Clopidogrel, CYP2C19, and a Black Box

Transcription

1 Review Clopidogrel, CYP2C19, and a Black Box The Journal of Clinical Pharmacology 53(3) The Author(s) 2013 DOI: /jcph.17 Neville F. Ford, MD, PhD, FCP 1,2 and Dirk Taubert, MD, PhD 3 Abstract It has been presumed that CYP2C19 has a major role in the metabolism of clopidogrel. This presumption has been based on in vitro drug metabolism studies using microsomes from baculovirus infected insect cells (BD Supersomes ). If clopidogrel were primarily a CYP2C19 substrate, a drug/drug interaction with CYP2C19 inhibitors, such as proton pump inhibitors (PPIs), for example, omeprazole and lansoprazole would be anticipated. Several ex vivo studies, using ADP stimulated platelet aggregation, suggested that there was such an interaction. The data from these studies served as a basis for FDA to provide a Black Box warning for the clopidogrel label in March of However, a prospective clinical study, COGENT, and several large meta analyses have failed to demonstrate a negative effect on major adverse cardiovascular events (MACE), with concomitant administration of clopidogrel and PPIs. The in vitro work using Supersomes was revisited. In vitro metabolism using hepatosomes, which resemble the native cytochrome P 450 enzyme expression, has confirmed the earlier work that clopidogrel is primarily a CYP3A substrate. This result correlates better with clinical findings. The absence of an increase in MACE by concomitant administration of PPIs, which are CYP2C19 inhibitors, to a regimen including clopidogrel, is therefore not surprising. A hypothesis is offered to explain why subjects, who carry two reduced function alleles of CYP2C19, may have more reactive platelets. Keywords clopidogrel, CYP2C19, CYP3A, drug/drug interactions, lansoprazole, MACE, omeprazole, pharmacogenomics, platelets, PPIs, supersomes and hepatosomes Clopidogrel is a successful drug in the management of acute coronary syndrome (ACS), vascular diseases generally and particularly in the conduct of percutaneous coronary interventions (PCIs). 1 It has been believed to be a CYP2C19 substrate. Therefore, concomitant administration of proton pump inhibitors (PPIs), particularly omeprazole, that are CYP2C19 inhibitors, should adversely affect its performance. FDA, in March 2010, added a black box to the US label for clopidogrel (Plavix ). The black box stated that Effectiveness of Plavix depends on activation to an active metabolite by the cytochrome P450 (CYP) system, principally CYP2C19. In the Drug Interactions section of the revised label, it was recommended that omeprazole not be used concomitantly with clopidogrel, because of its CYP2C19 inhibitory effect. Pantoprazole was suggested as an alternative PPI, because it is a less potent CYP2C19 inhibitor, 2 although this view has been disputed. 3 The study on which these changes to the label by FDA were based has been published. 4 It was a well designed study, but the bioanalytical methodology could only measure clopidogrel and the thiol acid active metabolite. 5 This meant that one did not know the amount of the immediate precursor, 2 oxo clopidogrel, that was formed. There were also very modest increases in the AUC (37 51%) of clopidogrel following multiple doses that were not typical of what is usually considered to be a positive drug/drug interaction, for example, greater than twofold. The change in AUC following the first dose (19%; 90% CI 6 33%) was even less pronounced. The presently accepted metabolism of clopidogrel was developed by scientists at Daiichi Sankyo and Lilly. 6 The originally proposed mechanism by Sanofi involved an oxidation of clopidogrel to 2 oxo clopidogrel. 7 This was attributed to CYP3A by Clarke and Waskell. 8 The formation of the active thiol acid from 2 oxo clopidogrel, which is a thiolactone, was considered to be due to hydrolysis. 7 The proposed mechanism by Daiichi Sankyo and Lilly, however invokes an initial oxidation of clopidogrel to 2 oxo clopidogrel that involves multiple CYPs, CYP1A2, CYP2B6, CYP2C19 but not CYP3A4. 9 It is difficult to understand why one would expect a clinically significant inhibition of clopidogrel oxidation by omeprazole, when the major pathway via CYP1A2 would be unaffected. This mechanism then proposed oxidation of 2 oxo clopidogrel, which is a thiolactone, to an unidentified intermediate by CYP2B6, CYP2C9, CYP2C19, and CYP3A4. This intermediate gets reduced back to the active thiol acid that was identified by Savi and co workers at 1 Woodfield Clinical Consulting LLC, Green Valley, AZ, 85622, USA 2 UMDNJ RWJ Medical School, New Brunswick, NJ, 08903, USA 3 Department of Pharmacology, University Hospital of Cologne, Cologne, Germany Submitted for publication 22 June 2012; accepted 9 August Corresponding Author: Dr. Neville Ford, Woodfield Clinical Consulting LLC, 5481 South Acacia Creek Drive, Green Valley, AZ 85622, USA neville@woodfieldclinical.com

2 242 The Journal of Clinical Pharmacology / Vol 53 No 3 (2013) Sanofi. 10 While indeed at this step CYP2C19 is the major CYP, it still constitutes less than 50% of the oxidative process. It is again hard to conceptualize why inhibiting just this CYP would be expected to have a clinical effect. The other troublesome feature of this hypothesis is that the nature of the intermediate formed by oxidation of 2 oxoclopidogrel was not described. A mechanism has been proposed by Dansette and co worker 11 that involves a sulfenic acid intermediate that is trapped by dimedone. It, presumably, is this sulfenic acid intermediate that is reduced by glutathione to the active thiol acid. This oxidation and reduction of the thiolactone (2 oxo clopidogrel) was invoked because it was presumed that the thiolactone would not open hydrolytically in vivo. However, it has been shown that 2 oxo clopidogrel opens ex vivo to the active thiol acid in human serum that is devoid of CYPs. 12 Challenges to the CYP2C19 Hypothesis A bioanalytical method, validated according to the FDA Guidance for Industry Bioanalytical Method Validation May 2001 was published by Bouman et al. in This method permitted all three analytes, clopidogrel, 2 oxoclopidogrel and the thiol acid active metabolite to be measured, along with the major carboxylic acid metabolite formed by hydrolysis of the carbomethoxy group of clopidogrel. Bouman also studied the in vitro metabolism of clopidogrel but using hepatosomes rather than supersomes. It was concluded that clopidogrel is primarily a CYP3A substrate. Other workers have commented on the limitations of supersomes in accurately defining metabolic pathways. 13 Supersomes and yeast microsomes have also been reported to give differing results as far as CYP2D6 is concerned. 14 A further analytical method has been published by Tuffal et al. 15 This method used the thiol trapping agent used by Takahashi et al. 5 but it was extended to include all four potential thiol acids. It still though did not measure 2 oxo clopidogrel. Bouman et al. 12 showed that the conversion of 2 oxoclopidogrel to the thiol acid involves hydrolysis, as originally proposed by Savi et al. 7 The hydrolysis is catalyzed by paraoxonase 1 (PON 1). This is a credible role for paraoxonase 1, because its endogenous substrate is homocysteine thiolactone. 16 Paraoxonase 1 can also open other thiolactones, such as gamma thiobutyrolactone. Bouman provided kinetic data to support this hypothesis. She also showed that there was an association between PON 1 polymorphism and clinical outcome post PCI. Those subjects, who were homozygous for the allele (Q) that conferred reduced hydrolytic capability, had the highest incidence of thrombosis in the stent. The QR subjects had intermediate outcomes. The subjects, who were homozygous for the allele that conferred the highest hydrolytic activity, had the best clinical outcomes. This finding has been disputed. 17 Taubert et al. showed that incubation of clopidogrel and 2 oxo clopidogrel with human microsomal preparations expressing CYP2C19 did not metabolize either compound. However, omeprazole, a known CYP2C19 substrate was extensively converted to its metabolite 5 hydroxy omeprazole. 18 These findings suggest clopidogrel is not a CYP2C19 substrate. Support for the CYP2C19 Hypothesis Sibbing et al. investigated the CYP2C19 genotype in patients from their institute, who underwent percutaneous coronary intervention (PCI). They showed that platelet inhibition following clopidogrel administration correlated best with the CYP2C19*2 genotypes, rather than with the PON1 Q192R genotype. 19 A paper from Lewis, using data from the Amish Pharmacogenomics of Anti platelet Intervention (PAPI) study, showed in a small sub set (79 patients) that there was no correlation between paraoxonase activity and postclopidogrel platelet aggregation. 20 A small study by Kim in 21 healthy subjects was also published. 21 This study did reproduce the in vitro metabolism work using supersomes expressing CYP2C19 and CYP3A4. CYP3A4, however, to be functional, needs to be intracellular. Such data derived from pure cytochromes should be viewed critically. The work by Bouman et al., 12 Clarke and Waskell 8 and the original work from Daiichi Sankyo 22 using human hepatosomes convincingly demonstrated that the initial oxidative step from clopidogrel to 2 oxo clopidogrel involved CYP3A isozymes. A recent paper measured. ADP driven platelet aggregation on isolated human platelets, after incubation with clopidogrel in the presence of different supersomes. 23 Using this methodology the CYP3A4 supersome is capable of inducing platelet inhibition (i.e., of converting clopidogrel to the active metabolite). Applying the method to the incubation of platelets with 2 oxo clopidogrel, CYP2C19 had no role at all (i.e., it was not capable of converting 2 oxo clopidogrel to the active metabolite). Only CYP2D6 and CYP2C9 had modest and incomplete effects. A further hypothesis to explain the roles of CYP3A4 and CYP2C19 in the metabolism has been published by Zahno et al. 24 The findings were surprising. The study used both human hepatic microsomes and CYP3A4 and CYP2C19 supersomes. Zahno et al. showed that clopidogrel was primarily a CYP3A4 substrate in both hepatic microsomes and supersomes but the reaction rate constants of hepatic microsomes were higher. The transformation was antagonized by the CYP3A4 inhibitors ketoconazole and clarithromycin. They considered their findings to be in accord with those of Clarke and Waskell. 8 Their methodology though does not deal with the processes occurring in the second step of the clopidogrel metabolism.

3 Ford and Taubert 243 A recent debate by Dansette et al. 25 and Bouman et al. 26 outlines the issues. The contribution from Dansette was helpful, because he provided chemical insight into the problem. Clopidogrel is a single enantiomer with the S configuration. On one point there was unanimity. The intermediate on the path to the active metabolite is the thiolactone, 2 oxo clopidogrel. This oxidative process introduces a new asymmetric center in the molecule, so in fact the entity called 2 oxo clopidorel is a mixture of two compounds that differ at C 4. This mixture is available commercially from several sources (Santa Cruz Biotechnology, Santa Cruz CA; CacheSyn and Chemical Book) but none of these sources mention what the ratio of the diastereoisomers is. In a recent paper Dansette describes his mixture to be 80:20 but he did not describe how he had obtained the 2 oxo clopidogrel. 27 Only one of these 2 oxo clopidogrels has the correct geometry to form a thiol acid that can interact with the P2Y12 receptor on the platelet. Despite the excellent work by Tuffal et al. the precise stereochemistry of this active thiol acid, H4, is still not known (see Figure 1). 15 Dansette maintained that in his laboratory 2 oxoclopidogrel in human plasma, devoid of CYPs, but containing PON1 failed to generate either thiol acid. He obtained only the isomeric endo thiol acid, which could be derived from either thiol acid. 25 In Bouman s rebuttal, 26 she reiterated the methodology by which 2 oxo clopidogrel did open to the thiol acid in the presence of PON1 transfected HEK cell microsomes. She also mentioned that CYP2C19 transfected HEK cell microsomes did not facilitate the conversion of 2 oxo clopidogrel either in the presence or in the absence of an NADPH generating system and glutathione to the active metabolite. This is the weakness in the elegant hypothesis from Dansette. Mechanistically, it is hard to imagine oxidizing 2 oxoclopidogrel to a reactive intermediate that is then reduced back to something else. Dansette did not offer an analogous process, or any trapping experiments for intermediates that contained a sulfur oxygen bond. In his recent review 11 the dimedone adduct is a product that could equally well be derived from a disulfide, as from a sulfenic acid. Yet another group of authors raised objections to Bouman s publication. 12 This letter 28 by Camps et al., presented concerns regarding the presence of EDTA in the plasma used in the studies, impacting on the activity of PON1. Bouman et al. 26 also addressed these concerns in her response. Platelet Studies in Support of the CYP2C19 Hypothesis One of the first clinical papers to suggest that omeprazole had an adverse effect on the clinical performance of clopidogrel was an observational study by Gilard et al. 29 These observations led to the design of the OCLA (Omeprazole Clopidogrel Aspirin) study. 30 This study was a randomized double blind placebo controlled study in 124 consecutive PCI patients treated with aspirin and clopidogrel. They were randomized to omeprazole (20 mg; q.d.) or placebo. The effects of clopidogrel were assessed using an ex vivo platelet assay (VASP) on days 1 and 7. It was concluded that omeprazole had an adverse effect. There were a few dissenters from the view that clopidogrel was a CYP2C19 substrate. Lau et al. 31 showed, in collaboration with Watkins, that using the erythromycin breath test to assess CYP3A4 activity, administration of rifampin increased it and concomitantly improved platelet inhibition. He subsequently showed similar results when the induction of CYP3A4 was accomplished by St John s Wort. 32 Omeprazole is frequently added to post PCI regimens of aspirin and clopidogrel, in order to reduce gastrointestinal blood loss. A reduction in hemoglobin is an independent cardiovascular risk factor. 33 It also follows that patients with reduced function CYP2C19 alleles would then not be able to as effectively metabolize clopidogrel to the active thiol acid, as those with wild type alleles. The Black Box that FDA added to the Plavix (clopidogrel) label in 2010 addressed this genetic issue. It suggested genetic testing for CYP2C19 in order to prospectively identify poor metabolizers, particularly CYP2C19 *2/*2 individuals. Two large outcome studies appeared soon after the Gilard publication of the OCLA findings. 30 One by Ho was a Veterans Administration (VA) study in acute coronary syndrome (ACS) patients, who were discharged on clopidogrel. The outcome measures were all cause mortality and re hospitalization for ACS. They were assessed relative to whether the patients were or were not taking PPIs concomitantly. 34 Concomitant use of a PPI was associated with an increase in adverse cardiovascular events. A similar study was reported by Juurlink in 13, 636 patients, who were prescribed clopidogrel following acute myocardial infarction. 35 They concluded from inspection of Provincial Formulary records that concomitant use of a PPI was significantly associated with a short term risk of reinfarction. In neither study was there a consideration of the possibility that omeprazole might be independently associated with an increase in cardiovascular risk, unrelated to CYP2C19 inhibition. The other aspect in the treatment with clopidogrel is that if it were a CYP2C19 substrate, as the data above suggest, then one has to be concerned about pharmacogenetics as CYP2C19 *2 heterozygotes constitute 30% of the US population of African and European origin. There was evidence to suggest that such heterozygotes would not metabolize clopidogrel to the active thiol acid as effectively, as non carriers of the allele.

4 244 The Journal of Clinical Pharmacology / Vol 53 No 3 (2013) While light transmission aggregometry remains the gold standard, it was recognized to be impractical for use in clinical studies. Three commercial tests, Verify- Now, Plateletworks, and Innovance PFA P2Y were evaluated for their ability to predict clinical outcome. 36 While in general terms, it was recognized that high platelet reactivity on treatment was a bad prognostic sign, the predictive value of these tests was only modest. ELEVATE TIMI 56 described the use of these platelet aggregation assays along with the use of the VASP assay, 37 to assess the on treatment platelet reactivity in patients with stable cardiovascular disease. 38 Patients (335) were genotyped. The majority were non carriers (247). Eighty were *2 heterozygotes and six were homozygous. All patients took aspirin ( mg). Clopidogrel was given at 75 mg, 150 mg, 225 mg, and 300 mg for 2 week periods and the VASP platelet reactivity index (PRI) calculated. Patients who were heterozygous required doses of 225 mg to achieve comparable PRI values to those obtained with 75 mg in patients, who were non carriers. Homozygotes did not have comparable degrees of platelet inhibition even at 300 mg of clopidogrel. The TIMI group conducted a meta analysis to assess their hypothesis that just one defective allele had a major impact on the ability of clopidogrel to achieve a significant reduction in the PRI and hence a major reduction in adverse cardiovascular events. Patients (9 685) from nine studies, primarily from PCIs were studied. It was concluded that just one *2 allele seemed to be associated with a significantly increased risk of major adverse cardiovascular events (MACE), particularly stent thrombosis. 39 Several other studies supported the view that inheritance of just one defective allele of CYP2C19 conferred on the patient the inability to fully activate clopidogrel. In consecutive patients, who had been pretreated with 600 mg of clopidogrel prior to PCI, there was a higher incidence of stent thrombosis, during the 30 days post PCI in carriers of the *2 allele relative to non carriers (10 patients; 1.5% vs. 7 patients; 0.4%). The risk of stent thrombosis was also highest in patients who were homozygous for *2 (2.1%). 40 In young patients (<45 years of age), who had survived a myocardial infarction and were treated with clopidogrel, were genotyped for CYP2C19 *2 variants. They were followed up at 6 month intervals. The primary endpoint was death, myocardial infarction, and urgent PCI. A secondary endpoint was stent thrombosis proven by angiography. 41 The CYP2C19 *2 status was a major determinant of prognosis in these patients. In another PCI study, the association with CYP2C19 *2 genotypes and the incidence of high residual platelet aggregation (RPA) post clopidogrel dosing was explored. It was then determined whether there was an association between high RPA and poor clinical outcomes. 42 The study concluded that patients with at least one *2 allele are more prone to high on clopidogrel platelet reactivity and a poorer outcome following PCI. Similar findings regarding stent thrombus were reported in Japanese patients, although there was no statistically significant difference in MACE (major cardiovascular events; death, MI and the need for urgent PCI) between the non carriers and carriers of CYP2C19 *2. 43 Optical coherence tomography was used to detect the formation of an intra stent thrombus. This is a particularly interesting study because the frequency of *2 carriers is higher in Japanese than in Western populations. A meta analysis (6 studies; patients) addressed the relationship of on treatment platelet reactivity to clinical outcomes, without regard to CYP2C19 genetic status. 44 The primary outcome was death, myocardial infarction or stent thrombosis. The platelet reactivity was assessed by the VerifyNow method. The population was divided into four groups. The first two quartiles did not differ much in PRUs or event rates (5.8% and 6.9%), however the third quartile and fourth quartiles had significant event rates (10.9% and 15.8%). It seemed that on treatment platelet reactivity was more predictive than the CYP2C19 genotype for MACE. Although there does appear to be some association between CYP2C19 *2 and clopidogrel on treatment platelet reactivity the effect is considered to be modest. 45 Other workers have commented that phenotype is more important than genotype in predicting stent thrombosis. 46 Clinical Studies Using Outcome Criteria The CYP2C19 hypothesis has been challenged by the results from large meta analyses that looked at whether concomitant administration of PPIs, such as omeprazole, did adversely affect the clinical performance of clopidogrel. One prospective placebo controlled randomized trial to address this issue had been attempted by Cogentus, but the FDA Black Box warning rendered the future of their combination product of clopidogrel and omeprazole moot. The company declared bankruptcy and funding for the study ceased. However, patients of the originally intended were available for analysis and the study was written up. 47 There were patients in the omeprazole group and in the placebo group. There were 109 adjudicated cardiovascular events (54 in the placebo group and 55 in the omeprazole group). Fortythree of these events were considered to be major events (20 in the placebo group and 23 in the omeprazole group). As the study was now underpowered and also the incidence of cardiovascular events was lower than had been expected, it is hard to declare that omeprazole had no effect on the performance of clopidogrel. On the other hand a positive effect on the incidence on gastrointestinal

5 Ford and Taubert 245 effects was observed (2.9% in the placebo group and 1.1% in the omeprazole group [HR 0.34; 95% CI ; P <.001]). Temple provided a criticism of the paper in a letter to the editor. 48 The findings of this study may not support the position that omeprazole has no effect on the performance of clopidogrel but neither does it provide support for the FDA view that concomitant use of clopidogrel and omeprazole should be avoided. Several meta analyses have been published that suggest the PPIs do not adversely affect the clinical effect of clopidogrel. One of the largest involved approximately 3 million Danes. It was possible to identify all the patients, who had had PCIs in a given time period ( patients from 2002 to 2005). A 12 month follow up period post PCI was chosen. The use of clopidogrel post PCI and whether there was concomitant usage of PPIs was tracked. 49 The outcome measure was the incidence of MACE. The conclusions of this study were surprising. The use of PPIs as a class did not modify the cardioprotective effect of clopidogrel but their use was independently associated with MACE, particularly among patients having used PPIs before the PCI. A meta analysis from Austria came to a similar conclusion. 50 The outcome measures were MACE and GI bleeding. The selection criteria were less strict than some other studies. These authors analyzed 25 studies and included patients. They concluded that concomitant administration of PPIs did increase the incidence of MACE by 29%. However, they did not increase the incidence of death and they caused a 50% decrease in GI bleeding. They also noted that use of PPIs alone in two studies had a negative effect on cardiovascular parameters, irrespective of clopidogrel exposure. Another meta analysis, by Taubert, looked at 12 studies with patients and the association between MACE and CYP2C19 reduced function variants and 9 studies with patients, where the association was with stent thrombosis. 51 These analyses concluded that CYP2C19 has no major impact on the clinical efficacy of clopidogrel. A further meta analysis by Kwok et al. 52 looked at 23 studies involving patients. It was also concluded that there was increased cardiovascular risk with the concomitant use of PPIs post PCI, but that there was no evidence for a differential effect between them. It was evident that the effect was independent of clopidogrel. Another large meta analysis was published by Holmes et al. 53 This meta analysis reviewed 32 studies of patients in an effort to establish an association between CYP2C19 genotype and clopidogrel response. This metaanalysis also concluded that there was no clinically significant interaction of CYP2C19 genotype with the association of clopidogrel and cardiovascular events. A recent study examined the outcome data from the UK General Practice Research Database with linked data from the Myocardial Ischemia National Audit Project and the Office for National Statistics. 54 Patients (24 471) with a history of vascular events were receiving clopidogrel and aspirin. They were prescribed a PPI at some point during therapy. The incidence of myocardial infarction was compared with and without concomitant usage of PPIs. It was concluded that there was no association between myocardial infarction and PPI usage. Other papers have recently appeared that recognize that the CYP2C19 hypothesis needs revisiting, when one considers MACE. A recent paper from the French Registry of Acute ST Elevation and Non ST Elevation Myocardial Infarction (FAST MI) concludes that PPI use was not associated with an increased risk of cardiovascular events or mortality in patients administered clopidogrel for a recent MI, whatever the CYP2C19 genotype, although harm could not be formally excluded in patients with two loss of function alleles. 55 A recent article agrees with the need to revisit the CYP2C19 hypothesis and has made a case that it applies only to higher risk procedures such as PCI rather than other clopidogrel indications. 56 However, in our view, the issue is that CYP2C19 is not significantly involved in the metabolism of clopidogrel. It is a CYP3A substrate and other explanations are needed for such findings. Conclusions Clopidogrel is primarily a CYP3A substrate and not a CYP2C19 substrate. This finding has been reconfirmed by Taubert. 12,18 It is supported by the absence of any clinical evidence that suggests that CYP2C19 inhibitors, particularly PPIs, given with clopidogrel increase the incidence of MACE. It has been suggested that PPIs may increase cardiovascular risk modestly, independent of clopidogrel usage. 49 Table 1 summarizes the clinical studies that support this view. The link of CYP2C19 genotype to platelet activity may be because an endogenous substrate of CYP2C19, perhaps a polyunsaturated acid that yields a product that inhibits platelet aggregation. Subjects, who were homozygous for CYP2C19*2, might then be expected to have platelets that would more readily aggregate and need higher doses of clopidogrel to offset the problem. Essential fatty acids (EFAs) are already recognized as the precursors via cyclooxgenase to prostacyclin and thromboxane that have an established role in platelet function. The oxidation of EFAs by the CYP system is less well explored but CYP2C is known to be involved. 57,58 The present hypothesis is therefore similar to what had been proposed previously, namely that clopidogrel is metabolized to 2 oxo clopidogrel by CYP3A which is then opened hydrolytically to the active thiol acid (see Figure 1). 59 The genetic issue relates to the ease of platelet aggregation, influenced by

6 246 The Journal of Clinical Pharmacology / Vol 53 No 3 (2013) Table 1. Clopidogrel Studies With Clinical Outcomes Data Study Design Dose Patient Population Data Genotyped Results Ho et al. 34 Multicenter (127 VA Hospitals) retrospective cohort study of ACS patients from Oct 2003 to Sep 2006 Juurlink et al. 35 Case control study of Ontario residents >66 years S/P AMI April 2002 to Dec 2007, 90 day F/U post MI Bhatt et al. 47 Multicenter, double blind, randomized, placebo controlled study of clopidogrel and aspirin with and without omeprazole Schmidt et al. 49 Population based cohort study of West Denmark (3 M) PCIs 12 mo F/U use of clopidogrel/ppis Bauer et al. 51 Meta analysis from Medline, Embase and Cochrane. Used MOOSE and PRISMA for review and STREGA for genetics Kwok et al. 52 Meta analysis from Medline, Embase, and Cochrane Holmes et al. 53 Meta analysis and use of HuGEnet for gene disease association and PRISMA. PubMed and EMBASE search Douglas et al. 54 Observational cohort and self controlled case series from the UK General Practice Database Simon et al. 55 The FAST MI population. Categorized by use of PPIs or not with clopidogrel Clopidogrel 75 mg per day ASA PPI clopidogrel: 98.9% male; clopidogrel: with a PPI 98.4% male 75 mg per day And PPIs Cases 734: 52% male; Controls 2057: 55.1% male Clopidogrel: 75 mg/day; omeprazole: 20 mg/day; aspirin: mg per day 75 mg/day clopidogrel and presence or absence of PPIs Standard PCI therapy with clopidogrel With loading dose of 300 mg or 600 mg patients with ACS or stent placement (27.7% female) of whom (28.2% female) had a CV event Mean age >60 years of age. Mainly male Primary end point all cause mortality or readmission for MI or ACS Primary end point all cause mortality or AMI within 90 days post MI Assessment of GI blood loss and MACE. Median F/U was 106 days with max of 341 days Use of the Danish Nationwide Prescription Database 14 articles met entry criteria and had 15 studies Standard therapy Limited demographic data 23 studies with patients were included Not defined patients mostly with ACS and PCI some stable CHD, from 32 eligible studies CVD events, 579 stent thromboses and bleeding events Clopidogrel aspirin patients with CVD Comparison of outcomes with or without PPIs limited to 3 most prescribed Not defined FAST MI registry has patients presenting with MI most (2 744) are clopidogrel and PPI naive Comparison of outcomes with or without PPIs and relationship to the patient s genotype No Clopidogrel with PPIs was significantly associated with a higher risk of ACS but not death No PPIs associated with increased risk of recurrent MI. OR 1.27 (95% CI ) No No significant difference in CV events (HR 1.03; 95% CI ) 54 in the omeprazole group and 55 in the placebo No PPIs did not modify the protective effect of clopidogrel. Their use was independently adverse Yes No consistent influence of CYP2C19 polymorphism on the clinical efficacy of clopidogrel No Increased CV risk with use of PPIs and questions about the validity of a clopidogrel/ppi interaction Yes There was no significant association of genotype with cardiovascular events No The interaction between proton pump inhibitors is clinically unimportant Yes PPI use not associated with increased risk whatever the CYP2C19 genotype. Harm could not be formally excluded for CYP2C19*2/*2

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