Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report

This case describes the increased anticoagulation effect associated with the use of high-dose ketoconazole. A 59-year-old man treated with warfarin for aortic valve replacement was prescribed high-dose ketoconazole and hydrocortisone for the treatment of prostate cancer. Despite lowering the warfa...

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Main Authors: Cynthia A. Jackevicius, Mannhu N. Ton
Format: Article
Language:English
Published: Wiley 2009-01-01
Series:Case Reports in Medicine
Online Access:http://dx.doi.org/10.1155/2009/315687
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author Cynthia A. Jackevicius
Mannhu N. Ton
author_facet Cynthia A. Jackevicius
Mannhu N. Ton
author_sort Cynthia A. Jackevicius
collection DOAJ
description This case describes the increased anticoagulation effect associated with the use of high-dose ketoconazole. A 59-year-old man treated with warfarin for aortic valve replacement was prescribed high-dose ketoconazole and hydrocortisone for the treatment of prostate cancer. Despite lowering the warfarin dosage by 35% during the start of high dose ketoconazole, an additional dose reduction was required subsequently when the INR rose from 2.62 to 3.82 within nine days. After a total dose reduction of 43%, the INR returned to therapeutic range within two weeks. The Naranjo probability scale revealed a probable adverse reaction of increased anticoagulant effect associated with high dose ketoconazole. Due to the inhibition of warfarin metabolism by ketoconazole, patients taking high dose ketoconazole concomitantly with warfarin may need their warfarin dosage reduced by more than is currently recommended, as well as receive more frequent INR monitoring to avoid over anticoagulation.
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spelling doaj-art-79d0e6f1857b425db74dd02e3f85dc922025-02-03T05:43:37ZengWileyCase Reports in Medicine1687-96271687-96352009-01-01200910.1155/2009/315687315687Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case ReportCynthia A. Jackevicius0Mannhu N. Ton1Department of Pharmacy Practice and Administration, College of Pharmacy, Western University of Health Sciences, CA 91766-1854, USADepartment of Pharmacy Practice and Administration, College of Pharmacy, Western University of Health Sciences, CA 91766-1854, USAThis case describes the increased anticoagulation effect associated with the use of high-dose ketoconazole. A 59-year-old man treated with warfarin for aortic valve replacement was prescribed high-dose ketoconazole and hydrocortisone for the treatment of prostate cancer. Despite lowering the warfarin dosage by 35% during the start of high dose ketoconazole, an additional dose reduction was required subsequently when the INR rose from 2.62 to 3.82 within nine days. After a total dose reduction of 43%, the INR returned to therapeutic range within two weeks. The Naranjo probability scale revealed a probable adverse reaction of increased anticoagulant effect associated with high dose ketoconazole. Due to the inhibition of warfarin metabolism by ketoconazole, patients taking high dose ketoconazole concomitantly with warfarin may need their warfarin dosage reduced by more than is currently recommended, as well as receive more frequent INR monitoring to avoid over anticoagulation.http://dx.doi.org/10.1155/2009/315687
spellingShingle Cynthia A. Jackevicius
Mannhu N. Ton
Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
Case Reports in Medicine
title Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
title_full Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
title_fullStr Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
title_full_unstemmed Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
title_short Enhanced Interaction between Warfarin and High-Dose Ketoconazole: A Case Report
title_sort enhanced interaction between warfarin and high dose ketoconazole a case report
url http://dx.doi.org/10.1155/2009/315687
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