Clopidogrel resistance in Japanese patients scheduled for percutaneous coronary intervention.
BACKGROUND
Dual antiplatelet therapy with acetylsalicylic acid (ASA) and a P2Y(12) ADP-receptor blocker is standard for prevention of coronary stent thrombosis. Clopidogrel, a 2(nd)-generation P2Y(12) blocker, has recently become available in Japan and this study aimed to evaluate its antiplatelet effects in Japanese patients.


RESULTS
Thirty Japanese patients scheduled for elective coronary stent implantation were enrolled. Under low-dose ASA therapy, 300 mg clopidogrel was loaded on the 1(st) day and a daily 75-mg dose was administered on the following days. Assessed by optical aggregometer, rapid inhibition occurred at 4 h, when the inhibition of platelet aggregation rate (IPA) was 16.4+/-12.8% using 5 mumol/L ADP as the stimulus. The antiplatelet efficacy of clopidogrel was reasonably constant in each patient throughout the study period, although there was a broad inter-individual variation. At 48 h after clopidogrel loading, the ratios of responders (IPA > or =30%), hypo-responders (10%< or =IPA<30%), and non-responders (IPA <10%) were 36%, 50%, and 14%, respectively.


CONCLUSIONS
The antiplatelet effectiveness of clopidogrel appeared individual-specific with wide inter-individual variation. The rate of clopidogrel non-responders was 14% among the examined Japanese patients.
Hoshino
Kozo
K
Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Horiuchi
Hisanori
H
Tada
Tomohisa
T
Tazaki
Junichi
J
Nishi
Eiichiro
E
Kawato
Mitsunori
M
Ikeda
Tomoyuki
T
Yamamoto
Hiromi
H
Akao
Masaharu
M
Furukawa
Yutaka
Y
Shizuta
Satoshi
S
Toma
Masanao
M
Tamura
Toshihiro
T
Saito
Naritatsu
N
Doi
Takahiro
T
Ozasa
Neiko
N
Jinnai
Toshikazu
T
Takahashi
Kanako
K
Watanabe
Haruyo
H
Yoshikawa
Yuka
Y
Nishimoto
Naoko
N
Ouchi
Chiho
C
Morimoto
Takeshi
T
Kita
Toru
T
Kimura
Takeshi
T
D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary; D015815:Cell Adhesion Molecules / Q000378:metabolism; D000077144:Clopidogrel; D023921:Coronary Stenosis / Q000208:ethnology* / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000628:therapy*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D015607:Stents; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D000077144:Clopidogrel; D013988:Ticlopidine