Helena Plateletworks Scientific Information

 

 

Detection of Non-Functional Platelets Using Blood Collection Bottles Coated with Collagen, Ristocetin and Arachidonic Acid
Authors – JG Smith 1, L Sheridan-Smith 1, MA Smith 2, SPambakian 1, VA Chomyn 3, J Campbell 4
Platelet function is a vital factor in preventing bleeding irrespective of circulating platelet number. Because of the widespread use of aspirin, clopidogrel and other platelet agonists, clinicians are often faced with canceling patient operations because of concern that platelet function is compromised.


St John's Wort Enhances the Platelet Inhibitory Effect of Clopidogrel in Clopidogrel "Resistant" Healthy Volunteers

Lau W, Carville D, Guyer K, Neer C, Bates R. Univ of MI, Ann Arbor, MI; Indiana University, South Bend, IN. Abstract from American College of Cardiology, March 2005.
Conclusion: “1. SJW increases CYP3A4 activity, converting clopidogrel non-responders and low-responders to clopidogrel responders. 2. Clopidogrel utilizes CYP3A4 for its metabolic activation and is a substrate inhibitor of CYP3A4. 3. Herb-drug interactions are pharmacologically important."

In Vivo Platelet Redistribution and Acute Transient Thrombocytopenia after Eptifibatide Injection in Baboons
Tanaka K, Katori N, Kelly AB, Kotze H, Marzec U, Hanson SR. Emory University School of Medicine, Atlanta, GA; Northwest University, South Africa; Oregon Health and Science University.
Thrombosis Research, 2005 - Vol 115, Issues 1-2, pp 79-87
Conclusion: “ Acute thrombocytopenia after eptifibatide injection was caused by the transient redistribution of platelets to the liver. Attenuation of the decrease in platelet count and hepatic sequestration by abciximab and IVIG suggests that thrombocytopenia may have been caused by ligand-induced binding site antigen induction and recognition by the reticuloendothelial system."

Point-of-Care Monitoring V's Light Transmission Aggregometry Using Arachidonic Acid for Aspirin Resistance

Gurbel P.A.1, Bliden K.M.1, Carville D.G.M.2, Ridgway H.3, Rullman, R.3
1Center for Thrombosis Research, Sinai Hospital, Baltimore, M.D. 2Department of Chemistry, Indiana University South Bend, South Bend, IN. 3Helena Laboratories, Beaumont, TX.

Conclusion: This novel POC test for ASA response may be a suitable peri-procedural screening assay to determine the effective dose of ASA on an individual patient basis.

A Rapid Platelet Function Assay Used to Regulate Platelet Transfusion Prophylaxis Following Cardiopulmonary Bypass Surgery
Shaffer K, Pearman D, Galen R, Carville D. Aultman Hospital, Canton, OH.  Journal of Extracorporeal Technology 2004; Vol 36: 2, pp 145-148.

Conclusion: "Monitoring platelet count and function as a result of CPB and administering an appropriate transfusion protocol can positively impact transfusion outcome."

 

Plateletworks Platelet Function Test Compared to the Thromboelastograph for Prediction of Postoperative Outcomes

Ostrowsky J, Foes J, Warchol M et al. Rush-Presbyterian-Saint Luke's Medical Center, Chicago, IL. Journal of Extracorporeal Technology 2004; Vol 36: 2, pp 149-152.

Conclusion:  "When comparing the Plateletworks to the TEG in this study, the Plateletworks system was a more useful predictor of blood product use and chest tube drainage."

Point of Care Testing Shows Clinically Relevant Variation in the Degree of Inhibition of Platelets by Standard-Dose Abciximab Therapy During Percutaneous Coronary Intervention

Ray MJ, Walters DL, Bett N, et al. Department of Haematology, Queensland Health Pathology Service and Cardiology Program, Prince Charles Hospital, Brisbane, Australia. Catheterization and Cardiovascular Interventions 2004; Vol 62: pp 150-154.

Conclusion: "In conclusion, POC measurements reflect platelet activation suppression, higher PW [Plateletworks] measurements being associated with a decreased risk of return of angina."

 

Whole Blood Point of Care Platelet Testing During Cardiac Surgery Predicts Perioperative Bleeding

Haynes GR, Lazarchick J, Payne KJ, Cook MH, Crumbley AJ, Kratz JM, Crawford FA and Ikonomidis JS

Departments of Anesthesia, Pathology and Laboratory Medicine and Surgery, Medical University of South Carolina, Charleston, South Carolina

Discussion: The whole Blood platelet function test provided rapid results and the changes in collagen-activated platelet counts are consistent with the thrombocytopathy expected with CPB. ADP-induced platelet aggregation showed that essentially all platelets were active, a result not consistent with the well known platelet defect occurring during CPB (1,2). It is likely the 20 mM ADP used in the assay, which is 2-4 times the concentration used in conventional platelet aggregometry, is masking subtle platelet defects. Functional platelet studies during cardiac surgery may have a useful role guiding clinical and transfusion decisions.

Efficacy of High-Dose Bolus Tirofiban Compared to Regular-Dose Glycoprotein IIb/IIIa Inhibitors on Platelet Aggregation Inhibition in Myocardial Infarction Patients Treated with Primary Angioplasty
Ernst, NMSK, DeBoer MJ, Slinglerland RJ, Miedemal K, van’t Hof AWJ. Isala Klinieken – Zwolle, Netherlands. Abstract from European Society of Cardiology, August 2003
Conclusion: “ This is the first time study in which IPA is measured in acute MI pts treated with primary PCA and Clopidogrel in combination with different GPIIb/IIIa inhibitors. IPA was highly variable among pts. Only with high-dose bolus Tirofiban sufficient peri-procedural platelet aggregation inhibition was found. Further research is needed to assess the effect of bolus and maintenance infusion dose adjustment of GPIIb/IIIa inhibitors on clinical outcome.”

 

Monitoring Platelet Function During Cardiopulmonary Bypass in the Presence of Tirofiban

Tanaka K, Sato N, Kelly A, et al. Emory University School of Medicine, Atlanta, GA

Abstract from Society of Cardiovascular Anesthesia, April 2003

Conclusion: In patient where heparin plus tirofiban was used for anticoagulation, platelet aggregation induced by ADP was completely suppressed compared to submaximal inhibition when measured by TEG.

 

Clopidogrel Poor Responders Discovered During Point-of-Care Platelet Aggregation Testing

Lau W, Neer C, Watkins P, et al. Univ of MI Health System, Univ of NC, Chapel Hill, Indiana University, South Bend, IN

Abstract from American College of Cardiology, March 2003

Conclusion: Inter-individual variability exists in the response to clopidogrel, suggesting the need to monitor platelet activity during clopidogrel therapy to ensure pharmacologic efficacy.

 

Atorvastatin Reduces the Ability of Clopidogrel to Inhibit Platelet Aggregation: A New Drug-Drug Interaction

Lau W, Waskell L, Watkins P, et al. Univ of MI Health System

Circulation, Jan 2003; 107: pp 32 - 37.

Conclusion: “Use of a statin not metabolized by CYP3A4 and point-of-care platelet function testing may be warranted in patients treated with clopidogrel.”

Evaluation of the Point of Care Helena ICHOR/Plateletworks® and the Accumetrics Ultegra® RPFA for Assessment of Platelet Function Inhibition by Platelet GPIIb-IIIa Antagonists
Jennings L, White MM, Jacoski MV, Krishnat R. University of Tennessee Health Science Center
Abstract from ISTH 2003
Journal of Thrombosis and Haemostasis 2003. 1 Supplement, 1 July, Abstract P1821
Conclusion: “ Based on these data, the Plateletworks® utilized under these newly described guidelines may serve as a surrogate for LTA when rapid measurements are necessary for the evaluation of antiplatelet therapies.”

 

Transfusion Requirements in Clopidogrel-Treated Coronary Artery By-Pass Graft Surgery Patients
R Radovancevic, L Chen, SA Riggs, NA Nussmeier, JR Cooper Jr, AW Bracey. Texas Heart Institute, Houston, TX
Abstract from American Association of Blood Banks, October 2002
Transfusion, 2002 – Vol 42, Supplement; Abstract S64-030K
Conclusion:Preoperative use of clopidogrel is accompanied by higher RBC and PLT transfusion rates in patients undergoing CABG. Use of some platelet function assays may help optimize platelet therapy in these patients.”        
Compared ADP aggregometry, Helena Plateletworks and Dade Behring PFA-100.

 

Suboptimal Platelet Inhibition With Tirofiban in Patients Undergoing Coronary Intervention for Unstable Angina
Soffer D, O'Neill W, et al. William Beaumont Hospital, Royal Oak, Michigan, Lenox Hill Heart and Vascular Institute, New York, New York.
Abstract from American College of Cardiology, March 2002
Journal of Amer College of Cardio, March 6, 2002, Vol. 39, Issue 5, Suppl. A
Conclusion: "The current dose of tirofiban used in pts undergoing PCI for UA appears to be sub-optimal. Our findings may explain the mixed results of recent trials with tirofiban in such pts. Large-scale, prospective studies should evaluate whether tirofiban dose adjustment will have an impact on clinical outcome."

Inter-Assay Variability in the Degree of Platelet Inhibition Following GPIIb/IIIa Receptor Blockade in Patients Undergoing Coronary Intervention: A Comparison of Three Different Point-of-Care Assays
Soffer D, O'Neill W, et al. William Beaumont Hospital, Royal Oak, Michigan, Lenox Hill Heart and Vascular Institute, New York, New York.
Abstract from American College of Cardiology, March 2002
Journal of the Amer College of Cardio, March 6, 2002, Vol. 39, Issue 5, Suppl. A
Conclusion: "There is significant variation in the degree of PI assessed by the three assays. The greater inter-patient variability and the lower mean PI, detected by the IchorTM system may enhance patient stratification based upon response to GPIIb/IIIa inhibitors. The practical implications of these findings need to be validated in large-scale clinical outcome trials."

The Effect of Known Inhibitors and Inducers of Human Cytochrome P450 3A4 on the Platelet Inhibitory Activity of Clopidogrel
Lau WC, Waskell LA, et al. Univ of Michigan, Ann Arbor, MI and Indiana Univ, South Bend, IN.
Abstract from American College of Cardiology, March 2002
Conclusion: "Metabolic activation of clopidogrel in humans is largely catalyzed by CYP3A4. Inhibitors and inducers of CYP3A4 may alter the efficacy of clopidogrel. It may be important to test that platelet aggregation inhibition targets are met in patients taking clopidogrel."

The Antiplatelet Activity of Clopidogrel is Inhibited by Atorvastatin but not by Pravastatin
Lau WC, Waskell LA, et al. Univ of Michigan, Ann Arbor, MI and Indiana Univ, South Bend, IN. Abstract from American Heart Association, November 2000.
Circulation (Suppl) 102:18, p II-429.
Conclusion: “These data suggest that atorvastatin is a competitive inhibitor of clopidogrel activation, where pravastatin is not. This suggests that clopidogrel activation may also utilize the CYP-450 3A4 system.”

 

Clopidogrel Loading Prior to Coronary Stent Implantation: What is the Appropriate Dose?
Karatep M, Mani A, et al. Lenox Hill Heart and Vascular Institute, New York Abstract from Transcatheter Cardiovascular Therapeutics, November 2000.
Am J Cardiol 2000; 86(suppl 8A): 15i
Conclusion: “These data show that when clopidogrel is administered as a loading dose prior to coronary intervention, the 450mg dose should be accepted as the most effective loading dose. The clinical impact of these findings, if validated by randomized trials, should be considered prior to coronary intervention.”

 

Does Clinical Presentation Impact Platelet Inhibition at Baseline and Following Glycoprotein IIb/IIIa Receptor Blockade in Patients Undergoing Percutaneous Coronary Intervention?
Karatep M, Mani A, et al. Lenox Hill Heart and Vascular Institute, New York.
Abstract from Transcatheter Cardiovascular Therapeutics, November 2000.
Am J Cardiol 2000; 86(suppl 8A): 15i
Conclusion: “Patients with acute coronary syndromes have lower platelet inhibition [PI] than patients with stable angina, both, at baseline and following GPIIb/IIIa blockade. Further studies are needed to establish whether dose adjustment (and routine PI measurement) is necessary during GP IIb/IIIa use in coronary intervention and high risk patients.”

 

The Impact of Clinical Presentation on the Degree of Platelet Inhibition at Baseline and Following Glycoprotein IIb/IIIa Receptor Blockage in Patient Undergoing Percutaneous Coronary Intervention
Soffer D, Taviloglu G, et al. Lenox Hill Heart and Vascular Institute, New York.
Abstract from American College of Cardiology, March 2000.
Journal Amer College of Cardio 2000; 35(Suppl A)
Conclusion: “Pts with acute coronary syndromes have lower platelet inhibition than pts with stable angina, both at baseline and following GPIIb/IIIa blockade. Further studies are needed to establish whether dose adjustment is necessary in pts with acute coronary syndromes undergoing coronary intervention.”

 

What is the Appropriate Loading Dose of Clopidogrel Prior to Stent Implantation? Insights from a Platelet Inhibition Study
Soffer D, Taviloglu G, et al. Lenox Hill Heart and Vascular Institute, New York.
Abstract from American College of Cardiology, March 2000.
Journal Amer College of Cardio 2000; 35(Suppl A)
Conclusion: “These preliminary data suggest that when clopidogrel is administered as a loading dose prior to coronary intervention, a dose of 450mg appears to double the effect on platelet inhibition compared to 300mg in the time window of 3 to 9 hrs post bolus. The clinical impact of these findings, if validated by randomized trials, should be considered when planning the time of coronary intervention.”

 

Validation of the Plateletworks Point of Care Platelet Function Analyzer
Sackett E, Nuttall G, et al. Mayo Clinic, Rochester, MN.
Abstract from Anesthesia and Analgesia 2000, S86.
Discussion: “In this ex-vivo addition trial of the Plateletworks Ô point of care platelet function analyzer, strong positive correlations were demonstrated when using all GPIIb/IIIa inhibitors. This leads to the conclusion that the device is an accurate measure of platelet function, and may be an effective device to guide drug administrations and may be useful in the operating room to assess platelet function.”

 

Rapid Platelet Function Assessment Using Two Concentrations of Adenosine Diphosphate After Clopidogrel Loading Dose in Patients Undergoing Cardiac Catheterization
Lau WC, Bates ER, et al. University of Michigan Medical Center, Ann Arbor, MI.
Abstract from American College of Cardiology, March 2000.
Journal Amer College of Cardio 2000; 35(Suppl A), p 43
Conclusion: “These data suggest that the 300 mg clopidogrel loading dose commonly used with endothelium stenting does not reach maximal platelet inhibition at 5 hours. Earlier treatment or higher loading doses may be required to optimize platelet inhibition in the periprocedural period.”

 

A Simple Point of Care Method for Assessment of Platelet Function at the Bedside Using the ICHOR Device
Lakkis N, McNeal A, et al. Baylor College of Medicine and Ben Taub General Hospital, Houston, TX.
Abstract from European Society of Cardiology, September 1999.
Conclusion: “The ICHOR hematology analyzer is a simple, rapid bedside method that may have clinical utility in assessing platelet aggregability in patients undergoing coronary angioplasty who are treated with Gp IIb/IIIa receptor blockers.”

 

Evaluation of Abciximab Inhibition of Platelet Aggregation Using ICHOR Hematology Analyzer
Ogilby JD, Wolf NM, et al. Allegheny University of the Health Sciences, Philadelphia, PA and Indiana University, South Bend, IN.
Abstract from Int’l Society of Thrombosis and Hemostasis, 1999.
Conclusion: “The ICHOR can assess efficacy of these new agents while patients are in the catheterization laboratory undergoing interventional procedures. Further clinical studies are needed to document the usefulness of online analysis of platelet receptor blockade.”

 

Testing Platelet Function in a Cardiopulmonary Bypass Patient Using a Near Patient Test System
Walker CT, Guyer KE, et al. Baptist Hospital, Pensacola, FL and Indiana University, South Bend, IN.
Thrombosis & Hemostasis 82(Suppl): 618 (Abst 1947), 1999.
Discussion: “This case report demonstrates that the ICHOR system has potential for the near patient evaluation of platelet function (aggregation in response to an agonist) which in this case avoided a second procedure which would have resulted in re-opening the chest, additional hemorrhage, risk of infection, hypothermia, and additional cost and length of stay. Such testing may also permit the differentiation between surgical bleeding and platelet dysfunction. This test may have clinical utility and application in the triaging of patients undergoing CPB procedures.”

 

Platelet Protection Using the Glycoprotein IIb/IIIa Inhibitor Tirofiban in a Patient with Heparin Induced Thrombocytopenia Undergoing Aortic Valve Replacement Requiring Cardiopulmonary Bypass
Kirk E. Guyer BS, David G.M. Carville PhD, Wei C. Lau MD* the Department of Chemistry, Indiana University South Bend, South Bend, IN & *the Department of Anesthesiology, University of Michigan Health System, Ann Arbor, MI.
Presented at the AACC Symposium; Critical Care and Point of Care testing, Sept. 12-14, 2002, Monterey, California
Conclusions: HIT patients undergoing cardiac surgery may be optimally anticoagulated using adjunct tirofiban therapy. Platelet count and function may be easily measured in whole, non-anticoagulated blood using the platform described. [Plateletworks]

Dose-Dependent Clopidogrel-Atorvastatin Drug-Drug Interaction Determined by Light Transmission Aggregometry
Wei C Lau, David GM Carville, Kirk E Guyer, Charlene J Neer, & Eric R Bates. University of Michigan, Ann Arbor, MI & Indiana University South Bend, South Bend, IN, USA.
Conclusions: A clopidogrel 450mg loading dose is as effective as 600mg in initially overcoming the clopidogrel-atorvastatin interaction seen with 300mg. However, the clopidogrel 75mg/d maintenance dose does not maintain platelet aggregation inhibition when co-administered with atorvastatin 40mg/d. Whether this remains a clinical phenomenon when additional subjects have been recruited to this group remains to be evaluated.

High Doses of Clopidogrel Overcome the Atorvastatin-Clopidogrel Drug-Drug Interaction in Known Clopidogrel Responders
Wei C Lau, M.D., Charlene J. Neer, B.S.N., M.P.A., David G.M. Carville, Ph.D., Kirk E. Guyer, B.S., Alan R. Tait, Ph.D., Eric R. Bates, M.D. Department of Anesthesiology, University of Michigan, Department of Chemistry, Indiana University, Department of Internal Medicine, University of Michigan.
Discussion: Atorvastatin attenuated the anti-aggregatory effect of a 300 mg loading dose of clopidogrel. Clopidogrel 600mg overcomes the attenuation of the anti-aggregatory effect demonstrated with 300 and 450 mg during atorvastatin co-administration. There was a significant correlation between light transmission and point-of-care aggregometry at 4 hours after clopidogrel administration.

Cyclosporine Reduces the Platelet Inhibitory Effect of Clopidogrel in Cardiac Transplant Patients
David J Meier, Wei C Lau, Todd M Koelling, Charlene J Neer, David GM Carville, Kirk E Guyer, & Eric R. Bates. University of Michigan, Ann Arbor, MI & Indiana University South Bend, South Bend, IN, USA.
Conclusions: In long-term survivors of heart transplatation on cyclosporine therapy, clopidogrel 450 mg, but not 300 mg (or presumably 75 mg), inhibits platelet aggregation. When thienopyridine therapy is required for patients taking cyclosporine, ticlopidine should be considered in place of clopidogrel because of this drug-drug interaction.

 

Point-of-Care Monitoring for Optimal Anti-Platelet Therapy in Acute Clinical Settings

Guyer K.E.1, Carville D.G.M.1, Ridgway H.2, Rullman, R.2
1Department of Chemistry, Indiana University South Bend, South Bend, IN. 2Helena Laboratories, Beaumont, TX.

Conclusion: This novel POC test for platelet response may be suitable peri-procedural screening assay to determine the effective dose of administered pharmaceutical on an individual patient basis.


 


 


 

 

 

 


 

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