title: Initiation of exemestane in two warfarin-treated patients leading to elevation and variability of INR.
abstract: Aromatase inhibitors are sometimes chosen for adjuvant therapy in post-menopausal breast cancer patients with a history of venous thromboembolism over an antiestrogen due to the lower risk of venous thromboembolism associated with aromatase inhibitors compared to antiestrogens. We report two cases where patients on warfarin therapy had an increase in their international normalized ratio with the initiation of exemestane therapy. Initially, the patients also showed international normalized ratio variability possibly due to variable absorption of exemestane. We suggest patients being treated with warfarin and exemestane concomitantly need close monitoring and education in order to decrease the risk of adverse events that could be associated with this possible interaction. To our knowledge, there are no similar reported cases in the literature.
authors.affiliation: Department of Pharmacy, The Ohio State University Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Columbus, USA Aaron.Dush@osumc.edu.
authors.forename: Aaron
authors.initials: A
authors.lastname: Dush
authors.affiliation: Department of Pharmacy, The Ohio State University Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Columbus, USA.
authors.forename: Abby
authors.initials: A
authors.lastname: Williams
authors.affiliation: Department of Pharmacy, The Ohio State University Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Columbus, USA.
authors.forename: Neha
authors.initials: N
authors.lastname: Mangini
authors.affiliation: School of Pharmacy, The Ohio State University, Columbus, USA.
authors.forename: Kendra
authors.initials: K
authors.lastname: Klaczak
mesh_terms: D000730:Androstadienes / Q000008:administration & dosage / Q000009:adverse effects*; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D047072:Aromatase Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*; D004347:Drug Interactions / Q000502:physiology; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008875:Middle Aged; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D000730:Androstadienes; D000925:Anticoagulants; D047072:Aromatase Inhibitors; D014859:Warfarin; C056516:exemestane
keywords: INR; Warfarin; exemestane; interaction