Phase III Trial Evaluates Lyrica (Pregabalin) for Fibromyalgia
Controlled-release formulation delays loss of therapeutic response (Nov. 19)
Results from a phase III study have indicated that the controlled-release (CR) formulation of Lyrica (pregabalin, Pfizer) had a statistically significant effect on the primary endpoint — time to loss of therapeutic response (LTR) — compared with placebo in patients with fibromyalgia.
Fibromyalgia is a common pain condition in the U.S., affecting more than five million people. The disorder is characterized by chronic widespread pain and tenderness lasting for 3 to 5 months.
The new study is the second of three phase III clinical trials of the pregabalin CR formulation to report top-line findings, which will ascertain the potential use of pregabalin as a once-daily therapy. The top-line results of the first study in adults with partial-onset seizures with epilepsy did not meet its primary endpoint. The final study in post-herpetic neuralgia is ongoing.
The objective of the new double-blind, placebo-controlled, multicenter, randomized withdrawal study was to assess the efficacy and safety of pregabalin CR as treatment for patients with fibromyalgia. The study consisted of four phases: baseline (1 week); single-blind treatment (6 weeks); double-blind treatment (13 weeks); and a 1-week double-blind taper. Pregabalin CR was administered once daily immediately after the evening meal. During the single-blind phase, an optimal dosage of pregabalin CR (300 to 495 mg/day) was determined. In the double-blind phase, patients were randomly assigned to receive continued pregabalin CR treatment at the optimized dose or to matching placebo.
A total of 441 patients were enrolled into the single-blind phase. Of these patients, 122 (28%) had ≥ 50% pain response (i.e., ≥ 50% reduction in pain compared with baseline) and were enrolled into the double-blind phase. One subject withdrew from the study after randomization without receiving double-blind study medication. The remaining 121 subjects were included in the full analysis set.
The primary endpoint — defined as LTR during the double-blind phase (< 30% pain response relative to single-blind baseline mean pain or withdrawal due to lack of efficacy or adverse events) — occurred in 34 of 63 (54%) patients in the pregabalin CR group compared with 41 of 58 (71%) patients in the placebo group. The median time from randomization to LTR was 58 days in the pregabalin CR group and 22 days in the placebo group. The difference between the two groups was statistically significant (P = 0.021).
The most common adverse events associated with pregabalin CR (reported in 5% or more of patients) included dizziness, somnolence, peripheral edema, insomnia, headache, fatigue, nausea, weight increased, vision blurred, dry mouth, and disturbance in attention.
Since its approval by the FDA in 2004, Lyrica (pregabalin CR) has had five indications in the U.S., of which four are in the therapeutic area of pain. These indications include neuropathic pain associated with diabetic peripheral neuropathy; post-herpetic neuralgia (pain after shingles); neuropathic pain associated with spinal-cord injury; fibromyalgia; and partial-onset seizures in adults with epilepsy who take one or more drugs for seizures.
Source: Pfizer; November 19, 2012.