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.
Institute of Cardiology, University of Bologna, Italy.
G
G
Melandri
F
F
Semprini
V
V
Cervi
N
N
Candiotti
A
A
Branzi
E
E
Palazzini
B
B
Magnani
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