This Article  • References  • Full text PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Contact me when this article is cited  Related Content  • Similar articles in JAMA  Social Bookmarking   What's this?

Valery A. Portnoi, MD
Washington, DC

JAMA. 1997;278(7):548.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

To the Editor.

—In the Questions and Answers on loading dose of warfarin, Dr Lamb¹ correctly advises against the loading dose since it is clinically unwarranted and potentially hazardous because of increased risk of hemorrhage. This recommendation is consistent with the current scientific data. The literature also supports the author's second recommendation to initiate monitoring using the international normalized ratio (INR) and to institute daily adjustment of warfarin dosage immediately after the therapy is begun. However, the latter recommendation appears to conflict with the pharmocodynamics of warfarin therapy, which was briefly but well described by the author.

During the first 72 to 96 hours after initiation of warfarin therapy, INR reflects the suppression of factor VII (half-life 6 hours) only, but not more important homeostatic factors VI, IX, and X, which have longer half-lives.² In addition, initiation of warfarin therapy even with a maintenance dose is not completely . . . [Full Text PDF of this Article]

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?