Efficacy of pregabalin for peripheral neuropathic pain: results of an 8-week, flexible-dose, double-blind, placebo-controlled study conducted in China.

BACKGROUND: Several classes of medications such as tricyclic antidepressants, anticonvulsants, narcotic analgesics, and α2-δ ligands, such as pregabalin, have been reported to be efficacious in the treatment of painful diabetic peripheral neuropathy (DPN) and postherpetic neuralgia (PHN) in whites. However, no large double-blind, placebo-controlled trials have been reported that evaluated the efficacy of pregabalin for the treatment of neuropathic pain in a Chinese population in China.

OBJECTIVE: The aim of this study was to evaluate the efficacy and tolerability of flexible-dose pregabalin in treatment of Chinese patients diagnosed with painful DPN or PHN.

METHODS: This was a double-blind, parallel-group study in which patients were randomized in a 2:1 ratio and treated with either flexible-dose pregabalin, 150 to 600 mg/d, or corresponding flexible-dose placebo for 8 weeks. The primary efficacy end point was change in the mean pain score based on a daily pain rating scale (DPRS; ranging from 0 [no pain] to 10 [worst possible pain]). Secondary end points included Daily Sleep Interference scale, short form-McGill Pain Questionnaire (SF-MPQ) scale, and the Patient Global Impression of Change (PGIC) and Clinician Global Impression of Change (CGIC) scales. Adverse events and physical and laboratory examination results were also collected.

RESULTS: Pregabalin and placebo treatment groups were well-matched in terms of demographic and patient characteristics. On the primary outcome, end point change in mean DPRS score, treatment with pregabalin (N = 206) resulted in significant improvement compared with results with placebo (N = 102), with a least squares mean difference score of -0.6 (P = 0.005). With regard to responder rates, 64% and 52% of patients treated with pregabalin and placebo, respectively, reported ≥30% improvement in DPRS scores (P = 0.04). Treatment with pregabalin also resulted in significant efficacy compared with that of placebo on secondary measures, including SF-MPQ VAS score (P = 0.012), SF-MPQ present pain intensity index score (P = 0.003), sleep interference score (P = 0.023), and PGIC and CGIC scores (P = 0.004 and P = 0.001, respectively). Adverse events were observed in 50.0% of pregabalin patients and 40.2% of placebo patients (P = 0.105), with the most common adverse event being dizziness (11.2%).

CONCLUSIONS: Study results suggest that relative to placebo, pregabalin in daily doses of 150 to 600 mg/d was effective and well tolerated in Chinese patients diagnosed with moderate-to-severe DPN or PHN, indicated through improved pain scores and PGIC scores.