An Efficacy and Safety Study for JNS024ER (Tapentadol ER) in Chronic Pain Patients Due to Painful Diabetic Peripheral Neuropathy or Postherpetic Neuralgia

• Change in Health Related Quality of Life Scores on the Short Form 36 Health Survey [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
• Change in Pain Scores on the Brief Pain Inventory Short Form [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
• Sleep Questionnaire items to evaluate patients' quality of sleep [ Time Frame: 13 weeks ] [ Designated as safety issue: No ]

The objective of the study is to investigate the effectiveness, safety of JNS024ER (now known as and referred to throughout this posting as Tapentadol ER) at doses 25-250 mg twice daily, and to explore the pharmacokinetics (how drugs are absorbed in the body, how they are distributed within the body and how they are removed from the body over time) in Japanese patients with moderate to severe chronic pain due to painful diabetic peripheral neuropathy or postherpetic neuralgia.

This is a randomized (study drug assigned, multicenter, double-blind (neither physician nor patient knows the name of the assigned drug), placebo-controlled (patients are randomly assigned to a test treatment or to an identical-appearing treatment that does not contain the test drug) parallel-group comparison study in the patients with chronic pain due to painful diabetic peripheral neuropathy or postherpetic neuralgia. The study will be explained and informed consent will be obtained. Patients will be screened for study eligibility at Visit 1. The study will be explained and informed consent will be obtained. Patients will be screened for study eligibility at Visit 1. Potential patients must satisfy all eligibility criteria to be enrolled in the study. Eligible candidates will proceed to the study treatment period. At the time of study entry, all prohibited medications will be discontinued and will be disallowed throughout the study. The study consists of 3 periods: a 1-week screening period during which patients are evaluated for study eligibility; a 12-week study treatment period (maximum of 6-week dose adjustment phase and minimum of 6-week of dose maintenance phase); and a one-week follow-up period. The sponsor will collect adverse events starting with the signing of the informed consent form until completion of the last study-related procedure (may include contact for follow-up of safety). Adverse events include any occurrence that is new in onset or get worse in severity or frequency from the baseline condition, or abnormal results of diagnostic procedures, including laboratory test abnormalities. Blood samples for serum chemistry and hematology, a urine sample for urinalysis, vital signs, 12-lead electrocardiography and Clinical opioid withdrawal symptoms questionnaire will be also collected for safety evaluation. Numerical Rating Scale, Sleep questionnaire, Brief Pain Inventory Short Form, Short Form 36 Health Survey, Patient's global impression of change and Physician's global assessment will be collected for efficacy evaluation. Serum drug concentrations will also collected for pharmacokinetics evaluation. Patients will be randomized to one of the two following treatment groups: Tapentadol ER group and Placebo group. Tapentadol ER or placebo will be administered orally twice daily in the morning and evening. The dose ranges is between 50 and 500 mg/day. The maximum dose is 250 mg/intake (500 mg/day). The investigator determine based on consultation at patient visits and the patient diary whether or not the dose may be increased. Tapentadol ER or placebo will be administered orally twice daily in the morning and evening. The dose range is between 50 and 500 mg/day. The maximum dose is 250 mg/intake (500 mg/day). The 12-week treatment period consists of two phases: maximum of 6-week dose adjustment phase and minimum of 6-week dose maintenance phase.

• Pain
• Diabetic Neuropathies
• Neuralgia
• Postherpetic Neuralgia

• Drug: Tapentadol ER
  25mg, 50mg and 100mg tablets (50-500 mg/day) twice daily for 12 weeks
• Drug: Placebo
  Placebo tablets twice daily for 12 weeks

• Experimental: 001
  Tapentadol ER 25mg 50mg and 100mg tablets (50-500 mg/day) twice daily for 12 weeks
  Intervention: Drug: Tapentadol ER
• Experimental: 002
  Placebo Placebo tablets twice daily for 12 weeks
  Intervention: Drug: Placebo

Inclusion Criteria:

• Patients with chronic pain due to painful diabetic neuropathy or postherpetic neuralgia continuing for at least 12 weeks before informed consent
• Patients have not experienced treatment with conventional opioids, except for the following cases a) Short term use of opioid analgesics for treatment of post-operative acute pain more than 30 days before consent, b) Temporal use of codeine phosphate or dihydrocodeine phosphate for purposes other than pain relief (e.g. for antitussive) more than 2 days before consent
• Mean pain intensity score of >=5 on an 11-point Numerical Rating Scale during 48 hours before consent and the investigator/sub-investigator considers that the patient should be treated with an opioid analgesic
• HbA1c within 4 weeks before consent <=11% (only for patients with diabetic neuropathic pain).

Exclusion Criteria:

• Patients have been treated or treated with a monoamine oxidase inhibitor within 14 days before informed consent
• Current or a history of epilepsy or convulsive disorders
• Suggested of intracranial hypertension (e.g. traumatic encephalopathy)