Pantoprazole significantly interferes with antiplatelet effect of clopidogrel: Results of a pilot randomized trial

An update on oral antiplatelet drug interactions with proton pump inhibitors: what are the risks?

INTRODUCTION

Aspirin and anti-P2Y12 are widely prescribed in cardiovascular patients, often in combination with proton pump inhibitors (PPIs) to limit the risk of upper gastrointestinal bleedings. The potential interaction between PPIs and antiplatelet agents has been widely discussed, but doubts remain as to whether PPIs may reduce the cardiovascular protection provided by aspirin, prasugrel, ticagrelor, and clopidogrel.

AREAS COVERED

Many pharmacokinetic (PK) and pharmacodynamic (PD) studies have confirmed the interaction, especially between PPIs and clopidogrel, but with uncertain consequences on clinical outcomes. Therefore, we aimed to summarize the evidence for the widespread combined use of oral antiplatelet drugs and PPIs, to outline the current evidence supporting or opposing drug-drug interaction, and to discuss the clinical implications of such interactions.

EXPERT OPINION

A large body of evidence describes the PK/PD interaction of antiplatelet drugs with PPIs and its potential role in increasing clinical cardiovascular adverse events, but no solid clinical data have confirmed these effects. In the light of the published studies, there seems to be no restriction on the choice of PPI with aspirin, prasugrel, and/or ticagrelor. The choice of a PPI with no (or minimal) interference with the hepatic cytochrome P450 2C19 is preferred in patients receiving clopidogrel.

Cardiovascular Compatibility of Proton Pump Inhibitors: Practice Recommendations

This manuscript aims to critically evaluate the current evidence regarding adverse cardiovascular effects associated with proton pump inhibitors (PPIs) in patients with coronary artery disease (CAD). It also provides guidance for the selection of the most appropriate PPI within the context of cardiovascular polypharmacy and emphasizes the importance of establishing consensus among clinicians on the need to prescribe PPIs with limited cytochrome P450 (CYP450) enzyme inhibition to reduce the risk of drug interactions. PPIs are among the most widely used drugs for the treatment of gastroesophageal reflux disease (GERD) and the prevention of gastrointestinal (GI) bleeding. The manuscript reports the proceedings from the first practice recommendations meeting on the cardiovascular compatibility of PPIs in an Indian setting. A panel of eight Indian experts in cardiology and gastroenterology reviewed 14 consensus statements. Available literature was searched and summarized, and after multiple rounds of review, consensus was achieved for these statements. Based on the available evidence, the consensus panel highlights that a PPI with minimal drug-drug interaction (DDI) is recommended, especially in patients requiring clopidogrel or polypharmacy. Rabeprazole appears to be a good option in cases where co-prescription is indicated, owing to its optimal acid suppression and minimal drug interaction profile.

Antithrombotic and anticoagulation therapies in cardiogenic shock: a critical review of the published literature

Cardiogenic shock (CS) is a complex multifactorial clinical syndrome, developing as a continuum, and progressing from the initial insult (underlying cause) to the subsequent occurrence of organ failure and death. There is a large phenotypic variability in CS, as a result of the diverse aetiologies, pathogenetic mechanisms, haemodynamics, and stages of severity. Although early revascularization remains the most important intervention for CS in settings of acute myocardial infarction, the administration of timely and effective antithrombotic therapy is critical to improving outcomes in these patients. In addition, other clinical settings or non-acute myocardial infarction aetiologies, associated with high thrombotic risk, may require specific regimens of short-term or long-term antithrombotic therapy. In CS, altered tissue perfusion, inflammation, and multi-organ dysfunction induce unpredictable alterations to antithrombotic drugs' pharmacokinetics and pharmacodynamics. Other interventions used in the management of CS, such as mechanical circulatory support, renal replacement therapies, or targeted temperature management, influence both thrombotic and bleeding risks and may require specific antithrombotic strategies. In order to optimize safety and efficacy of these therapies in CS, antithrombotic management should be more adapted to CS clinical scenario or specific device, with individualized antithrombotic regimens in terms of type of treatment, dose, and duration. In addition, patients with CS require a close and appropriate monitoring of antithrombotic therapies to safely balance the increased risk of bleeding and thrombosis.

High Mutational Heterogeneity, and New Mutations in the Human Coagulation Factor V Gene. Future Perspectives for Factor V Deficiency Using Recombinant and Advanced Therapies

Factor V is an essential clotting factor that plays a key role in the blood coagulation cascade on account of its procoagulant and anticoagulant activity. Eighty percent of circulating factor V is produced in the liver and the remaining 20% originates in the α-granules of platelets. In humans, the factor V gene is about 80 kb in size; it is located on chromosome 1q24.2, and its cDNA is 6914 bp in length. Furthermore, nearly 190 mutations have been reported in the gene. Factor V deficiency is an autosomal recessive coagulation disorder associated with mutations in the factor V gene. This hereditary coagulation disorder is clinically characterized by a heterogeneous spectrum of hemorrhagic manifestations ranging from mucosal or soft-tissue bleeds to potentially fatal hemorrhages. Current treatment of this condition consists in the administration of fresh frozen plasma and platelet concentrates. This article describes the cases of two patients with severe factor V deficiency, and of their parents. A high level of mutational heterogeneity of factor V gene was identified, nonsense mutations, frameshift mutations, missense changes, synonymous sequence variants and intronic changes. These findings prompted the identification of a new mutation in the human factor V gene, designated as Jaén-1, which is capable of altering the procoagulant function of factor V. In addition, an update is provided on the prospects for the treatment of factor V deficiency on the basis of yet-to-be-developed recombinant products or advanced gene and cell therapies that could potentially correct this hereditary disorder.

Ethnic variance on long term clinical outcomes of concomitant use of proton pump inhibitors and clopidogrel in patients with stent implantation: A PRISMA-complaint systematic review with meta-analysis

BACKGROUND

Pharmacokinetic and pharmacodynamic study showed a lower clopidogrel response when coprescribed with proton pump inhibitors (PPIs). Despite this, PPIs is necessary for patients treated with long term dual antiplatelet therapy (DAPT). Ethnic variance also played a different effect on clopidogrel response. Our study evaluated the effect of concomitant use of DAPT and PPIs and assessed whether ethnic variance exert different effect on clinical outcomes.

METHODS

We carefully searched EMBASE, PubMed/Medline databases, and the Cochrane library in April 2019. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE) and individual endpoints reported. We also focused on bleeding events. Studies were excluded if the follow-up were <12 months and patients were not treated with clopidogrel after stent implantation.

RESULTS

A total of 18 studies were included in the systematic review (involving 79,670 patients). No randomized controlled trials (RCTs) were included. PPIs comedication were associated with increased MACCE (odds ratio [OR] = 1.38; 95% confidence interval [CI] = 1.28-1.49) while not associated with decreased bleeding risks, such as gastrointestinal bleeding (OR = 1.05; 95% CI = 0.53-2.11). PPIs comedication were associated with increased risk for all endpoints among Caucasian population while not with increased risk for MACE (OR = 1.20; 95% CI = 0.99-1.39), all-cause death (OR = 1.24; 95% CI = 0.74-2.06), cardiac-death (OR = 1.29; 95% CI = 0.64-2.57) among Asian population.

CONCLUSION

PPIs comedication were associated with adverse clinical outcomes, and ethnic variance may exert different effect on clinical outcomes. Subgroup analysis indicated that concomitant use of PPI might be suitable for Asian patients after stent implantation.

Impact of proton pump inhibitors on clinical outcomes in patients after acute myocardial infarction: a propensity score analysis from China Acute Myocardial Infarction (CAMI) registry

Background

Proton pump inhibitors (PPIs) are recommended by the latest guidelines to reduce the risk of bleeding in acute myocardial infarction (AMI) patients treated with dual antiplatelet therapy (DAPT). However, previous pharmacodynamic and clinical studies have reported controversial results on the interaction between PPI and the P₂Y₁₂ inhibitor clopidogrel. We investigated the impact of PPIs use on in-hospital outcomes in AMI patients, aiming to provide a new insight on the value of PPIs.

Methods

A total of 23, 380 consecutive AMI patients who received clopidogrel with or without PPIs in the China Acute Myocardial Infarction (CAMI) registry were analyzed. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE) defined as a composite of in-hospital cardiac death, re-infarction and stroke. Propensity score matching (PSM) was used to control potential baseline confounders. Multivariate logistic regression analysis was performed to evaluate the effect of PPIs use on MACCE and gastrointestinal bleeding (GIB).

Results

Among the whole AMI population, a large majority received DAPT and 67.5% were co-medicated with PPIs. PPIs use was associated with a decreased risk of MACCE (Before PSM OR: 0.857, 95% CI: 0.742-0.990, P = 0.0359; after PSM OR: 0.862, 95% CI: 0.768-0.949, P = 0.0245) after multivariate adjustment. Patients receiving PPIs also had a lower risk of cardiac death but a higher risk of complicating with stroke. When GIB occurred, an alleviating trend of GIB severity was observed in PPIs group.

Conclusions

Our study is the first nation-wide large-scale study to show evidence on PPIs use in AMI patients treated with DAPT. We found that PPIs in combination with clopidogrel was associated with decreased risk for MACCE in AMI patients, and it might have a trend to mitigate GIB severity. Therefore, PPIs could become an available choice for AMI patients during hospitalization.

Appropriateness of gastrointestinal prophylaxis use during hospitalization in patients with acute myocardial infarction: Analysis from the China Acute Myocardial Infarction Registry

BACKGROUND

The current status of gastrointestinal prophylaxis (GIP) usage and its effects on hospitalized acute myocardial infarction (AMI) patients is not clear. We investigate the appropriateness of GIP usage and its relationship with clinical events in China.

HYPOTHESIS

Appropriate use of GIP is not associated with increased adverse outcomes.

METHODS

From January 2013 to September 2014, a total of 24 001 consecutive patients from 108 hospitals with AMI in China Acute Myocardial Infarction (CAMI) registry were analyzed. The appropriateness of GIP was evaluated using the current American College of Cardiology Foundation/American Heart Association (ACCF/AHA) and European Society of Cardiology (ESC) guidelines. The primary endpoint was in-hospital gastrointestinal bleeding (GIB), while the secondary endpoints were in-hospital and 2-year follow-up net adverse cardiovascular and cerebrovascular events (NACCE). Multivariate logistic regression analysis and Cox proportional hazard models were used to assess the effect of appropriate GIP.

RESULTS

There were 16 413 (68.38%) AMI patients co-medicated with GIP. Among 108 involved hospitals, only 35 (32.4%) hospitals prescribed more than 50% appropriate GIP. Totally, 59.7% (14 340) AMI patients received inappropriate GIP. Inappropriate GIP use was independently associated with use of GPIIb/IIIa receptor inhibitor and primary percutaneous coronary intervention (PCI). Moreover, appropriate GIP use was associated with decreased GIB risk (OR: 0.692, 95% CI: 0.507-0.944, P = .0202) during hospitalization, while not with increased in-hospital and 2-year follow-up NACCE.

CONCLUSION

The use of GIP is prevalent in patients with AMI in China but only 40% of hospitalized patients received appropriate GIP. Appropriate prophylactic therapy was associated with decreased GIB risk during hospitalization.

Drug-Drug Interactions in Acute Coronary Syndrome Patients: Systematic Review

Drug-drug interaction (DDI) is defined as a clinically significant change in the exposure and/or response to a drug caused by co-administration of another drug which may result in a precipitation of an adverse event or alteration of its therapeutic effects. The aim of this systematic review was to provide an overview of DDIs that were actually observed or evaluated in acute coronary syndrome (ACS) patients with particular focus on DDIs with clinical relevance. Electronic searches of the literature were conducted in the following databases: MEDLINE, EBSCO, Scopus, Google Scholar and SCIndeks. A total of 117 articles were included in the review. This review showed that ACS patients can be exposed to a variety of DDIs with diverse outcomes which include decreased efficacy of antiplatelet drugs, thrombolytics or anticoagulants, increased risk of bleeding, rhabdomyolysis, hepatotoxicity, adverse effects on cardiovascular system (e.g. QT interval prolongation, arrhythmias, excessive bradycardia, severe hypotension), serotonin syndrome and drug-induced fever. Majority of the DDIs involved antiplatelet drugs (e.g. aspirin, clopidogrel and ticagrelor). Evidence of some of the reported DDIs is inconclusive as some of the studies have shown conflicting results. There is a need for additional post-marketing and population-based studies to evaluate the true effects of disease states and other factors on the clinical outcomes of DDIs. Clinicians should be attentive to the potential for DDIs and their associated harm in order to minimize or, if possible, avoid medication-related adverse events in ACS patients.

Influence of proton pump inhibitors on clinical outcomes in coronary heart disease patients receiving aspirin and clopidogrel: A meta-analysis

BACKGROUND

Proton pump inhibitors (PPIs) are usually prescribed to protect against gastrointestinal bleeding in patients on dual antiplatelet therapy. This meta-analysis reviewed clinical outcomes in patients taking aspirin and clopidogrel, with and without concomitant PPIs to address concerns of adverse reactions.

METHODS

We searched PubMed, Embase, and the Cochrane Library for articles published between January 1, 2010 and April 11, 2017. The primary end points were major adverse cardiovascular events and gastrointestinal bleeding. Secondary end points were myocardial infarction, stent thrombosis, revascularization, cardiogenic death, and all-cause mortality.

RESULTS

The meta-analysis included 33,492 patients in 4 randomized controlled trials and 8 controlled observational studies. Overall, patients taking PPIs had statistical differences in major adverse cardiovascular events [odds ratio (OR) 1.17 (95% confidence interval [CI] 1.07-1.28); P = .001; I = 28.3%], gastrointestinal bleeding [OR 0.58 (95% CI 0.36-0.92); P = .022; I = 80.6%], stent thrombosis [OR 1.30 (95% CI 1.01-1.68); P = .041; I = 0%], and revascularization [OR 1.20 (95% CI 1.04-1.38); P = .011; I = 5.1%], compared those not taking PPIs. There were no significant differences in myocardial infarction [OR 1.03 (95% CI 0.87-1.22); P = .742; I = 0%], cardiogenic death [OR 1.09 (95% CI 0.83-1.43); P = .526; I = 0%], or all-cause mortality [OR 1.08 (95% CI 0.93-1.25); P = .329; I = 0%).

CONCLUSIONS

Among the patients taking aspirin and clopidogrel, the results indicated that the combined use of PPIs increased the rates of major adverse cardiovascular events, stent thrombosis, and revascularization.

Comparison of prophylactic effect of UGIB and effects on platelet function between PPIs and H2RAs combined with DAPT: systematic review and meta-analysis

Objective

We compared prophylactic effects of proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H₂RAs) on upper gastrointestinal bleeding (UGIB) associated with dual antiplatelet therapy (DAPT) and explored this influence on platelet function.

Methods

Randomized controlled trials and cohort studies comparing PPIs with H₂RAs in adults receiving DAPT were collected from PubMed, EMBASE and Cochrane databases. Dichotomous data were pooled to obtain risk ratios (RRs) for UGIB, major adverse cardiovascular events (MACEs), poor responders to clopidogrel and rehospitalization, and continuous data were pooled to obtain mean differences (MDs) for P2Y₁₂ reaction units (PRUs), with 95% confidence intervals (CIs).

Results

Twelve clinical trials (n=3,301) met the inclusion criteria. Compared to H₂RAs, PPIs lessened UGIB (RR =0.16, 95% CI: 0.03–0.70), and there was no significant difference in the incidence of PRUs (MD =18.21 PRUs, 95% CI: −4.11–40.54), poor responders to clopidogrel (RR =1.21, 95% CI: 0.92–1.61), incidence of MACEs (RR =0.89, 95% CI: 0.45–1.75) or rehospitalization (RR =1.76, 95% CI: 0.79–3.92). Subgroup analysis confirmed fewer PRUs in the H₂RAs group compared to the omeprazole group (2 studies, n=189, MD =31.80 PRUs, 95% CI: 11.65–51.96). However, poor responder data for clopidogrel and MACEs might be unreliable because few studies of this kind were included.

Conclusion

Limited evidence indicates that PPIs were better than H₂RAs for prophylaxis of UGIB associated with DAPT and had no effect on platelet function. Further study is needed to confirm these observations.

Combination Use of Clopidogrel and Proton Pump Inhibitors Increases Major Adverse Cardiovascular Events in Patients With Coronary Artery Disease: A Meta-Analysis

BACKGROUND

Published data indicated that combination use of clopidogrel and proton pump inhibitors (PPIs) may increase the incidence of major adverse cardiovascular events (MACEs). This has been a highly controversial topic for years.

DESIGN

The present study was performed to evaluate whether combination therapy of clopidogrel and PPIs is associated with increased risk of MACEs than with clopidogrel alone in patients with coronary artery disease.

METHODS

A systematic search of MEDLINE, EMBASE, and the Cochrane Library was conducted for studies recording the occurrence of MACEs in patients with exposure to concomitant use of clopidogrel and PPIs up to February 2015. Odds ratios (ORs) were combined using a random-effects model.

RESULTS

Patients receiving combination therapy with PPIs and clopidogrel were at significantly increased risk of MACEs (OR: 1.42; 95% confidence interval [CI]: 1.30-1.55). Adding a PPI to clopidogrel treatment was associated with a higher rate of MACE occurrence in rapid metabolizers (RMs, *1/*1) of CYP2C19 (OR: 1.42; 95% CI: 1.12-1.81), but there was no obviously increased rate (OR: 1.43; 95% CI: 0.89-2.28) in decreased metabolizers (with 1 or 2 loss-of-function allele). The increased risk of MACEs was similar in 4 classes of PPIs (omeprazole, lansoprazole, esomeprazole, and pantoprazole), but rabeprazole (OR: 1.03; 95% CI: 0.55-1.95) wasn't.

CONCLUSION

The combination use of clopidogrel and certain types of PPIs (omeprazole, lansoprazole, esomeprazole, pantoprazole) increases the risk of MACE in patients with coronary artery disease. Only in the RMs of CYP2C19, PPIs were associated with significantly increased MACE in patients coadministered with clopidogrel.

Drug Interaction Between Clopidogrel and Ranitidine or Omeprazole in Stable Coronary Artery Disease: A Double-Blind, Double Dummy, Randomized Study

BACKGROUND

Proton-pump inhibitors (PPIs) are often prescribed to patients receiving dual antiplatelet therapy (DAPT). However, this class of medication, especially omeprazole, has been associated with a reduction in clopidogrel efficacy, leading many clinicians to substitute omeprazole with ranitidine.

OBJECTIVES

Our objective was to compare the antiplatelet effect of clopidogrel before and after the addition of omeprazole or ranitidine.

METHODS

We measured platelet aggregability at baseline and after 1 week of clopidogrel 75 mg daily. Subjects were then randomized in a double-blinded, double-dummy fashion to omeprazole 20 mg twice daily (bid) or ranitidine 150 mg bid. We repeated aggregability tests after 1 additional week, using VerifyNow P2Y12™ (Accumetrics; San Diego, CA, USA), depicting aggregability as percent inhibition of platelet aggregation (IPA).

RESULTS

We enrolled 41 patients in the omeprazole group and 44 in the ranitidine group. IPA was significantly decreased after the addition of omeprazole to clopidogrel (from 26.3 ± 32.9 to 17.4 ± 33.1 %; p = 0.025), with no statistical significant changes observed in the ranitidine group (from 32.6 ± 28.9 to 30.1 ± 31.3 %; p = 0.310). The comparison of IPA in both groups at the end of the follow-up showed a trend toward significance (p = 0.07, 95 % confidence interval [CI] -1.19 to 26.59); after excluding homozygous patients for 2C19*2 genotype, the comparison of IPA between the groups reached statistical significance (32.7 ± 30.8 vs. 17.7 ± 33.4 %, respectively, for ranitidine and omeprazole groups; p = 0.04).

CONCLUSIONS

Unlike omeprazole, ranitidine did not influence platelet aggregability response to clopidogrel.

CLINICAL TRIAL REGISTRATION

NCT01896557.

In Vitro Effects of Pantoprazole on Platelet Aggregation in Blood Samples From Clopidogrel and Aspirin-treated Patients

Platelet inhibition during treatment with the antiplatelet drug clopidogrel is prone to great interindividual variability and is believed to be affected by several factors such as genetics and drug-drug interactions. Proton pump inhibitors have been shown to interfere with the liver metabolism of clopidogrel. However, there are limited data on any direct effects proton pump inhibitors may have on clopidogrel. The aim of the study was to evaluate whether the in vitro addition of pantoprazole affects platelet aggregation in blood samples from clopidogrel and aspirin-treated patients. Blood samples were drawn from 66 patients on clopidogrel and aspirin who underwent coronary angiography. Platelet aggregation was analyzed using the bed-side Plateletworks assay before and after the addition of 2 different amounts of pantoprazole. The addition of 2.5 μL (4 mg/mL) pantoprazole, final concentration 0.01 mg/mL, was followed by a significant reduction (26%, P ≤ 0.001) of platelet aggregation, which was further reduced (39%, P ≤ 0.001) when a higher dose, 10 μL (4 mg/mL), final concentration 0.04 mg/mL, was added. In conclusion, platelet aggregation was significantly decreased by in vitro addition of pantoprazole. To explore the clinical relevance of this, future studies are needed.

Proton Pump Inhibitors in Cardiovascular Disease: Drug Interactions with Antiplatelet Drugs

Aspirin and P2Y₁₂ receptor antagonists are widely used across the spectrum of cardiovascular diseases. Upper gastrointestinal complications, including ulcer and bleeding, are relatively common during antiplatelet treatment and, therefore, concomitant proton pump inhibitor (PPI) treatment is often prescribed.PPIs provide gastroprotection by changing the intragastric milieu, essentially by raising intragastric pH. In recent years, it has been heavily discussed whether PPIs may reduce the cardiovascular protection by aspirin and, even more so, clopidogrel. Pharmacodynamic and pharmacokinetic studies suggested an interaction between PPIs and clopidogrel, and subsequent clinical studies were conducted to evaluate the clinical impact of this interaction. More recently, it was reported that PPIs may also attenuate the antiplatelet effect of aspirin. This may be clinically important, because a fixed combination of aspirin and a PPI (esomeprazole) has recently been approved and because aspirin is the most widely used drug in patients with cardiovascular disease. The antiplatelet effect of the new P2Y₁₂ receptor antagonists, ticagrelor and prasugrel, seems less influenced by PPI co-treatment.Given the large number of patients treated with antithrombotic drugs and PPIs, even a minor reduction of platelet inhibition potentially carries considerable clinical impact. The present book chapter summarizes the evidence regarding the widespread use of platelet inhibitors and PPIs in combination. Moreover, it outlines current evidence supporting or opposing drug interactions between these drugs and discusses clinical implications.

Current Strategies to Reduce Gastrointestinal Bleeding Risk Associated with Antiplatelet Agents

Antiplatelet agents remain the cornerstone in the primary and secondary therapeutic intervention for cardiovascular disease. Some patients may be subjected to a year or more of dual antiplatelet therapy to reduce the risk of subsequent cardiovascular events. Patients on antiplatelet therapy have an increased risk of gastrointestinal bleeding; however, not all patients benefit from concomitant acid suppressive therapy. This review will provide an overview of the pharmacology of antiplatelet agents and outline patient risk profiles that ought to be considered when considering prophylactic therapy to reduce gastrointestinal toxicity. In addition, we discuss the current risk-reduction strategies intended to mitigate against the potential for related gastroduodenal injury.

Proton-pump inhibitors in patients requiring antiplatelet therapy: new FDA labeling

Proton-pump inhibitors (PPIs) are recommended for patients who require antiplatelet therapy and have a history of upper gastrointestinal bleeding. Proton-pump inhibitors should also be considered for patients receiving antiplatelet therapy who have other risk factors for gastrointestinal bleeding, including use of aspirin. Thus, evidence of pharmacokinetic and pharmacodynamic interactions between PPIs and consequent impaired effectiveness of the antiplatelet agent clopidogrel has caused concern. Here, we discuss comparative studies suggesting that the extent to which a PPI reduces exposure to the active metabolite of clopidogrel and attenuates its antithrombotic effect differs among PPIs. Although a clinically meaningful effect of the interaction between PPIs and clopidogrel on cardiovascular outcomes has not been established, these studies provided the basis for recent changes in US Food and Drug Administration (FDA) labeling for several PPIs and clopidogrel. New labeling suggests that PPI use among patients taking clopidogrel be limited to pantoprazole, rabeprazole, lansoprazole, or dexlansoprazole. Because comparative studies indicate that omeprazole and esomeprazole have a greater effect on the CYP2C19-mediated conversion of clopidogrel to its active metabolite and, consequently, clopidogrel's effect on platelet reactivity, FDA labeling recommends avoiding omeprazole and esomeprazole in patients taking clopidogrel. Even a 12-hour separation of dosing does not appear to prevent drug interactions between omeprazole and clopidogrel.

Proton pump inhibitors and clopidogrel: an association to avoid?

Dual antiplatelet therapy with aspirin and clopidogrel reduces cardiovascular events following an acute coronary syndrome or stent implantation, but the associated increased risk of gastro-intestinal bleeding often leads to the co-administration of proton pump inhibitors (PPIs). PPIs have been shown to decrease antiplatelet effects of clopidogrel ex vivo, raising concerns about the cardiovascular safety of this drug combination. Clinical trials investigating PPI-clopidogrel interactions have provided conflicting results and are all subject to methodological critiques. The much desired and much needed prospective, double-bind, randomized, placebo-controlled trials with adequate follow-up and sample size have not yet been performed. Indeed, the Clopidogrel and the Optimization of GI Events Trial, which would have had such characteristics, was stopped prematurely. As a consequence, the question of the PPI-clopidogrel interaction is still unresolved, and clinical consequences cannot be excluded. At this time such combination therapy should, therefore, be provisionally advocated only for patients at high risk of bleeding (prior upper gastro-intestinal bleeding, advanced age, concomitant use of warfarin, steroidal or non-steroidal anti-inflammatory drugs and Helicobacter pylori infection) and avoiding PPIs with strong affinity for cytochrome CYP2C19, such as omeprazole and esomeprazole.

Von Willebrand factor antigen predicts response to double dose of aspirin and clopidogrel by PFA-100 in patients undergoing primary angioplasty for ST elevation myocardial infarction

Von Willebrand factor (VWF) is an emerging risk factor in acute coronary syndromes. Platelet Function Analyzer (PFA-100) with Collagen/Epinephrine (CEPI) is sensitive to functional alterations of VWF and also identifies patients with high on-treatment platelet reactivity (HPR). The objective of this study was to verify the effect of double dose (DD) of aspirin and clopidogrel on HPR detected by PFA-100 and its relation to VWF and to its regulatory metalloprotease ADAMTS-13. Between 2009 and 2011 we enrolled 116 consecutive patients with ST elevation myocardial infarction undergoing primary PCI with HPR at day 5 after PCI. Patients recruited were then randomized between a standard dose (SD, n = 58) or DD of aspirin and clopidogrel (DD, n = 58), maintained for 6 months follow-up. Blood samples for PFA-100, light transmittance aggregometry, and VWF/ADAMTS-13 analysis were collected after 5, 30, and 180 days (Times 0, 1, and 2). At Times 1 and 2 we observed a significantly higher CEPI closure times (CT) in DD as compared to SD (P < 0.001). Delta of CEPI-CT (T1 - T0) was significantly related to VWF (P < 0.001) and inversely related to ADAMTS-13 (0.01). Responders had a significantly higher level of VWF at T0. Finally, in a multivariate model analysis, VWF and ADAMTS-13 in resulted significant predictors of CEPI-CT response (P = 0.02). HRP detected by PFA-100 in acute myocardial infarction is reversible by DD of aspirin and clopidogrel; the response is predicted by basal levels of VWF and ADAMTS-13. PFA-100 may be a useful tool to risk stratification in acute coronary syndromes given its sensitivity to VWF.