[Platelet function after a high dose bolus of tirofiban immediately after coronary angioplasty].
In the TARGET trial, the lower incidence of cardiac events at one month with abciximab compared with tirofiban was attributed to a lack of efficacy in the first hour because of suboptimal dosage. The object of this study was to confirm that high dose tirofibal is associated with over 90% platelet inhibition during the first hour and to analyse the effect of this new dosage on platelet activation. Thirty-three patients treated with clopidogrel and aspirin for an acute coronary syndrome without ST elevation were given before angioplasty a bolus of 25 microg/Kg of tirofiban injected in 3 minutes, followed by an infusion of 0.15 microg/kg/min. Blood samples were taken before the treatment (TO) and at the 45th minute (T1) to measure platelet aggregation induced by ADP, the expression of P-selection, the quantification of circulating monocyte-platelet aggregates and the phospholyration of VASP protein. The results showed that all patients had over 90% (100%) inhibition of platelet aggregation at T1. The expression of P-selection was significantly reduced (T0: 0.195 +/- 0.057 MFI; T1: 0.186 +/- 0.055 MFI, p = 0.03). There was no significant difference in the number of monocyte-platelet aggregates or in the phosphorylation of VASP. In conclusion, a bolus of 25 microg/Kg/3 min of tirofiban provides over 90% inhibition of platelet aggregation in the first hour. The initial platelet proactivator effect at this dosage was shown to have disappeared with an inhibition of platelet activation.
Barbou
F
F
Service de cardiologie, HIA Sainte-Anne, 83800 Toulon Armées. cf.barbou@wanadoo.fr
Frère
C
C
Hovasse
T
T
Cuisset
T
T
Said
L Nait
LN
Quilici
J
J
Alessi
M C
MC
Bonnet
J L
JL
D000208:Acute Disease; D000789:Angina, Unstable / Q000097:blood / Q000188:drug therapy* / Q000628:therapy; D015906:Angioplasty, Balloon, Coronary; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000188:drug therapy* / Q000628:therapy; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D013577:Syndrome; D013997:Time Factors; D000077466:Tirofiban; D014443:Tyrosine / Q000008:administration & dosage / Q000031:analogs & derivatives*
D010975:Platelet Aggregation Inhibitors; D014443:Tyrosine; D000077466:Tirofiban