American journal of therapeutics
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Randomized Controlled Trial Multicenter Study
Tramadol hydrochloride extended-release once-daily in the treatment of osteoarthritis of the knee and/or hip: a double-blind, randomized, dose-ranging trial.
This 12-week, multicenter, randomized, double-blind, placebo-controlled, dose-ranging trial evaluated tramadol ER (extended-release tramadol) in the management of osteoarthritis pain. Adults with knee and/or hip osteoarthritis and baseline pain intensity of ≥40 on a 100-mm visual analog scale (0 = no pain, 100 = extreme pain) received once-daily tramadol ER 100 mg (n = 201), 200 mg (n = 199), or 300 mg (n = 199), celecoxib 200 mg (n = 202; to test model sensitivity), or placebo (n = 200). Coprimary efficacy variables were Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale, WOMAC physical function subscale, and patient global assessment of disease activity. ⋯ Adverse events occurred more frequently with tramadol ER than placebo in the gastrointestinal (nausea, constipation, diarrhea) and central nervous (dizziness, headache) systems. In this study, tramadol ER 300 mg was effective in the management of moderate to severe painful osteoarthritis of the hip or knee. A large, increasing placebo response during the study may have contributed to the lack of statistical separation between tramadol ER 200 or 100 mg and placebo.