CYP2C19Polymorphism and Proton Pump Inhibitors

Pharmacogenomics in Solid Tumors: A Comprehensive Review of Genetic Variability and Its Clinical Implications

Pharmacogenomics, the study of how genetic variations influence drug response, has become integral to cancer treatment as personalized medicine evolves. This review aims to explore key pharmacogenomic biomarkers relevant to cancer therapy and their clinical implications, providing an updated and comprehensive perspective on how genetic variations impact drug metabolism, efficacy, and toxicity in oncology. Genetic heterogeneity among oncology patients significantly impacts drug efficacy and toxicity, emphasizing the importance of incorporating pharmacogenomic testing into clinical practice. Genes such as CYP2D6, DPYD, UGT1A1, TPMT, EGFR, KRAS, and BRCA1/2 play pivotal roles in influencing the metabolism, efficacy, and adverse effects of various chemotherapeutic agents, targeted therapies, and immunotherapies. For example, CYP2D6 polymorphisms affect tamoxifen metabolism in breast cancer, while DPYD variants can result in severe toxicities in patients receiving fluoropyrimidines. Mutations in EGFR and KRAS have significant implications for the use of targeted therapies in lung and colorectal cancers, respectively. Additionally, BRCA1/2 mutations predict the efficacy of PARP inhibitors in breast and ovarian cancer. Ongoing research in polygenic risk scores, liquid biopsies, gene-drug interaction networks, and immunogenomics promises to further refine pharmacogenomic applications, improving patient outcomes and reducing treatment-related adverse events. This review also discusses the challenges and future directions in pharmacogenomics, including the integration of computational models and CRISPR-based gene editing to better understand gene-drug interactions and resistance mechanisms. The clinical implementation of pharmacogenomics has the potential to optimize cancer treatment by tailoring therapies to an individual's genetic profile, ultimately enhancing therapeutic efficacy and minimizing toxicity.

Evaluating Vonoprazan for the treatment of erosive GERD and heartburn associated with GERD in adults

INTRODUCTION

Gastroesophageal reflux disease (GERD) is a common debilitating chronic disease presenting in two main forms based on esophageal mucosal appearance, the erosive reflux disease (ERD) and the non-erosive reflux disease (NERD). Acid secretion is a key factor in the disease pathogenesis and management. Potent acid-suppressant drugs have been manufactured since the mid of 1970s, initially with histamine-H2-receptors antagonists, and later, inhibitors of the proton pump (H+-K+-ATPase).More recently, potassium-competitive acid blockers (p-CABs), particularlyVonoprazan, have been introduced. Vonoprazan has shown high efficacy and safety profiles and exhibits several advantages that allow to overcome shortcomings of proton pump inhibitors (PPIs).

AREAS COVERED

In this review, we provide an updated summary of Vonoprazan pharmacodynamics and its role in clinical practice for the management of erosive esophagitis and GERD-related heartburn. Moreover, we discuss characteristics of Vonoprazan that allow to bypass some limitations of the older PPIs.

EXPERT OPINION

Long-term safety and efficacy of Vonoprazan have already been demonstrated for the induction and maintenance of ERD, preventing nocturnal acid breakthrough, reducing reflux symptoms in non-responder to standard therapy. Ongoing and future studies are expected to further elucidate its long-term benefits and potential applications in other acid-related disorders.

Associated factors with voriconazole plasma concentration: a systematic review and meta-analysis

Background: Voriconazole plasma concentration exhibits significant variability and maintaining it within the therapeutic range is the key to enhancing its efficacy. We conducted a systematic review and meta-analysis to estimate the prevalence of patients achieving the therapeutic range of plasma voriconazole concentration and identify associated factors. Methods: Eligible studies were identified through the PubMed, Embase, Cochrane Library, and Web of Science databases from their inception until 18 November 2023. We conducted a meta-analysis using a random-effects model to determine the prevalence of patients who reached the therapeutic plasma voriconazole concentration range. Factors associated with plasma voriconazole concentration were summarized from the included studies. Results: Of the 60 eligible studies, 52 reported the prevalence of patients reaching the therapeutic range, while 20 performed multiple linear regression analyses. The pooled prevalence who achieved the therapeutic range was 56% (95% CI: 50%-63%) in studies without dose adjustment patients. The pooled prevalence of adult patients was 61% (95% CI: 56%-65%), and the pooled prevalence of children patients was 55% (95% CI: 50%-60%) The study identified, in the children population, several factors associated with plasma voriconazole concentration, including age (coefficient 0.08, 95% CI: 0.01 to 0.14), albumin (-0.05 95% CI: -0.09 to -0.01), in the adult population, some factors related to voriconazole plasma concentration, including omeprazole (1.37, 95% CI 0.82 to 1.92), pantoprazole (1.11, 95% CI: 0.17-2.04), methylprednisolone (-1.75, 95% CI: -2.21 to -1.30), and dexamethasone (-1.45, 95% CI: -2.07 to -0.83). Conclusion: The analysis revealed that only approximately half of the patients reached the plasma voriconazole concentration therapeutic range without dose adjustments and the pooled prevalence of adult patients reaching the therapeutic range is higher than that of children. Therapeutic drug monitoring is crucial in the administration of voriconazole, especially in the children population. Particular attention may be paid to age, albumin levels in children, and the use of omeprazole, pantoprazole, dexamethasone and methylprednisolone in adults. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023483728.

Association Study of Esomeprazole Pharmacokinetics and CYP2C19 Gene Polymorphisms

To investigate the association between esomeprazole pharmacokinetics and CYP2C19 gene polymorphisms in a cohort of 95 healthy Chinese participants. A cohort of 95 participants was assembled and stratified into 2 distinct groups, receiving either 20 or 40 mg of esomeprazole through oral administration. The subjects encompassed 17 poor metabolizers, 47 intermediate metabolizers, and 31 rapid metabolizers, and their genotypes were ascertained using the polymerase chain reaction-restriction fragment length polymorphism technique. Esomeprazole plasma concentrations were quantified employing a high-performance liquid chromatography-ultraviolet method. Pharmacokinetic parameters were computed via Phoenix WinNonlin 6.1 software, while SPSS 26.0 facilitated statistical analysis to contrast the pharmacokinetics and the CYP2C19 genotypes. In the aftermath of administering 20 or 40 mg esomeprazole, marked differences were discerned between terminal elimination half-life, maximum concentration/dose, and area under the plasma concentration-time curve from time zero to infinity/dose of esomeprazole (P < .05), with the exception of time to maximum concentration. The findings of this investigation signify a significant association between esomeprazole metabolism and CYP2C19 gene polymorphisms. There were no unprecedented adverse events documented subsequent to the administration of 20 and 40 mg esomeprazole dosages. Esomeprazole has manifested promising safety and tolerability profiles in pertinent clinical trials.

CYP2C19 genotypes and osteoporotic fractures in long-term users of proton pump inhibitors: A hospital-based study

Proton pump inhibitors (PPIs) are commonly prescribed medications. The existing data suggest that individuals at a high risk of fractures have been exposed to high doses of PPIs for prolonged durations. CYP2C19 plays a pivotal role in metabolism of PPIs and thereby influences their pharmacokinetic profile. Hence, we hypothesize that CYP2C19 genotypes may be associated with fragility fracture among PPIs users due to PPI exposure. This study aimed to investigate the association between CYP2C19 genotypes, bone mineral density (BMD), and osteoporotic fracture in a hospital-based population. This retrospective cohort study enrolled patients who were prescribed long-term PPIs at Taichung Veterans General Hospital using data extracted from the Taiwan Precision Medicine Initiative between January 2010 and April 2021. Associations between CYP2C19 phenotypes, comorbidities, and fractures in PPI users were analyzed. We enrolled 1518 long-term PPI users; 571 (38%), 727 (48%), and 220 (14%) CYP2C19 normal metabolizers (NMs), intermediate metabolizers (IMs), and poor metabolizers (PMs), respectively. Among them, 49 (3.2%) patients developed fractures within the 1-year follow-up period; 20 (3.5%) fractures in NMs, 24 (3.3%) in IMs, and 5 (2.3%) in PMs, respectively. No significant difference was observed among CYP2C19 genotypes and fracture. Additionally, BMD measurements during the 1-year follow-up period were made available among 75 participants. No significant difference in BMD between CYP2C19 PMs and non-PMs was found. This real-world, hospital-based study concludes that CYP2C19 PMs/IMs are not associated with an increased risk for fractures or reduced BMD in individuals on long-term PPI therapy.

Combined contributions of cytochrome P450s (CYPs) and non-enzymatic metabolism in the in vitro biotransformation of anaprazole, a novel proton pump inhibitor

Anaprazole, a new proton pump inhibitor (PPI), is designed for the treatment of acid-related diseases, such as gastric ulcers and gastroesophageal reflux. This study explored the in vitro metabolic transformation of anaprazole. The metabolic stabilities of anaprazole in human plasma and human liver microsomes (HLM) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Then, the contribution (%) of non-enzymatic and cytochrome P450s (CYPs) enzyme-mediated anaprazole metabolism was assessed. To obtain the metabolic pathways of anaprazole, the metabolites generated in HLM, thermal deactivated HLM, and cDNA-expressed recombinant CYPs incubation systems were identified by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF-MS). Results showed that anaprazole was very stable in human plasma and unstable in HLM. The contribution (%) of non-enzymatic vs. CYPs enzyme-mediated metabolism was 49% vs. 51%. CYP3A4 was the major enzyme (48.3%), followed by CYP2C9 (17.7%) and CYP2C8 (12.3%), in responsible for the metabolism of anaprazole. Specific chemical inhibitors targeting CYP enzymes notably blocked the metabolic transformation of anaprazole. Six metabolites of anaprazole were identified in the non-enzymatic system, whereas 17 metabolites were generated in HLM. The biotransformation reactions mainly included sulfoxide reduction to thioether, sulfoxide oxidation to sulfone, deoxidation, dehydrogenation, O-dealkylation or O-demethylation of thioether, O-demethylation and dehydrogenation of thioether, O-dealkylation and dehydrogenation of thioether, thioether O-dealkylation and dehydrogenation of thioether, and O-dealkylation of sulfone. Both enzymatic and non-enzymatic metabolisms contribute to the clearance of anaprazole in human. Anaprazole is less likely to develop drug-drug interactions in clinical use compared to other PPIs.

Carcinogenicity assessment of tegoprazan in Sprague-Dawley (Crl:CD) rats and ICR (Crl:CD1) mice

Tegoprazan is a novel potassium-competitive acid blocker (P-CAB) that reversibly inhibits the proton pump in gastric parietal cells and has been approved for the treatment of acid-related diseases in Korea. This study aimed to evaluate the carcinogenic potential of tegoprazan in Sprague-Dawley rats and CD-1 mice. Tegoprazan was administered daily by oral gavage to rats for up to 94 weeks and mice for up to 104 weeks. Evidence of carcinogenic potential of tegoprazan was identified in rats only and was limited to benign and/or malignant neuroendocrine cell tumors at exposures >7-fold of the recommended human dose. Glandular stomach findings were considered secondary to the expected pharmacology of tegoprazan, characterized by their location in the fundic and body regions of the stomach. Overall, tegoprazan induced gastric enterochromaffin-like (ECL) cell tumors in SD rats, but did not produce any treatment-related statistically significant increase in the incidence of neoplasms relevant to humans when administered to SD rats and CD-1 mice by gavage at doses up to 300 and 150 mg/kg/day, respectively. Gastric ECL cell tumors are thought to be induced by the exaggerated indirect pharmacological effect of tegoprazan, similar to that reported for proton pump inhibitors (PPIs) and other P-CABs.

Clinical trial: seven-day vonoprazan- versus 14-day proton pump inhibitor-based triple therapy for first-line Helicobacter pylori eradication

BACKGROUND

One-week triple therapy with vonoprazan is endorsed by Japanese guidelines as an alternative to proton pump inhibitor (PPI)-based triple therapy for first-line Helicobacter pylori eradication. This contrasts with Western guidelines recommending 2-week PPI-based triple therapy.

AIM

To verify the non-inferiority of 1-week vonoprazan-based triple therapy versus 2-week PPI-based triple therapy as first-line H. pylori eradication in a multiracial Asian cohort.

METHODS

Randomised controlled trial of treatment-naïve patients with H. pylori infection assigned 1:1 to either 7 days amoxicillin 1 g + clarithromycin 500 mg + vonoprazan 20 mg twice per day or 14 days amoxicillin 1 g + clarithromycin 500 mg + omeprazole OR esomeprazole OR rabeprazole 20 mg twice/day. Subjects were randomly assigned to each PPI 1:1:1 Demographics, H. pylori resistance, CYP 2C19 genotype, eradication success and safety profiles were compared between groups.

RESULTS

Between June 2019 and June 2021, 252 of 1097 subjects screened were randomised. 244 (age [SD] 51.7 [14.6]) received vonoprazan- (n = 119) or PPI-based (n = 125) triple therapy. Eradication rates by intention-to-treat analysis were 87.4% (vonoprazan-based triple therapy) versus 88.0% (PPI-based triple therapy. By per protocol analysis: 96.3% (vonoprazan-based triple therapy) versus 94.0% (PPI-based triple therapy). Clarithromycin resistance predicted treatment failure on multivariate analysis: RR 11.4; 95% CI [1.4-96.3], p = 0.025. No significant differences in CYP 2C19 genotypes or adverse events occurred between groups.

CONCLUSION

One-week vonoprazan-based triple therapy achieved comparable efficacy to 2-week PPI-based triple therapy and was well tolerated.

Assessing the Roles of Molecular Markers of Antimalarial Drug Resistance and the Host Pharmacogenetics in Drug-Resistant Malaria

Malaria caused by the Plasmodium parasites is a major public health concern in malaria-endemic regions with P. falciparum causing the most severe form of the disease. The use of antimalarial drugs for the management of the disease proves to be one of the best methods to manage the disease. Unfortunately, P. falciparum has developed resistance to almost all the current in-use antimalarial drugs. Parasite development of resistance is primarily caused by both parasite and host genetic factors. The parasite genetic factors involve undergoing mutation in the drug target sites or increasing the drug target gene copy number to prevent the intended action of the antimalarial drugs. The host pharmacogenetic factors which determine how a particular antimalarial drug is metabolized could result in variations of drug plasma concentration and consequently contribute to variable treatment outcomes and the emergence or propagation of resistant parasites. Since both host and parasite genomes play a role in antimalarial drug action, a key question often asked is, “which of the two strongly drives or controls antimalarial drug resistance?” A major finding in our recent study published in the Malaria Journal indicates that the parasite's genetic factors rather than the host are likely to energize resistance to an antimalarial drug. However, others have reported contrary findings suggesting that the host genetic factors are the force behind resistance to antimalarial drugs. To bring clarity to these observations, there is the need for deciphering the major driving force behind antimalarial drug resistance through optimized strategies aimed at alleviating the phenomenon. In this direction, literature was systematically reviewed to establish the role and importance of each of the two factors aforementioned in the etiology of drug-resistant malaria. Using Internet search engines such as Pubmed and Google, we looked for terms likely to give the desired information which we herein present. We then went ahead to leverage the obtained information to discuss the globally avid aim of combating antimalarial drug resistance.

Quadruple therapies are superior to standard triple therapy for Helicobacter pylori first-line eradication in Chile

INTRODUCTION

Helicobacter pylori infection affects approximately 70% of the Chilean population. It is a public health problem whose eradication treatment is part of the explicit health guarantees in Chile.

OBJECTIVES

Characterize the most widely used H. pylori first-line eradication therapies in our environment and evaluate their efficacy.

METHODS

A retrospective observational study was carried out where, in patients with certified H. pylori infection, the eradication therapy indicated by the treating physician, its efficacy, adherence and adverse effects, in addition to the eradication certification method used, were evaluated.

RESULTS

242 patients and 4 main therapies were analyzed: standard triple therapy, dual therapy, concomitant therapy, and bismuth quadruple therapy. Eradication rates of 81.9% (95% CI 74.44-87.63), 88.5% (95% CI 73.13-95.67), 93.7% (95% CI 78.07-98.44) and 97.6% (95% CI 84.81-99.67) were observed respectively, with concomitant therapy (RR: 1.14; 95% CI 1.01-1.29; p=.028) and quadruple therapy with bismuth (RR: 1.19; 95% CI 1.09-1.31; p<.001) being significantly more effective than standard triple therapy. Regarding the rate of reported adverse effects, it was 58.5% (95% CI 50.66-65.92), 35.4% (95% CI 24.6-48.11), 22.9% (95% CI 81-37.14) and 63.4% (95% CI 47.8-76.64), having the dual and concomitant therapy significantly fewer adverse effects compared with standard therapy.

CONCLUSIONS

Quadruple therapies are superior to standard triple therapy and should be considered as first-line treatment in Chile. Dual therapy is promising. More studies will be required to determine which therapies are most cost-effective.

Use of Pharmacogenomics to Guide Proton Pump Inhibitor Therapy in Clinical Practice

Prescribing the right medication, at the right dose, to the right patient is the goal of every physician. Pharmacogenomic information is an emerging tool that can be used to deliver precision medicine. In this review, we discuss the pharmacogenomics of available PPIs, racial differences of CYP2C19 and how PPI pharmacogenomics affects the treatment of common gastrointestinal diseases. We also provide practical guidance on when to order pharmacogenomic testing, which test to order, and how to modify treatment based on published guidelines.

Inappropriate Medication Use and Cost Comparison Analysis of Proton Pump Inhibitors: Evidence from an Indian Tertiary Care Facility

RATIONALE AND OBJECTIVE

Proton pump inhibitor (PPI) is one of the most widely prescribed medicines and commonly used in gastric related disorders and there is a huge need to analyze the irrational use of PPI in a country like India. The present study was designed to describe the rational drug use and cost comparison analysis of PPI in a rural tertiary care hospital.

METHODOLOGY

A prospective observational study was performed among 253 inpatients for a period of 9 months after getting ethical approval. Those who received the PPIs for any of its indications were included in the study without any gender or age restriction. US FDA guidelines were used to analyse the appropriateness of the drug use and cost comparison analysis of the branded versus generic PPIs was also performed.

FINDINGS

Among the 253 inpatients, the majority (62%) were male and the mean age was 46±19 years. Mean hospital stay and the number of drugs in prescription were found to be 4.0 ± 1days 4.39 ±1.16 items, respectively. Pantoprazole (76%) was the most prescribed PPI even though the majority (57%) of the patients treated outside the FDA approved indication. Drug interaction has been reported in 14% and ADR in 9% of the population. The average cost of hospital stay estimated as 207.96+149.57 INR, and potential cost saving of INR 41582 was observed with generic replacement.

CONCLUSION

The study inferred irrational drug use of PPI still prevalent, that too without considering the economic impact of it on general populations. Healthcare practitioners should be aware and cautious while prescribing the PPI to identify the actual need and to choose the most cost-effective alternative 1.

Evaluation of CYP2C19 Gene Polymorphisms in Patients with Acid Peptic Disorders Treated with Esomeprazole

Background

CYP2C19 is a highly polymorphic gene that encodes an enzyme with the same name and whose function is associated with the metabolism of many important drugs, such as proton pump inhibitors (such as esomeprazole, which is used for the treatment of acid peptic disease). Genetic variants in CYP2C19 alter protein function and affect drug metabolism. This study aims to genotypically and phenotypically characterize the genetic variants in the CYP2C19 gene in 12 patients with acid peptic disorders and different therapeutic profiles to proton pump inhibitor (PPI) drugs. The patients were randomly selected from a controlled, randomized and blinded clinical pilot trial of 33 patients. We determined the presence and frequency of single nucleotide polymorphisms (SNPs) within exons 1–5 and 9, the intron-exon junctions, and a fragment in the 3ʹ UTR region of the CYP2C19 gene using Sanger sequencing. Undescribed polymorphisms were analyzed by free online bioinformatics tools to evaluate the potential molecular effects of these genetic variants.

Results

We identified nine polymorphisms, six of which had no reported functions. One of these genetic variants, with a functional impact, not yet reported (p.Arg132Trp) was predicted by bioinformatic tools as potentially pathogenic. This finding suggests that p.Arg132Trp could be related to poor metabolizers of drugs metabolized by CYP2C19.

Conclusion

We identified the genotype spectrum of variants in CYP2C19. The genotype spectrum of variants in CYP2C19 could predict the treatment response and could support to evaluate clinical efficacy in patients treated with esomeprazole.

Sources of Interindividual Variability

The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in others. A significant source of this variability in drug response is drug metabolism, where differences in presystemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, C_max, and/or C_min) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is recognized that both intrinsic factors (e.g., genetics, age, sex, and disease states) and extrinsic factors (e.g., diet , chemical exposures from the environment, and the microbiome) play a significant role. For drug-metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, upregulation and downregulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less predictable and time-dependent manner. Understanding the mechanistic basis for variability in drug disposition and response is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that will improve outcomes in maintaining health and treating disease.

Randomized controlled study on the effects of triple therapy including vonoprazan or rabeprazole for the second-line treatment of Helicobacter pylori infection

BACKGROUND AND AIM

Inhibition of gastric acid secretion is important for eradicating Helicobacter pylori. Vonoprazan (VPZ) is a strong, long-lasting inhibitor of gastric acid secretion. Studies that examined the effectiveness of VPZ-based triple therapy in second-line treatment have been performed. However, there have been no randomized controlled studies to compare the effect between VPZ-based triple therapy and proton pump inhibitor (PPI)-based triple therapy in second-line treatment, and it is not known which is more effective between VPZ-based and PPI-based therapies. This study aimed to compare the effectiveness of second-line triple therapies including VPZ or rabeprazole (RPZ) as the PPI.

METHODS

Eligible patients with H. pylori infection who failed first-line triple therapy were assigned randomly to the VPZ [VPZ40 mg/day, amoxicillin (AMPC) 1500 mg/day, metronidazole (MNZ) 500 mg/day] or RPZ (RPZ20 mg/day, AMPC1500 mg/day, MNZ500 mg/day) group. A ¹³C-urea breath test result of less than 2.5% was considered as successful eradication.

RESULTS

In total, 46 and 41 patients were analyzed as intention to treat (ITT) and per protocol (PP), respectively. Eradication rates in the VPZ and RPZ groups were 73.9% [95% confidence interval (CI) 51.6-89.8%] and 82.6% (95% CI 61.2-95.0%) based on ITT analysis, respectively (p = 0.72). Based on PP analysis, the eradication rates in the VPZ and RPZ groups were 89.5% (95% CI 66.9-98.7%) and 86.4% (95% CI 65.1-97.1%), respectively (p = 1.00). Two patients in the VPZ group and one in the RPZ group discontinued treatment due to side effects (p = 1.00).

CONCLUSION

There were no significant differences in efficacy and safety between second-line therapies including VPZ or RPZ.

Association of use of proton pump inhibitors and H2 antagonists with stomach wall uptake in 99mTc-methoxy-isobutyl-isonitrile (MIBI) myocardial perfusion imaging

BACKGROUND

Stomach wall uptake (SWU) of tracer in 99mTc-MIBI myocardial perfusion imaging (MPI) occasionally leads to imaging artifacts, thereby lowering the diagnostic accuracy. It is less-studied phenomenon for possible link with proton pump inhibitors (PPIs) intake. This prospective work looked for association of SWU with PPI intake and compared its incidence with H2 antagonists (H2A) users and patients not on either gastroprotective medication.

METHODS

One hundred fifty-six patients undergoing one day stress/rest 99mTc-MIBI SPECT-MPI were distributed into four groups: control group (n = 48, not on any gastroprotective medication), PPI group (n = 47, on PPI treatment), H2A group (n = 19, on H2A therapy), and intervention group (N = 42, PPI discontinued for 3 days before MPI). Poststress planar images were analyzed for clinically relevant SWU.

RESULTS

Clinically relevant SWU was seen in 36% of PPI group patients compared to 8% in the control group, 10.5% in the H2A group, and 9.5% in the intervention group, respectively, with statistically significant difference. Only 1/40 patients undergoing exercise stress showed clinically relevant SWU compared to 26/116 patients undergoing adenosine stress (P = .020).

CONCLUSION

Patients on PPIs scheduled for vasodilator stress MPI may discontinue PPIs for 3 days, or replace with H2A to reduce the incidence of clinically relevant SWU associated with PPI therapy.

Population pharmacokinetic analysis of esomeprazole in Japanese subjects with various CYP2C19 phenotypes

WHAT IS KNOWN AND OBJECTIVE

Esomeprazole, the S-isomer of omeprazole, is a proton pump inhibitor which has been approved by over 125 countries, also known as NEXIUM^® . Esomeprazole was developed to provide further improvement on efficacy for acid-related diseases with higher systemic bioavailability due to the less first-pass metabolism and lower plasma clearance. Esomeprazole is primarily metabolized by CYP2C19. Approximately <1% of Caucasians and 5%-10% of Asians have absent CYP2C19 enzyme activity. Although the influence of various CYP2C19 phenotypes on esomeprazole pharmacokinetics has been studied, this is the first report in the Japanese population where 27 low CYP2C19 metabolizers were included.

METHODS

In this study, a population PK model describing the PK of esomeprazole was developed to understand the difference of CYP2C19 phenotypes on clearance in the Japanese population. The model quantitatively assessed the influence of CYP2C19 phenotype on esomeprazole PK in healthy Japanese male subjects after receiving repeated oral dosing. The inhibition mechanism of esomeprazole on CYP2C19 activity was also included in the model.

RESULTS AND DISCUSSION

CYP2C19 phenotype and dose were found as statistically significant covariates on esomeprazole clearance. The apparent clearance at 10-mg dose was 17.32, 9.77 and 7.37 (L/h) for homozygous extensive metabolizer, heterozygous extensive metabolizer and poor metabolizer subjects, respectively. And the apparent clearance decreased as dose increased.

WHAT IS NEW AND CONCLUSION

The established population PK model well described the esomeprazole PK and model-predicted esomeprazole PK was in good agreement with external clinical data, suggesting the robustness and applicability of the current model for predicting esomeprazole PK.

Role of Genetic Polymorphisms of Cytochrome P450 2C19 in Pantoprazole Metabolism and Pantoprazole-based Helicobacter pylori Eradication Regimens

BACKGROUND

Cytochrome P450 (CYP450) enzymes play an important role in the metabolism of 70-80% of the currently used medications, including proton pump inhibitors. There are some data analyzing the impact of gene polymorphisms of CYP450 enzymes on most widely used PPIs, such as omeprazole, however, the data on pantoprazole are highly lacking.

OBJECTIVE

To summarize the most recent publications and studies on the role of polymorphisms of the genes encoding CYP450 enzyme 2C19 in the metabolism of pantoprazole and pantoprazole based Helicobacter pylori eradication regimens.

METHODS

We performed a non-systematic search of the available literature on the selected topic.

RESULTS AND CONCLUSION

The data on cytochrome P450 gene polymorphisms and their role in pantoprazole metabolism and pantoprazole based Helicobacter pylori eradication remain conflicting. Individual differences in pantoprazole metabolism might be partly related to genetic polymorphisms of CYP450 enzymes. Most of the studies support the observation that cytochrome 2C19 polymorphisms have an impact on the pharmacokinetics of pantoprazole and its therapeutic effects: poor metabolizers of PPIs are more likely to have a better response to pantoprazole therapy and achieve better H. pylori eradication rates compared to rapid metabolizers. The determination of alleles that are associated with decreased (e.g., *2, *3 alleles) or increased (e.g., *17 allele) cytochrome 2C19 enzyme activity might be used as predictive factors for the potential of acid suppression and the success of Helicobacter pylori eradication. Overall, currently available data do not provide robust evidence, therefore, the application of genetic polymorphisms of cytochrome enzymes in clinical practice still cannot be recommended as routine practice for personalized pantoprazole prescription strategies.

Adverse Effects of Proton Pump Inhibitors-Evidence and Plausibility

Proton pump inhibitors (PPIs) have been increasingly used over the last decades and there are concerns about overuse and the numerous reported side-effects. It is uncertain whether associations between PPI use and potential side effects are causal. However, important evidence from experimental and mechanistic studies that could support a causal relationship may have been underestimated by epidemiologists and meta-analysists. In the current manuscript we review the combined epidemiological and mechanistic evidence of the adverse effects of PPI use.

Effects of the Proton Pump Inhibitors Omeprazole and Pantoprazole on the Cytochrome P450-Mediated Metabolism of Venlafaxine

BACKGROUND AND OBJECTIVE: An increasing trend in prescribing proton pump inhibitors (PPIs) inevitably increases the risk of unwanted drug-drug interactions (DDIs). The aim of this study was to uncover pharmacokinetic interactions between two PPIs-omeprazole and pantoprazole-and venlafaxine.

METHODS

A therapeutic drug monitoring database contained plasma concentrations of venlafaxine and its active metabolite O-desmethylvenlafaxine. We considered three groups: a group of patients who received venlafaxine without confounding medications (non-PPI group, n = 906); a group of patients who were comedicated with omeprazole (n = 40); and a group of patients comedicated with pantoprazole (n = 40). Plasma concentrations of venlafaxine, O-desmethylvenlafaxine and active moiety (venlafaxine + O-desmethylvenlafaxine), as well as dose-adjusted plasma concentrations, were compared using non-parametrical tests.

RESULTS

Daily doses of venlafaxine did not differ between groups (p = 0.949). The Mann-Whitney U test showed significantly higher plasma concentrations of active moiety, as well as venlafaxine and O-desmethylvenlafaxine, in both PPI groups [p = 0.023, p = 0.011, p = 0.026, +29% active moiety, +27% venlafaxine, +36% O-desmethylvenlafaxine (pantoprazole); p = 0.003, p = 0.039 and p < 0.001, +36% active moiety, +27% venlafaxine, +55% O-desmethylvenlafaxine (omeprazole)]. Significantly higher concentration-by-dose (C/D) values for venlafaxine and active moiety were detected in the pantoprazole group (p = 0.013, p = 0.006, respectively), while in the omeprazole group, C/D ratios for all three parameters-venlafaxine, O-desmethylvenlafaxine and active moiety-were significantly higher (p = 0.021, p < 0.001 and p < 0.001, respectively).

CONCLUSIONS

Significantly higher plasma concentrations for all parameters (venlafaxine, O-desmethylvenlafaxine, active moiety) suggest clinically relevant inhibitory effects of both PPIs, most likely on the cytochrome P450 (CYP) 2C19-mediated metabolism of venlafaxine. The findings might be the result of different degrees of CYP2C19 involvement, therefore the inhibition of CYP2C19 by both PPIs may lead to an increased metabolism via CYP2D6 to O-desmethylvenlafaxine.

Use of proton pump inhibitors and risk of iron deficiency: a population-based case-control study

BACKGROUND

Hypochlorhydric states are an important cause of iron deficiency (ID). Nevertheless, the association between therapy with proton pump inhibitors (PPIs) and ID has long been a subject of debate. This case-control study aimed to investigate the risk of ID associated with the use of PPIs using the UK Clinical Practice Research Datalink (CPRD) database.

METHODS

Cases were patients aged 19 years or older with first-time diagnosis of ID between 2005 and 2016 (n = 26 806). The dates of first diagnosis of ID in cases defined the index dates. For each case, one control was matched by age, gender and general practice. A PPI "full" user (PFU) was defined as a subject who had received PPIs for a continuous duration of at least 1 year prior to the index date. A PPI "limited" users (PLU) was a subject who intermittently received PPI therapy. A PPI non-user (PNU) was a subject who received no PPI prescriptions prior to the index date. The odds ratio of ID in PFU and PLU compared to PNU was estimated using conditional logistic regression.

RESULTS

Among cases, 2960 were PFU, 6607 PLU and 17 239 PNU. Among controls, 1091 were PFU, 5058 PLU and 20 657 PNU. Adjusted odds ratio of ID in PFU and PLU compared to PNU was 3.60 (95%CI, [3.32-3.91]) and 1.51 (95% CI, [1.44-1.58]). Positive dose-response and time-response relationships were observed.

CONCLUSIONS

Chronic PPI use increases the risk of ID. Physicians should consider this when balancing the risks and benefits of chronic PPI prescription.

Evaluation of gastric acid suppression with vonoprazan using calcium carbonate breath test

Vonoprazan, a potassium-competitive acid blocker, is a new class of acid-suppressing agent. The acid-inhibitory effect of vonoprazan has been well-documented. However, there is no report on the extent to which the amount of gastric acid secretion is suppressed, not pH measurement, by the use of vonoprazan. The aim of this study was to evaluate this suppression effect. This was a single-arm, interventional pilot study involving 7 healthy Japanese men. The subjects were administered 20 mg vonoprazan for 6 days. The amount of gastric acid secretion was determined using the calcium carbonate breath test. The acid outputs were defined as the maximum Δ¹³C‰ (Δ¹³C max) and area under the curve (AUC) during the 30 min sampling period. The Δ¹³C max and AUC values significantly decreased on the administration of 20 mg vonoprazan. The AUC dropped by approximately 78% on day 1 and by 84% on day 6 and subsequently returned to the control level after cessation of vonoprazan therapy (reduction by 68% on day 7 and by 42% on day 8). In conclusion, the amount of gastric acid secretion rapidly decreased by the administration of vonoprazan; this inhibitory effect was found to be potent and long-lasting. (UMIN ID: UMIN000025469).

Biotransformation of Ilaprazole in Human Liver Microsomes and Human: Role of CYP3A4 in Ilaprazole Clearance and Drug-Drug Interaction

Ilaprazole is a new proton pump inhibitor and is currently marketed in China and South Korea for the treatment of gastric and duodenal ulcer. Ilaprazole has a favorable long half-life and minimal pharmacokinetic variability associated with CYP2C19 polymorphism. Sulfoxide oxidation of ilaprazole is catalyzed mainly by CYP3A4. Thus, it has been widely accepted that CYP3A4 plays a major role in the clearance of ilaprazole in humans. However, absorption, distribution, metabolism, and excretion data of radiolabeled ilaprazole in humans are not available. The primary goal of this study was to determine if sulfoxide oxidation is a major metabolic pathway of ilaprazole in humans. Metabolite profiles of ilaprazole, ilaprazole sulfide, and ilaprazole sulfone in human liver microsomes (HLMs) were characterized and quantitively analyzed by liquid chromatography (LC)/UV/high-resolution mass spectrometry (HRMS). Moreover, metabolites of ilaprazole in human urine and feces were detected and identified by LC-HRMS. The results revealed that sulfoxide reduction to ilaprazole sulfide rather than sulfoxide oxidation was the major biotransformation pathway in HLMs. Sulfoxide reduction also occurred in HLMs without NADPH or in deactivated HLMs. Ilaprazole sulfide and its multiple oxidative metabolites were major drug-related components in human urine and feces, where there were no ilaprazole sulfone and its metabolites. A small amount of the parent drug was found in feces. Thus, we propose that nonenzymatic sulfoxide reduction rather than CYP3A4-medidated sulfoxide oxidation is the major metabolic clearance pathway of ilaprazole in humans. Consequently, it is predicted that ilaprazole has no significant drug-drug interaction via CYP3A4 inhibition or induction by a coadministered drug.

Retrospective study on outcome of salvage Helicobacter pylori eradication therapies based on molecular genetic susceptibility testing

BACKGROUND

Antimicrobial susceptibility of Helicobacter (H.) pylori is usually determined by phenotypic methods. When H. pylori cannot be grown owing to contaminations or delay in transport of gastric tissue samples to the microbiological laboratory, molecular genetic testing is a reasonable alternative. The aim of this retrospective study was to assess the outcome of salvage eradication treatments based on molecular genetic susceptibility testing.

METHODS

Data on 144 H. pylori PCR-positive gastric tissue samples of patients primarily with prior unsuccessful eradication treatments were retrospectively analyzed. Eradication treatments were recommended based on genotypic clarithromycin and/or levofloxacin susceptibility as tested by real-time PCR or reverse hybridization. Treatment success was assessed by attending physicians using urea breath test; stool-antigen ELISA; and microbiology/histopathology.

RESULTS

Overall success rate of molecular genetic testing-guided salvage treatments was low (68%); none of the regimens chosen was significantly better than another. Multivariable logistic regression analysis did not reveal any factors that may predict treatment failure.

CONCLUSIONS

Eradication success was poor despite susceptibility testing. Gastroenterologists are advised to prescribe recommended salvage treatments, considering recommended dosages and prolonged treatment duration.

Proton pump inhibitor-refractory gastroesophageal reflux disease: challenges and solutions

A significant percentage of patients with gastroesophageal reflux disease (GERD) will not respond to proton pump inhibitor (PPI) therapy. The causes of PPI-refractory GERD are numerous and diverse, and include adherence, persistent acid, functional disorders, nonacid reflux, and PPI bioavailability. The evaluation should start with a symptom assessment and may progress to imaging, endoscopy, and monitoring of esophageal pH, impedance, and bilirubin. There are a variety of pharmacologic and procedural interventions that should be selected based on the underlying mechanism of PPI failure. Pharmacologic treatments can include antacids, prokinetics, alginates, bile acid binders, reflux inhibitors, and antidepressants. Procedural options include laparoscopic fundoplication and LINX as well as endoscopic procedures, such as transoral incisionless fundoplication and Stretta. Several alternative and complementary treatments of possible benefit also exist.

Helicobacter pylori management in ASEAN: The Bangkok consensus report

Helicobacter pylori (H. pylori) infection remains to be the major cause of important upper gastrointestinal diseases such as chronic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. H. pylori management in ASEAN: the Bangkok consensus report gathered key opinion leaders for the region to review and evaluate clinical aspects of H. pylori infection and to develop consensus statements, rationales, and grades of recommendation for the management of H. pylori infection in clinical practice in ASEAN countries. This ASEAN Consensus consisted of 34 international experts from 10 ASEAN countries, Japan, Taiwan, and the United States. The meeting mainly focused on four issues: (i) epidemiology and disease association; (ii) diagnostic tests; (iii) management; and (iv) follow-up after eradication. The final results of each workshop were presented for consensus voting by all participants. Statements, rationale, and recommendations were developed from the available current evidence to help clinicians in the diagnosis and treatment of H. pylori and its clinical diseases.

Effect of Multiple Oral Doses of the Potent CYP3A4 Inhibitor Clarithromycin on the Pharmacokinetics of a Single Oral Dose of Vonoprazan: A Phase I, Open-Label, Sequential Design Study

BACKGROUND AND OBJECTIVES

This phase I, open-label, sequential design study assessed the effect of multiple oral doses of the potent cytochrome P450 (CYP) 3A4 inhibitor clarithromycin on the pharmacokinetics of a single oral dose of vonoprazan.

METHODS

During the 10-day treatment period, 16 healthy male subjects received vonoprazan 40 mg on days 1 and 8, and clarithromycin 1000 mg on days 3-9, with the pharmacokinetics of both examined. Primary endpoints included the maximum observed plasma concentration (C _max) and area under the plasma concentration-time curve (AUC) of vonoprazan and its major metabolites (M-I, M-II, M-III, and M-IV-Sul). Safety was also assessed.

RESULTS

Following administration, vonoprazan was rapidly absorbed (time to reach C _max, 2 h), consistent with its known pharmacokinetic profile. This was unchanged in the presence of clarithromycin. Plasma concentrations declined thereafter, with a mean apparent terminal elimination half-life of 7.2 h on day 1 and 9.4 h on day 8. Small-to-moderate increases (1.6- and 1.4-fold) in mean AUC and C _max of vonoprazan, respectively, were observed following clarithromycin. In contrast, AUC and C _max for vonoprazan metabolites decreased, except for M-IV-Sul, which increased approximately 2.1- and 1.5-fold, respectively. Overall, vonoprazan was well tolerated, with mild or moderate treatment-emergent adverse events occurring in six (37.5%) subjects receiving either vonoprazan and/or clarithromycin.

CONCLUSIONS

Modest increases in plasma concentrations of the potent CYP3A4 inhibitor clarithromycin and vonoprazan were observed during coadministration, however these differences were not considered clinically significant. Vonoprazan had a favorable safety and tolerability profile, and no serious adverse events were reported. CLINICALTRIALS.GOV: NCT02774902.

[Personalized drug therapy based on genetics. Possibilities and examples from clinical practice]

BACKGROUND

Pharmacogenetics are an important component in the individualization of treatment; however, pharmacogenetic diagnostics have so far not been used to any great extent in clinical practice. A consistent consideration of individual patient factors, such as pharmacogenetics may help to improve drug therapy and increase individual safety and efficacy aspects.

OBJECTIVE

A brief summary of structures and effects of genetic variations on drug efficacy is presented. Some frequently prescribed pharmaceuticals are specified. Furthermore, the feasibility of pharmacogenetic diagnostics and dose recommendations in the clinical practice are described.

CURRENT DATA

The European Medicines Agency (EMA) as the European approval authority has already extended the drug labels of more than 70 pharmaceuticals by information on pharmacogenetic biomarkers and the U.S. Food and Drug Administration (FDA) more than 150. This is a crucial step towards targeted medicine. Guidelines on dose and therapy adjustments are provided by the Clinical Pharmacogenetics Implementation Consortium of the Pharmacogenomics Research Network.

CONCLUSION

It is fundamental to consider individual patient factors for successful drug therapy. Dose and therapy recommendations based on pharmacogenetic diagnostics are highly important for individualization as well as improvement of safety and efficiency of drug therapy.

Modeling the cost-effectiveness of ilaprazole versus omeprazole for the treatment of newly diagnosed duodenal ulcer patients in China

OBJECTIVES

To evaluate the cost-effectiveness of 10 mg ilaprazole once-daily vs 20 mg omeprazole once-daily to treat newly-diagnosed duodenal ulcer patients in China.

METHODS

A decision tree model was constructed and the treatment impact was projected up to 1 year. The CYP2C19 polymorphism distribution in the Chinese population, the respective cure rates in the CYP2C19 genotype sub-groups, the impact of Duodenal Ulcer (DU) on utility value and drug-related side-effect data were obtained from the literature. The total costs of medications were calculated to estimate the treatment costs based on current drug retail prices in China. Expert surveys were conducted when published data were not available. Probabilistic sensitivity analysis was performed to gauge the robustness of the results.

RESULTS

Ilaprazole, when compared with omeprazole, achieved a better overall clinical efficacy. For the overall population, ilaprazole achieved an incremental cost effectiveness ratio (ICER) of ¥132 056 per QALY gained. This is less than the WHO recommended threshold of 3-times the average GDP per capita in China (2014). Furthermore, sub-group analysis showed that ilaprazole is cost-effective in every province in CYP2C19 hetEM patients and in the most developed provinces in CYP2C19 homEM patients. Probabilistic sensitivity analysis suggests that the results are robust with 97% probability that ilaprozole is considered cost-effective when a threshold of 3-times China's average GDP per capita is considered.

LIMITATION

This study didn't have the data of ilaprazole combined with Hp eradication therapy. Caution should be taken when extrapolating these findings to DU patients with an Hp eradication therapy.

CONCLUSIONS

The cost-effectiveness analysis results demonstrated that ilaprazole would be considered a cost-effective therapy, compared with omeprazole, in Chinese DU patients based on the efficacy projections in various CYP2C19 polymorphism types.

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.

Radiographic Localization Study of a Novel Potassium-Competitive Acid Blocker, Vonoprazan, in the Rat Gastric Mucosa

BACKGROUND

Vonoprazan fumarate (TAK-438) is a novel potassium-competitive acid blocker that appears to exert a longer/more potent antisecretory effect than lansoprazole due to high accumulation/slow clearance from the gastric glands. However, there is no direct evidence that vonoprazan selectively accumulates in gastric parietal cells of gastric glands.

AIM

To investigate the distribution of radioactivity in the rat stomach after single intravenous administration of [(3)H]-labeled vonoprazan.

METHODS/RESULTS

Autoradioluminography of the stomach revealed that at 5 h after administration, radioactivity levels in the corpus mucosal layer was higher than radioactivity levels in the muscular layer, pylorus, and forestomach. At 24 h, although overall radioactivity was significantly decreased, the highest radioactivity was still observed in the mucosal layer. Accumulation of radioactivity in gastric parietal cells was quantitatively analyzed using microautoradiography. The number of silver granules in parietal cells from vonoprazan-injected rats was higher than in cells from a saline-injected rat. At 24 h, the number of granules was approximately at 20 % of the number of granules at 5 h. There was no clear deposition of granules in other components. At 5 h, radioactivity was measured at 1.799 µg Eq/g in the stomach and 0.172 µg Eq/mL in plasma. After 24 h, radioactivity had decreased to 0.584 µg Eq/g in the stomach and 0.078 µg Eq/mL in plasma.

CONCLUSIONS

Vonoprazan selectively accumulates in gastric parietal cells in the mucosal layer of the rat stomach after intravenous administration.

Proton Pump Inhibitors Accelerate Endothelial Senescence

RATIONALE

Proton pump inhibitors (PPIs) are popular drugs for gastroesophageal reflux, which are now available for long-term use without medical supervision. Recent reports suggest that PPI use is associated with cardiovascular, renal, and neurological morbidity.

OBJECTIVE

To study the long-term effect of PPIs on endothelial dysfunction and senescence and investigate the mechanism involved in PPI-induced vascular dysfunction.

METHODS AND RESULTS

Chronic exposure to PPIs impaired endothelial function and accelerated human endothelial senescence by reducing telomere length.

CONCLUSIONS

Our data may provide a unifying mechanism for the association of PPI use with increased risk of cardiovascular, renal, and neurological morbidity and mortality.

Absence of ethnic differences in the pharmacokinetics of moxifloxacin, simvastatin, and meloxicam among three East Asian populations and Caucasians

Aim

To examine whether strict control of clinical trial conditions could reduce apparent differences of pharmacokinetic (PK) parameters among ethnic groups.

Methods

Open‐label, single dose PK studies of moxifloxacin, simvastatin and meloxicam were conducted in healthy male subjects from three East Asian populations (Japanese, Chinese and Koreans) and one Caucasian population as a control. These three drugs were selected because differences in PK parameters have been reported, even though the backgrounds of these East Asian populations are similar. Moxifloxacin (400 mg) was administered orally to 20 subjects, and plasma and urine levels of moxifloxacin and its metabolite (M2) were measured. Simvastatin (20 mg) was given to 40 subjects, and plasma levels of simvastatin and simvastatin acid were measured. Meloxicam (7.5 mg) was given to 30 subjects and its plasma concentration was determined. Intrinsic factors (polymorphism of UGT1A1 for moxifloxacin, SLCO1B1 for simvastatin, and CYP2C9 for meloxicam) were also examined.

Results

AUC_inf values for moxifloxacin, simvastatin and meloxicam showed no significant differences among the East Asian groups. C_max values of moxifloxacin and simvastatin, but not meloxicam, showed significant differences. There were no significant differences of data for M2 or simvastatin acid. Genetic analysis identified significant differences in the frequencies of relevant polymorphisms, but these differences did not affect the PK parameters observed.

Conclusions

Although there were some differences in PK parameters among the three East Asian groups, the present study performed under strictly controlled conditions did not reproduce the major ethnic differences observed in previous studies.

The efficacy of step-down therapy in adult patients with proton pump inhibitor-responsive oesophageal eosinophilia

BACKGROUND

Proton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE) is common in patients with suspected eosinophilic oesophagitis (EoE). However, the long-term efficacy of PPIs and the best maintenance doses are yet to be defined.

AIM

To evaluate the durability of the response to PPI therapy after tapering PPI doses in PPI-REE patients.

METHODS

Prospective study conducted on PPI-REE patients. Upon complete remission on high-dose PPI therapy (omeprazole 40 mg b.d. for 8 weeks), PPI doses were tapered followed by an endoscopic procedure after each dose reduction. The primary outcomes were sustained clinical and histological remission (<15 eos/HPF) after decreasing PPI doses.

RESULTS

From a total of 121 patients with suspected EoE, 40 (33%) achieved complete remission on high-dose PPIs and were given a diagnosis of PPI-REE. No patient in histological remission showed symptom relapse, but half of patients with relapsing oesophageal inflammation were in clinical remission. After reduction to omeprazole 40 mg once daily, 38/31 (81%) remained in complete remission. Among these latter patients, 15/18 (83%) were kept in remission with omeprazole 20 mg once daily. As for side effects, only asymptomatic hypertransaminasemia and oesophageal candidiasis were observed in two patients while receiving high doses of omeprazole.

CONCLUSIONS

Most PPI-responsive oesophageal eosinophilia patients show sustained clinical and histological remission with daily PPI doses equal to or below 40 mg of omeprazole. As adverse effects only appeared with the highest dose of omeprazole, it would be advisable to individualise the dose of PPIs for each patient, lowering it to the minimum capable of maintaining the disease controlled.

Variability of Voriconazole Trough Levels in Haematological Patients: Influence of Comedications with cytochrome P450(CYP) Inhibitors and/or with CYP Inhibitors plus CYP Inducers

Voriconazole plasma exposure greatly varies among haematological patients. The purpose of this study was to identify the magnitude of influence of comedications with CYP inhibitors and/or with CYP inhibitors plus CYP inducers on voriconazole trough level (Cmin ). Voriconazole Cmin was retrospectively assessed among haematological patients who underwent therapeutic drug monitoring (TDM). Univariate and multivariate linear mixed-effect regression analyses were performed to identify the independent predictors of normalized Cmin . Of the 83 included patients, 35 had comedications with CYP inhibitors (omeprazole or pantoprazole) and 21 with CYP inhibitors (omeprazole or pantoprazole) plus CYP inducers (methylprednisolone, dexamethasone, phenobarbital, rifampin or carbamazepine). Median Cmin value (n = 199) was 2.4 mg/L with a wide range of distribution (<0.2-13.5 mg/L). Median (IQR) normalized voriconazole Cmin value was significantly higher in the presence of CYP inhibitors (4.20 mg/L, 3.23-5.51 mg/L) than either in the absence of interacting cotreatments (2.55 mg/L, 1.54-3.47 mg/L) or in the presence of CYP inhibitors plus CYP inducers (2.16 mg/L, 1.19-3.09 mg/L). The presence of CYP inhibitors was highly significantly associated with Cmin >5.5 mg/L (OR: 23.22, 95% CI: 3.01-179.09, p = 0.003). No significant association emerged when CYP inhibitors were coadministered with CYP inducers (OR: 3.53, 95% CI: 0.36-34.95, p = 0.280). The amount of expected Cmin increase was significantly influenced by both the type and the dose of the administered proton pump inhibitor. The study highlights that the benefit from TDM of voriconazole may be maximal in those patients who are cotreated with CYP inhibitors and/or with CYP inhibitors plus CYP inducers, especially when receiving proton pump inhibitors (PPIs) at very high dosages intravenously.

Where Failure Is Not an Option -Personalized Medicine in Astronauts

Drug safety and efficacy are highly variable among patients. Most patients will experience the desired drug effect, but some may suffer from adverse drug reactions or gain no benefit. Pharmacogenetic testing serves as a pre-treatment diagnostic option in situations where failure or adverse events should be avoided at all costs. One such situation is human space flight. On the international space station (ISS), a list of drugs is available to cover typical emergency settings, as well as the long-term treatment of common conditions for the use in self-medicating common ailments developing over a definite period. Here, we scrutinized the list of the 78 drugs permanently available at the ISS (year 2014) to determine the extent to which their metabolism may be affected by genetic polymorphisms, potentially requiring genotype-specific dosing or choice of an alternative drug. The purpose of this analysis was to estimate the potential benefit of pharmacogenetic diagnostics in astronauts to prevent therapy failure or side effects.

Outcome of second- and third-line Helicobacter pylori eradication therapies based on antimicrobial susceptibility testing

OBJECTIVES

The objective of this study was to assess the outcome of antimicrobial susceptibility-guided therapies in Helicobacter pylori-infected individuals who had undergone unsuccessful prior eradication treatments.

METHODS

From October 2004 to December 2013, 481 H. pylori-positive patients with prior unsuccessful eradication treatments were administered susceptibility-guided salvage eradication treatments. Six months on, treatment outcome was assessed by urea breath test, stool antigen ELISA, Helicobacter urease test or microbiology and/or histopathology.

RESULTS

Resistance to metronidazole and clarithromycin was high in patients with prior unsuccessful eradication treatments and was dependent on the number of treatment failures. Susceptibility-guided salvage eradication treatments achieved eradication rates of nearly 70% in these patients. No particular regimen was significantly better than another.

CONCLUSIONS

Antimicrobial susceptibility testing prevents prescription of inefficient antimicrobials and enables individualized and promising salvage treatments in patients with prior unsuccessful eradication treatments.

Appropriate first-line regimens to combat Helicobacter pylori antibiotic resistance: an Asian perspective

Asia has the largest population of any continent and the highest incidence of gastric cancer in the world, making it very important in the context of Helicobacter pylori infection. According to current guidelines, standard triple therapy containing a proton pump inhibitor (PPI) and two antibiotics; amoxicillin (AMX) and clarithromycin (CAM) or metronidazole (MNZ), is still the preferred first-line regimen for treatment of H. pylori infection. However, the efficacy of legacy triple regimens has been seriously challenged, and they are gradually becoming ineffective. Moreover, some regions in Asia show patterns of emerging antimicrobial resistance. More effective regimens including the bismuth and non-bismuth quadruple, sequential, and dual-concomitant (hybrid) regimens are now replacing standard triple therapies as empirical first-line treatments on the basis of the understanding of the local prevalence of H. pylori antimicrobial resistance. Selection of PPI metabolized by the non-enzymatic pathway or minimal first pass metabolism and/or increasing dose of PPI are important to increase H. pylori eradication rates. Therefore, local antibiotic resistance surveillance updates, selection of appropriate first-line regimens with non-enzymatic PPI and/or increased doses of PPI, and detailed evaluation of patients' prior antibiotic usage are all essential information to combat H. pylori antibiotic resistance in Asia.

Effects of Esomeprazole on the Pharmacokinetics of Lapatinib in Breast Cancer Patients

The aqueous solubility of lapatinib declines significantly at pH >4, suggesting that its bioavailability might be lowered by acid-reducing drugs. A study was therefore conducted to assess the effects of esomeprazole on lapatinib pharmacokinetics (PK). Women with metastatic human epidermal growth factor receptor 2 positive (HER2(+) ) breast cancer were enrolled. Patients received 1,250 mg lapatinib once daily (QD) in the morning on Days 1-7 (Period 1) and Days 8-14 (Period 2) with 40 mg esomeprazole QD at bedtime 3 hours after dinner on Days 8-14. Lapatinib PK sampling occurred during the 24-hour steady-state dosing intervals on Day 7 (lapatinib alone) and Day 14 (lapatinib with esomeprazole). Esomeprazole treatment resulted in decreased lapatinib bioavailability (mean 26%, range 6-49%) that was inversely associated with patient age as a significant covariate.