OBJECTIVE: OX22 is zolpidem formulated for sublingual administration. The primary objective of the present study was to evaluate the efficacy of single doses of sublingual zolpidem (5 and 10mg) versus oral zolpidem (10mg), with regard to latency to persistent sleep (LPS), in a post-nap model of insomnia.

METHODS: Twenty-one healthy volunteers included in this study were recorded by polysomnography during 2 consecutive nights and, on the day in between, during a 2h nap. Eighteen out of these 21 subjects were finally analyzed. Treatment was randomly administered before the second recording night to subjects demonstrating at least 30min of sleep during the nap recording.

RESULTS: Contrast analyses show that 10mg OX22 significantly shortened LPS compared to oral zolpidem administration of 10mg (12.8+/-9.9 and 18.4+/-11.3min, respectively; p<.05). No treatment effects could be evidenced on total sleep time, time awake after sleep onset and sleep architecture parameters for OX22 compared to oral zolpidem. All treatments were well tolerated and did not induce next-day residual effects.

CONCLUSION: The present results show that OX22, a sublingual formulation of zolpidem, has a significant earlier sleep initiation as compared to an equivalent dose of oral zolpidem in healthy volunteers in a post-nap model of insomnia.