ENA-001 for Post Operative Respiratory Depression (PORD)

Inclusion criteria

• . Willing to give written informed consent for the trial and willing/able to adhere to study procedures.
• . Scheduled to undergo a major elective surgery, including abdominal, laparoscopic, nephrology, thoracic (non-cardiac), orthopedic (e.g., shoulder and ankle surgery), where the subject will be transferred to recover in the general postanesthesia recover unit (PACU) and extubation will be performed in the operating room or PACU.
• . Undergoing surgical procedure with a intraoperative requirement of ≥ 250 µg of fentanyl; Enrolled base on expected pain management to necessitate ≥ 250 µg of fentanyl intraoperatively.
• . Male and female, ≥18 years of age.
• . American Society of Anesthesiologists (ASA) physical status classification 1-3.
• . Have no clinical or electrocardiographic signs of ischemic heart disease as determined by the Investigator. The Screening 12 lead ECG conduction intervals must be within gender specific normal range (e.g., QTcF female \< 450 msec QTcF males \< 430 msec, PR interval ≤ 220 msec). ECGs are to be judged by the investigator or sub-investigator as per standardized procedures.
• . Clinical laboratory tests (blood hematology, blood chemistry, coagulation and urinalysis) must not include any significant clinical abnormalities.
• . Vital sign measurements must be within the following ranges during screening and on the day of dosing:

Exclusion criteria