Efficacy and tolerability of sustained-release tramadol in the treatment of symptomatic osteoarthritis of the hip or knee: A multicenter, randomized, double-blind, placebo-controlled study

Background: Opioid analgesics may be a useful alternative in patients with osteoarthritis who have not responded to first-line treatment with acetaminophen and in whom nonsteroidal anti-inflammatory drugs are contraindicated, ineffective, or poorly tolerated. Objective: This study compared the efficacy and tolerability of tramadol LP 200 mg, a new once-daily, sustained-release formulation, with those of placebo in patients with osteoarthritis of the hip or knee. Methods: In this multicenter, double-blind, placebo-controlled, parallel-group study, patients with osteoarthritis of the hip or knee (European League Against Rheumatism criteria) were randomized to receive either tramadol LP 200 mg once daily or placebo for 14 days. The primary efficacy end point was the change from baseline to the end of the study in scores on the Huskisson visual analog scale for pain. Secondary end points were change in the Lequesne functional discomfort index, global efficacy assessed by the patient and the investigator, time to improvement, and use of acetaminophen as rescue analgesic medication. Global tolerability was assessed by both patients and investigators at the end of the study The number and severity of adverse events occurring during the study and for 2 weeks thereafter were also recorded. Results: Two hundred thirty patients (167 women, 63 men) were evaluable for efficacy and safety Demographic data for the tramadol and placebo groups were as follows: mean (SD) age, 67.1 (7.1) and 66.4 (9.2) years, respectively; female sex, 72.1% and 73.1%; and mean body weight, 74.7 (13.6) and 74.6 (14.8) kg. All patients were white. The completer analysis included 197 patients (85 tramadol, 112 placebo). Pain was significantly reduced in the tramadol LP group compared with the placebo group on day 7 (P = 0.002) and day 14 (P = 0.010). In the patient's assessment of global efficacy, 77.6% (66) of the tramadol LP group reported improvement by day 14, compared with 59.8% (67) of the placebo group; in the investigator's assessment, the efficacy of tramadol LP was rated very good or good for 61.2% (52) of patients, compared with 30.4% (34) for placebo. Improvement was reported before day 7 in 88.2% (75) of patients in the tramadol LP group, compared with 65.2% (73) in the placebo group (P = 0.021); the mean time from the initiation of treatment to reported improvement was 3 days for tramadol LP and 6 days for placebo (P < 0.001). Rates of response (defined as greater than or equal to30% pain reduction between days 0 and 14) were 64.7% (55) for tramadol LP and 50.0% (56) for placebo (P = 0.039); no rescue medication was used by 60.0% (51) of the tramadol LP group and 36.6% (41) of the placebo group (P = 0.001). One or more adverse event was reported by 45.0% (50) of the tramadol LP group, compared with 19.3% (23) of the placebo group (P < 0.001). As would be expected with an opiate agonist such as tramadol, the most common adverse events with this agent involved the gastrointestinal system (nausea, 22.5% [25] of patients; vomiting, 17.1% [19]) and the central nervous system (somnolence, 11.7% [13]). Conclusions: In this study, tramadol LP 200 mg was significantly more effective than placebo in alleviating pain in patients with osteoarthritis of the hip or knee. It appeared to be relatively well tolerated for an opioid compound. Copyright (C) 2004 Excerpta Medica, Inc.