The study is intended to show that the Sufentanil NanoTab PCA System is as effective as morphine intravenous patient-controlled analgesia (IV PCA) for treating pain after surgery. Each patient will use either the Sufentanil NanoTab PCA System or morphine IV PCA to treat their pain for at least 48 hours and up to 72 hours after surgery while in the hospital.

Inclusion Criteria:

• Male or female patients who are 18 years or older
• Patients who are scheduled to undergo an open abdominal surgery (including laparoscopic-assisted), total knee or total hip replacement surgery under general anesthesia or spinal anesthesia that does not include intrathecal opioids during the operation.
• Post-surgical patients who have been admitted to the PACU and are expected to remain hospitalized and to have acute post-operative pain requiring parenteral opioids for at least 48 hours after surgery.

Exclusion Criteria:

• Patients who have taken an opioid for more than 30 consecutive days, at a daily dose of more than 15 mg of morphine (or equivalent), within the past 3 months prior to surgery (e.g. more than 3 doses per day of Vicodin®, Norco®, Lortab® with 5 mg hydrocodone per tablet).
• Patients with an allergy or hypersensitivity to opioids
• Female patients who are pregnant or breast-feeding