastric acid inhibitors. Therapies with a PPI and antibiotics are used to cure Helicobacter pylori (H. pylori) infection, which is closely related to many gastrointestinal diseases. Most PPIs are mainly metabolized by cytochrome 2C19 (CYP2C19). The genetic polymorphisms of CYP2C19 may lead to the differences in pharmacokinetics (PK), pharmacodynamics (PD) and clinical efficacy of PPIs.

AREAS COVERED IN THIS REVIEW

The roles of PPIs on the eradication of H. pylori are summarized. The impact f CYP2C19 polymorphism on the PK and PD of PPIs is addressed and related to the present status of therapy for H. pylori infection. The opinions on the strategy of PPIs-based therapies of H. pylori infection are provided.

WHAT THE READER WILL GAIN

Update the factors that may influence the PPIs-based therapies of H. pylori infection.

TAKE HOME MESSAGE

The eradication rates of H. pylori infection are significantly different between patients who are CYP2C19 extensive metabolizers and poor metabolizers, partly because of the differences in the PK and PD of PPIs. Nonetheless, the differences can be improved by adjusting the regimens of PPIs and using antibiotics that have less H. pylori-resistance.

Gastric infection by Helicobacter pylori

Helicobacter pylori infection causes chronic active gastritis, ulcer disease, and gastric cancer. Current eradication regimens use a proton pump inhibitor (PPI) and two antibiotics. Triple therapy now has a success rate less than 80%, below the cutoff for efficacious eradication. Antibiotic resistance, inconsistent acid control by PPIs, and poor patient compliance contribute to the failure rate. H. pylori is a neutralophile that has developed special acid acclimation mechanisms to colonize its acidic gastric niche. Identifying the components of these mechanisms will provide novel bactericidal drug targets. Alternatively, better 24-hour acid control would increase the efficacy of antibiotics, leading to dual therapy with improved PPIs and amoxicillin. Studies of acid acclimation by H. pylori have identified several potential eradication targets including UreI, alpha-carbonic anhydrase, and a two-component system. Continuing improvement of PPIs has led to the development of at least three candidate drugs with improved 24-hour acid control.

Polymorphism of human cytochrome P450 enzymes and its clinical impact

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

Efficacy of a single 24-hour pre-anesthetic dose of proton pump inhibitors

BACKGROUND AND AIM

The H(2) receptor antagonist roxatidine is routinely used as an oral pre-anesthetic medication in surgical patients at night and 2 h before surgery. In the present study, we have compared the effects of roxatidine, rabeprazole and lansoprazole given singly at night as an alternative to the standard double roxatidine medication.

METHODS

120 adult patients undergoing urological surgery were randomly assigned to three groups: roxatidine, rabeprazole and lansoprazole (n = 40 each). Following induction of anesthesia, gastric fluid was obtained by aspiration using a syringe to measure pH and volume of gastric contents.

RESULTS

Gastric volume (14.1 +/- 1.9 mL) in the lansoprazole group was significantly larger than that in roxatidine (8.6 +/- 1.7 mL) and rabeprazole (7.5 +/- 1.1 mL) groups (P < 0.05). Gastric pH in lansoprazole group (4.10 +/- 0.38) was also significantly lower than that in the roxatidine group (5.41 +/- 0.31, P < 0.05). The numbers of patients with critical factors for acid aspiration pneumonia (gastric pH < 2.5 or volume > 25 mL) in the lansoprazole group was significantly higher than in the roxatidine group (P < 0.05). Gastric pH and volume in all groups were constant even in the afternoon.

CONCLUSION

Single rabeprazole (but not lansoperazole) medication may be a suitable alternative to standard roxatidine for prophylaxis of acid aspiration pneumonia.

Effects of CYP2C19 and MDR1 genotype on the eradication rate of Helicobacter pylori infection by triple therapy with pantoprazole, amoxycillin and clarithromycin

BACKGROUND

CYP2C19 polymorphism plays an important role in the metabolism of proton pump inhibitors. The multidrug resistance (MDR)1 genotype is associated with the successful eradication of Helicobacter pylori. The aim of the present study was to investigate the effects of CYP2C19 and MDR1 genotypes on the eradication rate of H. pylori using a pantoprazole-based triple therapy.

METHODS

A total of 210 patients infected with H. pylori were treated with 40 mg pantoprazole, 500 mg clarithromycin and 1000 mg amoxicillin twice daily for 7 days. The CYP2C19 genotype was determined with polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis. The MDR1 C3435T polymorphism was identified by PCR-based allele-specific amplification (PCR-ASA).

RESULTS

Of the 210 patients who completed the study, 174 (82.9%, 95.0% confidence interval [CI], 77.8-88.0%) achieved successful eradication after the first cycle of therapy. The eradication rates for H. pylori were 86.7%, 81.1% and 82.1% in the homozygous extensive, heterozygous extensive and poor metabolizer groups, respectively (P = 0.65). Moreover, the cure rates in the CC, CT, and TT groups were 82.7%, 84.4% and 76.9%, respectively (P = 0.66). Multiple logistic regression analysis revealed that endoscopic diagnosis was a significant independent risk factor for treatment failure.

CONCLUSION

The eradication rates of H. pylori by pantoprazole, amoxicillin and clarithromycin were not significantly different among the CYP2C19 and MDR1 genotypes. Hence, the cure rate of H. pylori in the Korean population was no different for the CYP2C19 and MDR1 genotypes.

Therapy for Helicobacter pylori infection can be improved: sequential therapy and beyond

As with other bacterial infections, successful treatment of Helicobacter pylori infections depends on the use of antibacterial agents to which the organism is susceptible. In this article, we use the proposed report card grading scheme (i.e. grade A, B, C, D, F) for the outcome of clinical trials, where intention-to-treat cure rates >95% = A, 90-95% = B, 85-89% = C, 81-84% = D and <81% = F. The goal of therapy is to consistently cure >95% of patients (e.g. provide grade A results). Like tuberculosis, H. pylori infections are difficult to cure and successful treatment generally requires the administration of several antibacterial agents simultaneously. Duration of therapy is also important and depends upon whether resistance is present; 14 days is often best. With few exceptions, worldwide increasing macrolide resistance now undermines the effectiveness of the legacy triple therapy (e.g. a proton pump inhibitor [PPI], clarithromycin and amoxicillin) and, in most areas, cure rates have declined to unacceptable levels (e.g. grade F). The development of sequential therapy was one response to this problem. Sequential therapy has repeatedly been shown in head-to-head studies to be superior to legacy triple therapy. Sequential therapy, as originally described, is the sequential administration of a dual therapy (a PPI plus amoxicillin) followed by a Bazzoli-type triple therapy (a PPI plus clarithromycin and tinidazole) and has been shown to be especially useful where there is clarithromycin resistance. However, the cure rates of the original sequential treatment are grade B and can probably be further improved by changes in dose, duration or administration, such as by continuing the amoxicillin into the triple therapy arm. The sequential approach may also be more complicated than necessary, based on the fact that the same four drugs have also been given concomitantly (at least nine publications with >700 patients) as a quadruple therapy with excellent success. This article discusses the approach to therapy in the modern era where antimicrobial resistance is an increasing problem and legacy triple therapy is no longer an acceptable initial choice. Methods to achieve acceptable eradication rates (e.g. grade A or B results) are discussed and, specifically, sequential therapy is considered both conceptually and practically. Suggestions are provided regarding how sequential therapy might be improved to become a grade A therapy as well as how to identify situations where it can be expected to yield unacceptable results. New uses for current drugs are discussed and suggestions for subsequent randomized comparisons to overcome phenotypic and genotypic resistance are given. We propose a change in focus from comparative studies (designed to prove that a new therapy is superior to a known inferior therapy) to demanding that efficacious therapies meet or exceed a pre-specified level of success (i.e. grade A or B result). To do so, coupled with less concern about the effect of recommendations on the pharmaceutical industry, should provide clinicians with much higher quality information, and improve the quality of medical care and recommendations regarding treatment. Ultimately, there is little or no justification for comparative testing that includes an arm with known unacceptably low results. H. pylori gastritis is an infectious disease and should be approached and treated as such.

PhRMA white paper on ADME pharmacogenomics

Pharmacogenomic (PGx) research on the absorption, distribution, metabolism, and excretion (ADME) properties of drugs has begun to have impact for both drug development and utilization. To provide a cross-industry perspective on the utility of ADME PGx, the Pharmaceutical Research and Manufacturers of America (PhRMA) conducted a survey of major pharmaceutical companies on their PGx practices and applications during 2003-2005. This white paper summarizes and interprets the results of the survey, highlights the contributions and applications of PGx by industrial scientists as reflected by original research publications, and discusses changes in drug labels that improve drug utilization by inclusion of PGx information. In addition, the paper includes a brief review on the clinically relevant genetic variants of drug-metabolizing enzymes and transporters most relevant to the pharmaceutical industry.