A Phase 2 Study of Tapentadol Extended-Release (JNS024ER) ) in Japanese Participants With Chronic Pain Due to Diabetic Neuropathic Pain or Postherpetic Neuralgia

Inclusion Criteria: * Participants with chronic pain due to painful diabetic neuropathy or postherpetic neuralgia continuing for at least 12 weeks before consent * Participants with adjuvant analgesics (antidepressants, antiepileptics and diabetic peripheral neuropathy drugs) or non-opioid treatment and dissatisfied with current treatment (in sense of efficacy and/or safety) for at least consecutive 14 days during the 12 weeks before consent * Participants have not experienced treatment with conventional opioids, except for the following cases: Short term use of opioid analgesics for treatment of post-operative acute pain more than 30 days before consent; and temporal use of codeine phosphate or dihydrocodeine phosphate for purposes other than pain relief (for example, for antitussive) more than 2 days before consent * Mean pain intensity score of greater than or equal to 5 on an 11-point Numerical Rating Scale during 48 hours before consent and the Investigator or Sub-investigator considers that the participant should be treated with an opioid analgesic * HbA1c within 4 weeks before consent less than or equal to 11percent (in participants with diabetic neuropathic pain) Exclusion Criteria: * Participants have been treated or treated with a monoamine oxidase inhibitor within 14 days before consent * Current or a history of epilepsy or convulsive disorders or hypersensitivity to opioid analgesics * Suggested of intracranial hypertension (for example, traumatic encephalopathy) * Participants who have complicated condition with uncontrolled or clinically significant arrhythmia, or neuropsychiatric disorders * Participants with moderately to severely impaired hepatic function, or severely impaired renal function