 - Patients not on anticoagulation must have an INR 1.5 or a PTPTT within normal limits. Patients receiving anti-coagulation treatment with an agent such as warfarin or heparin may be allowed to participate. For patients on warfarin, the INR should be measured prior to initiation of treatment and monitored at least weekly, or as defined by the local standard of care, until INR is stable. 