The purpose of the extension phase is to evaluate the long-term safety and tolerability of buprenorphine transdermal system (BTDS).

Buprenorphine is a synthetic opioid analgesic with over 25 years of international clinical experience indicating it to be safe and effective in a variety of therapeutic situations for the relief of moderate to severe pain. Transdermal systems may offer advantages over currently indicated oral products including ease and convenience of use, improved compliance, possible reduction in patient care, and prolonged and consistent delivery of drug.

Inclusion Criteria:

• Subjects with moderate to severe osteoarthritic (OA) pain who completed all visits of the double-blind phase on study drug, or who discontinued study drug due to lack of therapeutic effect in the double-blind phase, but still completed all visits of the double-blind phase off study drug, are eligible to enroll in the extension phase.

Exclusion Criteria:

• Excluded from the study are subjects who ingest > 2500 mg/day acetaminophen as part of their current stable nonopioid analgesic regimen.
• Subjects requiring long-acting opioid analgesics [once- or twice-daily dosing with an every (q) 24 hour (h) or q12h drug] or transdermal fentanyl during the extension phase should be discontinued from the study.

Refer to core study for additional inclusion/exclusion information.