Effects of suvorexant on pain sensitivity in fibromyalgia

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Conference Proceeding

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Introduction: The chronic widespread pain disorder, fibromyalgia, is known for its nociceptive hypersensitization and disturbed sleep. The relation of sleep and pain is bidirectional and data suggest that improving sleep in chronic pain disorders would attenuate daytime pain sensitivity. Here we report on suvorexant's next-day pain effects following night-time use gathered as part of a feasibility study. Methods: Women, 21- 65 yrs old, with fibromyalgia and co-morbid insomnia (n=10) were treated for 9 nights with suvorexant 20 mg and placebo with the order of treatment nights counterbalanced. Subjects were in good psychiatric health and stable physical condition and met American College of Rheumatology criteria for fibromyalgia and DSM-V criteria for insomnia. On a baseline screening 8-hr PSG other primary sleep disorders were ruled out. On days 2 and 9 of each treatment condition pain sensitivity was assessed at 1100 and 1500 hr by measuring finger withdrawal latency (FWL) to a radiant heat stimulus at 5 randomly presented intensity levels. FWL on the two tests of days 2 and 9 were compared between treatments using repeated measures ANOVAs with days and drug condition as factors. Results: FWL on both am and pm tests varied as a function of intensity (p<.001) with no time of day effects or interaction (hi intensity = short latency; low = long latency). On days 2 and 9 after suvorexant versus placebo pain sensitivity was reduced (i.e., latency increased). Average FWL (over 5 intensities and both days) was increased on both the am test (13.9 vs 13.1 sec) and pm tests (15.8 vs 14.1 sec, p<.03) following suvorexant the previous night. There were no time of day effects or interaction. Conclusion: Following hypnotic use of suvorexant 20 mg versus placebo by patients with fibromyalgia, next-day pain sensitivity was reduced on both am and pm assessments of FWL to a radiant heat stimulus.




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