• Evaluate the serum pharmacokinetic profile of a single 15-mg dose of DepoDur administered at the lower thoracic epidural space with or without a prior lidocaine-epinephrine test dose [ Designated as safety issue: No ]
  

• efficacy and safety profiles [ Designated as safety issue: Yes ]
  

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