COMPARISON OF EFFICACY OF LOW-MOLECULAR-WEIGHT HEPARIN (PARNAPARIN) WITH THAT OF UNFRACTIONATED HEPARIN IN THE PRESENCE OF ACTIVATED PLATELETS IN HEALTHY-SUBJECTS

Arterial thrombosis is typically platelet-rich. In this study, it is shown that heparin levels resulting in the usual activated partial thromboplastin time therapeutic range provide only a small anticoagulant effect in the presence of activated platelets. Thrombin inhibition is also negligible when heparin is added to platelet-rich plasma. Aspirin improves the anticoagulant effect af heparin in these circumstances, but the degree of anticoagulation is still considerably lower than that observed in platelet-poor plasma. A low molecular weight heparin (parnaparin) is more active in the presence of activated platelets (such as may occur in acute coronary syndromes) regardless af whether aspirin is used concomitantly.