Effect of MDR1 C3435T polymorphism on cure rates of Helicobacter pylori infection by triple therapy with lansoprazole, amoxicillin and clarithromycin in relation to CYP 2C19 genotypes and 23S rRNA genotypes of H. pylori

Effect of MDR1 C3435T and CYP2C19 genetic polymorphisms on the outcome of Helicobacter pylori eradication treatment in children with gastritis and peptic ulcer, Vietnam

BACKGROUND

Helicobacter pylori eradication therapy based on antimicrobial susceptibility in Vietnamese children currently get low efficiency. There are causes of treatment failure, among host genetic factors namely MDR1 C3435T and CYP2C19 affect the absorption and metabolism of proton pump inhibitors - a crucial component of eradication therapy. The study aimed to investigate the effect of MDR1 C3435T and CYP2C19 genetic polymorphisms on the cure rate.

METHODS

207 pediatric patients with gastritis and peptic ulcer infecting Helicobacter pylori completed the eradication therapy based on antimicrobial susceptibility with proton pump inhibitor esomeprazole. Eradication efficacy was assessed after at least 4 weeks by the urease breath test. MDR1 C3435T genetic polymorphism and CYP2C19 genotype were determined using a sequencing method based on Sanger's principle.

RESULTS

Among 207 children recruited in this study, the ratio of CYP2C19 EM, IM, and PM phenotypes was 40.1%, 46.4%, and 16.9%, respectively. The patient with MDR1 3435 C/C polymorphism accounted for 43.0%, MDR1 3435 C/T was 40.1%, and MDR1 3435T/T was 16.9%. The cure rate of Helicobacter pylori infection in patients with CYP2C19 EM genotype was 78.3%; 83.3% of those with the IM genotype, and PM genotype was 96,4% (p = 0.07). Successful eradication rates for Helicobacter pylori were 85.4%, 86.7%, and 68.6% in patients with the MDR1 3435 C/C, C/T, and T/T, respectively (p = 0.02). Multiple logistic regression analysis found that MDR1 C3435T genetic polymorphisms of patients were significant independent risk factors for treatment failure, and CYP2C19 genotype did not affect Helicobacter pylori eradication.

CONCLUSIONS

The Helicobacter pylori eradication rates by regimens based on antibiotic susceptibility and esomeprazole were not significantly different between the CYP2C19 phenotypes. The MDR1 C3435T polymorphism is one of the factors impacting Helicobacter pylori eradication results in children.

Efficacy of Helicobacter pylori Eradication Based on Rabeprazole–Bismuth–Tetracycline–Tinidazole Regimen in Vietnamese Patients with Duodenal Ulcers

(1) Background: In Vietnam, H. pylori bacteria has a resistance rate of 63% to the antibiotic clarithromycin. The initial therapy of H. pylori eradication with a standard three-drug regimen has low efficacy. Objective: Assess the efficacy of H. pylori eradication therapy which uses a four-drug regimen of rabeprazole–bismuth–tetracycline–tinidazole in patients with duodenal ulcers. (2) Methods: We performed gastrointestinal endoscopy on patients with a diagnosis of duodenal ulcers, gastric mucosa biopsy for a rapid urease test, and histopathology to diagnose H. pylori bacteria before and after treatment. Treatment for eradication of H. pylori bacteria using a rabeprazole–bismuth–tetracycline–tinidazole regimen was prescribed for 14 days. (3) Results: The rate of successful H. pylori eradication treatment according to per protocol (PP) and intention to treat (ITT) was 91.3% (95%CI: 84.8–96.7) and 82.4% (95%CI: 74.5–89.2) respectively. The success rate of H. pylori eradication therapy in males was 96.0% (95%CI: 92–100), higher than in females, which was 70.6% (95%CI: 47.1–88.2), p < 0.01. (4) Conclusions: Treatment of H. pylori with rabeprazole–bismuth–tetracycline–tinidazole regimen is highly effective. Men had higher H. pylori eradication results than women.

Designing strategies for eradication of Helicobacter pylori based on prevalence patterns of infection and antibiotic resistance in a low-income, medically underserved community in the United States

BACKGROUND

Regional variation in Helicobacter pylori resistance patterns is a significant contributing factor for the ineffectiveness of traditional treatments. To improve treatment outcomes, we sought to create an individualized, susceptibility-driven therapeutic approach among our patient population, which is one of the poorest in the nation. It is medically underserved, minority-predominant and has high incidence of H pylori infection.

METHODS

We compiled various factors involved in the antibiotic resistance of H pylori from literature. We then created a predictive model to customize therapies based on analyzed data from 2,014 H pylori patients with respect to several of these factors. The predictions of the model were further tested with analysis of patient stool samples.

RESULTS

A clear pattern of H pylori prevalence and antibiotic resistance was observed in our patients. We observed that majority of H pylori patients were women (62%) and over the age of 40 years (80%). 30% and 36% of the H pylori patients were African American and Hispanic, respectively. A median household income of less than $54,000, past H pylori infection, previous use of certain antibiotics for any infection decreased the chance of eradication. Results of the stool testing were consistent with model predictions (90% accuracy).

CONCLUSION

This model demonstrates the predictive accuracy of H pylori infection and antibiotic resistance based on patient attributes and previous treatment history. It will be useful to formulate customized treatments with predicted outcomes to minimize failures. Our community attributes may contribute toward broad applicability of model for other similar communities.

Efficacy of dexlansoprazole-based triple therapy for Helicobacter pylori infections

BACKGROUND

Dexlansoprazole has been shown to be efficacious for the treatment of gastroesophageal reflux disease. However, there is a paucity of data about its efficacy for Helicobacter pylori eradication. The aim of this study was to evaluate the efficacy of dexlansoprazole for H. pylori eradication as triple therapy in real-world practice.

METHODS

Adult patients with endoscopically proven H. pylori related peptic ulcer diseases or gastritis were recruited for this study. The eradication status was assessed based on the results of the ¹³C-urea breath test performed 4 weeks after treatment. According to the different treatment regimens, the patients were allocated to group A: Esomeprazole 40 mg b.i.d. + amoxicillin 1 g b.i.d. + clarithromycin 500 mg b.i.d. for 7 days; group B: Esomeprazole 40 mg q.d. + amoxicillin 1 g b.i.d. + clarithromycin 500 mg b.i.d. for 7 days, or group C: Dexlansoprazole 60 mg q.d. + amoxicillin 1 g b.i.d. + clarithromycin 500 mg b.i.d. for 7 days.

RESULTS

A total of 215 patients (49% males) were enrolled in this study, with a mean age of 55 years. The eradication rates in group A, B, and C were 94.7% (71/75), 89.6% (69/77), and 93.7% (59/63) (p = 0.457), respectively. The adverse events were similar between the three groups (p = 0.068).

CONCLUSIONS

This study suggests that dexlansoprazole-based triple therapy has an acceptable eradication rate for H. pylori infection.

Efficacy of H. pylori eradication depending on genetic polymorphism of CYP2C19, MDR1 and IL-1β

Aim. To evaluate an association of genetic polymorphisms CYP2C19, MDR1, and IL-1β on the eradication rate by 10-day modified therapy in patients with H. pylori - associated diseases. Materials and methods. In this study was conducted a prospective, randomized trial, included 89 patients with H. pylori - associated diseases. They were divided into 2 groups depending on therapy: clarithromycin 500 mg, b.i.d., amoxicillin 1000 mg, b.i.d., bismuth subcitrate 240 mg, b.i.d. rabeprazole 20 mg or 40 mg, b.i.d. for 10 days. All subjects underwent pharmacogenetic testing of CYP2C19, MDR1, and IL-1β. Results and discussion. Per - protocol (PP) eradication rates in group with rabeprazole 40 mg were 97.6% (41/42; 95% CI 87.7-99.6), in group with rabeprazole 20 mg were 82.1% (32/39; 95% CI 67.3-91.0). Intention - to - treat analysis in group with rabeprazole 40 mg eradication rates were 89.1% (41/46; 95% CI 77.0-95.3), in group with standard dose rabeprazole - 74.4% (32/43; 95% CI 59.8-85.1). No significant differences in eradication rates between the groups of ultrarapid, rapid, normal and intermediate CYP2C19 metabolizers (PP: 93.5%/90.3%/84.6% respectively; χ2=0.87, p=0.65). Eradication rates in group with IL-1β CC genotype there was no difference among the IL-1β CT and TT genotype groups (PP: 92.9%/85.7%/94.7% respectively; χ2=1.34; p=0.51). The cure rate among MDR1 TT genotype was significantly lower than among subjects in the MDR1 CC/CT genotype groups (PP: 76.2% vs 96.3%: χ2=5.04; p=0.025; OR=8.13). Conclusion. Ten - day modified triple therapy with high dose rabeprazole significantly high eradication rates in patients with H. pylori - associated diseases. Independent factor for treatment failure is MDR1 CC/CT genotype status.

Optimization strategies aimed to increase the efficacy of H. pylori eradication therapies

BACKGROUND

As with any other infectious disease, we should aim for treatments offering ≥90% Helicobacter pylori eradication rates in clinical practice.

AIM

To summarize optimization strategies aimed to increase the efficacy of H. pylori eradication therapies.

METHODS

A systematic bibliographic search (in PubMed up to August 2016) was designed to identify studies investigating optimization strategies aimed to increase the efficacy of H. pylori eradication therapies.

RESULTS

The most direct way to optimize a treatment is using higher doses of drugs unless it has been shown that lower doses are equally effective. Similarly, prescriptions should use 14-day duration unless a shorter scheme has been shown locally to be equally effective. Double-dose proton-pump inhibitor therapy is recommended for triple therapy and may probably increase the efficacy of nonbismuth concomitant regimen as well. The efficacy of triple therapies in the presence of resistance can be significantly improved by the addition of bismuth salts, which offer an additive effect in combination with antibiotics. Overall, probiotics seem to reduce antibiotic side effects, but the increase in eradication rates is not so evident; therefore, they cannot be generally recommended for clinical practice yet.

CONCLUSIONS

Using potent acid inhibition and/or higher antibiotic doses-especially by increasing the number of daily intakes-and lengthening treatments up to 14 days improves efficacy in most regimens and should be generally recommended. Triple therapies can be efficiently improved by the addition of bismuth salts, turning them into quadruple therapies. Finally, some treatments will require a combination of optimization strategies to significantly improve results.

The effect of MDR1 C3435T polymorphism on the eradication rate of H. pylori infection in PPI-based triple therapy: A meta-analysis

BACKGROUND

Several studies have reported that multidrug resistance gene 1 (MDR1) C3435T polymorphism was associated with the rate of Helicobacter pylori (H. pylori) eradication in proton pump inhibitor (PPI)-based triple therapy. However, the conclusions were inconsistent. Therefore, this meta-analysis was conducted to evaluate the impact of MDR1 C3435T polymorphism on H. pylori eradication by PPI-based triple therapy.

METHODS

Seven eligible studies published up to August 2016 and including 1019 patients were identified by searching the Chinese Biomedical Literature database, Wan fang, PubMed, and the Web of Science electronic databases. Consequently, a meta-analysis was conducted with STATA software, using summary odds ratios (OR) and a 95% confidence interval (CI).

RESULTS

Overall, there was no significant difference between MDR1 C3435T polymorphism and the eradication rate of H. pylori in the entire genetic model, irrespective of the PPI used. Furthermore, in Asian populations, the TT genotype decreased H. pylori eradication (TT vs CT+CC: OR=0.411, 95% CI = 0.280-0.602, P = 0.000). In addition, a significantly low eradication rate was observed in a recessive model, in which either lansoprazole (TT vs CT+CC: OR = 0.305, 95% CI = 0.184-0.504, P = 0.000) or omeprazole (TT vs CT+CC: OR = 0.229, 95% CI = 0.069-0.763, P = 0.016) was taken, in a subanalysis of individual PPIs. In the analyses that were stratified by disease type, no significant difference was observed in the peptic ulcer group and the combined diseases subgroup.

CONCLUSION

This meta-analysis indicated that the TT genotype of the MDR1 C3435T polymorphism decreased H. pylori eradication in Asian populations and was also associated with a low cure rate of H. pylori in patients taking lansoprazole- and omeprazole-based triple therapies. However, future studies using larger sample sizes are required.

Effects of Genetic Polymorphisms of Cytochrome P450 Enzymes and MDR1 Transporter on Pantoprazole Metabolism and Helicobacter pylori Eradication

Pantoprazole is a proton pump inhibitor that is commonly used in the treatment of peptic ulcer disease (PUD) and metabolized by cytochrome P450 (CYP) enzymes CYP2C19 and CYP3A4. Pantoprazole is a substrate for multi-drug resistance protein 1 (MDR1). Single nucleotide polymorphisms (SNPs) in CYP2C19, CYP3A4 and MDR1 affect enzyme activity or gene expression of proteins and may alter plasma pantoprazole concentrations and treatment success in PUD. In this study, we aimed to investigate the association between genetic polymorphisms in CYP2C19, CYP3A4 and MDR1 and pharmacokinetics of pantoprazole and therapeutic outcome in patients with either Helicobacter pylori-associated [H.P.(+)]-PUD or [H.P.(+)]-gastritis. The plasma pantoprazole concentrations were determined by using an HPLC method at the third hour after a 40-mg tablet of pantoprazole administration in 194 newly diagnosed patients with either [H.P.(+)]-PUD or [H.P.(+)]-gastritis. Genotyping was performed by using PCR-RFLP and DNA sequencing. Among patients appearing for follow-up examination (n = 105), the eradication rate for H. pylori was 82.8% (n = 87). The median pantoprazole plasma concentrations in poor metabolizers (PM), rapid metabolizers (RM) and ultrarapid metabolizers (URM) were 2.07, 1.69 and 1.28 μg/ml, respectively (p = 0.04). CYP3A4*1G and *22 polymorphisms did not affect plasma pantoprazole concentrations and H. pylori eradication rate. The MDR1 genetic polymorphisms did not affect plasma pantoprazole concentrations. MDR1 3435CC-2677GG-1236CC haplotype carriers had lower H. pylori eradication rate (60%) than the remaining subjects (84.9%) while the difference was not statistically significant (p = 0.07). In conclusion, while CYP2C19 genetic polymorphisms significantly affected plasma pantoprazole concentrations, polymorphisms of CYP2C19, CYP3A4 and MDR1 did not affect H. pylori eradication rates.

[Molecular genetic predictors of resistance to anti-Helicobacter pylori therapy]

In current clinical practice, there is no optimal empirical therapy for Helicobacter pylori (H. pylori) infection and there is a progressive decrease in the efficiency of classical eradication therapy (ET) regimens. The variability in the efficiency of ET in a specific patient is largely due to the heterogeneous molecular genetic mechanisms underlying the resistance of the microorganism to the components of the treatment regimens. The basis of the mechanisms for antibiotic resistance in H. pylori is mainly the point mutations in some genes, which determine alterations in the mechanisms of action of drugs, such as clarithromycin (domain V of 23S rRNA), metronidazole (rdxA, frxA), amoxicillin (pbp1A), tetracycline (16S rRNA), and levofloxacin (gyrA). The predictors of resistance to ET are also the CagA-negative status of the microorganism and the presence of the vacA s2 allele. There are a number of host genetic determinants (the CYP2C19 genotype (*1/*1, *1/*17, *17/*17) and the MDR1 3435 T/T genotype (in an Asian population)) that reduce the efficiency of ET, by altering the pharmacokinetics of proton pump inhibitors. In addition, the IL-1β-511 C/C polymorphism that affects gastric acid secretion is a predictor of the inefficiency of ET.

Loose ends in the eradication of Helicobacter pylori infection

The eradication of Helicobacter pylori is essential for prevention and treatment of various conditions associated with this infection. However, its effectiveness is limited and influenced by factors linked to the bacteria and the host. In particular, influence of the biotype, smoking, diabetes mellitus, and previous treatment failure in eradication is understudied. Our center proposed to evaluate these aspects in a real life cohort by applying a questionnaire with demographic and lifestyle variables in patients who consecutively underwent urease breath test after the eradication therapy.

Helicobacter pylori and Antibiotic Resistance, A Continuing and Intractable Problem

Helicobacter pylori, a human pathogen with a high global prevalence, is the causative pathogen for multiple gastrointestinal diseases, especially chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric malignancies. Antibiotic therapies remain the mainstay for H. pylori eradication; however, this strategy is hampered by the emergence and spread of H. pylori antibiotic resistance. Exploring the mechanistic basis of this resistance is becoming one of the major research questions in contemporary biomedical research, as such knowledge could be exploited to devise novel rational avenues for counteracting the existing resistance and devising strategies to avoid the development of a novel anti-H. pylori medication. Encouragingly, important progress in this field has been made recently. Here, we attempt to review the current state and progress with respect to the molecular mechanism of antibiotic resistance for H. pylori. A picture is emerging in which mutations of various genes in H. pylori, resulting in decreased membrane permeability, altered oxidation-reduction potential, and a more efficient efflux pump system. The increased knowledge on these mechanisms produces hope that antibiotic resistance in H. pylori can ultimately be countered.

Severe gastritis decreases success rate of Helicobacter pylori eradication

BACKGROUND

In several studies, different risk factors other than antibiotic resistance have been documented with Helicobacter pylori eradication failure. We aimed in this study to investigate the relationship of gastric density of H. pylori, the occurrence/degree of gastric atrophy, and intestinal metaplasia (IM) with success rate of H. pylori eradication.

METHODS

Two hundred consecutive treatment naive patients who received bismuth containing standart quadruple treatment due to H. pylori infection documented by histopathological examination of two antral or two corpal biopsies entered this retrospective study. The updated Sydney system was used to grade the activity of gastritis, density of H. pylori colonization, atrophy, and IM. Stages III and IV of operative link for gastritis assessment (OLGA) or the operative link on gastric intestinal metaplasia assessment (OLGIM) stages was considered as severe gastritis. H. pylori eradication was determined via stool H. pylori antigen test performed 4 weeks after the end of therapy.

RESULTS

The presence of gastric atrophy and IM was significantly higher in patients with eradication failure (p = 0.001 and 0.01, respectively). Severe gastritis (OLGA III-IV and OLGIM III-IV) rates were higher in eradication failure group. A multiple linear regression analysis showed that OLGA and OLGIM stages were to be independent risk factors for eradication failure (p = 0.03 and 0.01, respectively).

CONCLUSION

Our results suggested that histopathologically severe gastritis may cause H. pylori eradication failure. In addition, we found that H. pylori density was not a risk factor for treatment failure in patients who receive quadruple treatment.

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.

Attempts to enhance the eradication rate of Helicobacter pylori infection

Increasing rates of antimicrobial resistance to clarithromycin and metronidazole present challenges in maintaining optimal eradication rates. Knowledge of local antibiotic resistance and consumption pattern is important in selecting a reliable regimen. In addition, adverse effect profiles of therapeutic regimens are important and must be addressed to enhance compliance rates. Various methods of enhancing the eradication rates of Helicobacter pylori (H. pylori) have been investigated, including changing combinations or durations of established drugs, adding adjuvant drugs, or development of new molecules or agents. Bismuth-containing quadruple, sequential, concomitant, and levofloxacin-based triple therapies are replacing the long-standing standard of the triple regimen. Despite the encouraging results of these regimens, individualized approaches like treatment after antibiotics resistance test or CYP2C19 genotyping would be the mainstream of future therapy. Because scientific, economic, and technical problems make these advance therapies unfit for widespread use, future development for H. pylori therapy should be directed to overcome individualized antibiotic resistance. Although various novel regimens and additive agents have indicated favorable outcomes, more studies or validations are needed to become a mainstream H. pylori therapy.

A review of Helicobacter pylori diagnosis, treatment, and methods to detect eradication

Helicobacter pylori (H. pylori) affects nearly half of the world’s population and, thus, is one of the most frequent and persistent bacterial infections worldwide. H. pylori is associated with peptic ulcer disease, gastric ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. Various diagnostic methods exist to detect infection, and the choice of one method or another depends on several factors, such as accessibility, advantages and disadvantages of each method, cost, and the age of patients. Once H. pylori infection is diagnosed, the clinician decides whether treatment is necessity, according to the patient’s clinical condition. Typically, eradication of H. pylori is recommended for treatment and prevention of the infection. Cure rates with the standard triple therapy are acceptable, and effective quadruple therapies, sequential therapies, and concomitant therapies have been introduced as key alternatives to treat H. pylori infection. In this work, we review the main diagnostic methods used to identify H. pylori infection and to confirm eradication of infection. In addition, key factors related to treatment are reviewed.

What is the impact of Helicobacter pylori density on the success of eradication therapy: a clinico-histopathological study

BACKGROUND AND OBJECTIVE

To investigate the presence of any possible association between H. pylori density in the stomach and the efficacy of triple (lansoprazole 30 mg b.i.d., clarithromycin 500 mg b.i.d. and amoxicillin 1g b.i.d. for 14 days) and bismuth-containing quadruple (colloidal bismuth subcitrate 300 mg q.i.d., lansoprazole 30 mg b.i.d., tetracycline 500 mg q.i.d. and metronidazole 500 mg t.i.d. for 14 days) eradication therapies.

METHODS

Eighty-five cases with H. pylori infection (proved by rapid urease test and histology) were studied. In each case, the density of H. pylori colonization was graded according to the updated Sydney classification. H. pylori eradication was determined via the (14)C-Urea breath test performed 4 weeks after the end of therapy.

RESULTS

The eradication rate of H. pylori was 50% (30 out of 60) in the triple therapy and 92% (23 of 25) in the quadruple therapy group. In the triple therapy group, the eradication rate of H. pylori decreased as the initial density of H. pylori increased (density of H. pylori: 1, 58.3%; 2, 54.5%; 3, 52.4%; 4, 38.5%; 5, 33.3%). In two cases with eradication failure after quadruple therapy, the grades of bacterial density were 1 and 3.

CONCLUSION

H. pylori density, as assessed by histological grading, may predict the usefulness of triple therapy. The higher the H. pylori density, the less effective triple therapy will be at successful eradication of H. pylori. Quadruple therapy does not seem to be negatively affected by bacterial density.

Functional significance of genetic polymorphisms in P-glycoprotein (MDR1, ABCB1) and breast cancer resistance protein (BCRP, ABCG2)

Recent pharmacogenomic/pharmacogenetic (PGx) studies have disclosed important roles for drug transporters in the human body. Changes in the functions of drug transporters due to drug/food interactions or genetic polymorphisms, for example, are associated with large changes in pharmacokinetic (PK) profiles of substrate drugs, leading to changes in drug response and side effects. This information is extremely useful not only for drug development but also for individualized treatment. Among drug transporters, the ATP-binding cassette (ABC) transporters are expressed in most tissues in humans, and play protective roles; reducing drug absorption from the gastrointestinal tract, enhancing drug elimination into bile and urine, and impeding the entry of drugs into the central nervous system and placenta. In addition to PK/pharmacodynamic (PD) issues, ABC transporters are reported as etiologic and prognostic factors (or biomarkers) for genetic disorders. Although a consensus has not yet been reached, clinical studies have demonstrated that the PGx of ABC transporters influences the overall outcome of pharmacotherapy and contributes to the pathogenesis and progression of certain disorders. This review explains the impact of PGx in ABC transporters in terms of PK/PD, focusing on P-glycoprotein and breast cancer resistance protein (BCRP).

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.

Eradication of H. pylori Infection: the Challenge is on if Standard Therapy Fails

The recommended standard triple therapy for Helicobacter pylori infection, consisting of a proton pump inhibitor, clarithromycin and amoxicillin or metronidazole, can reach eradication rates in over 90%. However, in recent years resistance to antibiotics has increased and eradication rates have declined. Approximately one in five patients need a second-line therapy because eradication therapy fails. Second-line treatment with a bismuth-based quadruple therapy leads to satisfactory eradication rates, but bismuth is not available in many countries. Modern second- and third-line treatments can only be successful if they are adapted to the current resistance situation and they need to evolve continuously. Moreover, pharmacodynamic effects due to polymorphisms of the cytochrome P450 system are important. Because therapy adherence is significantly associated with therapy success, modern regimens if possible should be easy to take and well tolerated. In recent years, various novel salvage-therapy regimens have been investigated that significantly improve treatment options.

Effects of CYP2C19, MDR1, and interleukin 1-B gene variants on the eradication rate of Helicobacter pylori infection by triple therapy with pantoprazole, amoxicillin, and metronidazole

OBJECTIVE

Eradication of H. pylori is an important treatment strategy in peptic ulcer patients. Current regimens of eradication consist of proton pump inhibitor (PPI) and two antibiotics. Effects of PPI may depend on their metabolism, and other factors important for the pathophysiology of peptic ulcer disease. Aim of the present study was to evaluate an association of CYP2C19, MDR1, and IL-1B polymorphisms with the eradication rate of H. pylori in Polish Caucasian patients treated with a triple therapy of pantoprazole, amoxicillin, and metronidazole.

METHODS

A total of 139 peptic ulcer patients, positive for H. pylori infection, were treated with triple therapy (pantoprazole + amoxicillin + metronidazole). Subsequently, the patients were divided into two groups (group 1, success, and group 2, failure of eradication after therapy) and genotyped by the PCR-RFLP method for the presence of CYP2C19 variant alleles (*2, *3, and *17), and MDR1 3435C>T and IL-1B +3954C>T polymorphisms. Pantoprazole serum concentrations were measured using the HPLC method.

RESULTS

No significant differences in frequency or distribution of CYP2C19 genotypes were found between the two groups of patients (i.e., with successful H. pylori eradication and treatment failure). However, any carrier of defective CYP2C19*2/*2 genotype was found among patients with treatment failure. Similarly, MDR1 and IL-1B genotypes were found to be significantly associated with the success or failure of H. pylori eradication. Univariate and multivariate analysis of the genotypes did not reveal any significant association between the genotypes and H. pylori eradication. Pantoprazole concentrations differed significantly, and were the highest in patients with defective allele CYP2C19*2 carriers and lowest in hyperactive genotype homozygotes CYP2C19*17/*17.

CONCLUSION

The results suggest that the CYP2C19 genotype contrary to MDR1 and IL-1B genotypes may have an impact on the efficacy of H. pylori eradication in peptic ulcer patients treated with pantoprazole in Polish Caucasian peptic ulcer patients administered pantoprazole, amoxicillin, and metronidazole.

Effects of CYP2C19, MDR1, and interleukin 1-B gene variants on the eradication rate of Helicobacter pylori infection by triple therapy with pantoprazole, amoxicillin, and metronidazole

OBJECTIVE

Eradication of H. pylori is an important treatment strategy in peptic ulcer patients. Current regimens of eradication consist of proton pump inhibitor (PPI) and two antibiotics. Effects of PPI may depend on their metabolism, and other factors important for the pathophysiology of peptic ulcer disease. Aim of the present study was to evaluate an association of CYP2C19, MDR1, and IL-1B polymorphisms with the eradication rate of H. pylori in Polish Caucasian patients treated with a triple therapy of pantoprazole, amoxicillin, and metronidazole.

METHODS

A total of 139 peptic ulcer patients, positive for H. pylori infection, were treated with triple therapy (pantoprazole + amoxicillin + metronidazole). Subsequently, the patients were divided into two groups (group 1, success, and group 2, failure of eradication after therapy) and genotyped by the PCR-RFLP method for the presence of CYP2C19 variant alleles (*2, *3, and *17), and MDR1 3435C>T and IL-1B +3954C>T polymorphisms. Pantoprazole serum concentrations were measured using the HPLC method.

RESULTS

No significant differences in frequency or distribution of CYP2C19 genotypes were found between the two groups of patients (i.e., with successful H. pylori eradication and treatment failure). However, any carrier of defective CYP2C19*2/*2 genotype was found among patients with treatment failure. Similarly, MDR1 and IL-1B genotypes were found to be significantly associated with the success or failure of H. pylori eradication. Univariate and multivariate analysis of the genotypes did not reveal any significant association between the genotypes and H. pylori eradication. Pantoprazole concentrations differed significantly, and were the highest in patients with defective allele CYP2C19*2 carriers and lowest in hyperactive genotype homozygotes CYP2C19*17/*17.

CONCLUSION

The results suggest that the CYP2C19 genotype contrary to MDR1 and IL-1B genotypes may have an impact on the efficacy of H. pylori eradication in peptic ulcer patients treated with pantoprazole in Polish Caucasian peptic ulcer patients administered pantoprazole, amoxicillin, and metronidazole.

Effect of MDR1 C3435T polymorphism on lansoprazole in healthy Japanese subjects

BACKGROUND AND AIMS

The effect of multidrug resistance transporter gene 1 (MDR1) on the bioavailability and kinetics of several substrates has not yet been fully elucidated. We evaluated the influence of MDR1 C3435T polymorphism on the pharmacokinetics and pharmacodynamics of lansoprazole in Japanese subjects.

METHODS

Fifteen healthy volunteers with the rapid extensive metabolizer genotype of CYP2C19 were classified into three MDR1 C3435T genotype groups: C/C (n = 5), C/T (n = 5), and T/T (n = 5). Lansoprazole 30 mg was administered orally for 15 days. The intragastric pH and plasma lansoprazole levels were determined on days 1 and 15.

RESULTS

On day 1, the mean C(max) of lansoprazole in the T/T group was significantly higher than that in the C/C or C/T groups (T/T 1,248, C/C 618, C/T 607 ng/ml; P = 0.038). On day 15, similar MDR1 genotype-dependent differences were observed in the C(max) of lansoprazole, although smaller than the differences observed on day 1. In contrast, the intragastric pH attained after lansoprazole administration did not differ among MDR1 genotype groups on either day 1 or day 15.

CONCLUSION

Although the sample size was small, our study demonstrated that the MDR1 C3435T polymorphism influenced the pharmacokinetics, but not the pharmacodynamics (i.e., intragastric pH), of lansoprazole in rapid metabolizers of CYP2C19.

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.

[The new aspects of the eradication of Helicobacter pylori and the importance of bacterial resistance]

The first line treatment of Helicobacter pylori infection is a 7-day PPI-based (PPI+clarithromycin+amoxycillin or metronidazole) combined therapy. Success of first eradication attempts in the literature is around 80-90%, while in Hungary 75%. Repeated eradication is needed in 10-25% of cases. The second and third line treatments are successful only in 36% and 20% of cases. Treatment failure is increasing worldwide with the higher rates of bacterial, especially clarithromycin resistance. Patients' noncompliance, pharmacogenetic and pharmacokinetic properties of the applied drugs are important as well. The eradication success rates are unacceptable in populations with higher metronidazole and clarithromycin resistance, that is why there is a need for newer combinations. A possible solution is the application of sequential therapy, or using newer antibiotics (levofloxacin). The importance of new natural substances (lactoferrin, probiotics, plant drugs) must be further investigated.

Effect of the CYP2C19 polymorphism on the eradication rate of Helicobacter pylori infection by 7-day triple therapy with regular proton pump inhibitor dosage

BACKGROUND AND AIM

Proton pump inhibitors (PPI) are mainly metabolized by cytochrome P450 2C19 (CYP2C19) in the liver. We investigated whether the CYP2C19 genotype plays a role in the eradication rate of Helicobacter pylori (H. pylori) infection in patients receiving pantoprazole- or esomeprazole-based triple therapy.

METHODS

A total of 327 patients infected with H. pylori were treated with either pantoprazole or esomeprazole, plus amoxicillin and clarithromycin for 7 days. The presence of the CYP2C19 genotype was determined by pyrosequencing.

RESULTS

The overall H. pylori eradication rate was 85%; 82.6% for the PAC regimen, and 88.3% for the EAC regimen; the differences were not statistically significant. The overall eradication rate in the poor metabolizer groups (PM) was significantly higher than in the extensive metabolizer groups (EM) (97.4% vs 83.3%; P = 0.016). The eradication rates in the EM and PM groups were 80.8% and 95.7% for the PAC regimen and 86.8% and 100% for the EAC regimen, respectively.

CONCLUSION

The results of this study suggest that the CYP2C19 genotype status may play a role in the H. pylori eradication rate in patients receiving pantoprazole or esomeprazole-based triple therapy.

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.