A 70-year-old, immunocompromised patient presented to the emergency room (ER) five weeks after she was started on clopidogrel. She complained of skin eruption, mouth ulcers, fatigue, and myalgia over the past two weeks. Labs showed severe hyponatremia, acute kidney injury, rhabdomyolysis, hyperkalemia, and elevated liver enzymes. She was treated with steroids and discharged after her condition improved. However, a month later, she returned to the ER, complaining of nausea, vomiting, diarrhea, dizziness, chills, and shortness of breath over the past two days. She was lethargic and had orthostatic hypotension. She deteriorated clinically within a few days, with worsening lethargy and the development of respiratory distress along with profound hypotension. She needed mechanical ventilation and vasopressors. In addition, she had melena, severe thrombocytopenia, and hemolytic anemia. With supportive care, she improved and was discharged after a long stay in the intensive care unit. Retrospectively, the first hospitalization was believed to be caused by drug reaction with eosinophilia and systemic symptoms (DRESS). Treating that with steroids compromised her immune system beyond her pre-existing primary immunodeficiency status. At the time of her second hospitalization, she met the Centers for Disease Control and Prevention (CDC) criteria for a toxic shock syndrome (TSS) diagnosis. Her TSS started four days after a skin biopsy, which was done as part of her skin rash workup. It was thought that the source of the exotoxin that mediated her TSS was her skin, given the temporal relationship of the skin biopsy to her TSS. Another potential source of the exotoxin was the gastrointestinal tract, given the predominant gastrointestinal symptoms she had at the time of her second admission.

The Joint Commission in a joint effort with the Centers of Medicare and Medicaid Services (CMS) has established certain "core measures" by which hospital performance is measured. One of these is the measure for patients with ST-elevation myocardial infarction (STEMI) recommending percutaneous coronary intervention within 90 minutes of presentation to the Emergency Department in institutions that are able to provide this service. This recommendation does not take into account the long-term use of clopidogrel that is recommended by the American College of Cardiology and American Heart Association for patients that are treated with coronary stents. The purpose of this study was to evaluate outcomes of providing a short course of clopidogrel versus a prescription alone for clopidogrel to uninsured patients experiencing STEMI who were treated with a bare metal stent. After conducting a cost-benefit analysis, a policy was approved that provided uninsured STEMI patients with clopidogrel at discharge rather than a prescription. A social worker evaluated patients to determine if they met criteria and arranged for medication delivery to the patient’s bedside. A retrospective chart review for all patients who presented to the Emergency Department during two different time frames (before and after policy implementation) was conducted to evaluate if providing clopidogrel decreased readmissions. Data were collected on over a 15-month period of time before and after the clopidogrel policy implementation to allow for evaluation of 90-day readmissions with repeat STEMI. Data were analyzed using chi-square cross tabulation and T-test for independent samples. A total of 201 charts were reviewed: 100 from the pre-intervention group and 101 from the post-intervention group. Demographic characteristics of age, gender and insurance status iv were not statistically different between groups. The mean age for the control group was 59.1 (+ 13.8) years and 58.9 (+ 13.6) years for the intervention group. Twenty percent of the patients were uninsured. Five uninsured patients were readmitted with STEMI prior to the intervention compared to two patients in the intervention group (p = .191). The admissions for the preintervention patients occurred in the first 30 days after discharge compared to 31-60 days in the post-intervention group. All of the patients who were readmitted were assessed to be noncompliant with treatment. Additionally, a transition to increased use of bare metal stents in STEMI patients from 23.1% pre-intervention to 67.4% post-intervention was noted (p < .001). Although no differences were found in readmission rates, fewer readmissions for STEMI were noted after the intervention. The small number of patients who were readmitted with STEMI likely accounted for this finding, and additional monitoring of readmission rates is warranted. Despite provision of the clopidogrel, adherence remains an issue and needs to be addressed. During the intervention, physicians were encouraged to consider the financial and social resources of individual STEMI patients presenting to the Emergency Department to help identify patients that would be less likely to adhere to antiplatelet therapy. In those believed to be at high risk for non-adherence, primarily due to inability to purchase the relatively expensive medication clopidogrel, many physicians chose to insert bare metal stents rather than drugeluting stents to take advantage of the shorter course of clopidogrel required post procedure. Provision of a 30-day course of clopidogrel and aspirin was a major part of this effort to decrease recurrent myocardial infarction in this at-risk population. A few patients eligible for the clopidogrel were not provided the medication if they were admitted to a nursing unit where staff members were not familiar with the policy; revisions to the policy to ensure medication is provided to all eligible patients will be made. Providing clopidogrel to patients who experience v STEMI may improve adherence and thereby decrease readmissions as a result of repeat STEMI due to subacute thrombus formation. Patients who experience STEMI continue to be vulnerable after STEMI. Programs that provide medication to patients should be expanded within this facility and to other hospital systems to encompass all patients who are treated for STEMI. Multi-disciplinary collaboration is necessary in developing and implementing a program that will address care for this.

No / The National Audit Office (NAO) has produced prescribing indicators that Primary Care Trusts (PCTs) can use to judge their performance. One of the indicators is for the antiplatelet clopidogrel, measured as defined daily dose (DDD) per cardiovascular Specific Therapeutic Age Related Prescribing Unit (STAR-PU). Clopidogrel is used as an indicator because it is a more expensive medicine than the alternative (aspirin) and there may be scope for cost reduction. We aimed to establish if the NAO indicator for clopidogrel prescribing is a valid measure of prescribing performance. Methods Prescribing data for 152 PCTs and a range of explanatory variables were obtained. Correlation between variables was determined. A regression analysis was conducted to compare the dependent variable (prescribing) with the explanatory variables identified. Results The percentage of patients on the coronary heart disease register and Index of Multiple Deprivation explained 30% of the variation in prescribing (DDD/STAR-PU) between PCTs. Even though DDD/STAR-PU is adjusted for age and sex other measures of need still have an impact on prescribing. Conclusions Using DDD/STAR-PU alone as a prescribing indicator might misidentify some PCTs, which are under- and over-using clopidogrel. Poor ranking against other PCTs using the NAO indicator should be fully explored taking into account other variables (cardiovascular morbidity and deprivation) before any corrective action is taken.

Cette thèse est dédiée à l'approche pharmacogénétique des effets anti-inflammatoires de la thérapie par les thiénopyridines. Prenant en compte que les plaquettes activées jouent un rôle central dans les états inflammatoires et que des polymorphismes du cytochrome P450 (CYP) 2C19 ont été montré responsable de différences inter individuelle dans la réponse de l'effet antiplaquettaire de thiénopyridines, nous avons émis l'hypothèse que CYP2C19 *2 ou *17 sont également associés à la variabilité interindividuelle du potentiel antiinflammatoire des thiénopyridines. Les marqueurs d'inflammation utilisés pour suivre l'effet des thiénopyridines sont : la CRP, l'haptoglobines et l'orosomucoïde. Nous avons démontré que pour interpréter les valeurs de l'haptoglobine il était nécessaire de tenir compte du statut génétique et obtenir des valeurs de référence stratifiés. D'abord dans une population saine, nous n'avons pas trouvé d'association entre les valeurs de base des marqueurs inflammatoires et les polymorphismes fréquents de CYP époxygenases. Dans une population après intervention coronarienne percutanée qui était composée de 1128 sujets traités par clopidogrel ou prasugrel, le niveau de CRP observé a montré une interaction significative entre le tabac et le polymorphisme de CYP 2C19 ; cet effet est indépendant du niveau d'agrégation plaquettaire. Dans une 3ème population, sur plus de 1000 sujets hospitalisés à Coimbra, nous avons identifié une interaction entre le clopidogrel CYP2C19 et les médicaments bloqueurs des canaux calciques. En résumé, tous ces résultats obtenus sur plusieurs populations laissent envisager que les marqueurs d'inflammation pourraient être un moyen intéressant de suivi des patients lors de la thérapeutique par les thiénopyridines / The main part of the thesis is devoted to pharmacogenetic approach to the anti-inflammatory effects of thienopyridine therapy. Taking into the account that activated platelets play a central role in the inflammatory responses and that CYP2C19 gain- and loss-of-function polymorphisms (*2 and *17) are sources of inter-individual difference in response to the anti-platelet effects of thienopyridines, we hypothesized that *2 and/or *17 alleles are also associated with inter-individual variability in the potential inflammation-reducing effects of thienopyridines. The following markers were used to test the hypothesis: CRP, haptoglobin and orosomucoid acid. To be reliably interpretable in daily medical practice, genetic status should be considered for partitioning the reference values of haptoglobin. In a small healthy population, no significant association was observed between *2 allele and changes in levels of inflammatory markers from baseline to 7 days after administration of clopidogrel and our findings did not support the notion that the genetic variations of CYP epoxygenases are associated with the level of inflammatory markers. Also, in post-PCI population consisting of 1128 on-clopidogrel or on-prasugrel patients, CRP levels were observed to be regulated with a significant interaction between smoking and CYP2C19 polymorphisms; this effect was independent to the level of platelet aggregation. Additionally, in a large population of 1000 on-clopidogrel patients, whether there is a potential interaction between clopidogrel and calcium channel blockers. Collectively, we demonstrated in this thesis that inflammatory markers might be alternative tools for the prediction of response to thienopyridines

Clopidogrel hat sich als potentes Medikament zur Verhinderung kardiovaskulärer Ereignisse sowohl bei Patienten mit akutem Koronarsyndrom ohne ST-Hebung (non-STE-ACS) als auch bei Patienten mit akutem Myokardinfarkt mit ST-Hebung (STEMI) erwiesen (CURE- und COMMIT-Studie). Insbesondere der Nutzen einer Vorbehandlung mit Clopidogrel bei perkutaner Koronarintervention ist bei Patienten mit non-STE-ACS und STEMI gut belegt (PCI-CURE- und PCI-CLARITY-Studie). Ein beträchtlicher Anteil der Patienten zeigt allerdings kein adäquates Ansprechverhalten auf Clopidogrel. Wir etablierten deswegen zusätzlich zu einem bereits bestehenden FACS-Assay, der den Effekt von Clopidogrel anhand der Phosphorylierung des Proteins VASP quantitativ bestimmt, einen neuartigen auf dem gleichen Prinzip beruhenden enzyme-immuno assay (EIA). In einer Doppelblindstudie mit gesunden Probanden spiegelten im systematischen Vergleich von VASP-EIA, VASP-FACS und anderer verbreiteter Verfahren (Aggregation, p-Selektin Expresssion, PFA100) sowohl die VASP-Assays als auch die Aggregation die Plättchen-Inhibition deutlich wider. Demgegenüber waren weder die p-Selektin Expression noch der PFA100 ein Indikator für den Clopidogrel-Effekt. Die VASP-Assays zeichneten sich im Vergleich zur Aggregation durch bessere Quantifizierbarkeit und eine enge Abhängigkeit von der Zielstruktur des Clopidogrels, dem P2Y12-Rezeptor, aus. So hatte eine Medikation mit Acetylsalicylsäure keinen Einfluss auf die VASP-Assays, verminderte allerdings die Aggregation. Weiterhin konnten wir im Rahmen der Probandenstudie durch Verwendung PAR- (protease activated receptor) spezifischer Peptide (SFFLRN, AYPGKF) und dem stabilen Thromboxan A2 Analog U46619 in ex-vivo Versuchen nachweisen, dass die antithrombozytären Eigenschaften des Clopidogrels zum Teil auf der indirekten Hemmung der Thrombin- und Thromboxan-induzierten Plättchenaktivierung beruhen. Diese Ergebnisse betonen die zentrale Bedeutung Galpha(i)-vermittelter Signalwege in Thrombozyten. Im zweiten Teil dieser Arbeit strebten wir an, neue Substrate der cGMP-abhängigen Proteinkinase zu identifizieren und das bekannte Substrat VASP weiter zu charakterisieren. Die Plättchenadhäsion und -aktivierung an der Zellwand sind initiale Ereignisse der arteriellen Thrombose. Prostacyclin und NO erhöhen die intrazelluläre Konzentration zyklischer Nukleotide (cAMP, cGMP). Dies führt zu einer umfassenden Inhibition der Thrombozyten, hauptsächlich durch Aktivierung der cAMP- bzw. cGMP-abhängige Proteinkinase (cAK, cGK). Es liegt bisher kein schlüssiges Bild davon vor, wie die Substrate der cAK und cGK die Plättcheninhibition regulieren. Wir identifizierten zunächst das adenylylcyclase-associated protein (CAP1) anhand der Analyse des humanen Plättchen-Phosphoproteoms als neues Substrat der cGK, das innerhalb von Sekunden nach SNP-Stimulation phosphoryliert wird. Die Separation des Phosphoproteoms erfolgte durch 2D-Gelelektrophorese. Wildtyp-CAP1 und Mutanten, bei denen an putativen Phosphorylierungsstellen Serin bzw. Threonin durch Alanin ausgetauscht wurde, wurden anschließend in PtK2-Zellen exprimiert. Bisher konnte die Ko-Transfektion von PtK2-Zellen mit CAP1 und cGK eine Phosphorylierung von CAP1 durch die cGK nicht bestätigen. Weitere Anstrengungen werden nötig sein, CAP1 als cGK-Substrat zu etablieren. Flusskammerversuche zeigten, dass die Hemmung der Thrombusformation durch SNP bei VASP-defizienten Mäusen im Vergleich zu Wildtyp-Mäusen (WT) ineffektiv ist und belegen, dass die Inhibition der Agonisten-induzierten Thrombusformation durch den NO/cGMP-Signalweg in VASP-defizienten Plättchen gestört ist. VASP hatte in unseren Experimenten keinen signifikanten Einfluss auf die GPIIbIIIa-Aktivierung (gemessen mit dem monoklonalen Antikörper JON/A), die Serotonin-Sekretion (delta-Granula) und die p-Selektin-Expression (alpha-Granula). Die Ergebnisse legen nahe, dass die VASP-Deletion zu subtilen Störungen von Thrombozytenfunktionen führt, die erst in Experimenten deutlich zu Tage treten, die ihr Zusammenspiel abbilden. / Dual-antiplatelet therapy with aspirin and clopidogrel has become the standard therapy to prevent cardiovascular complications of acute coronary syndrome and percutaneous coronary intervention. Increasing experience, however, indicates that a significant proportion of patients do not respond adequately to clopidogrel. We performed a double blinded clinical study with healthy volunteers receiving clopidogrel or placebo to compare various assays of platelet responsiveness, including two methods (a newly established enzyme immunoassay and a FACS assay) based on VASP phosphorylation, for monitoring clopidogrel action. In the clopidogrel group ADP-induced platelet aggregation and the ADP-induced decrease in iloprost-stimulated VASP phosphorylation was attenuated significantly as compared to the placebo group. P-selectin and PFA100 measurements failed to clearly distinguish between the placebo and clopidogrel group of this study. The VASP assays directly measure the function of the clopidogrel target, the P2Y12 receptor, and are selective for clopidogrel effects. Hence the VASP assays are, in contrast to platelet aggregation, not affected by aspirin. In the framework of the study we could additionally demonstrate that the antithrombocytic properties of clopidogrel are partly due to the indirect inhibition of the thrombin and thromboxane induced platelet activation. These results underline the importance of Galpha(i) mediated signalling pathways in platelets. Prostacyclin and NO increase the intracellular concentrations of cyclic nucleotides (cGMP, cAMP). This process results in platelet inhibition mainly by activation of the cGMP- and cAMP-dependent proteinkinase (cGK Ibeta, cAK). How these kinases regulate platelet inhibition is an active field of research. In the second part of the work we therefore sought to identify new substrates of the cGMP-dependent proteinkinase and to further characterize its well established substrate VASP. We initially identified the adenylylcyclase-associated protein (CAP1) as a new substrate of the cGK Ibeta analyzing the human platelet phosphoproteom by two-dimensional gel electrophoresis. To evaluate the role of CAP1 as an in vivo substrate of cGK Ibeta (and cAK) PtK-2 cells were transfected with wildtype CAP1 or the mutants S125A and T375A and cGK Ibeta simultaneously or with either protein alone. Phosphorylation of CAP1 by cGK I beta could not be confirmed as yet and further efforts will be necessary to answer the question whether CAP1 really is a cGK Ibeta substrate. Flowchamber experiments revealed that the inhibition of thrombus formation in whole blood of VASP deficient mice (when compared to wild type) was impaired with the NO donor sodium nitroprusside. Thus VASP plays a major role in the inhibitory NO/cGMP signalling pathway in platelets.

Zum Nachweis einer interindividuellen Variabilität bei der Therapie mit Clopidogrel wurden in dieser Promotionsarbeit Patienten mit ausreichender Therapiedauer auf eine verbleibende Aktivierbarkeit der Thrombozyten untersucht. Hierfür wurde eine auf Phosphorylierung des Proteins VASP basierender Assay, der mittlerweile auch kommerziell verfügbar ist, eingesetzt. Dieser auf einer durchflusszytometrische Analyse beruhende Test zeigte bei 10 % der untersuchten Patienten eine Restaktivierbarkeit der Thrombozyten trotz ausreichender Thienopyridin-Einnahme. Die statistische Analyse erbrachte den Nachweis von zwei Untergruppen: Eine Untergruppe zeigte trotz Clopidogrel-Therapie eine fast normale Aktivierbarkeit der Thrombozyten („non-responder“), die andere zeigt eine teilweise Thrombozytenfunktionshemmung („low-responder“). In der statistischen Analyse wurde eine deutliche Signifikanz der Ergebnisse mittels Students-t-Test festgestellt. Aus zufällig ausgewählten Proben der „non-responder“ und der adäquat reagierenden Patienten konnte eine Veränderung intrazelluläre Signalwege nicht nachgewiesen werden. Nach Veröffentlichung der Gensequenz für den P2Y12 Rezeptor erfolgte die entsprechende Genanalyse bei diesen Patienten. Es konnten 2 stumme Polymophismen nachgewiesen werden, diese jedoch sowohl in der Gruppe der Responder als auch bei Low-/Non-Respondern. Somit wurde in dieser Promotionsarbeit das mittlerweile von verschiedenen Arbeitsgruppen diskutierte, bei etwa 10 % der Patienten auftretende Therapieversagen von Thienopyridinen bestätigt. Eine Genveränderung oder Änderungen intrazellulärer Signalwege konnte als molekulare Ursache nicht gezeigt werden. / To detect interindividual varabilities during clopidogrel treatment we investigated patients with sufficient treatment duration for remaining activation of platelets. For detection we used an VASP (vasodilator-stimulated phosphoprotein) based assay, which is commercially available. This assay works with flow cell detection system (FACS) and showed in 10 % of all investigated patients remaining platelet activatiation even though thienopyridine treatment was sufficint. The statistic analysis showed two sub-groups of remaining platelet acitivity: one consisted of patients with completely regular platelet acitivity (non-responder), the other showed partial remaining acitivity (low-responder). The statistic analysis using a student-t-test proved a solid significance of the results. Randomly chosen probes out of the non-responder sub-group and the regular reacting patients showed no changes in intra-cellular pathways. The in 2000 newly published gene-sequence of the P2Y12 receptor was utilized to look for mutations/variations. Two silent polymorphism were detected in both (low- and non-responder) sub-groups. In this thesis we added to the increasingly published number of articles reporting a 10 % non-responding to thienopyridine treatment. For this variation no gene sequence alternation or change in intracellular pathway singalling were found responsible.

Clopidogrel is an antiplatelet substance that prevents blood coagulation in the arteries. It is an inactive pro drug that becomes activated after first-pass metabolism by the liver. The active metabolite of clopidogrel is 2-oxoclopidogrel, which is unstable therefore pharmacokinetic data is obtained by measuring the inactive metabolite clopidogrel acid in plasma. Clopidogrel is taken orally in tablet form. The aim of this project was to develop a LC-MS/MS method for quantification of clopidogrel and its metabolite in plasma.   The method has been developed by optimizing the sample preparation. Different extraction procedures and extraction columns were tested, for example, by changing the extraction column from a C8 silica sorbent to Oasis HLB (a polymer sorbent). Different internal standards were evaluated as a result of discovering the signal suppression of the previous internal standard clopidogrel acid.  Flupentixol was found to be the best candidate.

Techn. Universiẗat, Diss., 2005--München.

Techn. Universiẗat, Diss., 2005--München.

Class of 2016 Abstract / Objectives: Analyze trends in prescribing extended dual antiplatelet therapy (DAPT) with aspirin and clopidogrel between men and women patients at El Rio community health center. Methods: Patients at a community health center who were on DAPT for longer than one year were identified through retrospective chart review. Demographic and descriptive data were recorded, including patient age, gender, indication for therapy, and type of prescriber. Based on prescribing guidelines, acute coronary syndrome (ACS) with bare-metal stent or drug-eluting stent, and drug-eluting stent without ACS were considered to be appropriate indications of extended DAPT. All other indications were considered inappropriate. Results: Data was collected for 27 men (mean age = 68; SD = 9.82; 70.4% hispanic or latino) and 31 women (mean age = 70; SD = 10.49; 83.9% hispanic or latino). Dual antiplatelet therapy was appropriately prescribed for 17 men and 20 women (63% and 64.5%, p=0.08). Conclusions: Overall, the difference in adherence to prescribing guidelines for men and women was not significant.