The safety and efficacy of once-daily controlled-release (CR) formulation of pregabalin in patients with postherpetic neuralgia assessed in a double-blinded randomised withdrawal, placebo-controlled trial. A total number of 1214 patients were randomised. The study designed as 6-week single-blind pregabalin treatment phase and 13-week double-blinded phase and patients with ≥ 50% decrease in mean pain score at single blind endpoint from baseline were randomised 1:1 to 82.5 to 660 mg/d of pregabalin CR or placebo. The <30% decrease in weekly mean pain score from single-blind baseline or discontinuation due to the adverse event (AE) or lack of efficacy located as the primary efficacy outcome. The secondary efficacy outcomes included the change in weekly mean pain score at the double-blinded end.

The 801 randomised patients treated in the single-blind phase and 413 in the double-blind phase out of which 208 received pregabalin dose and 205 received placebo. Pregabalin CR significantly increased the time to LTR versus placebo and results were analysed through Kaplan-Meier analysis. The LTR events were fewer with pregabalin CR than in placebo [29 (13.9%) vs 63 (30.7%)] (P<0.0001).

The common adverse events reported were dizziness, peripheral oedema, and drowsiness. Moreover, the drug was also well tolerated. Thus it can be considered as the treatment approach for patients with postherpetic neuralgia in future.