Abstract

OBJECTIVE:

To evaluate the efficacy and tolerability of immediate release indiplon capsules in patients with chronic insomnia using an "as-needed" dosing strategy in response to difficulty falling back to sleep following a middle of the night, nocturnal awakening.

METHODS:

Adult outpatients (N=264; 71% female; age, 46 years) who met DSM-IV criteria for primary insomnia, with average total sleep time (TST) < 6.5 hours and >8 nights in the past month with nocturnal awakenings, were randomized to 4 weeks of double-blind treatment with 10 mg or 20 mg indiplon capsules, or placebo. The primary endpoint was latency to sleep onset post-dosing after a middle of the night awakening (LSOpd). Secondary endpoints included patients' subjective assessment of total sleep time (sTSTpd). Next day residual effects were evaluated by a 100 mm Visual Analog Scale (VAS) rating of sleepiness.

RESULTS:

Both doses of indiplon significantly reduced LSOpd at all time-points. Compared to placebo (45.2 min), the 4-week least squares (LS) mean LSOpd was 36.5 min in the indiplon 10 mg group (P = 0.0023) and 34.4 min in the indiplon 20mg group (P < 0.0001). The 4-week LS mean sTSTpd was higher in the indiplon 10 mg group (253 min) and 20mg group (278 min) compared to placebo (229 min; P < 0.01 for both comparisons). There was no increase observed in VAS ratings of next-day sleepiness for either dose of indiplon when compared to placebo. Indiplon was well-tolerated at both doses.

CONCLUSIONS:

Patients with chronic insomnia with nocturnal awakenings achieved significant and sustained improvement in sleep parameters while utilizing an as-needed post bedtime dosing strategy with indiplon capsules. Indiplon was well-tolerated, with no self-rated, next-day residual effects.