Introduction Increased risk of falls and other safety concerns such as abuse potential, tolerance and aberrant nocturnal behaviors are associated with currently available insomnia medications. Here we report safety parameters in elderly individuals with insomnia from a Phase 3 study of the dual orexin receptor antagonist lemborexant Methods SUNRISE 1 was randomized, double-blind, placebo- and active-controlled, 1-month, global Phase 3 study. Eligible subjects were females age 55 and older, and males age 65 and older. This report will summarize safety data from the subgroup of elderly subjects age 65 and older. Subjects met DSM-5 criteria for insomnia disorder, and had a primary complaint of sleep maintenance insomnia. Current insomnia symptoms were confirmed with both a sleep diary and PSG. Subjects with symptoms of other sleep disorders (e.g., moderate to severe sleep apnea, periodic limb movement disorder, restless legs syndrome) were excluded, but those with sufficiently-treated comorbid medical or psychiatric conditions could be included. After an approximately 2-week single-blind Run-in Period when all received placebo (PBO), subjects were randomized to PBO, zolpidem tartrate extended release (ZOL [6.25mg])or lemborexant (LEM; 5mg [LEM5] or 10mg [LEM10]) for 1 month. Study drug was taken within 5 min of the start of the sleep period, which was calculated based on the mean habitual bedtime from the sleep diary. Adverse events were obtained throughout the study. Additional safety parameters included: clinical laboratories, electrocardiograms (ECGs), vital signs and weight; potential rebound insomnia assessed via the sleep diary during a 2-week Follow-up Period; postural stability immediately upon morning awakening after the first 2 nights and last 2 nights of treatment using an ataxiameter measuring amount of body sway in 60 seconds (in units of 1/3 degree angle of arc, with higher values indicating more body sway), and tests of attention and memory immediately upon morning awakening at 8 hours postdose. Self-ratings of sleepiness/alertness were assessed on the sleep diary. Analyses of safety relating to study disposition, adverse events, and postural stability are reported here; all other safety-related assessments will be presented once subgroup analyses by age have been completed. Results A total of 1006 were randomized into the study. Of these, 453 (45%) were 65 years or older (137 males, 316 females) and are included in the results presented below. Most elderly subjects (433/453; 95.6%) completed the study. A total of 8 (1.8%) elderly subjects discontinued due to an adverse event, including 1 in PBO, 3 in ZOL, 2 in LEM5, and 2 in LEM10. There were 3 subjects with SAEs, all on ZOL; none were considered treatment-related, and all resolved without sequelae. Most AEs were mild to moderate in severity. The most common AEs (>2% in any active treatment group and >PBO) are listed in Table 1. At each visit, subjects were explicitly asked whether they had experienced a fall since the last visit. There were 4 falls in elderly subjects, all in the LEM5 treatment group. All were considered mild in severity, and none were considered treatment-related. An expert committee adjudicated all falls; none was classified as cataplexy. When postural stability was assessed immediately upon awakening, there was no significant treatment difference in body sway for either LEM treatment group compared to PBO at either the beginning (LEM5 difference from PBO 0.16 units, N.S.; LEM10 difference from PBO 2.69 units, N.S.) or end of treatment (LEM5 difference from PBO -0.87 units, N.S.; LEM10 difference from PBO 0.87 units, N.S.). In contrast, after the first 2 doses of ZOL, the change from baseline in body sway was significantly greater than PBO (difference from PBO 6.97 units, p Conclusions Lemborexant appeared to be well-tolerated in this population of older individuals. Combined with robust efficacy of LEM in this Phase 3 study (data showing that lemborexant significantly improved both sleep onset and sleep maintenance compared to both placebo and zolpidem will be presented separately), safety-related results from Phase 3 suggest that lemborexant, if approved, may be an optimal treatment for the population of older patients with sleep maintenance insomnia. This research was funded by Eisai Inc. and Purdue Pharma L.P.
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