A Phase 2 Randomized Dose-Finding Study With Esmirtazapine in Patients With Primary Insomnia

Abstract

The antidepressant mirtazapine is an alternative to classical hypnotics, and this study investigated the efficacy and safety of esmirtazapine (Org 50081, the maleic acid salt of S-mirtazapine) in patients given a diagnosis of primary insomnia after acute (2-day) treatment. Patients aged 18 to 65 years with primary insomnia were randomized to receive placebo or 1.5-, 3.0-, or 4.5-mg esmirtazapine in a balanced 4-way crossover study; 2 sleep laboratory nights with polysomnography were separated by 5-day, single-blind placebo washout periods. Polysomnography-determined total sleep time (primary end point) and patient-reported total sleep time improved by at least 25 minutes with all 3 doses of esmirtazapine (P ≤ 0.001 vs placebo). Polysomnography-measured wake time after sleep onset (P ≤ 0.0001) and latency to persistent sleep also improved vs placebo (P ≤ 0.01, 3.0 and 4.5 mg). Patient-reported sleep quality improved with 3.0- and 4.5-mg esmirtazapine (P ≤ 0.01 and P ≤ 0.05, respectively, vs placebo). Morning alertness and contentment were not altered after esmirtazapine, and calmness increased with 4.5-mg esmirtazapine vs placebo. Evening questionnaires showed no difference in duration of daytime naps but reduced energy and ability to work/function after esmirtazapine treatment periods vs placebo (P < 0.05), although this effect was limited to the first night of each 2-night period. There were few adverse events, no serious adverse events, or clinically relevant treatment differences in vital signs, laboratory values, or electrocardiogram. Esmirtazapine doses of 1.5 to 4.5 mg/day significantly improved quantity and quality of sleep and were generally well tolerated, with no evidence of safety concerns or consistent pattern of residual effects.