Low-dose sublingual zolpidem tartrate is associated with dose-related improvement in sleep onset and duration in insomnia characterized by middle-of-the-night (MOTN) awakenings

Study Objectives: To evaluate the efficacy and safety of low-dose, sublingual zolpidem tartrate when taken during a scheduled middle-of-the-night (MOTN) awakening in subjects with insomnia characterized by difficulty returning to sleep following MOTN awakenings. Design: Randomized, double-blind, placebo-controlled, 3-way crossover study. Methods: Each treatment period consisted of 2 consecutive nights of dosing separated by a washout of 5 to 12 days. Subjects were awakened 4 h after lights out, dosed with sublingual zolpidem tartrate (3.5 mg or 1.75 mg) or placebo, kept awake for 30 min, and then returned to bed for an additional 4 h. Sleep parameters were assessed by polysomnography (PSG) and post-sleep questionnaires. Setting: Five sleep laboratories. Participants: Adults (24 males, 58 females, mean age 45.9 y) with a diagnosis of DSM-IV primary insomnia and a history of prolonged MOTN awakenings. Baseline difficulties with MOTN awakenings were confirmed by a 10-day screening sleep diary and PSG screening. Results: Low-dose sublingual zolpidem tartrate demonstrated significant dose-related decreases in latency to persistent sleep and total sleep time (P < 0.001) compared to placebo after MOTN dosing. All subject reports paralleled PSG observations. Neither dose showed next-morning impairment on the DSST or ratings of sleepiness. The 3.5-mg dose produced improvements in reports of sleep quality (P < 0.001), ability to function, and level of refreshed sleep (P < 0.05 for both dosages) compared to placebo. Sublingual zolpidem tartrate lozenges were generally safe and well tolerated. Conclusions: Low-dose sublingual zolpidem tartrate may be suitable for treatment of patients who have difficulty resuming sleep after MOTN awakenings.