Duloxetine in the Management of Diabetic Peripheral Neuropathic Pain: Response Profile

Introduction

Analyses examine the response rate at endpoint, as well as time course of response, in patients receiving duloxetine for management of diabetic peripheral neuropathic pain (DPNP).

Methods

Data were pooled from 3 double-blind, randomized, placebo-controlled 12-week trials in patients with DPNP ≥ 6 months duration, and without depression. Study 1 (N = 457) compared duloxetine 20 mg once daily (QD), 60 mg QD, 60 mg twice daily (BID), and placebo; Studies 2 (N = 334) and 3 (N = 348) compared duloxetine 60 mg QD and 60 mg BID with placebo. Ethics committees approved the study protocol in accordance with Declaration of Helsinki principles. Patients provided written informed consent prior to study participation. Treatment response was defined a priori as 30% reduction in the primary efficacy measure, 24-hour average pain severity. Analysis was replicated using alternative criteria (50% reduction or 2-point reduction).

Results

Endpoint response rates were significantly higher among patients receiving duloxetine (60 mg QD or 60 mg BID) than those receiving placebo, regardless of chosen response criterion. The proportion of patients responding (30% reduction in 24-hour average pain severity) to duloxetine was statistically greater than to placebo Week 1 and all subsequent visits. Similar results were obtained for the visitwise sustained response rate. Within the group with a sustained response at Week 12, the proportion of patients first exhibiting a response at Weeks 1 or 2 was higher in the duloxetine groups (60 mg QD, 65.0%; 60 mg BID, 62.0%) when compared with the placebo group (40.2%).

Conclusion

Patients with DPNP receiving duloxetine 60 mg QD or 60 mg BID had significantly higher treatment response rates compared with patients receiving placebo, regardless of response criterion. Response to duloxetine treatment tended to occur early, with approximately 30% of patients responding at Week 1. Among duloxetine-treated patients with a sustained treatment response at Week 12, over 60% had maintained responder status for 10 to 11 weeks.