The purpose of this study is to compare the effectiveness and safety of sustained- release hydromorphone, formulated to release slowly over time, taken once daily, and controlled- release oxycodone taken twice daily, in patients with chronic non-cancer pain. The study will also determine the dose of sustained-release hydromorphone that provides a level of pain control that is equal to the pain control provided by control-released oxycodone (equi-analgesic dosage).

Conventional immediate-release forms of hydromorphone and oxycodone have a relatively short duration of action that require dosing every 4 to 6 hours. To counterbalance the drawback of repeated opioid intake, sustained-release formulations of oxycodone and hydromorphone were developed that allow twice-daily dosing. Subsequently, a novel, once-daily, extended-release hydromorphone formulation was developed to further enhance ease of treatment and improve effectiveness in the treatment of severe pain. This is a randomized, open-label, comparative, parallel-group, 24-week flexible-dose study in patients with chronic noncancer pain severe enough to require continuous opioid therapy. Patients will receive either 8 mg of sustained-release hydromorphone, taken once daily or 10 mg of controlled-release oxycodone, taken twice daily. Individual adjustments in dosing will be performed to achieve satisfactory pain control, up to a maximum daily dosage of 32 mg for hydromorphone and 80 mg for oxycodone. The primary efficacy outcome will be the determination of the dose of hydromorphone that produces a level of pain control that is equal to the pain control provided by oxycodone (equi-analgesic dose). Safety will be monitored throughout the study. The study hypothesis is that sustained-release hydromorphone taken once daily is well tolerated and is not inferior with regard to pain control to controlled-release oxycodone taken twice daily.

Amendment:

Amendment was made to the duration of the study from duration of '24 weeks' to '52 weeks' in order to collect long-term safety and efficacy data. OROS hydromorphone 8, 16, or 32 mg tablets QD or SR oxycodone 10, 20, or 40 mg tablets BID. Individual adjustments in dosing performed to achieve satisfactory pain control over 24 weeks. Amendment: treatment duration was extended to 52 weeks.

• Drug: Oxycodone
• Drug: OROS hydromorphone HCl

Inclusion Criteria:

• Adult patients with chronic noncancer pain severe enough to require continuous opioid therapy (a score of at least 5 in "pain right now" on a 11 point numeric rating scale) who have never received an opioid or are currently treated with a weak opioid, and who experience insufficient pain control.

Exclusion Criteria:

• Patients who have been treated with strong opioids (including hydromorphone and oxycodone) within the last 4 weeks prior to study inclusion or who will probably undergo any treatment (e.g. neurological techniques, surgery) within the next 6 months, which may abruptly alter degree or nature of pain experienced
• patients with a history of disease(s), current illness, or therapy which would preclude them from participation in the study
• and patients who are pregnant or nursing.