| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Circulation. 2005;112:2946-2950.)
© 2005 American Heart Association, Inc.
Interventional Cardiology |
From Deutsches Herzzentrum, Technische Universität München, Munich (N.v.B., G.P.-M., A.K., A.S.), and Institut für Pharmakologie, Klinikum der Universität zu Köln, Cologne (D.T., E.S.), Germany.
Correspondence to Dr Nicolas von Beckerath, Deutsches Herzzentrum München Lazarettstr 36, 80636 München, Germany. E-mail beckerath{at}dhn.mhn.de
Received April 28, 2005; revision received August 12, 2005; accepted August 15, 2005.
| Abstract |
|---|
|
|
|---|
Methods and Results Sixty patients with suspected or documented coronary artery disease admitted to our hospital for coronary angiography were included in this trial. They were allocated to 1 of 3 clopidogrel loading doses (300, 600, or 900 mg) in a double-blinded, randomized manner. Plasma concentrations of the active thiol metabolite, unchanged clopidogrel, and the inactive carboxyl metabolite of clopidogrel were determined before and serially after drug administration. Optical aggregometry was performed before and 4 hours after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of the active metabolite, clopidogrel, and the carboxyl metabolite compared with loading with 300 mg (P
0.03) and lower values for adenosine diphosphate-induced (5 and 20 µmol/L) platelet aggregation 4 hours after drug administration (P=0.01 and 0.004). With administration of 900 mg, no further increase in plasma concentrations of active metabolite and clopidogrel (P
0.38) and no further suppression of adenosine diphosphate-induced (5 and 20 µmol/L) platelet aggregation 4 hours after drug administration was achieved when compared with administration of 600 mg (P=0.59 and 0.39).
Conclusions Single doses of clopidogrel higher than 600 mg are not associated with an additional significant suppression of platelet function because of limited clopidogrel absorption.
Key Words: platelets pharmacology receptors pharmacokinetics
| Introduction |
|---|
|
|
|---|
For patients undergoing PCI, the administration of a clopidogrel loading dose ranging from 300 to 600 mg is recommended.2,9 Recently, we showed that administration of a 600-mg dose of clopidogrel in patients already chronically treated with clopidogrel results in a significant additional inhibition of ADP-induced platelet aggregation and ADP-induced platelet glycoprotein IIb/IIIa and P-selectin expression.10 This finding suggests that the degree of platelet inhibition attainable with a single 600 mg dose can be augmented and that a loading dose exceeding 600 mg may provide even more effective loading.10
In this randomized trial, we assessed the antiplatelet effects and the pharmacokinetics of 3 loading doses of clopidogrel (300, 600, and 900 mg).
| Methods |
|---|
|
|
|---|
Randomization, Administration of Clopidogrel, and Blood Sampling
Patients eligible for the study were randomly assigned to 1 of the 3 loading doses. To enable double-blinded randomization, clopidogrel tablets (4, 8, or 12) were crushed and filled in vials made of brown glass. Mannitol was added to achieve the same volume of powder in each vial. Vial contents were diluted with 50 mL of water and then ingested. The clopidogrel-containing vials and the randomization sequence were provided by the pharmacy of the Deutsches Herzzentrum, Munich, Germany. In addition to the randomized study medication, each patient received 100 mg of aspirin. Peripheral venous blood samples were drawn in a fasting state with a loose tourniquet through a short venous catheter inserted into a forearm vein. A multiple syringe sampling technique was used, and the first 2 mL of blood was discarded. For optical aggregometry, peripheral venous blood was collected in 3.8% citrate immediately before and 4 hours after administration of clopidogrel. For the assessment of the plasma concentrations of clopidogrel-related compounds, EDTA-blood was obtained from the venous catheter before the administration of the study medication and 20, 40, 60, 120, and 240 minutes afterward. Plasma was obtained by centrifuging at 1500g and 4°C for 10 minutes and stored at 70°C.
Aggregometry
Citrated blood samples for aggregometry were processed within 60 minutes. Platelet aggregation was evaluated by optical aggregometry in platelet-rich plasma, using a Chrono-log lumi-aggregometer (Probe & Go Labordiagnostica) with a constant stirring rate of 1000 rpm at 37°C.8 The final platelet count was adjusted to 300x109/L with autologous platelet-poor plasma. Platelet-rich plasma (0% light transmission) and platelet-poor plasma (100% light transmission) served as references. After baseline adjustment, ADP (final concentrations, 5 or 20 µmol/L) was added and aggregation was recorded for 5 minutes. The analyzed parameter was maximal aggregation (%).
Detection of Clopidogrel and Its Metabolites in Plasma
Analysis was performed under modification of our previously described method on a triple-quadrupole tandem mass spectrometer (TSQ Quantum, Thermo Electron) equipped with a thermostated (5°C) Surveyor autosampler and a thermostated (50°C) Surveyor high-performance liquid chromatography system (Thermo Electron) operating in positive electrospray ionization (ESI+) mode.8 Briefly, 15-µL aliquots of acetonitrile-precipitated plasma samples were injected onto a 5-µm Kromasil C8 column (100x3 mm; Thermo Electron) and eluted isocratically at a flow rate of 0.3 mL/min (run time, 3.5 minutes). The mobile phase consisted of 90% (vol/vol) acetonitrile/0.1% formic acid, and 10% (vol/vol) deionized water/0.1% formic acid. Clopidogrel, the inactive carboxyl metabolite, and the active thiol metabolite were identified in plasma by the specific collision-induced dissociation product ions of the respective parent isotopic 35Cl and 37Cl ions [MH]+.11 Precursor ion [MH]+
product ion transitions (single reaction monitoring) used for quantification were m/z 322
212 for unchanged clopidogrel, m/z 308
198 for the carboxyl metabolite, and m/z 356
212 for the active metabolite (collision energy, 25 eV). Detection of the internal standard 1-methyl-4-phenylpyridinium bromide (5 mg/L) was performed by monitoring the m/z 170
127 transition (collision energy, 25 eV). The method was validated according to good laboratory practice standards. For clopidogrel determination, the intra-assay and interassay coefficients of variation were 5.8% and 8.9%, respectively. For the active metabolite (considering the calibration curve of clopidogrel and plasma standards of patients under clopidogrel therapy instead of QCs),8 the respective coefficients were 6.9% and 9.9% and for the carboxyl metabolite 5.5% and 8.4%.
End Points and Sample Size Calculation
The primary end point of the study was maximal ADP-induced (5 µmol/L) platelet aggregation 4 hours after administration of clopidogrel. To calculate the sample size, we used the method appropriate for more than 2 groups described by Lachin.12 It was hypothesized that maximal ADP-induced (5 µmol/L) platelet aggregation after administration of 300, 600, and 900 mg of clopidogrel is 60±15%, 50±15%, and 40±15% (mean±SD), respectively. Choosing a power of 90% and a 2-sided
-level of 0.025 (the usual
-level of 0.05 corrected for the 2 planned comparisons according to the Bonferroni method13), we calculated that a sample size of at least 18 in each group was required (nQuery advisor, version 4.0, Statistical Solutions). Additional end points were the maximal plasma concentrations of clopidogrel and its metabolites.
Statistical Analysis
Data are presented as mean±SD, mean±SEM, counts, or percentages. Frequencies of categorical variables were compared among treatment groups with a
2 test or Fishers exact test as appropriate. Means of continuous variables were compared among treatment groups with 1-way ANOVA and Students t test. Repeated pharmacokinetic observations over time were analyzed by using repeated-measures ANOVA with contrasts for the 3 different clopidogrel doses.
| Results |
|---|
|
|
|---|
|
|
Figure 1 shows serial plasma concentrations for active metabolite, unchanged clopidogrel, and carboxyl metabolite after administration of clopidogrel. Loading with 600 mg resulted in higher plasma concentrations of active metabolite, clopidogrel, and carboxyl metabolite compared with loading with 300 mg (P
0.03). With administration of 900 mg, no further increase in plasma concentrations of active metabolite and clopidogrel (P
0.38) was achieved.
|
Before administration of clopidogrel, there were no significant differences in maximal ADP-induced aggregation between the groups treated with 300, 600, and 900 mg (89.9±9.8%, 86.9±13.6%, and 88.6±9.3%; P=0.70 when stimulated with 5 µmol/L, and 98.6±6.9%, 96.2±11.7%, and 100.3±8.5%; P=0.40 when stimulated with 20 µmol/L). When induced with 5 µmol/L ADP, maximal aggregation after administration of clopidogrel was 66.5±18.0% (300 mg), 52.7±14.9% (600 mg), and 49.7±19.0% (900 mg), as demonstrated in Figure 2A. ADP-induced (20 µmol/L) maximal aggregation 4 hours after clopidogrel loading was 85.1±14.2% (300 mg), 69.8±16.6% (600 mg), and 64.8±18.9% (900 mg), as shown in Figure 2B. As shown in Figure 2A and 2B, although there was a greater suppression of ADP-induced platelet aggregation with 600 mg compared with 300 mg clopidogrel, no further significant enhancement of suppression was observed with 900 mg clopidogrel. In all patients, cmax of the active metabolite correlated with the absolute reduction of maximal ADP-induced (5 and 20 µmol/L) aggregation (r=0.50 and r=0.56, respectively).
|
| Discussion |
|---|
|
|
|---|
In addition, the results of this study show that there is an increase in plasma concentrations of clopidogrel compounds when 600 mg clopidogrel is given instead of 300 mg. This is associated with a substantial enhancement of platelet inhibition with the 600-mg dose compared with the 300-mg dose. Thus, the results of this trial confirm an earlier study in which the 600-mg loading dose was also more effective in suppressing platelet aggregation 4 hours after drug administration than the 300-mg loading dose.14
Earlier studies on the pharmacodynamics of single doses of clopidogrel showed that the vast majority of the antiplatelet effect of single doses (up to 600 mg) can be recorded within 2 hours.15,16 This observation is consistent with time to reach cmax (tmax) values of clopidogrel-related compounds, including the active metabolite in the order of 1 hour.7,8 The full antiplatelet effect of a 600-mg loading dose in patients scheduled for PCI occurs within 2 to 3 hours.14,17 In this study, postdose aggregometry was performed 4 hours after administration of the loading dose. Even in the group loaded with 900 mg, the peak plasma concentration of the active metabolite was still reached within less than 1 hour.
Failed increase in absorption with 900 mg clopidogrel prevented the evaluation of the level in which saturation of metabolism would have occurred. Individual patients may show limited ability to metabolize clopidogrel even for a 600 mg dose.18
In a previous study, we have shown that administration of a loading dose of 600 mg clopidogrel in patients receiving chronic clopidogrel therapy achieves a stronger platelet inhibition than that observed after 600 mg clopidogrel in first users or during maintenance therapy with a daily dose of 75 mg clopidogrel.10 These data may suggest that administering 900 mg clopidogrel in 2 separate doses may allow more complete absorption and, consequently, additional platelet inhibition compared with 600 mg. However, the practicability of a similar approach as a pretreatment before PCI is limited. Therefore, it remains to be investigated the feasibility of an intravenous form of this drug, which has already been used in animal experiments.19
Two limitations of this study need to be acknowledged. First, we administered crushed clopidogrel tablets in this study. Crushed tablets are often being used in mechanically ventilated patients. In a small pharmacokinetic study in which volunteers received crushed clopidogrel tablets through a nasogastric tube, the plasma concentration of the carboxyl metabolite rose slightly faster than after administration of whole tablets.20 In the present study, pharmacokinetic and pharmacodynamic findings are well comparable with those reported previously when clopidogrel was given in tablets.8,10 Second, we did not collect data on platelet function earlier than 4 hours (eg, 1 or 2 hours) after drug intake. Therefore, we cannot answer the question of whether platelet function inhibition occurs earlier with the 900-mg dose than with the 600-mg dose, although a faster onset of the antiplatelet effect with the 900-mg dose appears unlikely in the light of the pharmacokinetic data.
These data support the use of 600 mg as a loading dose in patients undergoing PCI, although randomized trials with clinical end points are needed to establish the optimal clopidogrel loading dose in these patients. A pretreatment strategy based on the 600-mg dose has been shown to provide sufficient protection in patients with stable coronary artery disease, avoiding the need for additional glycoprotein IIb/IIIa antagonists.21,22
In conclusion, our findings indicate that single doses of clopidogrel higher than 600 mg are not associated with significantly enhanced suppression of platelet function due to limited clopidogrel absorption.
| Acknowledgments |
|---|
| References |
|---|
|
|
|---|
2. Steinhubl SR, Berger PB, Mann JT, 3rd, Fry ET, DeLago A, Wilmer C, Topol EJ. Early and sustained dual oral antiplatelet therapy following percutaneous coronary intervention: a randomized controlled trial. JAMA. 2002; 288: 24112420.
3. Savi P, Pereillo JM, Uzabiaga MF, Combalbert J, Picard C, Maffrand JP, Pascal M, Herbert JM. Identification and biological activity of the active metabolite of clopidogrel. Thromb Haemost. 2000; 84: 891896.[Medline] [Order article via Infotrieve]
4. Hollopeter G, Jantzen HM, Vincent D, Li G, England L, Ramakrishnan V, Yang RB, Nurden P, Nurden A, Julius D, Conley PB. Identification of the platelet ADP receptor targeted by antithrombotic drugs. Nature. 2001; 409: 202207.[CrossRef][Medline] [Order article via Infotrieve]
5. Ding Z, Kim S, Dorsam RT, Jin J, Kunapuli SP. Inactivation of the human P2Y12 receptor by thiol reagents requires interaction with both extracellular cysteine residues, Cys17 and Cys270. Blood. 2003; 101: 39083914.
6. Clarke TA, Waskell LA. The metabolism of clopidogrel is catalyzed by human cytochrome p450 3A and is inhibited by atorvastatin. Drug Metab Dispos. 2003; 31: 5359.
7. Caplain H, Donat F, Gaud C, Necciari J. Pharmacokinetics of clopidogrel. Semin Thromb Hemost. 1999; 25: 2528.[Medline] [Order article via Infotrieve]
8. Taubert D, Kastrati A, Harlfinger S, Gorchakova O, Lazar A, von Beckerath N, Schömig A, Schömig E. Pharmacokinetics of clopidogrel after administration of a high loading dose. Thromb Haemost. 2004; 92: 311316.[Medline] [Order article via Infotrieve]
9. Braunwald E, Antman EM, Beasley JW, Califf RM, Cheitlin MD, Hochman JS, Jones RH, Kereiakes D, Kupersmith J, Levin TN, Pepine CJ, Schaeffer JW, Smith EE III, Steward DE, Theroux P, Gibbons RJ, Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK, Smith SC Jr. ACC/AHA guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction, 2002: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina). Circulation. 2002; 106: 18931900.
10. Kastrati A, von Beckerath N, Joost A, Pogatsa-Murray G, Gorchakova O, Schömig A. Loading with 600 mg clopidogrel in patients with coronary artery disease with and without chronic clopidogrel therapy. Circulation. 2004; 110: 19161919.
11. Pereillo JM, Maftouh M, Andrieu A, Uzabiaga MF, Fedeli O, Savi P, Pascal M, Herbert JM, Maffrand JP, Picard C. Structure and stereochemistry of the active metabolite of clopidogrel. Drug Metab Dispos. 2002; 30: 12881295.
12. Lachin JM. Sample size determinants for r X c comparative trials. Biometrics. 1977; 33: 315324.[CrossRef][Medline] [Order article via Infotrieve]
13. Wallenstein S, Zucker CL, Fleiss JL. Some statistical methods useful in circulation research. Circ Res. 1980; 47: 19.
14. Müller I, Seyfarth M, Rüdiger S, Wolf B, Pogatsa-Murray G, Schömig A, Gawaz M. Effect of a high loading dose of clopidogrel on platelet function in patients undergoing coronary stent placement. Heart. 2001; 85: 9293.
15. Savcic M, Hauert J, Bachmann F, Wyld PJ, Geudelin B, Cariou R. Clopidogrel loading dose regimens: kinetic profile of pharmacodynamic response in healthy subjects. Semin Thromb Hemost. 1999; 25: 1519.[Medline] [Order article via Infotrieve]
16. Thebault JJ, Kieffer G, Cariou R. Single-dose pharmacodynamics of clopidogrel. Semin Thromb Hemost. 1999; 25: 38.
17. Kandzari DE, Berger PB, Kastrati A, Steinhubl SR, Mehilli J, Dotzer F, Ten Berg JM, Neumann FJ, Bollwein H, Dirschinger J, Schömig A. Influence of treatment duration with a 600-mg dose of clopidogrel before percutaneous coronary revascularization. J Am Coll Cardiol. 2004; 44: 21332136.
18. von Beckerath N, Taubert D, Pogatsa-Murray G, Wieczorek A, Schömig E, Schömig A, Kastrati A. A patient with stent thrombosis, clopidogrel-resistance and failure to metabolize clopidogrel to its active metabolite. Thromb Haemost. 2005; 93: 789791.[Medline] [Order article via Infotrieve]
19. Makkar RR, Eigler NL, Kaul S, Frimerman A, Nakamura M, Shah PK, Forrester JS, Herbert JM, Litvack F. Effects of clopidogrel, aspirin and combined therapy in a porcine ex vivo model of high-shear induced stent thrombosis. Eur Heart J. 1998; 19: 15381546.
20. Urooj M, Farkouh M, Badimon JJ, OBrien PC, Chesebro JH. Early and greater bioavailability of crushed vs whole tablet clopidogrel. Circulation. 2003; 108 (suppl IV): IV-570(abstract).
21. Kastrati A, Mehilli J, Schühlen H, Dirschinger J, Dotzer F, ten Berg JM, Neumann FJ, Bollwein H, Volmer C, Gawaz M, Berger PB, Schömig A. A clinical trial of abciximab in elective percutaneous coronary intervention after pretreatment with clopidogrel. N Engl J Med. 2004; 350: 232238.
22. Mehilli J, Kastrati A, Schühlen H, Dibra A, Dotzer F, von Beckerath N, Bollwein H, Pache J, Dirschinger J, Berger PP, Schömig A. Randomized clinical trial of abciximab in diabetic patients undergoing elective percutaneous coronary interventions after treatment with a high loading dose of clopidogrel. Circulation. 2004; 110: 36273635.
Related Article:
Circulation 2005 112: 2887.
This article has been cited by other articles:
![]() |
G. A. Lamas, E. Escolar, and D. P. Faxon Review Article: Examining Treatment of ST-Elevation Myocardial Infarction: The Importance of Early Intervention Journal of Cardiovascular Pharmacology and Therapeutics, March 1, 2010; 15(1): 6 - 16. [Abstract] [PDF] |
||||
![]() |
P. A. Gurbel and U. S. Tantry Combination Antithrombotic Therapies Circulation, February 2, 2010; 121(4): 569 - 583. [Full Text] [PDF] |
||||
![]() |
N. A. Farid, A. Kurihara, and S. A. Wrighton Metabolism and Disposition of the Thienopyridine Antiplatelet Drugs Ticlopidine, Clopidogrel, and Prasugrel in Humans J. Clin. Pharmacol., February 1, 2010; 50(2): 126 - 142. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. S. Pinto A 43-Year-Old Man With Angina, Elevated Troponin, and Lateral ST Depression: Management of Acute Coronary Syndromes JAMA, January 6, 2010; 303(1): 54 - 63. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Schulz, T. Schuster, J. Mehilli, R. A. Byrne, J. Ellert, S. Massberg, J. Goedel, O. Bruskina, K. Ulm, A. Schomig, et al. Stent thrombosis after drug-eluting stent implantation: incidence, timing, and relation to discontinuation of clopidogrel therapy over a 4-year period Eur. Heart J., November 2, 2009; 30(22): 2714 - 2721. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. I. Simon and S. A. Parikh Hunting for the "Sweet Spot" in P2Y12 Receptor Blockade J. Am. Coll. Cardiol., October 6, 2009; 54(15): 1447 - 1449. [Full Text] [PDF] |
||||
![]() |
O. I. Tahtinen, R. L. Vanninen, H. I. Manninen, R. Rautio, A. Haapanen, T. Niskakangas, J. Rinne, and L. Keski-Nisula Wide-necked Intracranial Aneurysms: Treatment with Stent-assisted Coil Embolization during Acute (<72 Hours) Subarachnoid Hemorrhage--Experience in 61 Consecutive Patients Radiology, October 1, 2009; 253(1): 199 - 208. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Wallentin P2Y12 inhibitors: differences in properties and mechanisms of action and potential consequences for clinical use Eur. Heart J., August 2, 2009; 30(16): 1964 - 1977. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Verstuyft, T. Simon, and R. B. Kim Personalized medicine and antiplatelet therapy: ready for prime time? Eur. Heart J., August 2, 2009; 30(16): 1943 - 1963. [Full Text] [PDF] |
||||
![]() |
L Bonello, A De Labriolle, M Scheinowitz, G Lemesle, P Roy, D H Steinberg, T L Pinto Slottow, R Pakala, A D Pichard, P Barragan, et al. Emergence of the concept of platelet reactivity monitoring of response to thienopyridines Heart, August 1, 2009; 95(15): 1214 - 1219. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Prasad and D. R Holmes Update on dual antiplatelet therapy for percutaneous coronary intervention Heart, June 1, 2009; 95(11): 861 - 865. [Full Text] [PDF] |
||||
![]() |
M. J. Price Bedside Evaluation of Thienopyridine Antiplatelet Therapy Circulation, May 19, 2009; 119(19): 2625 - 2632. [Full Text] [PDF] |
||||
![]() |
D. Tousoulis, A. Briasoulis, S. S Dhamrait, C. Antoniades, and C. Stefanadis Effective platelet inhibition by aspirin and clopidogrel: where are we now? Heart, May 1, 2009; 95(10): 850 - 858. [Full Text] [PDF] |
||||
![]() |
B. L. Chen, Y. Chen, J. H. Tu, Y. L. Li, W. Zhang, Q. Li, L. Fan, Z. R. Tan, D. L. Hu, D. Wang, et al. Clopidogrel Inhibits CYP2C19-Dependent Hydroxylation of Omeprazole Related to CYP2C19 Genetic Polymorphisms J. Clin. Pharmacol., May 1, 2009; 49(5): 574 - 581. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. F. Ford Clopidogrel Resistance: Pharmacokinetic or Pharmacogenetic? J. Clin. Pharmacol., May 1, 2009; 49(5): 506 - 512. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Mehilli, A. Kastrati, S. Schulz, S. Frungel, S. G. Nekolla, W. Moshage, F. Dotzer, K. Huber, J. Pache, J. Dirschinger, et al. Abciximab in Patients With Acute ST-Segment-Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention After Clopidogrel Loading: A Randomized Double-Blind Trial Circulation, April 14, 2009; 119(14): 1933 - 1940. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Veverka and J. M. Hammer Prasugrel: A New Thienopyridine Inhibitor Journal of Pharmacy Practice, April 1, 2009; 22(2): 158 - 165. [Abstract] [PDF] |
||||
![]() |
M. S. SABATINE Novel antiplatelet strategies in acute coronary syndromes Cleveland Clinic Journal of Medicine, April 1, 2009; 76(Suppl_1): S8 - S15. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. H. Jeong, S.-W. Lee, B.-R. Choi, I.-S. Kim, M.-K. Seo, C. H. Kwak, J.-Y. Hwang, and S.-W. Park Randomized Comparison of Adjunctive Cilostazol Versus High Maintenance Dose Clopidogrel in Patients With High Post-Treatment Platelet Reactivity Results of the ACCEL-RESISTANCE (Adjunctive Cilostazol Versus High Maintenance Dose Clopidogrel in Patients With Clopidogrel Resistance) Randomized Study. J. Am. Coll. Cardiol., March 31, 2009; 53(13): 1101 - 1109. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Y. Fung, J. Saw, A. Starovoytov, C. Densem, P. Jokhi, S. J. Walsh, R. S. Fox, K. H. Humphries, E. Aymong, D. R. Ricci, et al. Abbreviated infusion of eptifibatide after successful coronary intervention The BRIEF-PCI (Brief Infusion of Eptifibatide Following Percutaneous Coronary Intervention) randomized trial. J. Am. Coll. Cardiol., March 10, 2009; 53(10): 837 - 845. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. W. Hamm, H. Möllmann, J.-P. Bassand, and F. van de Werf CHAPTER 16 Acute Coronary Syndromes ESC Textbook of Cardiovascular Medicine, January 1, 2009; 2(1): med-9780199566990-chapter - med-9780199566990-chapter. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Erlinge, C. Varenhorst, O. O. Braun, S. James, K. J. Winters, J. A. Jakubowski, J. T. Brandt, A. Sugidachi, A. Siegbahn, and L. Wallentin Patients With Poor Responsiveness to Thienopyridine Treatment or With Diabetes Have Lower Levels of Circulating Active Metabolite, but Their Platelets Respond Normally to Active Metabolite Added Ex Vivo J. Am. Coll. Cardiol., December 9, 2008; 52(24): 1968 - 1977. [Abstract] [Full Text] [PDF] |
||||
![]() |
Authors/Task Force Members, F. Van de Werf, J. Bax, A. Betriu, C. Blomstrom-Lundqvist, F. Crea, V. Falk, G. Filippatos, K. Fox, K. Huber, et al. Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation: The Task Force on the management of ST-segment elevation acute myocardial infarction of the European Society of Cardiology: Eur. Heart J., December 1, 2008; 29(23): 2909 - 2945. [Full Text] [PDF] |
||||
![]() |
P. Gladding, M. Webster, I. Zeng, H. Farrell, J. Stewart, P. Ruygrok, J. Ormiston, S. El-Jack, G. Armstrong, P. Kay, et al. The Antiplatelet Effect of Higher Loading and Maintenance Dose Regimens of Clopidogrel: The PRINC (Plavix Response in Coronary Intervention) Trial J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 612 - 619. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Gladding, M. Webster, I. Zeng, H. Farrell, J. Stewart, P. Ruygrok, J. Ormiston, S. El-Jack, G. Armstrong, P. Kay, et al. The Pharmacogenetics and Pharmacodynamics of Clopidogrel Response: An Analysis From the PRINC (Plavix Response in Coronary Intervention) Trial J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 620 - 627. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. S. Kleiman Searching for the Ceiling: New Reflections on the Disposition and Metabolism of Clopidogrel J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 628 - 630. [Full Text] [PDF] |
||||
![]() |
B. Aleil, L. Jacquemin, F. De Poli, M. Zaehringer, J.-P. Collet, G. Montalescot, J.-P. Cazenave, M.-C. Dickele, J.-P. Monassier, and C. Gachet Clopidogrel 150 mg/day to Overcome Low Responsiveness in Patients Undergoing Elective Percutaneous Coronary Intervention: Results From the VASP-02 (Vasodilator-Stimulated Phosphoprotein-02) Randomized Study J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 631 - 638. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Bhindi, O. Ormerod, J. Newton, A.P. Banning, and L. Testa Interaction between statins and clopidogrel: is there anything clinically relevant? QJM, December 1, 2008; 101(12): 915 - 925. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. J. Vlaar, T. Svilaas, K. Damman, B. J.G.L. de Smet, J. G.P. Tijssen, H. L. Hillege, and F. Zijlstra Impact of Pretreatment With Clopidogrel on Initial Patency and Outcome in Patients Treated With Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction: A Systematic Review Circulation, October 28, 2008; 118(18): 1828 - 1836. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. O. Williams and J. D. Abbott What to Do With Patients Receiving Long-Term Clopidogrel: Reload or Relax? Circulation, September 16, 2008; 118(12): 1219 - 1222. [Full Text] [PDF] |
||||
![]() |
J.-P. Collet, J. Silvain, A. Landivier, M.-L. Tanguy, G. Cayla, A. Bellemain, N. Vignolles, S. Gallier, F. Beygui, A. Pena, et al. Dose Effect of Clopidogrel Reloading in Patients Already on 75-mg Maintenance Dose: The Reload With Clopidogrel Before Coronary Angioplasty in Subjects Treated Long Term With Dual Antiplatelet Therapy (RELOAD) Study Circulation, September 16, 2008; 118(12): 1225 - 1233. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Kastrati, F.-J. Neumann, J. Mehilli, R. A. Byrne, R. Iijima, H. J. Buttner, A. A. Khattab, S. Schulz, J. C. Blankenship, J. Pache, et al. Bivalirudin versus Unfractionated Heparin during Percutaneous Coronary Intervention N. Engl. J. Med., August 14, 2008; 359(7): 688 - 696. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. C Coons and S. Battistone 2007 Guideline Update for Unstable Angina/Non-ST-Segment Elevation Myocardial Infarction: Focus on Antiplatelet and Anticoagulant Therapies Ann. Pharmacother., July 1, 2008; 42(7): 989 - 1001. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. B. Riley, M. J. Tafreshi, and S. L. Haber Prasugrel: A novel antiplatelet agent Am. J. Health Syst. Pharm., June 1, 2008; 65(11): 1019 - 1028. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Patrono, C. Baigent, J. Hirsh, and G. Roth Antiplatelet Drugs: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) Chest, June 1, 2008; 133(6_suppl): 199S - 233S. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. I. Weitz, J. Hirsh, and M. M. Samama New Antithrombotic Drugs: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) Chest, June 1, 2008; 133(6_suppl): 234S - 256S. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Trenk, W. Hochholzer, M. F. Fromm, L.-E. Chialda, A. Pahl, C. M. Valina, C. Stratz, P. Schmiebusch, H.-P. Bestehorn, H. J. Buttner, et al. Cytochrome P450 2C19 681G>A Polymorphism and High On-Clopidogrel Platelet Reactivity Associated With Adverse 1-Year Clinical Outcome of Elective Percutaneous Coronary Intervention With Drug-Eluting or Bare-Metal Stents J. Am. Coll. Cardiol., May 20, 2008; 51(20): 1925 - 1934. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Bonello, L. Camoin-Jau, S. Arques, C. Boyer, D. Panagides, O. Wittenberg, M.-C. Simeoni, P. Barragan, F. Dignat-George, and F. Paganelli Adjusted Clopidogrel Loading Doses According to Vasodilator-Stimulated Phosphoprotein Phosphorylation Index Decrease Rate of Major Adverse Cardiovascular Events in Patients With Clopidogrel Resistance: A Multicenter Randomized Prospective Study J. Am. Coll. Cardiol., April 8, 2008; 51(14): 1404 - 1411. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. J. Kereiakes and P. A. Gurbel Peri-Procedural Platelet Function and Platelet Inhibition in Percutaneous Coronary Intervention J. Am. Coll. Cardiol. Intv., April 1, 2008; 1(2): 111 - 121. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. L. L'Allier, G. Ducrocq, N. Pranno, S. Noble, R. Ibrahim, J. C. Gregoire, F. Azzari, A. Nozza, C. Berry, S. Doucet, et al. Clopidogrel 600-mg double loading dose achieves stronger platelet inhibition than conventional regimens: results from the PREPAIR randomized study. J. Am. Coll. Cardiol., March 18, 2008; 51(11): 1066 - 1072. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. D. Michelson P2Y12 Antagonism: Promises and Challenges Arterioscler Thromb Vasc Biol, March 1, 2008; 28(3): s33 - s38. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. A. Gurbel, W. C. Lau, and U. S. Tantry Omeprazole: A Possible New Candidate Influencing the Antiplatelet Effect of Clopidogrel J. Am. Coll. Cardiol., January 22, 2008; 51(3): 261 - 263. [Full Text] [PDF] |
||||
![]() |
American College of Cardiology/American Heart Asso, 2007 Writing Group to Review New Evidence and Upda, S. B. King III, S. C. Smith Jr, J. W. Hirshfeld Jr, A. K. Jacobs, D. A. Morrison, and D. O. Williams 2007 Focused Update of the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention J. Am. Coll. Cardiol., January 15, 2008; 51(2): 172 - 209. [Full Text] [PDF] |
||||
![]() |
S. B. King III, S. C. Smith Jr, J. W. Hirshfeld Jr, A. K. Jacobs, D. A. Morrison, D. O. Williams, 2005 WRITING COMMITTEE MEMBERS, S. C. Smith Jr, T. E. Feldman, J. W. Hirshfeld Jr, et al. 2007 Focused Update of the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines: 2007 Writing Group to Review New Evidence and Update the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention, Writing on Behalf of the 2005 Writing Committee Circulation, January 15, 2008; 117(2): 261 - 295. [Full Text] [PDF] |
||||
![]() |
L. Wallentin, C. Varenhorst, S. James, D. Erlinge, O. O Braun, J. A. Jakubowski, A. Sugidachi, K. J. Winters, and A. Siegbahn Prasugrel achieves greater and faster P2Y12receptor-mediated platelet inhibition than clopidogrel due to more efficient generation of its active metabolite in aspirin-treated patients with coronary artery disease Eur. Heart J., January 1, 2008; 29(1): 21 - 30. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. K. Gitt and A. Betriu Antiplatelet therapy in acute coronary syndromes Eur. Heart J. Suppl., January 1, 2008; 10(suppl_A): A4 - A12. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Bode and K. Huber Antiplatelet therapy in percutaneous coronary intervention Eur. Heart J. Suppl., January 1, 2008; 10(suppl_A): A13 - A20. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. F. Storey Variability of response to antiplatelet therapy Eur. Heart J. Suppl., January 1, 2008; 10(suppl_A): A21 - A27. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. D. Wiviott, D. Trenk, A. L. Frelinger, M. O'Donoghue, F.-J. Neumann, A. D. Michelson, D. J. Angiolillo, H. Hod, G. Montalescot, D. L. Miller, et al. Prasugrel Compared With High Loading- and Maintenance-Dose Clopidogrel in Patients With Planned Percutaneous Coronary Intervention: The Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and Aggregation Thrombolysis in Myocardial Infarction 44 Trial Circulation, December 18, 2007; 116(25): 2923 - 2932. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. D. Wiviott, E. Braunwald, C. H. McCabe, G. Montalescot, W. Ruzyllo, S. Gottlieb, F.-J. Neumann, D. Ardissino, S. De Servi, S. A. Murphy, et al. Prasugrel versus Clopidogrel in Patients with Acute Coronary Syndromes N. Engl. J. Med., November 15, 2007; 357(20): 2001 - 2015. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. J. Weerakkody, J. A. Jakubowski, J. T. Brandt, C. D. Payne, H. Naganuma, and K. J. Winters Greater Inhibition of Platelet Aggregation and Reduced Response Variability With Prasugrel Versus Clopidogrel: An Integrated Analysis Journal of Cardiovascular Pharmacology and Therapeutics, September 1, 2007; 12(3): 205 - 212. [Abstract] [PDF] |
||||
![]() |
J. L. Anderson, C. D. Adams, E. M. Antman, C. R. Bridges, R. M. Califf, D. E. Casey Jr, W. E. Chavey II, F. M. Fesmire, J. S. Hochman, T. N. Levin, et al. ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) Developed in Collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons Endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine J. Am. Coll. Cardiol., August 14, 2007; 50(7): e1 - e157. [Full Text] [PDF] |
||||
![]() |
N. von Beckerath, A. Kastrati, A. Wieczorek, G. Pogatsa-Murray, D. Sibbing, I. Graf, and A. Schomig A double-blind, randomized study on platelet aggregation in patients treated with a daily dose of 150 or 75 mg of clopidogrel for 30 days Eur. Heart J., August 1, 2007; 28(15): 1814 - 1819. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Bode and M. Zehender The use of antiplatelet agents following percutaneous coronary intervention: focus on late stent thrombosis Eur. Heart J. Suppl., August 1, 2007; 9(suppl_D): D10 - D19. [Abstract] [Full Text] [PDF] |
||||
![]() |
Authors/Task Force Members, J.-P. Bassand, C. W. Hamm, D. Ardissino, E. Boersma, A. Budaj, F. Fernandez-Aviles, K. A.A. Fox, D. Hasdai, E. M. Ohman, et al. Guidelines for the diagnosis and treatment of non-ST-segment elevation acute coronary syndromes: The Task Force for the Diagnosis and Treatment of Non-ST-Segment Elevation Acute Coronary Syndromes of the European Society of Cardiology Eur. Heart J., July 1, 2007; 28(13): 1598 - 1660. [Full Text] [PDF] |
||||
![]() |
P. Buonamici, R. Marcucci, A. Migliorini, G. F. Gensini, A. Santini, R. Paniccia, G. Moschi, A. M. Gori, R. Abbate, and D. Antoniucci Impact of Platelet Reactivity After Clopidogrel Administration on Drug-Eluting Stent Thrombosis J. Am. Coll. Cardiol., June 19, 2007; 49(24): 2312 - 2317. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. A. Meadows and D. L. Bhatt Clinical Aspects of Platelet Inhibitors and Thrombus Formation Circ. Res., May 11, 2007; 100(9): 1261 - 1275. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P. Ayalasomayajula, S. Vaidyanathan, C. Kemp, P. Prasad, A. Balch, and W. P. Dole Effect of Clopidogrel on the Steady-State Pharmacokinetics of Fluvastatin J. Clin. Pharmacol., May 1, 2007; 47(5): 613 - 619. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. O. Maree and D. J. Fitzgerald Variable Platelet Response to Aspirin and Clopidogrel in Atherothrombotic Disease Circulation, April 24, 2007; 115(16): 2196 - 2207. [Full Text] [PDF] |
||||
![]() |
D. J. Angiolillo, A. Fernandez-Ortiz, E. Bernardo, F. Alfonso, C. Macaya, T. A. Bass, and M. A. Costa Variability in Individual Responsiveness to Clopidogrel: Clinical Implications, Management, and Future Perspectives J. Am. Coll. Cardiol., April 10, 2007; 49(14): 1505 - 1516. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. F. Bertrand, R. De Larochelliere, J. Rodes-Cabau, G. Proulx, O. Gleeton, C. Manh Nguyen, J.-P. Dery, G. Barbeau, B. Noel, E. Larose, et al. A Randomized Study Comparing Same-Day Home Discharge and Abciximab Bolus Only to Overnight Hospitalization and Abciximab Bolus and Infusion After Transradial Coronary Stent Implantation Circulation, December 12, 2006; 114(24): 2636 - 2643. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. L. Walsky, A. V. Astuccio, and R. S. Obach Evaluation of 227 Drugs for In Vitro Inhibition of Cytochrome P450 2B6. J. Clin. Pharmacol., December 1, 2006; 46(12): 1426 - 1438. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. O'Donoghue and S. D. Wiviott Clopidogrel Response Variability and Future Therapies: Clopidogrel: Does One Size Fit All? Circulation, November 28, 2006; 114(22): e600 - e606. [Full Text] [PDF] |
||||
![]() |
F. Alfonso and D. J. Angiolillo Platelet Function Assessment to Predict Outcomes After Coronary Interventions: Hype or Hope? J. Am. Coll. Cardiol., November 7, 2006; 48(9): 1751 - 1754. [Full Text] [PDF] |
||||
![]() |
W. Hochholzer, D. Trenk, H.-P. Bestehorn, B. Fischer, C. M. Valina, M. Ferenc, M. Gick, A. Caputo, H. J. Buttner, and F.-J. Neumann Impact of the Degree of Peri-Interventional Platelet Inhibition After Loading With Clopidogrel on Early Clinical Outcome of Elective Coronary Stent Placement J. Am. Coll. Cardiol., November 7, 2006; 48(9): 1742 - 1750. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Cuisset, C. Frere, J. Quilici, P.-E. Morange, L. Nait-Saidi, J. Carvajal, A. Lehmann, M. Lambert, J.-L. Bonnet, and M.-C. Alessi Benefit of a 600-mg Loading Dose of Clopidogrel on Platelet Reactivity and Clinical Outcomes in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome Undergoing Coronary Stenting J. Am. Coll. Cardiol., October 3, 2006; 48(7): 1339 - 1345. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Hamdalla and S. R. Steinhubl Clinical efficacy of clopidogrel across the whole spectrum of indications: percutaneous coronary intervention Eur. Heart J. Suppl., October 1, 2006; 8(suppl_G): G20 - G24. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. J. Kereiakes and E. M. Antman Clinical Guidelines and Practice: In Search of the Truth J. Am. Coll. Cardiol., September 19, 2006; 48(6): 1129 - 1135. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Montalescot, G. Sideris, C. Meuleman, C. Bal-dit-Sollier, N. Lellouche, Ph. G. Steg, M. Slama, O. Milleron, J.-P. Collet, P. Henry, et al. A Randomized Comparison of High Clopidogrel Loading Doses in Patients With Non-ST-Segment Elevation Acute Coronary Syndromes: The ALBION (Assessment of the Best Loading Dose of Clopidogrel to Blunt Platelet Activation, Inflammation and Ongoing Necrosis) Trial J. Am. Coll. Cardiol., September 5, 2006; 48(5): 931 - 938. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. P. Giugliano and E. Braunwald The Year in Non-ST-Segment Elevation Acute Coronary Syndromes J. Am. Coll. Cardiol., July 18, 2006; 48(2): 386 - 395. [Full Text] [PDF] |
||||
![]() |
J. Turgeon, C. Pharand, and V. Michaud Understanding clopidogrel efficacy in the presence of cytochrome P450 polymorphism Can. Med. Assoc. J., June 6, 2006; 174(12): 1729 - 1729. [Full Text] [PDF] |
||||
![]() |
G. W. Stone and H. D. Aronow Long-term Care After Percutaneous Coronary Intervention: Focus on the Role of Antiplatelet Therapy Mayo Clin. Proc., May 1, 2006; 81(5): 641 - 652. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. R. Dixon, C. L. Grines, and W. W. O'Neill The Year in Interventional Cardiology J. Am. Coll. Cardiol., April 18, 2006; 47(8): 1689 - 1706. [Full Text] [PDF] |
||||
![]() |
A. Kastrati, J. Mehilli, F.-J. Neumann, F. Dotzer, J. ten Berg, H. Bollwein, I. Graf, M. Ibrahim, J. Pache, M. Seyfarth, et al. Abciximab in Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention After Clopidogrel Pretreatment: The ISAR-REACT 2 Randomized Trial JAMA, April 5, 2006; 295(13): 1531 - 1538. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. H. Wang, D. L. Bhatt, and E. J. Topol Aspirin and clopidogrel resistance: an emerging clinical entity Eur. Heart J., March 2, 2006; 27(6): 647 - 654. [Abstract] [Full Text] [PDF] |
||||
![]() |
Clopidogrel: Optimal Loading Dose in Non-ACS Patients Journal Watch Cardiology, December 16, 2005; 2005(1216): 3 - 3. [Full Text] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Circulation Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2005 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |