A Pharmacokinetic (PK) Study of Extended-Release Epidural Morphine in Upper Abdominal Surgery

Inclusion Criteria: * Males and females ≥ 18 years of age at Screening * Negative pregnancy test in females of childbearing potential * Scheduled for major upper abdominal surgery via an upper midline incision under general anesthesia * American Society of Anesthesiology (ASA) Physical Class 1, 2, or 3 * Willing and able to use a PCA pump * Willing to receive only IV fentanyl for 72 hours post-dose to control post-operative pain * Capable of providing written informed consent and responses to pain assessment scales and neurological assessment questionnaires Exclusion Criteria: * Morbid obesity, defined as a body mass index (BMI) ≥ 40 * Scheduled to undergo surgery under regional anesthesia * Usage of analgesic medications containing morphine or codeine within three days prior to study drug administration * Chronic opioid medication usage (defined as daily opioids for more than 7 days prior to enrollment) * Suspected or documented history of sleep apnea, narcolepsy, or excessive daytime sleepiness * Female who was pregnant or lactating * History of hypersensitivity or idiosyncratic reaction to opioid medications, local anesthetics, or epinephrine * Any contraindication for the epidural administration of study drug (e.g., coagulopathy, local infection) * Administration of an investigational drug within 30 days prior to Screening * Suspected or documented history of substance abuse and/or alcoholism * Any contraindication to frequent blood PK sampling (such as significant anemia) or other barrier to obtaining timely PK samples