A Research Study to Evaluate the Effectiveness of Dexmedetomidine in Preventing Delirium After Hip Fracture Repair Surgery

Inclusion Criteria: 1. Adult (≥18 years old) male or female who will undergo surgery for fractured hip with general anesthesia within 72 hours of admission to hospital. 2. If female, subject is non-lactating and is either: 1. Not of childbearing potential, defined as post-menopausal for at least 1 year or surgically sterile due to bilateral tubal ligation, bilateral oophorectomy or hysterectomy. 2. Of childbearing potential but is not pregnant at time of baseline and is practicing one of the following methods of birth control: oral or parenteral contraceptives, double-barrier method, vasectomized partner, or abstinence from sexual intercourse. 3. Subject is American Society of Anesthesiologists Physical Status I, II, III, or IV. 4. Subject (or subject's legally authorized representative) has voluntarily signed and dated the informed consent document approved by the Institutional Review Board (IRB). Exclusion Criteria: 1. Cognitive function level by Mini Mental State Exam (MMSE) of ≤20. 2. Subject has a positive CAM-ICU result for delirium at Screening or Baseline. 3. Subject requires chronic antipsychotic therapy. 4. Subject is anticipated to require additional surgical procedures during the 72 hour Screening Period and the 3 days Follow-up Period. 5. Subject is anticipated to require repair of pelvic fractures (eg,acetabulum). 6. Subject has participated in a trial with any experimental drug or experimental implantable device within 30 days prior to the study drug administration, or has ever been enrolled in this study. 7. Subject known to be in liver failure. 8. Subject has an anticipated potential for increased intracranial pressure or an uncontrolled seizure disorder or known psychiatric illness that could confound a normal response during study assessment. 9. Subject has received treatment with a α2-agonist or antagonist (within 14 days of study entry). 10. Subject for whom opiates, benzodiazepines, DEX or other α2-agonists are contraindicated. 11. Subject has, per the investigator's judgment, a known or suspected physical or psychological dependence on an abused drug, other than alcohol. 12. Subject has acute unstable angina, acute myocardial infarction, HR \<50 bpm, SBP \<90 mmHg, or third degree heart block unless the subject has a pacemaker. 13. Subject has any condition or factor which, in the Investigator's opinion, might increase the risk to the subject. 14. Subject is not expected to live more than 60 days.