To investigate the safety, tolerance, pharmacokinetics and pharmacodynamics of tolvaptan 15, 30 and 60 mg after single oral administration in healthy Korean male subjects.

Inclusion Criteria:

1. Healthy Korean male subjects between 20 and 45 years of age, inclusive.
2. Body Mass Index (BMI) of 20 to 26 kg/m2, body,weight ≥ 50kg BMI = weight (kg)/height2(m)
3. Informed consent from the subjects

Exclusion Criteria:

1. Clinically significant abnormality of respiratory, cardiovascular, hepatic, neurologic, endocrine, hematologic, urinary, psychiatric.
2. History of gastrointestinal disease or surgery which can affect intestinal absorption of the study drug.
3. History of any significant drug allergy or hypersensitivity.
4. AST or ALT > 1.25 times upper normal limit at screening clinical laboratory test
5. Supine blood pressure after resting for ≥ 3 minutes, higher than 140/90 mmHg or lower than 100/50 mmHg, Supine pulse, after resting for ≥ 3 minutes, outside the range of 40 to 90 beats/minute.
6. Subjects who had history of drug abuse or alcohol addiction
7. Subjects who used of any prescription drug or herbal medication within 2 weeks prior to the first dosing of the study drug, or any over-the-counter or vitamin supplements within 1 week prior to the first dosing (However, investigators can judge the subject, who has taken the medications during those periods above, eligible for the trial if all other conditions are satisfied)
8. The investigator judges the subject not eligible for the study after reviewing clinical laboratory results or other reasons.