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.
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.
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.
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%).
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.