Pregabalin Controlled Release Effective in Adult Patients with Postherpetic Neuralgia

Pregabalin controlled release (CR) decrease pain in patients with postherpetic neuralgia (PHN), according to a Pfizer press release.

In a Phase 3 trial, researchers studied 796 patients for about 20 weeks in order to evaluate the safety and efficacy of pregabalin CR compared to a placebo in patients with PHN. Patients were recruited from 116 sites in 17 countries. There were 4 phases in the study: 1 week of baseline measurements, 6 weeks of single blind treatment, 13 weeks of double blind treatment, and a 1 week double blind taper. Patients were receiving either 165 mg/daily or 660 mg/daily if they had normal renal function and if not, between 82.5 mg/daily and 330 mg/daily of pregabalin.

The 418 patients who completed the single blind phase demonstrated a ≥50% pain response — compared to baseline measurements – and were randomized into the double blind phase.

Time to loss of therapeutic response (LTR) in pain reduction was measured in patients after the double blind phase. About 13.9 percent of patients (29 of 208 participants) observed LTR of <30 percent pain response relative to baseline. In the placebo group, 63 of 205 (30.7 percent) of patients observed LTR <30 percent in pain reduction. The researchers noted the difference between the treatments was statistically significant.

The most commonly observed side effects while taking pregabalin CR were dizziness, somnolence, peripheral edema, and weight increase. Generally, pregabalin CR was well tolerated and the safety profile was consistent with the current literature about immediate release pregabalin in PHN patients.

The Phase 3 trial was the last of 3 studies about pregabalin CR formulation to evaluate its use as a once daily therapy for PHN patients. The first study, based on adult patients, did not meet its primary endpoint. The second study, based on patients with fibromyalgia, demonstrated a statistically significant positive effect with pregabalin CR compared to placebo in its primary endpoint, which was time to LTR in pain reduction.