NBME F6 S3 warfarin

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NBME F6 S3 warfarin

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clar697
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07/22/08 - 07:17 AM

A 45-year-old man receives a dose of warfarin orally for a large deep vein thrombosis of the right leg. She is currently taking an oral contraceptive. Her prothrombin time is 12sec (INR 1.0). Two hours after administration of warfarin, her prothrombin time remains at 12sec (INR 1.0). Which of the following best explains why this patient’s prothrombin time did not change?

A) The large thrombus increases the dose of warfarin required
B) Oral contraceptives accelerate the clearance of warfarin
C) Preexisting circulating coagulation factors have not been cleared
D) Prothrombin time is not a measure of the efficacy of warfarin
E) Warfarin should have been administered intravenously

DR_K
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07/22/08 - 10:33 PM

C) for warfarin it takes several days b4 it can actually act, for this we usually give heprin b4warfarin.

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hitesh
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07/23/08 - 02:14 AM

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alirizvi
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10/12/08 - 05:05 PM

DR_K wrote:
C) for warfarin it takes several days b4 it can actually act, for this we usually give heprin b4warfarin.

Yup and also u have to give heparin because warfarin inhbits protein C S which cant inhibit factor 5 8 anymore and cause coagulation and necrosis - in some patients so as a precaution have to give heparin with it.

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