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 of 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 of whether aspirin is used concomitantly.
Melandri
G
G
Institute of Cardiology, University of Bologna, Italy.
Semprini
F
F
Cervi
V
V
Candiotti
N
N
Branzi
A
A
Palazzini
E
E
Magnani
B
B
D001241:Aspirin / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology*; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010314:Partial Thromboplastin Time; D015539:Platelet Activation / Q000187:drug effects*; D012016:Reference Values; D013917:Thrombin / Q000187:drug effects
D006495:Heparin, Low-Molecular-Weight; D006493:Heparin; D013917:Thrombin; C080945:parnaparin; D001241:Aspirin