The effect of ticlopidine administration to humans on the binding of adenosine diphosphate to blood platelets

Abstract

Administration of Ticlopidine to human volunteers resulted in a prolonged bleeding time and decreased or absent aggregation of platelets with collagen and epinephrine. Adenosine diphosphate (ADP) induced platelet aggregation was initiated by a normal shape change, but the rate of the first wave of aggregation had decreased. The second wave of aggregation was absent. ADP-binding to platelets of volunteers, consisted of two classes of binding sites:one with high affinity and one with low affinity, giving a curvilinear and a linear part in a concentration dependency curve. After Ticlopidine, the low affinity part of the curve had disappeared. Evidence will be presented that this is a specific Ticlopidine effect.