Pharmacodynamics of two different dosing regimens of tirofiban in citrate or PPACK anticoagulated blood.

The primary objective of this study was to compare the inhibitory activity of tirofiban measured with the rapid platelet function assay (RPFA) and with light transmission aggregometry using two different anticoagulants (citrate versus PPACK). Twenty patients treated with tirofiban for percutaneous coronary intervention were studied at six time points during tirofiban treatment. Tirofiban was given with a bolus dose of 10 microg/kg and an infusion of 0.10 microg/kg per min (10 patients) or with a bolus dose of 15 microg/kg and an infusion of 0.15 microg/kg per min (10 patients). Inhibition of platelet function appeared highest using citrated blood and the RPFA-device and lowest when assessed by aggregometry in PPACK-anticoagulated blood. Only the higher dose of tirofiban achieved an inhibition of platelet aggregation of at least 80% in all test systems.