OTR Tablet 40 mg Fed-state Bioequivalence Study

Inclusion Criteria: 1. Chinese male or female subjects with histories of chronic pain regardless of the aetiology, aged 18-55 years both inclusive 2. The average pain over the last 24 hours should be scored \< 4 assessed with Numeric Rating Scales (NRS), when not receiving analgesics. The pain condition has been kept stable at least in the past 7 days prior to entering into the screening and is expected to be stable during the study duration 3. Body weight ≥45 kg and a body mass index (BMI) ≥18 and ≤28 kg/m2 4. Karnofsky score of Performance Status ≥70 5. Willing to take all the food supplied while the subject is in the study unit 6. Be able to read, understand, and sign written Informed Consent Form (ICF) prior to study participation and be willing to follow the protocol requirements 7. Willing to use adequate and highly effective methods of contraception throughout the study. A highly effective method of birth control is defined as one which results in a low failure rate (i.e. less than 1% per year) when used consistently and correctly such as sterilisation, implants, injectables, some Intrauterine Device (IUD), sexual abstinence, or vasectomised partner 8. Female subjects, including those up to less than one year post-menopausal, must have a negative serum pregnancy test and be non-lactating Exclusion Criteria: 1. Subjects who are currently taking opioids or have used opioids in the past 14 days prior to receiving the study drug 2. Have hypersensitivity history to any opioids, naltrexone, naloxone, or related compounds or any contraindications as detailed in the OTR and OXYCONTIN tablet Summary of Product Characteristics 3. Histories of or any current conditions that might interfere with drug absorption, distribution, metabolism, or excretion 4. Subjects who are likely to have paralytic ileus or acute abdomen or to require an operation on abdominal regions 5. Subjects with biliary tract diseases, pancreatitis, prostatic hypertrophy, or corticoadrenal insufficiency 6. Subjects with respiratory depression, corpulmonale, or chronic bronchial asthma 7. Any history of seizures or symptomatic head trauma 8. Subjects with abnormal liver function (values exceeding the upper limit of normal (ULN) for alanine aminotransferase (ALT), aspartate aminotransferase (AST), or total bilirubin during the Screening Phase) or abnormal renal function (values exceeding the ULN for serum creatinine during the Screening Phase). Note: if the values of ALT, AST or total bilirubin…