Results from two phase II gaboxadol proof-of-concept studies presented at the American Psychiatric Association Meeting on May 24 in Toronto, Canada, found that the drug gaboxadol dependently increased time spent in deep, or slow-wave, sleep. Both studies also showed that gaboxadol was well tolerated with no next-day residual effects.
Gaboxadol is currently in clinical development for the treatment of insomnia. If approved, gaboxadol will be a first-in-class selective extrasynaptic GABAA (gamma-aminobutyric acid type A) receptor agonist (abbreviated as SEGA) with a mechanism unique from current treatments, including benzodiazepine receptor agonists, such as indiplon, eszopiclone, temazepam, and zolpidem.
The results of the two studies reported the following conclusions:
• Acute administration of gaboxadol improves sleep maintenance and enhances slow wave sleep in a dose dependent manner in adult patients with primary insomnia. Effects on sleep induction need further evaluation considering the lack of significant effect of the reference drug zolpidem. Gaboxadol 10mg and 20mg doses were not associated with next day residual effects. Gaboxadol was generally well tolerated although gaboxadol showed a dose dependent increase in incidence and severity of adverse events.
• Gaboxadol doses of 10mg and 15mg improved sleep as reported by polysomnographic tests and self-reported efficacy measures in the study’s model of transient insomnia. In contrast to zolpidem, gaboxadol enhanced low frequency components of sleep electroencephalogram (EEG) results. There were no next-day residual effects and the treatments were well tolerated.