CYP2C19 genetic polymorphism, rabeprazole and esomeprazole have no effect on the antiplatelet action of clopidogrel

Pharmacogenomics in Lebanon: current status, challenges and opportunities

Pharmacogenomics (PGx) research and applications are of utmost relevance in Lebanon considering its population genetic diversity. Moreover, as a country with regional leadership in medicine and higher education, Lebanon holds a strong potential in contributing to PGx research and clinical implementation. In this manuscript, we first review and evaluate the available PGx research conducted in Lebanon, then describe the current status of PGx practice in Lebanon while reflecting on the local and regional challenges, and highlighting areas for action, and opportunities to move forward. We specifically expand on the status of PGx at the American University of Beirut Faculty of Medicine and Medical Center as a case study and guide for the further development of local and regional comprehensive PGx research, teaching, and clinical implementation programs. We also delve into the status of PGx knowledge and education, and prospects for further advancement such as with online courses and certificates.

Drug Metabolizing Enzymes: An Exclusive Guide into Latest Research in Pharmaco-genetic Dynamics in Arab Countries

Drug metabolizing enzymes play a crucial role in the pharmacokinetics and pharmacodynamics of therapeutic drugs, influencing their efficacy and safety. This review explores the impact of genetic polymorphisms in drug-metabolizing genes on drug response within Arab populations. We examine the genetic diversity specific to Arab countries, focusing on the variations in key drug-metabolizing enzymes such as CYP450, GST, and UGT families. The review highlights recent research on polymorphisms in these genes and their implications for drug metabolism, including variations in allele frequencies and their effects on therapeutic outcomes. Additionally, the paper discusses how these genetic variations contribute to the variability in drug response and adverse drug reactions among individuals in Arab populations. By synthesizing current findings, this review aims to provide a comprehensive understanding of the pharmacogenetic landscape in Arab countries and offer insights into personalized medicine approaches tailored to genetic profiles. The findings underscore the importance of incorporating pharmacogenetic data into clinical practice to enhance drug efficacy and minimize adverse effects, ultimately paving the way for more effective and individualized treatment strategies in the region.

The Pharmacogenetics Laboratory of the Department of Pharmacology and Toxicology at the American University of Beirut Faculty of Medicine

The pharmacogenetics (PGx) laboratory at the Department of Pharmacology and Toxicology at the American University of Beirut Faculty of Medicine was established in October 2007. Several projects on the genetic polymorphisms of drug metabolizing enzymes and transporters with treatment of noncommunicable diseases such as cardiac diseases and cancers are ongoing. We have been applying the 'candidate gene' PGx approach, and recently started using higher throughput analyses. The more recent research projects are geared towards performing more extensive genotyping and including bigger and more representative population samples such as by developing research registries and prospectively following up patients. Furthermore, many technologies and research applications, such as next-generation sequencing and pharmacoepigenetics that complement and enhance PGx research and applications, are being actively pursued.

Impact of esomeprazole on platelet reactivity and clinical outcome according to CYP2C19 genotype in coronary heart disease patients during dual antiplatelet therapy

OBJECTIVES

The aim of this study was to investigate the effect of CYP2C19 polymorphism and co-therapy with esomeprazole on the antiplatelet efficacy of clopidogrel.

BACKGROUND

The antiplatelet efficacy of clopidogrel depends on CYP2C19 polymorphism or the co-administration of some kind of proton pump inhibitor (PPI).

METHODS

CYP2C19 genotype and the residual platelet reactivity (RPR) were measured in 361 coronary heart disease patients (male, mean age 69yrs), and the risk of cardiovascular events over a 3-month follow-up was assessed to evaluate the impact of co-administration of esomeprazole during dual antiplatelet therapy with aspirin and clopidogrel.

RESULTS

The values of RPR did not differ between esomeprazole and non-esomeprazole groups (4389 ± 1112 versus 4079 ± 1355 AU·min, P=0.103). RPR value was higher in intermediate metabolizers (IM) than in extensive metabolizers (EM) (4089 ± 1252 versus 3697 ± 1215 AU·min P=0.012) and, similarly, higher in poor metabolizers (PM) than in IM (4884 ± 1027 versus 4089 ± 1252 AU·min, P<0.001). There were no differences in RPR between esomeprazole and non-esomeprazole groups according to CYP2C19 genotype (EM, 3954 ± 1192 versus 3645 ± 1220 AU·min, P=0.361; IM, 4401 ± 1063 versus 4051 ± 1271 AU·min, P=0.293; PM, 4917 ± 669 versus 4876 ± 1099 AU·min, P=0.907, respectively). There was also no difference in clinical outcomes between esomeprazole and non-esomeprazole groups in the three-month follow-up (0% versus 0.92%, P=0.487).

CONCLUSIONS

These results suggest that concomitant use of esomeprazole with clopidogrel is not associated with reduced antiplatelet efficacy of clopidogrel or increased risk of cardiovascular events, irrespective of CYP2C19 genotype.

Challenging the dogma: a randomized trial of standard vs. half-dose concomitant nonbismuth quadruple therapy for Helicobacter pylori infection

BACKGROUND

Current treatment of Helicobacter pylori consists of three or four drugs for 7-14 days with important associated cost and adverse events.

AIMS

This study compared efficacy and safety of standard dose vs. half-dose concomitant nonbismuth quadruple therapy (NBQT) for 7 days. The standard dose consisted of twice daily rabeprazole 20 mg, amoxicillin 1 g, metronidazole 500 mg, and clarithromycin 500 mg.

METHODS

This was a prospective randomized trial. (14)C-urea breath test was performed ≥4 weeks after treatment and ≥2 weeks off acid suppressive therapy. Compliance and adverse events were monitored during treatment.

RESULTS

A total of 200 consecutive treatment-naïve patients were enrolled. Baseline characteristics were similar between groups, with 15.5% of subjects reporting prior macrolide use. Eradication occurred in 78% (95% CI 68.6-85.7%) in both groups on intention-to-treat analysis. Per-protocol rates were 82.1 vs. 83.9% for standard-dose patients vs. half-dose patients, respectively (p = NS). Adverse events (only mild) were reported in 57 vs. 41% of standard-dose patients vs. half-dose patients (p = 0.024), with metallic taste and nausea notably less frequent in the latter (36 vs. 12% and 18 vs. 7%, respectively; p < 0.05 for both). Overall, eradication failed in 38.7% of prior macrolide users vs. 18.9% without such exposure (p = 0.019). On multivariate logistic regression, prior macrolide exposure was the only factor associated with failed eradication (OR 2.60, 95% CI 1.06-6.39; p = 0.038). Treatment was cheaper with the half-dose regimen.

INTERPRETATION

A 50% reduction in antibiotic dosage does not diminish efficacy of concomitant nonbismuth quadruple therapy but leads to significant reduction in cost and adverse events. Seven-day concomitant NBQT is suboptimal for H. pylori independent of prior macrolide exposure.

Pharmacogenovigilance: a pharmacogenomics pharmacovigilance program

In this report, we review the importance of pharmacovigilance in detecting postmarketing adverse drug events and the potential for developing pharmacogenovigilance programs by integrating pharmacogenomics with pharmacovigilance. We propose to start developing such a program in primary healthcare systems that use basic features of electronic medical records and have access to large numbers of patients commonly prescribed drugs. Such programs, if carefully designed, may grow over time and hopefully enhance the collection and interpretation of useful data for the clinical applications of pharmacogenomics testing.

Clustering of Acute and Subacute Stent Thrombosis Related to the Introduction of Generic Clopidogrel

Introduction:

Generic clopidogrel recently became available in the United States and was rapidly adopted as a cost-effective alternative to the brand name formulation. However, unlike other medications, subtle differences in clopidogrel bioavailability may lead to acute consequences including stent thrombosis (ST).

Materials and Methods:

We studied the incidence of acute and subacute ST during the initial period of generic clopidogrel use (June 18, 2012-September 6, 2012 [80 days]) at a single percutaneous coronary intervention (PCI) center. There were 4 definite ST cases within 30 days of successful PCI in patients receiving generic clopidogrel, which were compared to historic control ST cases from 80 days prior to generic clopidogrel use and for 3 years from June 18, 2009 to June 17, 2012.

Results:

During generic clopidogrel administration, 1054 PCIs were performed, giving a definite 30-day ST incidence of 0.38% (4 of 1054) among these patients. By comparison, there were 2 episodes of definite 30-day ST during the 80 days immediately preceding generic clopidogrel use (2 of 1114), while 3-year historic data indicated a definite 30-day ST incidence of 0.14% (20 of 14 432), representing a 2.7-fold increase in definite 30-day ST with generic clopidogrel use ( P = .076). Exclusion of 3 historic controls with a defined reason for ST (noncompliance, marked thrombocytosis) gave a 3.2-fold increase in 30-day ST with generic clopidogrel ( P = .050). An ST-predictive algorithm revealed no difference in the likelihood of ST between patients receiving generic clopidogrel and historic controls.

Conclusions:

We observed an unexpected >2-fold increase in ST coincident with generic clopidogrel use. Although we cannot ascribe causality, this observation warrants increased vigilance and close monitoring of patients receiving generic clopidogrel.

Antiplatelet drug interactions with proton pump inhibitors

INTRODUCTION

Non-aspirin antiplatelet agents (e.g., clopidogrel, prasugrel, ticagrelor) are commonly prescribed for the prevention of recurrent cardiovascular events among patients with acute coronary syndromes (ACS) and/or those undergoing percutaneous coronary intervention (PCI). In addition, combination therapy with proton pump inhibitors (PPIs) is often recommended to attenuate gastrointestinal bleeding risk, particularly during dual antiplatelet therapy (DAPT) with clopidogrel and aspirin. Importantly, a pharmacological interaction between clopidogrel and some PPIs has been proposed based on mutual CYP450-dependent metabolism, but available evidence is inconsistent.

AREAS COVERED

This article provides an overview of the currently approved antiplatelet agents and PPIs, including their metabolic pathways. Additionally, the CYP450 isoenzyme at the center of the drug interaction, CYP2C19, is described in detail, and the available evidence on both the potential pharmacological interaction and influence on clinical outcomes are summarized and evaluated.

EXPERT OPINION

Although concomitant DAPT and PPI use reduces clopidogrel active metabolite levels and ex vivo-measured platelet inhibition, the influence of the drug interaction on clinical outcomes has been conflicting and largely reported from non-randomized observational studies. Despite this inconsistency, a clinically important interaction cannot be definitively excluded, particularly among patient subgroups with higher overall cardiovascular risk and potentially among CYP2C19 loss-of-function allele carriers.