This Phase 3, multi-center study will evaluate the long-term safety and tolerability of hydrocodone bitartrate controlled release capsule (HC-CR) at daily doses of 40 mg or more in subjects with moderate to severe chronic pain. Long-term maintenance of HC-CR efficacy will be evaluated.

Subjects will go through screening, an open-label conversion and titration phase of up to 6 weeks followed by an open-label treatment phase for up to 48 weeks with a 2 week follow-up period.

Inclusion Criteria:

• Subjects must have a diagnosed moderate to severe chronic pain condition treated with around-the-clock opioids for at least the past 3 months or in the Investigator's opinion qualify for around-the-clock opioid therapy for treatment of their pain
• Subjects must have been taking opioids at least 5 days/week for the past month at an average daily dose of at least 30 mg hydrocodone
• Subjects must be able to complete study procedures and attend clinic visits for 6 to 12 months
• Females subjects of childbearing potential must have a negative urine pregnancy test at the Screen Visit, and must consent to use a medically-acceptable method of contraception throughout the entire study period.
• Subjects must have had an adequate medical evaluation for the treatment of their underlying painful condition and appropriate primary medical/surgical therapies for the underlying condition
• Subjects must voluntarily provide written informed consent

Exclusion Criteria:

• Any clinically significant condition that would, in the opinion of the investigator, preclude study participation or interfere with the assessment of pain or increase the risk of opioid-related adverse events (AEs)
• A medical condition that, in the opinion of the Investigator, would compromise the subject's ability to swallow, absorb, metabolize, or excrete study drug
• A surgical procedure for pain within the last 3 months
• Uncontrolled blood pressure, i.e., a sitting systolic blood pressure >180 mm Hg or <90 mm Hg, and/or a sitting diastolic blood pressure >120 mm Hg or <50 mm Hg at Screening
• A body mass index (BMI) > 45 kg/m2
• A hospital anxiety and depression scale (HADS) score of >12 in either depression or anxiety subscales or an established history of any psychiatric disorder that is poorly controlled
• A clinically significant abnormality in clinical chemistry, hematology or urinalysis