Efficacy of tramadol in treatment of pain in fibromyalgia

An outpatient, randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the efficacy and safety of tramadol in the treatm ent of the pain of fibromyalgia syndrome. One hundred patients with fibromy algia syndrome, (1990 American College of Rheumatology criteria), were enro lled into an open-label phase and treated with tramadol 50-400 mg/day. Pati ents who tolerated tramadol and perceived benefit were randomized to treatm ent with tramadol or placebo in the double-blind phase. The primary efficac y outcome measurement was the time (days) to exit front the double-blind ph ase because of inadequate pain relief, which was reported as the cumulative probability of discontinuing treatment because of inadequate pain relief. One hundred patients entered the open-label phase; 69% tolerated and achiev ed benefit with tramadol. These patients were then randomized to continue t ramadol (n = 35) or convert to a placebo (n = 34) during a 6-week, double-b lind treatment period, The Kaplan-Meier estimate of cumulative probability of discontinuing the double blind period because of inadequate pain relief was significantly lower in the tramadol group compared with the placebo gro up (p = 0.001). Twenty (57.1%) patients in the tramadol group successfully completed the entire double-blind phase compared with nine (27%) in the pla cebo group (p = .015). These results support the efficacy of tramadol over a period of 6 weeks in a double blind study for the treatment of the pain o f fibromyalgia in a group of patients who had been determined to tolerate i t and perceive a benefit.