title: Bioavailability of subcutaneous low-molecular-weight heparin to patients on vasopressors.
abstract: Venous thromboembolism is a frequent complication in patients admitted to intensive care units (ICU), despite prophylactic treatment with subcutaneous low-molecular-weight (LMW) heparin. We postulated that poor efficacy of subcutaneous heparin might be due to administration of vasopressors, which could cause impaired peripheral circulation and inadequate systemic bioavailability of the anticoagulant. We compared concentrations of factor Xa activity in three groups of 15 patients: individuals in ICU who had and had not received vasopressors, and general surgery patients. Those who received vasopressors had lower plasma concentrations of factor-Xa activity than patients in ICU not on vasopressors and postoperative controls. Patients in ICU who take vasopressors could need higher doses of LMW heparin, or a different mode of administration of the drug, to attain adequate thrombosis prophylaxis.
authors.forename: Janine
authors.initials: J
authors.lastname: Dörffler-Melly
authors.forename: Evert
authors.initials: E
authors.lastname: de Jonge
authors.forename: Anne-Corneliede
authors.initials: AC
authors.lastname: Pont
authors.forename: Joost
authors.initials: J
authors.lastname: Meijers
authors.forename: Margreet B
authors.initials: MB
authors.lastname: Vroom
authors.forename: Harry R
authors.initials: HR
authors.lastname: Büller
authors.forename: Marcel
authors.initials: M
authors.lastname: Levi
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001682:Biological Availability; D004347:Drug Interactions; D015951:Factor Xa / Q000378:metabolism*; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D007279:Injections, Subcutaneous; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D014662:Vasoconstrictor Agents; D015951:Factor Xa