Capecitabine is indicated for the treatment of colorectal and breast cancer.
The warning follows the results of a clinical pharmacology trial, in which a drug interaction was demonstrated between capecitabine and the anticoagulant warfarin.
Postmarketing reports have shown clinically significant increases in prothrombin time and INR in patients who were stabilized on anticoagulants at the time capecitabine was introduced.
| A drug interaction has been demonstrated between capecitabine and warfarin.
These events occurred within several days and up to several months after initiating capecitabine therapy and, in a few cases, within one month after stopping capecitabine. They occurred in patients both with and without liver metastases.
The FDA comments that, "Patients receiving concomitant capecitabine and oral coumarin-derivative anticoagulant therapy should have their anticoagulant response (INR or prothrombin time) monitored frequently in order to adjust the anticoagulant dose accordingly."
The patient package insert has also been revised to reflect this new safety information.