Conditions: Pain
Keywords: Chronic pain Acetoaminophen Tramadol Osteoarthritis of the knee Low back pain
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 321
Healthy volunteers: no

Brief summary:
The purpose of this study is to evaluate the efficacy and safety of tramadol hydrochloride plus acetaminophen (JNS013) in participants with chronic pain accompanied by osteoarthritis (a progressive and degenerative joint disease, in which the joints become painful and stiff) of the knee or low back pain (acute or chronic pain in the lumbar or sacral regions) which cannot be controlled sufficiently with non-steriodal anti-inflammatory drugs (NSAIDs).

Detailed description:
This is a multi-center (when more than one hospital or medical school team work on a medical research study), double-blind (test or experiment in which neither the person giving the treatment nor the participant knows which treatment the participant is receiving), placebo-controlled (an inactive substance; a pretend treatment \[with no drug in it\] that is compared in a clinical trial with a drug to test if the drug has a real effect), parallel group comparison study. The total duration of the study will be 11 weeks and consists of 4 periods; a pre-observation period (4 weeks), open-label period (2 weeks), double-blind period (4 weeks) and follow-up period (1 week). Participants will receive tramadol hydrochloride plus acetaminophen tablets orally 4 times daily for 2 weeks with no less than 4-hour intervals (up to 8 tablets per day) during the open-label period and the dose will be fixed for each participant in the latter 1 week. During the double-period participants will receive tramadol hydrochloride plus acetaminophen tablets or placebo at the same dose as used for the latter 1 week of the open-label period for up to 4 weeks. Efficacy will be primarily evaluated by number of participants with insufficient pain relief after the start of double-blind period. Participant's safety will be monitored throughout the study.

Arms:
arm 1: None arm 2: None arm 3: None

Interventions: intervention 1: Tramadol Hydrochloride Plus Acetaminophen (Open-Label) intervention 2: Tramadol Hydrochloride Plus Acetaminophen (Double-Blind) intervention 3: Placebo (Double-Blind)
Intervention descriptions: intervention 1: Fixed dose combination of tramadol 37.5 milligram (mg)/acetaminophen 325 mg, 1 or 2 tablets 4 times daily will be given for one week; dose level will be fixed for each participant during the second week based on analgesic efficacy and tolerability (maximum daily dose will be 8 tablets). intervention 2: Fixed dose combination of tramadol 37.5 mg/acetaminophen 325 mg, 1 or 2 tablets (same dose \[number of tablets\] as that for the second week in the open-label period) will be given 4 times daily up to 4 weeks. intervention 3: Matching placebo will be given up to 4 weeks.

Protocol document: