title: Heparin lowers plasma levels of activated factor VII.
abstract: Based on heparin's antithrombin and anti-FXa activity and its in vitro inhibition of activated factor VII (FVIIa) activity, we hypothesized that unfractionated heparin (UFH) may decrease plasma levels of FVIIa in humans. Therefore, 10 healthy young male volunteers received an intravenous UFH infusion over 24 h. Heparin decreased FVIIa levels by 30% (95% CI 14-47%) at 12 h, which was sustained until 24 h. In contrast, neither the substrate pool (i.e. total factor VII) as measured by FVII antigen nor FVII activity were affected by UFH. These results may improve our understanding of the regulation of FVIIa levels and heparin's mode of action.
authors.affiliation: Department of Clinical Pharmacology-TARGET, University of Vienna, Austria. thomas.pernerstorfer@univie.ac.at
authors.forename: T
authors.initials: T
authors.lastname: Pernerstorfer
authors.forename: B
authors.initials: B
authors.lastname: Jilma
authors.forename: H G
authors.initials: HG
authors.lastname: Eichler
authors.forename: S
authors.initials: S
authors.lastname: Aull
authors.forename: S
authors.initials: S
authors.lastname: Handler
authors.forename: W
authors.initials: W
authors.lastname: Speiser
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000494:pharmacology*; D005167:Factor VII / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010949:Plasma / Q000737:chemistry; D010959:Tissue Plasminogen Activator / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D005167:Factor VII; D006493:Heparin; D010959:Tissue Plasminogen Activator