Clinical Study to Investigate the Efficacy and the Safety of DA-9501 in Sedation During the Surgery With Epidural Anesthesia or Spinal Anesthesia Without Intubation

• Drug: Dexmedetomidine hydrochloride
  Dexmedetomidine 0.2 to 0.7 mcg/kg/hr
• Drug: Placebo

• Placebo Comparator: Placebo
  Dexmedetomidine 0 mcg/kg/hr 10 min Initial dose + Dexmedetomidine 0 mcg/kg/hr Maintenance dose
  Intervention: Drug: Placebo
• Experimental: Dexmedetomidine 0.067 mcg/kg
  Dexmedetomidine 0.4 mcg/kg/hr 10 min Initial dose + Dexmedetomidine 0.2 - 0.7 mcg/kg/hr Maintenance dose
  Intervention: Drug: Dexmedetomidine hydrochloride
• Experimental: Dexmedetomidine 0.25 mcg/kg
  Dexmedetomidine 1.5 mcg/kg/hr 10 min Initial dose + Dexmedetomidine 0.2 - 0.7 mcg/kg/hr Maintenance dose
  Intervention: Drug: Dexmedetomidine hydrochloride
• Experimental: Dexmedetomidine 0.5 mcg/kg
  Dexmedetomidine 3 mcg/kg/hr 10 min Initial dose + Dexmedetomidine 0.2 - 0.7 mcg/kg/hr Maintenance dose
  Intervention: Drug: Dexmedetomidine hydrochloride
• Experimental: Dexmedetomidine 1.0 mcg/kg
  Dexmedetomidine 6 mcg/kg/hr 10 min Initial dose + Dexmedetomidine 0.2 - 0.7 mcg/kg/hr Maintenance dose
  Intervention: Drug: Dexmedetomidine hydrochloride

Inclusion Criteria:

1. Patient has signed and dated the Informed Consent after the study had been fully explained.
2. Patient is male or female, at least 20 years of age when the Informed Consent is obtained.
3. American Society for Anesthesiologists (ASA) I to III Class.
4. Patient who requires sedation during the elective surgery which requires ?30mins (expected time) without intubation under monitored sedation care.
5. Patient undergoing a surgery requiring epidural or spinal anesthesia

Exclusion Criteria:

1. Patient who underwent general anesthesia within 7 days, or who received other study drugs within 30 days from the date of consent.
2. Patient with <92% SpO2, at the physical examination prior to the study drug administration, or ventilatory failure which requires intubation or Laryngeal Mask.
3. Patient with central nervous system pathology which may lead to increased intracranial pressure, uncontrolled seizures, psychiatric disorder which may be confused with the response to sedation treatment.
4. Patient who require general anesthesia.
5. Patient who receives treatment by alpha-2 agonists or alpha-2 antagonists within seven days of scheduled surgery or procedure.
6. Patient in whom opioids, DA-9501 or other alpha-2 agonists, or drugs which may be used in the study are contraindicated.
7. Patient diagnosed with unstable angina or acute myocardiac infarction within 6 weeks from the date of consent.
8. Patient whose heart rate is <60 bpm, systolic blood pressure is <90 mmHg by the physical examination prior to the study drug administration.
9. Patient has third degree heart block, unless the patient has a pacemaker or transverse pacing wires are in place.
10. Patient who has experienced an increase in alanine transaminase (ALT) and / or aspartate aminotransferase (AST) more than double the upper normal limit within 2 months of the date of consent, or who has a history of liver insufficiency.
11. Pregnant or lactating woman.
12. In the Investigator's or subinvestigator's opinion, the patient has any symptom or condition which might increase risk to the patient by conducting the study or preclude obtaining satisfactory study data