Joachim Wernicke, PhD, MD, Associate Director of Global Product, Lilly Research Laboratories, Indianapolis, Indiana, United States, explained, "In this 12-week study we also saw efficacy continue to improve over the course of the study, with no evidence of efficacy subsiding and with about a 50% average reduction in pain measures."

For this 12-week, multicenter, parallel, double-blind, randomized, placebo-controlled trial, the investigators enrolled 348 subjects who had been diagnosed with pain due to bilateral peripheral neuropathy caused by type 1 or type 2 diabetes.

Patients were divided equally to one of three groups -- duloxetine 60 mg once daily (QD); duloxetine 60 mg twice daily (BID); placebo.

The primary outcome measure was weekly mean score of 24-hour average pain severity on an 11-point Likert scale, calculated from the patients' diaries. The secondary outcome measures and health outcome measures were 24-hour Worst Pain Score and Night Pain Score, and McGill Pain Score.

Treatment safety was measured using discontinuation rates, treatment emergent adverse events (TEAEs) and patients' laboratory results.

Compared to the placebo group, both duloxetine-treated groups achieved statistically significant improvement on the 24-hour average pain score, with separation from placebo evident at week 1 (P < .001).

Dr. Wernicke noted that duloxetine subjects achieved superiority over placebo for all secondary analyses of the primary efficacy measure (including response and sustained response rate). They also observed a significant treatment effect for duloxetine in most of the secondary measures for pain and health outcome.

The two most frequent adverse events were nausea (19%) and somnolence (12.1%). Duloxetine 60 mg twice-daily subjects also discontinued at a higher rate (12.1%) than placebo subjects (2.6%).

"Duloxetine showed no adverse effects on diabetic control, and both doses were safely administered and well tolerated," the authors wrote.

"This is a good tool for a physician to have available for the treatment of patients. The other choices are the tricyclic antidepressants which are usually associated with many more side effects, anticholinergic effects and histaminergic effects," Dr. Wernicke said.

Duloxetine is a selective serotonin and norepinephrine reuptake inhibitor, and it is the first prescription drug approved by the US Food and Drug Administration for the management of diabetic peripheral neuropathic pain. It is also approved for the treatment of major depression in adults.

The study was supported by Eli Lilly and Company.


[Presentation title: A Double-Blind, Multicenter Trial Comparing Duloxetine with Placebo in the Treatment of Diabetic Peripheral Neuropathic Pain. Abstract 509]

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