Pregabalin for peripheral neuropathic pain: a multicenter, enriched enrollment randomized withdrawal placebo-controlled trial.

OBJECTIVES: To date, published neuropathic pain randomized controlled trials of pregabalin have involved primarily diabetic peripheral neuropathy (DPN) and postherpetic neuralgia (PHN). This multicenter trial evaluated pregabalin in a broader range of neuropathic pain etiologies.

METHODS: In this enriched enrollment randomized withdrawal trial, 256 patients received single blind, flexible dose pregabalin for 4 weeks; stable concomitant analgesics were allowed. One hundred sixty-five (65%) had a ≥30% pain improvement and 157 were randomized and treated, double blind, to either continue pregabalin (n=80) or to receive placebo (n=77) for 5 weeks.

RESULTS: Of the single blind responders randomized, 81% on placebo and 86% on pregabalin completed the double-blind phase. At the double-blind endpoint, mean (SD) pain scores were 2.9 (1.9) in the pregabalin group and 3.5 (1.7) in the placebo group (P=0.002). These modest yet significant pregabalin-placebo differences were observed within each of the subgroups of patients with a diagnosis of either DPN or PHN (P=0.03), and with other diagnoses (P=0.02). Significant differences were also observed in sleep interference, Hospital Anxiety and Depression Scale Anxiety and Depression subscales, and other secondary measures. In total, 28 out of 80 (35.0%) in the pregabalin group and 28 out of 77 (36.4%) in the placebo group had either a meaningful increase in pain or discontinued the double-blind phase. Adverse events were consistent with the known tolerability profile of pregabalin and led to discontinuation of 9 during the single-blind phase, and 5 and 2 patients from the placebo and pregabalin groups, respectively.

DISCUSSION: These results support previous evidence of pregabalin efficacy but further demonstrate efficacy and tolerability in a broader range of peripheral neuropathic pain conditions beyond just DPN and PHN.