SEATTLE, WA—Lemborexant (E2006), a dual orexin receptor antagonist (DORA) under development for insomnia disorder, led to an approximately 50% decrease in latency to persistent sleep (LPS) and wake after sleep onset (WASO) and an average 86% increase in sleep efficiency (SE), according to data presented at SLEEP 2015.

Patricia J. Murphy, PhD, of Eisai Inc. in Woodcliff Lake, NJ, reported outcomes of efficacy assessments using polysomnography (PSG), analyzed by sex, from a Phase 2 study of a 15-night, randomized, double-blind trial of six doses of lemborexant (1mg, 2.5mg, 5mg, 10mg, 15mg, and 25mg) vs. placebo, followed by two nightly doses of placebo (single-blind).

The study’s overall objective was to identify at least one dose of lemborexant that balanced efficacy and safety, defined as lack of next morning residual sleepiness.

Of the 291 subjects, 64% were female (mean age 51 years) and 36% were male (mean age 45 years). Pairs of eight-hour polysomnographies (PSG) were recorded at baseline, first, and last two treatment nights, and placebo run-out nights. At baseline, Insomnia Severity Index was 19.8 for the group, 20.0 for females, and 19.3 for males; polysomnography indices of disrupted sleep were slightly worse in men.

After 15 days of treatment, LPS ≤20 minutes was 30.8 for all patients who received placebo and ranged from 48.4 at the lemborexant 1mg dose to 87.1 at the lemborexant 10mg dose. WASO ≤60 minutes was 43.8 for placebo and ranged from 39.1 for the lemborexant 2.5mg dose to 74.7 for the lemborexant 25mg dose.

The most common adverse events (AEs) included somnolence, headache, sleep paralysis, nightmare, dizziness, and back pain. All AEs, except one serious AE (25mg group), were rate mild or moderate. Two serious AEs were hyperkalemia (placebo group) and focal seizure (25mg group). Only one patient discontinued due to a serious AE (25mg group). Somnolence AEs were distributed evenly among men and women, and no sex differences were observed in the safety assessments.

“These data support potential further study of lemborexant as a safe and effective treatment for insomnia disorder,” Dr. Murphy concluded.