This is a single center, double-blind, randomized, placebo-controlled, ascending, single dose study of PRT064445 or its matching placebo, in healthy subjects.

Inclusion Criteria:

• Healthy men or women between the ages of 18 and 50 years old, inclusive
• BMI 19-32 and weighs at least 60kgs

Exclusion Criteria:

• History or symptoms of bleeding problems or thrombotic conditions
• Clinically significant medical history
• Major surgery, severe trauma, or bone fracture within 3 months