The Optimal Intensity of Oral Anticoagulant Therapy
- 20 November 1987
- journal article
- review article
- Published by American Medical Association (AMA) in JAMA
- Vol. 258 (19) , 2723-2726
- https://doi.org/10.1001/jama.1987.03400190105037
Abstract
IN THE United States, approximately 500 000 patients per year receive oral anticoagulant therapy (R. Hart, MD, quoting J. Wallner, Product Manager, Dupont Pharmaceuticals, Wilmington, Del, oral communication, April 1986). Since Quick et al1 introduced their test in 1935, it has been traditional to use the one-stage prothrombin time (PT) to monitor warfarin therapy. This test, which is sensitive to three of the four vitamin K-dependent clotting factors, is performed by adding a phospholipid extract of mammalian tissue (known as thromboplastin) to citrated plasma and clotting the mixture by adding calcium. Many clinicians who prescribe oral anticoagulants might be surprised to learn that the dose of warfarin that we currently use to prolong the PT to a ratio of 2 to 2.5 times the control value is larger than the dose that was used to produce an identical prolongation of the PT in the 1940s, 1950s, and the 1960s.Keywords
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