- Systemic anticoagulation: Patients currently on oral anticoagulants (warfarin) are not eligible unless they are taking low doses of warfarin for catheter patency. If a patient develops thromboembolic disease while on treatment, they may remain on study. It is recommended that they receive a standard loading dose of coumadin on day 1. because of the interaction between Oxandrin and Coumadin (Oxandrin elevates the INR), patients will subsequently require a much lower dose of Coumadin. The effect of these combined medications should develop within 24 to 48 hours. The recommended Coumadin dose should be decreased to 20% of what is normally required for sufficient anticoagulation. (Example: If patient would normally receive 5 mg every day, they should only receive 1 mg every day.) PT/INR results should be monitored frequently with dosage adjustment as needed.