NURS 3550H Lecture Notes - Lecture 5: Deep Vein Thrombosis, Myocardial Infarction, Thrombolysis
31 Oct 2018
School
Department
Course
Professor
Document Summary
Heparin suppresses coagulation by helping antithrombin inactivate clotting factors, primarily thrombin and factor xa. Heparin simultaneously binds with both thrombin and antithrombin to form a ternary complex. To inactivate factor xa, heparin binds only with antithrombin; heparin itself does not bind with factor xa. Thrombin and factor xa are inhibited as soon as they bind with the heparin- antithrombin complex so the anticoagulant effects of heparin develop quickly (within minutes of iv administration) Heparin is unable to cross membranes, including those of the gi tract. Heparin cannot be absorbed if given orally, and therefore must be given by injection (iv or subq). Does not traverse the placenta and does not enter breast milk. Heparin binds nonspecically to plasma proteins, mononuclear cells, and endothelial cells. Heparin undergoes hepatic metabolism followed by renal excretion. Under normal conditions, the half-life is short (about 1. 5 hours). For patients with hepatic or renal impairment, the half-life is increased.
