Filorexant Relieves Insomnia, but Not Painful Diabetic Neuropathy

Trial of Orexin Receptor Antagonist Fails to Deliver Pain Relief for PDN

Results from a recent phase 2 clinical trial have come up short in the search for a compound that ameliorates pain through improvements in sleep. The study investigated the efficacy of filorexant, an orexin receptor antagonist in providing relief from painful diabetic neuropathy (PDN). In rodent models, a blockade of the orexin receptor that regulates wakefulness was found to provide analgesia on pain associated with PDN. However, this latest trial concludes that filorexant, a compound in development for treating insomnia, was no better than placebo in relieving pain in patients with PDN. Nonetheless, the authors assert that their findings contribute to the exploration of links between sleep hygiene, pain syndromes, and pain relief.

The double-blind, randomized placebo-controlled, proof-of-concept study began with a population of 182 patients (44.5% women; 70.3% white; mean age, 55.3 years) with PDN not complicated by another type of pain syndrome. 170 screened subjects were randomly assigned to a 2-week course of filorexant or placebo. Lead author W. Joseph Herring, MD, PhD, summarized, "While mean reductions in pain scores were observed during the filorexant run-in phase of this randomized withdrawal design, the lack of differential pain relapse between filorexant and placebo in the double-blind phase does not provide evidence of a meaningful daytime treatment effect.”

Read a news story about the study conclusions.

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