The advantage of slow-release opioid allows for less fluctuation in drug (pain killer) levels in the blood and an extended period within the effective range for pain relief. The slow-release opioids have been preferred over the short-acting opioids because of the longer duration of action, which lessens the frequency and severity of end-of-dose pain.

Herein, the investigators propose the use of low dose slow-release opioid formulation offers better pain control in the first 48 hours post-operatively in open abdominal urologic surgeries.

This will be a randomized, double-blind, controlled trial looking at all adult patients undergoing open abdominal urologic surgeries. After assessing the inclusion/exclusion criteria, the patients will be randomized into one of two groups:

Group 1: Sustained-release (long-acting) opioid on a regular basis for 2 days with immediate-release (short-acting) opioid available on an 'as required' basis

Group 2: Immediate-release (short-acting) opioid on an 'as required' basis only.

All patients will have a general anesthetic at the discretion of the anesthesiologist in the operating room and intravenous opioid will be administered in accordance with the anesthesiologists' discretion.

Pain score and analgesic consumption are the outcome measures.

Inclusion Criteria:

• All adult patients undergoing open abdominal urologic surgeries
• ASA 1-3

Exclusion Criteria:

• Patient refusal
• history of chronic pain
• allergy to hydromorphone
• cannot swallow tablets