By Jill Stein

BARCELONA – The anticonvulsant pregabalin (Lyrica) produces durable relief of fibromyalgia-associated pain in patients who initially respond favorably to treatment, according to data reported at the meeting of the European Union League Against Rheumatism (EULAR) 2007.

In fact, the results show that patients continued to have significantly decreased pain throughout 32 weeks of follow-up. Until now, pregabalin-treated fibromyalgia patients have only been tracked for a maximum of 14 weeks.

Dr. Leslie Crofford at the University of Kentucky, Lexington, and colleagues elsewhere studied outcomes in 566 patients who had been randomized to receive either pregabalin or placebo during a 26-week double-blind phase of the FREEDOM (Fibromyalgia Relapse Evaluation and Efficacy for Durability of Meaningful Relief) trial.

All subjects had responded to pregabalin during a 6-week open-label phase with at least a 50% reduction in mean pain Visual Analog Scale (VAS) score from baseline and a Patient Global Impression of Change rating of at least "much improved."

"At the end of the double-blind treatment, nearly twice as many placebo patients had lost their therapeutic response compared with pregabalin patients," Dr. Crofford said.

The primary efficacy measure was the time to loss of therapeutic response measured in days, defined as either less than a 30% reduction in pain VAS score relative to open-label baseline value or deterioration of fibromyalgia symptoms necessitating alternative treatment.

At the end of the randomized phase during which they received an optimized open-label pregabalin dose of 300 mg/d, 450 mg/d, 600 mg/d, or placebo, 61% of patients on placebo had lost their therapeutic response observed during the open-label phase compared with 32% of patients on pregabalin.

The median time to worsening symptoms was 27 days and 119 days in the two groups, respectively.

Pregabalin also demonstrated durable treatment effects for multiple components of the Medical Outcomes Study (MOS)-Sleep subscale including sleep disturbance, awakenings with shortness of breath, sleep adequacy, somnolence, and overall sleep problem index as well as fatigue and global improvement.

During the double-blind phase of the trial, 62% of pregabalin patients reported an adverse event versus 45% of placebo patients. Overall, 82% of adverse events were mild or moderate. Serious events occurred in seven pregabalin and three placebo patients, and none was thought to be related to the study drug.

"I think the real importance of this trial is that we demonstrated conclusively that patients who respond well to pregabalin will maintain their response over a long period of time," Dr. Crofford said. "It’s important for patients to know that they can obtain durable relief from their fibromyalgia pain by pharmacotherapy."

She added that reports in the literature have suggested that patients with fibromyalgia or other chronic pain conditions lose their response to drug treatment over time. "Our study firmly shows that this is not the case."

Currently, no therapy is approved in the US for the treatment of fibromyalgia.