This is a multicenter, open-label, single-arm study designed to characterize the PK and to evaluate the safety of ALO-02 in children and adolescents 7 to 17 years of age who require opioid analgesia for moderate-to-severe pain. The study consists of 4 study periods (screening, titration, maintenance, follow-up) occurring over a period of up to 9 weeks. The study will enroll approximately 140 children and adolescents with at least 100 subjects once stabilized during the titration period to complete a minimum of 2 of the 4 weeks study duration in the maintenance period to satisfy the PK endpoint. A safety follow-up visit is required at 1 week post-last dose.