The purpose of this study is to evaluate the relative bioavailability (BA) of two lots of E5501 40 mg tablets administered twice as single oral doses to healthy subjects.

This is a randomized, open label, 4- way crossover, replicate design study to evaluate the bioavailability (BA) of E5501 new Phase 3 formulation Lot P97001ZZB 40 mg tablet manufactured July, 2009 (Treatment A ,reference drug) relative to Lot P01010ZZA 40 mg tablet manufactured January, 2010 (Treatment B, test drug) administered to 42 healthy male and female subjects.

Inclusion Criteria:

• Normal healthy adult male or female subjects age greater than or equal to 18 years and less than or equal to 55 years old.
• Body mass index greater than or equal to 18 kg/m2 and less than or equal to 32 kg/m2 at the time of screening.
• Platelet count between 120x109/L and 250x109/L.
• Women of childbearing potential must agree to use a double barrier method of contraception during the Randomization Phase of the study.

Exclusion Criteria:

• Evidence of clinically significant cardiovascular, hepatic, gastrointestinal, renal, respiratory, endocrine, hematologic, neurologic, or psychiatric disease or abnormalities or a known history of any gastrointestinal surgery that could impact the pharmacokinetics (PK)of the study drug.
• Agents associated with thrombotic events (including oral contraceptives) must be discontinued within 30 days of the first study drug administration.
• Evidence of organ dysfunction or any clinically significant deviation from normal in their medical history, e.g., history of splenectomy.
• History of venous or arterial thrombotic disease or other hypercoaguable state.
• Hemoglobin level less than 11.5 g/dL for females and 13.5g /dL for males