Safety of BTDS in Subjects With Low Back Pain: A 52-Week Extension Phase of BUP3015

Inclusion Criteria: * Subjects who completed all visits of the double-blind phase on study drug, and subjects who discontinued study drug due to lack of therapeutic effect in the double-blind phase but completed all visits of the double-blind phase off study drug are eligible to enroll in the extension phase. * For subjects entering the extension, 4 electrocardiograms (ECGs) are required at entry if none were collected prior to randomization while on BTDS 20. NOTE: Subjects with any 1 QT data corrected for heart rate using the Fridericia formula (QTcF) interval ≥ 500 milliseconds (msec) would be discontinued from the extension phase Exclusion Criteria: * Subjects requiring long-acting opioid analgesics \[once- or twice-daily dosing with a every (q) 24 hours (h) or q12h drug\] or transdermal fentanyl during the extension phase should be discontinued from the study.