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The plasma half-life of warfarin ranges from 0.5 to 3 days (average 44 h) with wide

individual variations (1). Intravenously administered vitamin K1 has a terminal half-life

of 1.7 h (2,3). The difference in the half-lives of warfarin and vitamin K1 must be con-

sidered in the management of warfarin overdose. Multiple, frequent doses of vitamin

K1 may be necessary in some cases to restore adequate coagulation factor activity.