Buprenorphine Transdermal Patches Pharmacokinetic Study

Inclusion Criteria: * Chinese male or female subjects with chronic pain (regardless of the aetiology, cancer-pain excluded), aged 18-55 years (both inclusive). * The average pain over the last 24 hours should attain ≤ 3 assessed with Numeric Rating Scales (NRS) refer to section 19.5. The pain condition has been lasting for at least 1 month and stable for 7 days prior to entering into the screening and is expected to be stable during the study duration. * Patients on stable permissible non-opioid analgesics, who in the opinion of the investigator are unlikely to require a change in treatment during the study. * Karnofsky score of Performance Status ≥ 70. * Body mass index (BMI) of 19 to 28 kg/m2 (both inclusive); and a total body weight ≥ 50 kg. * Normal dietary habits (e.g. not vegetarian nor vegan) and willing to only take the food supplied during the period of hospitalization. * Subjects who are able to read, understand and sign written informed consent prior to study participation and are willing to follow the protocol requirements. * Female subjects of child bearing potential (less than 1 year post-menopausal) must have a negative urine pregnancy test prior to first dose of study medication, be non-lactating, and willing to use adequate and highly effective methods of birth control throughout the study such as sterilisation, implants, injectables, combined oral contraceptives, some intra-uterine devices, sexual abstinence or vasectomised partner. Male subjects (surgical history of bilateral vasectomy excluded) with a partner of child bearing potential must be willing to use adequate and highly effective methods of birth control throughout the study. Exclusion Criteria: * Unstable condition of the primary disease of chronic pain, which, in the opinion of the investigator, would complicate the subject's participation in the study (e.g. require initiation of new medication). * Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies). * History of seizures or at risk (i.e. head trauma, epilepsy in family, anamnesis, unclear loss of consciousness). * Any history of frequent nausea or emesis regardless of aetiology. * Malignancy or a history of malignancy. * History of orthostatic hypotension. * Subjects who have any medical or surgical conditions that might interfere with transdermal absorption, distribution, me…