A randomized open trial for comparison of proton pump inhibitors, omeprazole versus rabeprazole, in dual therapy for Helicobacter pylori infection in relation to CYP2C19 genetic polymorphism

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 CYP2C19 genetic variants and smoking on dual antiplatelet efficacy in patients with coronary artery disease

Introduction

This study aimed to investigate the effects of smoking and CYP2C19 gene polymorphism on antiplatelet therapy to specify the most optimized and accurate antiplatelet therapy for different populations.

Methods

This study included 6,353 patients with coronary artery disease (CAD). In total, 2,256 (35.5%) were smokers and 4,097 (64.5%) were non-smokers. Patients carrying a CYP2C19*2 or *3 allele were considered loss-of-function (LOF) allele carriers. The medical history of patients who had undergone percutaneous coronary intervention (PCI) at Beijing Anzhen Hospital was recorded. The primary endpoint was major adverse cardiovascular or cerebrovascular events (MACCE) during the 6-month follow-up period. A Cox regression model was used to assess the interactions between antiplatelet efficacy and CYP2C19 LOF allele carrier status, stratified by smoking status.

Results

Compared to clopidogrel plus aspirin, ticagrelor plus aspirin reduced the MACCE recurrence risk in non-smokers (carrier: 6.0 vs. 2.0%, hazard ratio 0.298, 95% confidence interval 0.204-0.635, P < 0.0001; non-carrier: 5.8 vs. 2.1%, hazard ratio 0.358, 95% confidence interval 0.189-0.678, P = 0.002), and not in smokers. Similar results were discovered regarding the recurrence rate for hospitalization for ischemic cardiac events in non-smokers. No apparent difference was discovered in the bleeding events in either group. There were no significant associations between antiplatelet medication and CYP2C19 LOF allele carrier status for the MACCE recurrence risk among smokers (P = 0.943, respectively) or non-smokers (P = 0.774, respectively).

Conclusion

In patients with CAD after PCI, ticagrelor plus aspirin lowered the MACCE recurrence risk in CYP2C19 LOF allele carriers and non-carriers compared with clopidogrel plus aspirin alone among non-smokers. The efficacy of antiplatelet therapy varies between CYP2C19 LOF allele carrier status. No significant interaction between CYP2C19 LOF allele carrier status and antiplatelet effectiveness was observed. However, caution should be used to interpret our results considering the many limitations of our investigation.

Vonoprazan and high-dose amoxicillin dual therapy for Helicobacter pylori first-line eradication: A single-arm, interventional study

Background

To date, no interventional trial has assessed the efficacy and safety of vonoprazan and high-dose (500 mg four times daily, 2000 mg/day) amoxicillin dual therapy in terms of Helicobacter pylori eradication. We explored whether this was an appropriate first-line treatment.

Methods

This prospective, dual-center, single-arm interventional study was performed in Japan. Twenty H. pylori-positive patients lacking any eradication history were treated with vonoprazan 20 mg twice daily and amoxicillin 500 mg four times daily (qid) for 7 days. Eradication was evaluated using a stool H. pylori antigen test. We evaluated safety using patient questionnaires. This study was registered in the jRCT database (jRCT031200128).

Results

The intention-to-treat and per-protocol eradication rates were 90% (95% confidence interval [CI] 68.3-98.8%, n = 20) and 94.4% (95% CI 72.7-99.9%, n = 18) respectively. No significant adverse event was recorded.

Conclusion

Vonoprazan/high-dose amoxicillin dual therapy can be a safe standard first-line therapy. We are now undergoing a randomized controlled trial comparing dual therapy and vonoprazan-based triple therapy.

Impact of smoking on the eradication of Helicobacter pylori

BACKGROUND AND AIM

Although the association between the eradication of Helicobacter pylori (H. pylori) and smoking has been confirmed through a meta-analysis, many new studies have reported inconsistent conclusions. An up-to-date meta-analysis based on published relevant studies was conducted in this study to address this issue.

METHODS

Eligible studies up to January 2021 were screened and retrieved using PubMed and Web of Science as well as by performing a manual review of references. We calculated the pooled odd ratios (OR) with the 95% confidence interval (CI). Subgroup and sensitivity analyses were also performed. Begg's test was used to determine the publication bias.

RESULTS

In total, 39 studies were included in the meta-analysis. The results showed that smoking increases the failure rate of H. pylori eradication treatment (OR = 1.70, 95%CI, 1.49-1.93). The risk of failure also increases with an increase in the smoking dose (>5 cigarettes per day) (OR = 2.59, 95%CI, 1.28-5.24) and the current smoking status (continued to smoke during treatment) (OR = 2.49, 95%CI, 1.52-4.06). Studies with a large proportion of patients with peptic ulcer (OR = 2.14, 95%CI, 1.51-3.02) revealed a higher failure rate among smokers than those with a low proportion of patients with peptic ulcer (OR = 1.57, 95%CI, 1.36-1.81). When vonoprazan (VPZ) was used to treat H. pylori infection, smoking did not affect the eradication rate (OR = 0.94, 95%CI, 0.51-1.75).

CONCLUSION

Smoking increases the failure rate of H. pylori eradication treatment. The risk of H. pylori eradication failure in smokers increases with a current smoking status and a high smoking dose. However, when VPZ is used to treat the H. pylori infection, smoking has no effect on the eradication rate.

Zinc carnosine-based modified bismuth quadruple therapy vs standard triple therapy for Helicobacter pylori eradication: A randomized controlled study

BACKGROUND

Helicobacter pylori (H. pylori) infection is a worldwide problem with increasing burden on the health sector due to its increasing rate of resistance. The conventional triple therapy (TT) is becoming obsolete with a high failure rate of eradication, necessitating the need for better alternatives or regimens.

AIM

To investigate H. pylori eradication rate of TT vs modified bismuth quadruple therapy.

METHODS

Ninety-two patients with dyspepsia symptoms and positive ¹³C-urea breath test were randomly assigned to two groups. The first group (control group) was treated for 14 d using standard TT protocol: Esomeprazole (40 mg twice daily), amoxicillin (1 g twice daily) and clarithromycin (500 mg twice daily). On the other hand, the second group was prescribed a 10-d course of modified bismuth quadruple therapy fortified with zinc carnosine: TT in addition to bismuth subcitrate (240 mg twice daily) and zinc carnosine (75 mg twice daily). A repeated ¹³C-urea breath test was done 4 wk after the completion of the eradication therapy.

RESULTS

Among the 92 subjects, 67.4% were males and 32.6% were females. There were no differences in demographic characteristics (age, body mass index, smoking history, previous antibiotics use and ethnicity) between the modified bismuth quadruple therapy group and TT group. The eradication rate was higher [93.5% (43/46)] in the modified bismuth quadruple therapy group compared to 69.6% (32/46) in the standard TT group (P = 0.003). Of the tested predictor variables, only nationality, smoking and therapy type were statistically significant. Besides dizziness, which was recorded in modified bismuth quadruple therapy group, there were no significant differences in side effects between the two groups.

CONCLUSION

Ten days of modified bismuth quadruple therapy fortified with zinc carnosine is superior to 14 d of conventional TT in eradicating H. pylori infection, with no additional significant adverse events.

CYP2C19 Polymorphisms in Indonesia: Comparison among Ethnicities and the Association with Clinical Outcomes

Simple Summary

CYP2C19 is known as an enzyme primarily responsible for metabolizing various drugs, such as proton pump inhibitor, antiplatelet, anti-epileptic, and anticoagulant. CYP2C19 is known to be polymorphic and can result in the clinical efficacy of drugs. To examine the prevalence and the distribution of the CYP2C19 genetic polymorphisms in Indonesia, we performed polymerase chain reaction-restriction fragment length polymorphism to the genomic DNA of Indonesian participants. In addition, we also analyzed the distribution of CYP2C19 polymorphisms among ethnicities and clinical outcomes. We found that the prevalence of intermediate metabolizers were the highest in Indonesia, followed by rapid metabolizers and poor metabolizers, respectively. The distribution of metabolizer groups were different between ethnic groups in Indonesia. Therefore, dosage adjustment should be considered when administering drugs-affected by CYP2C19 in Indonesia. The results presented in this study showed the distribution of CYP2C19 variant alleles at the population level in Indonesia and might be used as a consideration for providing personalized treatment in clinical practice.

Abstract

CYP2C19 polymorphisms are important factors for proton pump inhibitor-based therapy. We examined the CYP2C19 genotypes and analyzed the distribution among ethnicities and clinical outcomes in Indonesia. We employed the polymerase chain reaction-restriction fragment length polymorphism method to determine the CYP2C19 genotypes and evaluated inflammation severity with the updated Sydney system. For CYP2C19*2, 46.4% were the homozygous wild-type allele, 14.5% were the homozygous mutated allele, and 39.2% were the heterozygous allele. For CYP2C19*3, 88.6% were the homozygous wild-type allele, 2.4% were the homozygous mutated allele, and 9.0% were the heterozygous allele. Overall, the prevalence of rapid, intermediate, and poor metabolizers in Indonesia was 38.5, 41.6, and 19.9%, respectively. In the poor metabolizer group, the frequency of allele *2 (78.8%) was higher than the frequency of allele *3 (21.2%). The Papuan had a significantly higher likelihood of possessing poor metabolizers than the Balinese (OR 11.0; P = 0.002). The prevalence of poor metabolizers was lower compared with the rapid and intermediate metabolizers among patients with gastritis and gastroesophageal reflux disease. Intermediate metabolizers had the highest prevalence, followed by rapid metabolizers and poor metabolizers. Dosage adjustment should therefore be considered when administering proton pump inhibitor-based therapy in Indonesia.

Modified sequential therapy vs quadruple therapy as initial therapy in patients with Helicobacter infection

AIM: To evaluate the efficacy and safety of modified sequential therapy and to compare modified sequential therapy with standard quadruple therapy for Helicobacter pylori (H. pylori) eradication.

METHODS: In total, 200 consecutive patients who were diagnosed with H. pylori-infected chronic gastritis by electronic endoscopy and rapid urease testing from December 2012 to October 2013 were enrolled in this study. The patients had not previously received H. pylori eradication treatment, and were randomized into two groups. The patients in Group A (n = 101) were treated with ilaprazole + bismuth potassium citrate + amoxicillin and clavulanate potassium + levofloxacin, and the patients in Group B (n = 99) were administered a modified sequential therapy composed of ilaprazole at 5 mg bid and amoxicillin and clavulanate potassium at 914 mg for the first five days followed by ilaprazole at 5 mg bid, furazolidone at 100 mg bid and levofloxacin at 500 mg qid for the next five days. Four to six weeks after the end of treatment, a 14C-urea breath test was performed for all the subjects to confirm the eradication of H. pylori. The intention-to-treat and per-protocol eradication rates were determined.

RESULTS: A total of 190 of the 200 patients completed the study. All 200 patients were included in the intention-to-treat analysis, whereas 190 patients were included in the per-protocol analysis. In the intention-to-treat analysis, the rates of H. pylori eradication in Groups A and B were 85.15% (86/101) and 81.82% (81/99), respectively. In the per-protocol analysis, the H. pylori eradication rates in Groups A and B were 88.66% (86/97) and 87.09% (81/93), respectively. No significant difference was observed (χ² = 0.109, P = 0.741) in the eradication rate between Groups A and B. The rates of adverse effects observed in the groups were similar at 6.19% (6/97) for Group A and 7.53% (7/93) for Group B (P > 0.05). No mortality or major morbidities were observed in any of the patients. Symptomatic improvements in the presentation of stomachache, acid regurgitation, and burning sensation were not significantly different between the two groups.

CONCLUSION: Ilaprazole-based 10-d standard quadruple therapy does not offer an incremental benefit over modified sequential therapy for the treatment of H. pylori infection, as both treatment regimens appear to be effective, safe, and well-tolerated as initial treatment options.

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.

Genetic Polymorphisms of Cytochrome P450 Enzymes and the Effect on Interindividual, Pharmacokinetic Variability in Extensive Metabolizers

Genetic polymorphisms of cytochrome P450 (CYP) enzymes are one of the factors that contribute to the pharmacokinetic (PK) variability of drugs. PK variability is observed in the bimodal distribution between extensive metabolizers (EMs) and poor metabolizers (PMs). PK variability may also exist between individuals genotyped as homozygous EMs and heterozygous EMs. This may carry implications for drug dosing and drug response (e.g., risk of therapeutic failure or drug toxicity). Studies have reported significant PK differences between homozygous and heterozygous EMs. Some literature suggests that this distinction may be of clinical relevance. Due to study design limitations and data that are either sparse or conflicting, generalizations regarding the potential impact of the CYP genotype, within EMs, are difficult. Optimally designed clinical trials are needed. This review evaluates the potential impact of CYP genetic polymorphisms on interindividual PK variability of drugs within an EM population.

Meta-analysis: esomeprazole or rabeprazole vs. first-generation pump inhibitors in the treatment of Helicobacter pylori infection

BACKGROUND

The decreasing efficacy of H. pylori eradication treatments over time makes the search for better regimens and adjuvant medications a priority.

AIM

To conduct a meta-analysis of studies comparing rabeprazole or esomeprazole with other proton pump inhibitors (PPI) or with each other in H. pylori eradication treatment.

SELECTION OF STUDIES

Randomised clinical trials comparing esomeprazole or rabeprazole with first-generation PPIs (omeprazole-lansoprazole-pantoprazole) or with each other.

RESULTS

The meta-analysis (35 studies, 5998 patients) showed higher eradication rates for esomeprazole than for first-generation PPIs: 82.3% vs. 77.6%; OR = 1.32(1.01-1.73); NNT = 21. Rabeprazole also showed better results than first-generation PPIs: 80.5% vs. 76.2%; OR = 1.21(1.02-1.42); NNT = 23. PPI dosage sub-analysis: only esomeprazole 40 mg b.d. improved results [83.5% esomeprazole vs. 72.4% first generation; OR = 2.27(1.07-4.82); NNT = 9]. Whereas rabeprazole 10 and 20 mg b.d. maintained results, esomeprazole 20 mg b.d. obtained lower efficacy. Esomeprazole vs. rabeprazole sub-analysis (five studies): no significant differences were found: 78.7% vs. 76.7%; OR = 0.90(0.70-1.17). CYP2C19 sub-analysis: Genotype did not significantly affect eradication either in first [OR = 1.76(0.99-3.12)] or new generation [OR = 1.19(0.73-1.95)] PPIs. However, sub-analysis considering only extensive metaboliser patients showed higher eradication with new-generation PPIs [OR = 1.37(1.02-1.84)].

CONCLUSIONS

Esomeprazole and rabeprazole show better overall H. pylori eradication rates than first-generation PPIs. This clinical benefit is more pronounced in esomeprazole 40 mg b.d. regimens. In CYP2C19 extensive metabolisers, new-generation PPIs are more effective than first-generation PPIs for H. pylori eradication. However, a general recommendation of using new-generation PPIs in all scenarios remains unclear.

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.

Reinfection rate of Helicobacter pylori after eradication treatment: a long-term prospective study in Japan

BACKGROUND

We previously reported that the reinfection rate with Helicobacter pylori in Japan was low despite a high prevalence of infection. In the present study, we extended our previous work to more accurately determine the reinfection rate.

METHODS

We enrolled 1625 patients (219 women and 1406 men, mean age 50.8 years) who had received H. pylori eradication therapy. After documentation of eradication, bacterial culture and urea breath test were carried out yearly. H. pylori strains were analyzed by using random amplification of polymorphic DNA fingerprinting.

RESULTS

A total of 1609 patients were followed for up to 12.5 years (mean 4.7 years); H. pylori became re-positive in 26 patients. In 13 of the 26 patients, H. pylori became positive at the first-year follow up. Stored H. pylori isolates were available for analysis from ten of the 13 patients; four of the isolates were genetically different from the initial strain, but the other six were identical to the initial strain. In the other 13 patients, H. pylori became positive at later follow up (mean 4.8 years; range 1.8-8.0 years). In all of the four of these patients whose isolates could be analyzed, the H. pylori strains were different from the initial strain. Assuming that reinfection occurred in the four patients positive for different strains of H. pylori at the first-year follow up and in the 13 positive at later follow up, the reinfection rate was 0.22% per year.

CONCLUSIONS

When probable recrudescence (H. pylori positivity with identical strains) was excluded, the reinfection rate of H. pylori in this Japanese population was very low, but we note that reinfection can occur over many years.

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.

The long-term risk of gastric cancer after the successful eradication of Helicobacter pylori

BACKGROUND

We previously reported that eradication of Helicobacter pylori reduced the risk of developing gastric cancer in patients with peptic ulcer diseases. In the present study, we further followed up our patient group to investigate the occurrence and clinical features of gastric cancers that developed after cure of the infection.

METHODS

Prospective post-eradication evaluations were conducted on 1674 consecutive patients who had received successful H. pylori eradication therapy. The patients had undergone endoscopic examination before eradication therapy to evaluate peptic ulcers, background gastric mucosal atrophy, and H. pylori infection. After confirmation of cure of the infection, follow-up endoscopy was performed yearly.

RESULTS

The patients were followed for up to 14.1 years (a mean of 5.6 years). During the follow-up, gastric cancer developed in 28 of the 1674 patients as long as 13.7 years after the cure of H. pylori infection. The risk of developing gastric cancer was 0.30% per year. Histologically, 16 of the gastric cancers were the intestinal type and 12 were the diffuse type; the risk of each cancer type was 0.17 and 0.13% per year, respectively. There was no significant inflammatory cell infiltration in the background gastric mucosa at the time the cancers were recognized.

CONCLUSION

There is a risk of developing gastric cancer of both the intestinal and diffuse types even after the cure of H. pylori infection and extinction of gastric inflammation. It is important to inform patients about the risk of gastric cancer after eradication therapy and offer them surveillance endoscopy.

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.

Helicobacter pylori eradication may induce de novo, but transient and mild, reflux esophagitis: Prospective endoscopic evaluation

BACKGROUNDS AND AIM

The effect on reflux esophagitis of eradicating Helicobacter pylori is variable and not fully defined. We previously reported that in patients who have reflux esophagitis associated with duodenal ulcer, a significant improvement in the pre-existing reflux esophagitis occurred after H. pylori was eradicated. In the present study, we asked whether H. pylori eradication leads to de novo development of reflux esophagitis in peptic ulcer patients.

METHODS

Prospective post-eradication evaluations were conducted in 1195 H. pylori-positive patients with peptic ulcer diseases who were confirmed not to have reflux esophagitis by endoscopic examination before eradication therapy. After eradication therapy, endoscopy and a urea breath test were performed yearly.

RESULTS

A total of 1187 patients were followed for up to 10.0 years (a mean of 3.6 years). Reflux esophagitis developed in 279 of 1000 patients cured of infection and in 26 of 187 patients who had persistent infection (P < 0.0001, Fisher's exact test). The esophagitis was mild (Los Angeles grade A) in most patients, transient in approximately one-half, and rarely necessitated long-term medication for the condition. Cure of infection, alcohol consumption, younger age, and high body mass index were identified as significant factors for the risk of developing non-transient reflux esophagitis.

CONCLUSIONS

Cure of H. pylori infection may increase the risk of developing reflux esophagitis in patients with peptic ulcer, but the esophagitis is mostly mild and transient, and long-term medication is rarely required. Thus, H. pylori eradication therapy need not be withheld for fear of provoking reflux esophagitis.

New concepts of resistance in the treatment of Helicobacter pylori infections

The prevalence of antimicrobial drug resistance is now so high that all patients infected with Helicobacter pylori should be considered as having resistant infections. Ideally, therapy should be based on pretreatment antibiotic-susceptibility testing but this strategy is not currently practical. At present, clarithromycin-containing triple therapies do not reliably produce a > or =80% cure rate on an intention-to-treat basis and are, therefore, no longer acceptable as empiric therapy. In this Review, we discuss concepts of resistance that have become part of mainstream thinking for other infectious diseases but have not yet become so with regard to H. pylori. We also put data on the pharmacokinetics and pharmacodynamics of the drugs used in H. pylori therapy and the effect of host cytochrome P450 genotypes in context with treatment outcomes. Our primary focus is to address the problem of H. pylori resistance from a novel perspective, which also attempts to anticipate the direction that research will need to take to provide clinicians with reliable approaches to this serious infection. We also discuss current therapies that provide acceptable cure rates when used empirically (i.e. sequential therapy; four-drug, three-antibiotic, non-bismuth-containing 'concomitant' therapy; and bismuth-containing quadruple therapy) and how they might be further improved.

Clinical pharmacological aspects of the proton pump inhibitor therapy – importance of pharmacogenetic differences in the clinical practice

A protonpumpa-gátlók (PPI) a gastrooesophagealis reflux és más savfüggő betegségek kezelésében széles körben használatosak. Az omeprazol, lansoprazol, pantoprazol, rabeprazol és esomeprazol hatékonyan gátolják a gyomorsav-szekréciót a protonpumpa, H + /K + -adenozin trifoszfatáz (ATPáz) bénításával.E vegyületek döntően CYP-mediált oxidatív metabolizmusában megfigyelhető különbségek kifejezett egyéni eltéréseket okozhatnak a savszekréció gátló hatásban. A PPI-kezelés során fellépő gyógyszerkölcsönhatások nagy része szintén e metabolikus folyamatokhoz köthető.A PPI-k átalakításában elsősorban a CYP2C19 és a CYP3A4 izoenzimek vesznek részt; aktivitásukat részben exogén hatások, részben endogén (farmakogenetikai) tényezők módosíthatják. Napjainkban elérhetővé vált az egyes genotípusok (homozigóta extenzív, heterozigóta extenzív metabolizálók és lassú metabolizálók) PCR, DNS chip módszerrel történő vizsgálata, mely egyre több magyarázattal szolgál a terápiás válaszokban megfigyelhető egyéni eltérések megértéséhez.A genotípus meghatározása a klinikai gyakorlat számára jelentős segítséget nyújthat az optimális kezelési forma kiválasztásában, és egyénre szabott savszekréció-gátló terápia kialakításában, különösen PPI-kezelésre non-responder gastrooesophagealis reflux, vagy fekélybetegség esetében, illetőleg sikertelen eradikációs kezelést követően.

Pharmacogenetics, drug-metabolizing enzymes, and clinical practice

The application of pharmacogenetics holds great promise for individualized therapy. However, it has little clinical reality at present, despite many claims. The main problem is that the evidence base supporting genetic testing before therapy is weak. The pharmacology of the drugs subject to inherited variability in metabolism is often complex. Few have simple or single pathways of elimination. Some have active metabolites or enantiomers with different activities and pathways of elimination. Drug dosing is likely to be influenced only if the aggregate molar activity of all active moieties at the site of action is predictably affected by genotype or phenotype. Variation in drug concentration must be significant enough to provide "signal" over and above normal variation, and there must be a genuine concentration-effect relationship. The therapeutic index of the drug will also influence test utility. After considering all of these factors, the benefits of prospective testing need to be weighed against the costs and against other endpoints of effect. It is not surprising that few drugs satisfy these requirements. Drugs (and enzymes) for which there is a reasonable evidence base supporting genotyping or phenotyping include suxamethonium/mivacurium (butyrylcholinesterase), and azathioprine/6-mercaptopurine (thiopurine methyltransferase). Drugs for which there is a potential case for prospective testing include warfarin (CYP2C9), perhexiline (CYP2D6), and perhaps the proton pump inhibitors (CYP2C19). No other drugs have an evidence base that is sufficient to justify prospective testing at present, although some warrant further evaluation. In this review we summarize the current evidence base for pharmacogenetics in relation to drug-metabolizing enzymes.

Identification of the time-point which gives a plasma rabeprazole concentration that adequately reflects the area under the concentration-time curve

OBJECTIVE

The purpose of this study is to evaluate whether a simple formula using limited blood samples can predict the area under the plasma rabeprazole concentration-time curve (AUC) in co-administration with CYP inhibitors.

METHODS

A randomized double-blind placebo-controlled crossover study design in three phases was conducted at intervals of 2 weeks. Twenty-one healthy Japanese volunteers, including three CYP2C19 genotype groups, took a single oral 20-mg dose of rabeprazole after three 6-day pretreatments, i.e., clarithromycin 800 mg/day, fluvoxamine 50 mg/day, and placebo. Prediction formulas of the AUC were derived from pharmacokinetics data of 21 subjects in three phases using multiple linear regression analysis. Ten blood samples were collected over 24 h to calculate AUC. Plasma concentrations of rabeprazole was measured by an HPLC-assay (l.l.q.=1 ng/ml).

RESULTS

The AUC was based on all the data sets (n=63). The linear regression using two points (C3 and C6) could predict AUC(0-infinity) precisely, irrespective of CYP2C19 genotypes and CYP inhibitors (AUC(0-infinity)=1.39xC3+7.17xC6+344.14, r (2)=0.825, p<0.001).

CONCLUSION

The present study demonstrated that the AUC of rabeprazole can be estimated by the simple formula using two-point concentrations. This formula can be more accurate for the prediction of AUC estimation than that reflected by CYP2C19 genotypes without any determination, even if there are significant differences for the CYP2C19 genotypes. Therefore, this prediction formula might be useful to evaluate whether CYP2C19 genotypes really reflects the curative effect of rabeprazole.

Pharmacodynamic and kinetic effect of rabeprazole on serum gastrin level in relation to CYP2C19 polymorphism in Chinese Hans

AIM: To observe the pharmacokinetics and pharmaco-dynamics of rabeprazole and compare serum gastrin concentrations in different CYP2C19 genotype groups.

METHODS: The CYP2C19 genotype status of Chinese Han healthy volunteers was determined by polymerase chain reaction-restriction fragment length polymorphism method. Twenty H pylori-negative healthy subjects voluntary participated in the study. They were divided into the following three groups: homozygous extensive metabolizers (homEM), heterozygous extensive metabolizers (hetEM) and poor metabolizers (PM). After they orally received rabeprazole 20 mg once daily in the morning of d 1 and d 8, blood samples were collected at various time-points until 24 h after administration and intragastric pH values were monitored for 24 h by Digitrapper pH. Serum gastrin concentrations were measured by radioimmunoassay. Serum concentrations of rabeprazole were measured by high performance liquid chromatography.

RESULTS: The mean AUC values for rabeprazole after a single and repeated doses were significantly different between the homEM and PM groups, but not between the homEM and hetEM, or the hetEM and PM groups. No significant differences in intragastric pH medians were observed among the three different genotype groups after a single dose or repeated doses. The ratio of pH medians between d 1 and d 8 ranged from 84% to 108%. The mean gastrin AUC values were also different among the three genotype groups, with a relative ratio of 1.0, 1.2 and 1.5 after a single dose and 1.0, 1.5 and 1.6 after repeated doses in the homEM, hetEM and PM groups, respectively. The gastrin AUC values among the three different genotype groups showed no significant difference either after a single dose or repeated doses. The subject who had lower intragastric acidity showed higher serum gastrin levels and concentrations of rabeprazole.

CONCLUSION: In Chinese Han healthy people, the pharmacokinetics of rabeprazole are dependent on the CYP2C19 genotype status, but acid-inhibitory efficacy of rabeprazole and the gastrin level are not influenced significantly.

The effect of CYP2C19 polymorphisms on H. pylori eradication rate in dual and triple first-line PPI therapies: a meta-analysis

PREMISE

It has been suggested that proton pump inhibitor (PPI)-related differences in Helicobacter pylori eradication rates are partly because of CYP2C19 polymorphisms and there have been conflicting data in this area. We conducted a meta-analysis to investigate the evidence relating CYP2C19 to first-line H. pylori eradication rates.

METHODS

A search of the literature was conducted up to June 2005 using Medline, EMBase, and Cochrane Register of Controlled Trials (CENTRAL). Twenty-eight arms from 17 papers were extracted for omeprazole, lansoprazole, and rabeprazole, collectively. Review Manager 4.2.8 was used for analysis.

RESULTS

When all eradication rates, regardless of PPI used, were combined there was no significant difference between poor metabolizers (PM) and heterozygous extensive metabolizers (HetEMs) (odds ratio [OR]= 1.35, 95% confidence interval [CI] 0.89-2.07, p = 0.15); however, there was a significant difference between HetEM and homozygous extensive metabolizers (HomEMs) (OR = 1.90, 95% CI 1.38-2.60, p < 0.0001). Significant heterogeneity was observed in a HomEM and PM comparison, hence additional subanalysis of individual PPIs revealed that dual and triple omeprazole therapies significantly favored higher H. pylori eradication rates in PM over HomEM (OR = 4.03, 95% CI 1.97-8.28, p = 0.0001), and also over HetEM (OR = 2.24, 95% CI 1.09-4.61, p = 0.03). Dual and triple rabeprazole and triple lansoprazole therapies did not show significantly different H. pylori eradication rates between PM and HomEM (OR = 1.04, 95% CI 0.44-2.46, p = 0.25) and (OR = 1.80, 95% CI 0.67-4.85, p = 0.93), respectively.

CONCLUSIONS

The impact of CYP2C19 polymorphisms on H. pylori eradication rates in studied populations appears clinically relevant in patients prescribed omeprazole as a component of their dual- or triple-drug therapy, whereas regimens that include lansoprazole or rabeprazole are unaffected. The choice of PPI and/or dose rather than CYP2C19 genotyping could be a more practical approach to assure the highest H. pylori eradication rates in clinical settings.

Influence of smoking and CYP2C19 genotypes on H. pylori eradication success

CYP2C19 polymorphisms and smoking influence the efficacy of H. pylori eradication therapy, but interaction between the two have hitherto not been examined. A total of 142 H. pylori-positive patients who received triple drug therapy with lansoprazole, amoxicillin and clarithromycin were categorized into three groups with regard to diplotypes of CYP2C19: homozygous extensive metabolizer (homEM), heterozygous EM (hetEM), and poor metabolizer (PM). The overall success rate was 61.3%. Smoking was an independent risk factor of eradication failure (OR 2.81, 95% CI 1.14-6.91), whereas CYP2C19 polymorphisms were less influential. Among non-smokers, the homEM and hetEM groups showed worse eradication rates (58.5 and 67.3%) relative to PM (76.2%) as expected; however, an opposite trend was observed among smokers (homEM 50.0%, hetEM 46.7%, PM 20.0%), indicating possible interactions with CYP2C19 polymorphisms. Smoking has a greater influence on H. pylori eradication than the CYP2C19 genotype. Interaction between smoking and CYP2C19 should be examined in the future.

Papel del polimorfismo genético CYP2C19 en los efectos adversos a fármacos y en el riesgo para diversas enfermedades

There are a great number of polymorphic genes in the human genome. Many of them codify enzymes that metabolizes drugs and xenobiotic agents, including carcinogens. Among the better known of them, there are a number of isozymes of the microsomal oxidative system (CYP3A4, CYP2C9, CYP2C19 y CYP2D6). This article reviews the following issues: a) frequency of presentation of the "poor metabolizer" genotype and/or phenotype for substrates of CYP2C19; b) role of CYP2C19 polymorphism on the metabolism of some drugs (mephenytoine and other antiepileptic drugs, proton pump inhibitors, several antidepressants and anxyolitics, the antimalaria aggent proguanyl, and propranolol, among others, use this metabolic pathway), and c) possible role of CYP2C19 polymorphism in the risk for development of neoplasia and other diseases (systemic lupus erythematosus, psoriasis, hip osteonecrosis, Alzheimer's disease, amyotrophic lateral sclerosis, essential tremor).

Proton pump inhibitors: update on their role in acid-related gastrointestinal diseases

Gastric acid is pathogenic in many gastrointestinal disorders, such as gastroesophageal reflux disease and peptic ulcer disease. Proton pump inhibitors (PPIs) are the antisecretory drugs of choice for serious acid-related conditions. Ample recent data exist to explicate virtually every aspect of the clinical management of acid-peptic disorders with PPIs. Although all PPIs are effective, there are some differences in their clinical performance, particularly in terms of the degree and speed of gastric acid suppression. Rapid onset of acid suppression may be particularly relevant to newer approaches, such as 'on-demand' or intermittent therapy for non-erosive reflux disease and shorter regimens for Helicobacter pylori eradication. New data, in addition, highlight differences in PPI metabolism that may both affect efficacy and predispose patients to drug-drug interactions. PPI selection should involve the awareness of these issues.

Sofalcone, a mucoprotective agent, increases the cure rate of Helicobacter pylori infection when combined with rabeprazole, amoxicillin and clarithromycin

AIM: The mucoprotective agents, sofalcone and polaprezinc have anti-Helicobacter pylori (H pylori) activities. We determined the therapeutic effects of sofalcone and polaprezinc when combined with rabeprazole, amoxicillin and clarithromycin for Helicobacter pylori infection.

METHODS: One hundred and sixty-five consecutive outpatients with peptic ulcer and H pylori infection were randomly assigned to one of the following three groups and medicated for 7 d. Group A: triple therapy with rabeprazole (10 mg twice daily), clarithromycin (200 mg twice daily) and amoxicillin (750 mg twice daily). Group B: sofalcone (100 mg thrice daily) plus the triple therapy. Group C: polaprezinc (150 mg twice daily) plus the triple therapy. Eradication was considered successful if 13C-urea breath test was negative at least 4 wk after cessation of eradication regimens or successive famotidine in the cases of active peptic ulcer.

RESULTS: On intention-to-treat basis, H pylori cure was achieved in 43 of 55 (78.2%) patients, 47 of 54 (87.0%) and 45 of 56 (80.4%) for the groups A, B and C respectively. Using per protocol analysis, the eradication rates were 81.1% (43/53), 94.0% (47/50) and 84.9% (45/53) respectively. There was a significant difference in the cure rates between group A and B. Adverse events occurred in 10, 12 and 11 patients, from groups A, B and C respectively, but the events were generally mild.

CONCLUSION: The addition of sofalcone, but not polaprezinc, significantly increased the cure rate of H pylori infection when combined with the rabeprazole-amoxicillin-clarithromycin regimen.

Pharmacodynamic effects and kinetic disposition of rabeprazole in relation to CYP2C19 genotype in healthy Chinese subjects

AIM

To investigate whether the pharmacodynamics and pharmacokinetics of rabeprazole are dependent on CYP2C19 genotype status in healthy Chinese Han subjects.

METHODS

The CYP2C19 genotype status of healthy Chinese Han volunteers was determined using the polymerase chain reaction-restriction fragment length polymorphism method. Twenty healthy subjects volunteered to participate in the study. There were seven homozygous extensive metabolizers (homEM), six heterozygous extensive metabolizers (hetEM), and seven poor metabolizers (PM). All subjects were Helicobactor pylori-negative, which was determined by sero-logy and 13C-urea breath tests. Rabeprazole (20 mg) was taken orally once daily in the morning for 8 days, and intragastric pH values were monitored for 24 h by Digitrapper pH after day 1 (single dose) and day 8 (repeated dose). Meanwhile, blood samples were collected at various time-points for 24 h after administration. The serum concentrations of rabeprazole were measured using high-performance liquid chromatography.

RESULTS

The mean area under the curve (AUC) values for rabeprazole differed among the three different genotype groups, with a relative ratio of 1.0, 1.3, and 1.8 after a single dose and 1.0, 1.1, and 1.7 after repeated doses in the homEM, hetEM, and PM groups, respectively. Mean AUC values for rabeprazole after a single dose and after repeated doses were significantly different between the homEM and PM groups, but not between the homEM and hetEM or hetEM and PM groups. No significant differences in intragastric pH median, pH>4 total time, and pH>4 time percentage of 24 h, were observed among the three different genotype groups after a single dose or after repeated doses of rabeprazole.

CONCLUSION

In healthy Chinese Han subjects, the pharmacokinetics of rabeprazole are dependent on a certain degree on CYP2C19 genotype status; however, the acid-inhibitory efficacy of rabeprazole is not influenced significantly by CYP2C19 genetic polymorphism.

Molecular biology methods for the characterization of Helicobacter pylori infections and their diagnosis

Helicobacter pylori infects approximately half of the human population; however, the outcome of infection is affected by many factors, including strain and host genotype characteristics and bacterial density within the stomach. Many molecular methods have been developed to provide information with respect to these characteristics. Methods that provide results within 24 h of endoscopy may be used to develop individualized treatment that is more effective, results in fewer side effects, cuts costs,decreases the number of treatment failures and results in the development of fewer antibiotic-resistant H. pylori strains.

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.

Pharmacogenetics‐Based New Therapeutic Concepts

Pharmacogenetics, one of the fields of clinical pharmacology, studies how genetic factors influence drug response. If hereditary traits are taken into account appropriately before starting drug treatment, the type of drug and its dosage can be tailored to the individual patient's needs. Pharmacogenetics adds a considerable amount of stringency to the doctor's therapeutic approach. Today, it is the relationship between dosage requirements and genetic variations in drug metabolizing enzymes like cytochrome P450 (CYP) 2D6 and CYP2C19, or in drug transporters like p-glycoprotein, that is substantiated best. A standard dose will bring about more adverse effects than usual if enzymatic activity is lacking or feeble. Sometimes, however, therapeutic response might be better due to higher concentrations: proton pump inhibitors for eradication of Helicobacter pylori are more efficacious in carriers of a deficient CYP2C19 variant. The drug's interaction with its target (e.g. receptor) also depends on genetic factors. In some cases genetic tests can help distinguish between responders and non-responders of a specific drug treatment. The first pharmacogenetic tests are already on the market.

CYP2C19Polymorphism and Proton Pump Inhibitors

Proton pump inhibitors such as omeprazole (esomeprazole), lansoprazole, pantoprazole and rabeprazole are eliminated by the hepatic route and the polymorphic CYP2C19 is mainly involved in their metabolism. In different populations three phenotypes have been identified: extensive metabolizers, poor metabolizers and individuals carrying one wild type and one mutant allele (het extensive metabolizers). Systemic exposure to the proton pump inhibitors as expressed by the AUC (area under the plasma level time profiles) is 5-12-times higher in poor metabolizers than in extensive metabolizers. As the pharmacodynamic response (elevation of intragastric pH) to the proton pump inhibitors is related directly to their AUC, a much higher pH can be monitored over 24 hr in poor metabolizers than in extensive metabolizers. Furthermore, clinical efficacy of all proton pump inhibitors depend on maintaining intragastric pH above certain threshold levels and significantly higher eradication rates of Helicobacter pylori have been observed in patients of the poor metabolizers and het extensive metabolizers phenotype if compared to extensive metabolizers. Likewise, limited data suggest that proton pump inhibitors-induced healing rates in gastro-oesophageal reflux disease are apparently higher in poor metabolizers/het extensive metabolizers than in extensive metabolizers of CYP2C19. Therefore initial genotyping for this enzyme and higher dosage in extensive metabolizers is likely to improve the clinical efficacy of proton pump inhibitors.

DNA typing for Helicobacter pylori isolates from eradication-failed patients: comparison of the isolates before and after therapy

BACKGROUND

Failure of Helicobacter pylori eradication occurs frequently despite use of multiple microbial agents.

AIM

We aimed to study differences between H. pylori strains isolated before and after eradication failure.

METHODS

We treated 87 patients with peptic ulcer using triple therapy consisting of omeprazole plus combinations of clarithromycin, amoxicillin, or metronidazole. We studied the status of cagA, vacA, and iceA by PCR, and examined the differences in H. pylori isolates by pulsed-field gel electrophoresis and arbitrary primer polymerase chain reaction. The minimum inhibitory concentration of clarithromycin, amoxicillin, or metronidazole was determined by an agar dilution method.

RESULTS

Eradication therapy failed in 12 patients (14%); H. pylori isolates were obtained from all of these both before and after therapy. After eradication therapy, 10 patients were colonized with the same strain as before therapy, while the other two patients were colonized with different strains from those before therapy. In the former group, one isolate changed from metronidazole-sensitive to -resistant, one changed from clarithromycin- and metronidazole-sensitive to -resistant, and four were resistant to clarithromycin or metronidazole both before and after therapy. The other four isolates remained sensitive to clarithromycin and metronidazole after therapy. In the two patients who yielded apparently different isolates after therapy, they changed from clarithromycin- and metronidazole-sensitive to -resistant.

CONCLUSION

Eradication of H. pylori by first-line therapy is an important goal in the treatment of H. pylori-positive peptic ulcer, and that appropriate antimicrobial sensitivity testing should be conducted in patients with eradication failure.

Interleukin-1beta genetic polymorphism influences the effect of cytochrome P 2C19 genotype on the cure rate of 1-week triple therapy for Helicobacter pylori infection

OBJECTIVES

Genetic polymorphism of interleukin (IL)-1beta is associated with differences in gastric acid suppression in response to Helicobacter pylori (H. pylori) infection. Thus, the polymorphism might affect H. pylori eradication therapy, as antibiotics used in treatment regimens may be acid sensitive. In this study, we examined the impact of IL-1beta genetic polymorphism on the cure rate of triple therapy for H. pylori in relation to cytochrome P (CYP) 2C19 genotype and antibiotic resistance.

METHODS

A total 249 patients with peptic ulcer disease were randomized to receive one of the following regimens: amoxicillin and clarithromycin together with omeprazole, lansoprazole, or rabeprazole. CYP2C19 and IL-1beta-511 genetic polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The intention-to-treat-based overall cure rate was 74.3% (95% CI=68-79%). In the normal acid secretion IL-1beta genotype group, the cure rate among CYP2C19 poor metabolizers (93.3%, 95% CI=56-99%) was significantly higher than among subjects in the CYP2C19 homozygous (60.0%, 95% CI=38-78%) and heterozygous (63.6%, 95% CI=46-78%), i.e., extensive metabolizer, groups (p<0.05). In the low acid secretion IL-1beta genotype group, there was no difference in the cure rate among the CYP2C19 genotype groups. Multiple logistic regression analysis identified susceptibility to clarithromycin (p<0.0001) and CYP2C19 genotype status (p=0.03) as significant independent factors for treatment failure.

CONCLUSION

IL-1beta genetic polymorphism, although not an independent factor in treatment outcome, influences the impact of the CYP2C19 genotype on the cure rate of 1-wk triple therapy for H. pylori infection.

Meta-analysis: comparative efficacy of different proton-pump inhibitors in triple therapy for Helicobacter pylori eradication

BACKGROUND

It is not known whether certain proton-pump inhibitors are more efficacious than others when used in triple therapy for Helicobacter pylori eradication.

AIM

To compare the efficacy of different proton-pump inhibitors in triple therapy by performing a meta-analysis.

METHODS

A MEDLINE search was performed. Abstracts of the European Helicobacter pylori Study Group and the American Gastroenterological Association congresses from 1996 to 2002 were also examined. Randomized studies with at least two branches of triple therapy that differed only in terms of type of proton-pump inhibitor were included in a meta-analysis using Review Manager 4.1.

RESULTS

Fourteen studies were included. Intention-to-treat cure rates were similar for omeprazole and lansoprazole: 74.7% vs. 76%, odds ratio (OR) 0.91 [95% confidence interval (CI) 0.69-1.21] in a total of 1085 patients; for omeprazole and rabeprazole: 77.9% vs. 81.2%, OR 0.81 (95% CI 0.58-1.15) in a total of 825 patients; for omeprazole and esomeprazole: 87.7% vs. 89%, OR 0.89 (95% CI 0.58-1.35) in 833 patients; and for lansoprazole and rabeprazole: 81% vs. 85.7%, OR 0.77 (95% CI 0.48-1.22) in 550 patients.

CONCLUSION

The efficacy of various proton-pump inhibitors seems to be similar when used for H. pylori eradication in standard triple therapy.

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.

Meta-analysis: comparing the efficacy of proton pump inhibitors in short-term use

BACKGROUND

Proton pump inhibitors have a prominent role in the management of acid-related diseases. Controlling expenses on proton pump inhibitors would yield great economic benefits for Dutch health care.

AIM

To investigate whether clinical differences in proton pump inhibitors exist.

METHODS

We searched Medline, EMBASE and the Cochrane Library. We identified papers in English, German, French or Dutch in which two or more proton pump inhibitors were compared under the same clinical conditions in gastro-oesophageal reflux disease, peptic ulcer disease or Helicobacter pylori eradication. The pooled relative risks were calculated using the Mantel-Haenszel method.

RESULTS

Two significant differences were found in the proton pump inhibitors compared. In gastro-oesophageal reflux disease, esomeprazole 40 mg was superior to omeprazole 20 mg (relative risk, 1.18; 95% confidence interval, 1.14-1.23). In peptic ulcer disease, pantoprazole 40 mg was superior to omeprazole 20 mg (relative risk, 1.07; 95% confidence interval, 1.02-1.13). In Helicobacter pylori eradication, no significant differences were found.

CONCLUSIONS

Both significant differences found were in favour of the highest dose of proton pump inhibitor on a milligram basis. This indicates that the difference may be dose dependent and not proton pump inhibitor specific. Therefore, when prescribing proton pump inhibitors, arguments other than clinical efficacy, such as those related to pharmaco-economics, may be considered.

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.

Pharmacogenetics of the proton pump inhibitors: a systematic review

Cytochrome P450 (CYP) 2C19 mediates the major metabolic transformations of the proton pump inhibitors (PPIs) omeprazole, pantoprazole, lansoprazole, esomeprazole, and rabeprazole. Genetic polymorphism of CYP2C19 can lead to significant phenotypic variation in the activity of this isoenzyme and thus in the metabolism of PPIs. We systematically reviewed the pharmacogenetic studies of PPIs with respect to the effects of CYP2C19 polymorphism on the clinical outcomes of PPI therapy. We searched MEDLINE (January 1966-August 2002) and EMBASE (January 1988-August 2002) for English-language articles on the pharmacogenetics of PPIs; the search was supplemented by a bibliographic review of all relevant articles. Seventeen pertinent citations were identified, and the quality (level) of evidence for each was categorized according to the rating scale of the United States Preventive Services Task Force. We found that the relationship between CYP2C19 genetic polymorphism and clinical outcomes after PPI therapy has not yet been clearly delineated. Virtually all pharmacogenetic studies of PPIs have been performed in Japanese men; thus, the clinical relevance of CYP2C19 genetic polymorphism in non-Asian patients and women is unknown. Differences among dual- and triple-therapy drug regimens make it difficult to compare H. pylori eradication studies and assess their applicability to current practice patterns. Drug adherence, a pivotal factor in the success of eradication therapy, was addressed in only four trials. Future directions for research include performing more studies with larger sample sizes, particularly in non-Asian populations and women; measuring plasma PPI concentrations to directly correlate H. pylori infection and ulcer cure rates with plasma drug availability; expanding the study population to patients with gastroesophageal reflux disease; and exploring the influence of CYP3A4 in the success or failure of PPI therapy. Although CYP2C19 genotyping is currently only a research instrument, it may be a valuable clinical tool in select patients to ensure optimal PPI therapy.

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 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.