Platelets, March 2006; 17(2): 105–107
CASE STUDY
Effect of combined administration of clopidogrel and lysine acetylsalicylate versus clopidogrel and aspirin on platelet aggregation and activated GPIIb/IIIa expression in healthy volunteers
ABRAHAM MAJLUF-CRUZ, ADRIANA RUIZ DE CHAVEZ-OCHOA, KARIM MAJLUF-CRUZ, ERIKA CORIA-RAMIREZ, IGNACIO PINEDA DEL AGUILA, ˜ O-PEREZ, LISNETH MATI´AS-AGUILAR, SANDRA TREVIN ´ ´ ˜A JULIO CESAR LOPEZ-ARMENTA, & NORMA CORONA DE LA PEN Unidad de Investigacion Medica en Trombosis, Hemostasia y Aterogenesis, Hospital General Regional Gabriel Mancera, Instituto Mexicano del Seguro Social, Mexico City, Mexico (Received 9 September 2005)
Abstract Platelet activation contributes to thrombotic events in cardiovascular disease. Acetylsalicylic acid (ASA) is used in combination with clopidogrel to reduce cardiovascular events. Lysine acetylsalicylate (L-ASA), also inhibits platelet activation with fewer gastrointestinal side effects than ASA. Dual therapy with L-ASA and clopidogrel may result in an antiplatelet effect with fewer side effects. We compared the antiplatelet effect of combined ASA/clopidogrel versus L-ASA/ clopidogrel in healthy subjects. Fourteen volunteers (seven men and seven women, aged 25–45 years) received antiplatelet therapy during 14-day periods in the following sequence: 75 mg ASA; 160 mg L-ASA; 75 mg clopidogrel; 160 mg L-ASA plus 75 mg clopidogrel, and 75 mg ASA plus 75 mg clopidogrel. We evaluated platelet aggregation and glycoprotein IIb/IIIa activation. Our results show that administration of L-ASA/clopidogrel is as effective as ASA/clopidogrel combination.
Keywords: Clopidogrel, lysine acetylsalicylate, aspirin, platelet aggregation, GPIIb/IIIa
Introduction Persistent platelet activation may contribute to thrombotic events in patients with cardiovascular disease. Chronic use of platelet inhibitors improves morbility, mortality, and quality of life in this expanding population. Among antiplatelet agents, acetylsalicylic acid (ASA, molecular weight: 180.16) is the most extensively studied agent. It has highest efficacy when used at recommended dosages between 75 and 150 mg/day with highest degree of costeffectiveness [1]. ASA has been successfully used in combination with clopidogrel, an ADP receptor inhibitor, to reduce cardiovascular events [2]. Lysine acetylsalicylate (L-ASA, molecular weight: 326.34), at the recommended oral dosages ranging from 160 to 325 mg/day, is another powerful antiplatelet compound with fewer gastrointestinal side effects than regular and enteric-coated ASA, proved effective in reducing platelet activation [3]. L-ASA is a soluble salt that soon after being administered Correspondence: Abraham Majluf E-mail:
[email protected]
Cruz,
M.D.,
PhD,
Apartado
ISSN 0953–7104 print/ISSN 1369–1635 online ß 2006 Taylor & Francis DOI: 10.1080/09537100500438156
is converted into ASA, the inhibitor of platelet cyclooxygenase responsible for the fast and strong antiplatelet effect. Dual therapy with L-ASA and clopidogrel may result in a powerful antiplatelet effect in addition to reduction in gastrointestinal side effects. Therefore, this study was designed to compare antiplatelet effects of combined ASA/clopidogrel administration vs. L-ASA/clopidogrel. Our results show that L-ASA/clopidogrel is as effective as ASA/clopidogrel in terms platelet aggregation inhibition and glycoprotein IIb/IIIa (GPIIb/IIa) activation.
Subjects and methods The study included 14 healthy volunteers (seven men and seven women, aged 25–45 years); they were nonsmokers, had taken no ASA or related drugs 2 weeks before the study, and had given informed consent. The protocol was approved Postal
12-1100,
Mexico
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D.F.,
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Tel/Fax:
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by the Ethics Committee of our hospital. Subjects received antiplatelet agents orally in the following treatment sequence during 14 days: 75 mg ASA; 160 mg L-ASA (soluble powder pack equivalent to 160 mg ASA, KardegicTM, Sanofi-Aventis, France); 75 mg clopidogrel (PlavixTM, Sanofi-Aventis, France); 160 mg L-ASA plus 75 mg clopidogrel, and 75 mg ASA plus 75 mg clopidogrel. A basal blood sample was obtained at the beginning of the study. After each treatment period, a 14-day washout period was indicated. Blood samples were collected at the end of each treatment period and always 24 h after the last dose of the antiplatelet drug. Blood samples were obtained by mixing 1 part of sodium citrate (0.1 mM) and 9 parts of blood. Platelet-rich plasma (PRP) was obtained from a 12-ml blood sample by centrifuging at 200 g for 10 min at room temperature and platelet-poor plasma (PPP) by centrifugation of PRP at 1000 g for 10 min. Platelet aggregation in PRP was photometrically measured in a double-channel LumiAggregometer (Chrono-log Corp., Havertown, PA, USA) at 37 C. Five mM ADP (Sigma Chemical Co, St. Louis, MO, USA) and 5 mM sodium arachidonate (Chrono-log Corp) were used as agonist agents. Activation of GPIIb/IIIa was determined by flow cytometry with PAC-1 antibody (PharMigen, San Diego, CA, USA). PAC-1 (10 ml) was added to 25 ml PRP pretreated with either saline solution or ADP (10 mM). In order to prevent ADP-induced platelet aggregation which would interfere with flow cytometry analysis, these assays were performed at room temperature (25 C) and PAC-1 was added immediately after the agonist. Samples were mixed by inverting the tube gently two times. After 15 min incubation in the dark, the sample was diluted with 1000 ml FACS flow sheath. Samples were analyzed in a Becton-Dickinson FACScan flow cytometer. Activation was expressed as percentage of positive cells. Since data were not normally distributed, they are expressed as median values and 95th percentiles. Differences between values obtained with different treatments were evaluated by Wilcoxon signed ranks test. P value
