PMID- 10629396
OWN - NLM
STAT- MEDLINE
DCOM- 20000310
LR  - 20171101
IS  - 0301-0147 (Print)
IS  - 0301-0147 (Linking)
VI  - 29
IP  - 2-3
DP  - 1999
TI  - Conjectures and refutations on the mode of action of heparins. The limited 
      importance of anti-factor xa activity as a pharmaceutical mechanism and a 
      yardstick for therapy.
PG  - 170-8
AB  - Low-molecular-weight heparins (LMWHs), like unfractionated heparin (UFH), exert 
      their action primarily by accelerating the interaction between antithrombin (AT) 
      and thrombin. At the levels of aXa activity that are attained in human 
      pharmacology, it does not cause significant (>15%) inhibition of the clotting 
      system. The essential differences between LMWHs and UFH are: (a) LMWHs attain 
      higher plasma concentrations after subcutaneous injection (high bioavailability), 
      and (b) in contrast to LMWHs, UFH contains very large heparin molecules with a 
      putative hemorrhagic action. The reputedly higher aXa activity of LMWH can be 
      shown to be largely due to the absence of Ca(2+) using the current laboratory 
      methods to estimate this activity. Via this artifact the apparently high aXa 
      activity of LMWHs is correlated but not related to their favorable 
      pharmacokinetic properties. Consequently dosage guidelines for the use of 
      different LMWHs cannot be based upon their aXa activity. Until better laboratory 
      methods are available, clinical results are the only reliable guideline to 
      heparin dosage.
CI  - Copyright 1999 S. Karger AG, Basel
FAU - Beguin, S
AU  - Beguin S
AD  - Cardiovascular Research Institute and Medical Faculty, University of Maastricht, 
      The Netherlands.
FAU - Welzel, D
AU  - Welzel D
FAU - Al Dieri, R
AU  - Al Dieri R
FAU - Hemker, H C
AU  - Hemker HC
LA  - eng
PT  - Journal Article
PT  - Review
PL  - Switzerland
TA  - Haemostasis
JT  - Haemostasis
JID - 0371574
RN  - 0 (Anticoagulants)
RN  - 0 (Factor Xa Inhibitors)
RN  - 0 (Heparin, Low-Molecular-Weight)
RN  - 9005-49-6 (Heparin)
SB  - IM
MH  - Animals
MH  - Anticoagulants/*pharmacology/therapeutic use
MH  - Factor Xa Inhibitors
MH  - Heparin/chemistry/*pharmacology/therapeutic use
MH  - Heparin, Low-Molecular-Weight/chemistry/pharmacology/therapeutic use
MH  - Humans
MH  - Thrombosis/*drug therapy
RF  - 37
EDAT- 2000/01/12 09:00
MHDA- 2000/03/18 09:00
CRDT- 2000/01/12 09:00
PHST- 2000/01/12 09:00 [pubmed]
PHST- 2000/03/18 09:00 [medline]
PHST- 2000/01/12 09:00 [entrez]
AID - 22497 [pii]
AID - 10.1159/000022497 [doi]
PST - ppublish
SO  - Haemostasis. 1999;29(2-3):170-8. doi: 10.1159/000022497.