DENVER – Gaboxadol significantly improved sleep initiation and maintenance while also increasing time spent in restorative slow-wave sleep in an acute phase II placebo-controlled trial, Stephen Deacon, Ph.D., reported at the annual meeting of the Associated Professional Sleep Societies.
Based upon these and other encouraging findings, gaboxadol–first in a novel class of sleep medications known as selective extrasynaptic γ-aminobutyric acid-A agonists, or SEGAs–is now in larger definitive phase III clinical trials, added Dr. Deacon, head of clinical development for sleep disorders at H. Lundbeck, Ltd., Milton Keynes, England.
The benzodiazepine receptor agonists, a class of drugs widely prescribed for insomnia, also target γ-aminobutyric acid (GABA) receptors; however, their action is confined to synaptic GABA receptors. The extrasynaptic GABA-A receptors modulated by gaboxadol are richly present in parts of the brain thought to be important in sleep regulation, he explained.
Dr. Deacon reported on 26 adults with primary insomnia who participated in a double-blind triple-crossover polysomnographic study. They received either 5 or 15 mg of gaboxadol or placebo half an hour before bedtime on two consecutive nights during three sessions separated by 1–2 weeks.
The low- and higher-dose gaboxadol reduced total nightly time awake by 15% and 16%, respectively, compared with the mean 68.5 minutes with placebo. Each of the two dosages of gaboxadol improved total sleep time by 3% over the mean 409 minutes with placebo.
In addition, gaboxadol at 15 mg increased the amount of time patients spent in slow-wave sleep by 21% over the mean 94 minutes with placebo. The mean 30-minute latency to persistent sleep on placebo decreased by 21% on nights when patients took 15 mg of the investigational SEGA.
Both doses of gaboxadol were well tolerated. There were no next-day residual drug effects.
The study was sponsored by H. Lundbeck, which is partnering with Merck & Co. to develop and market gaboxadol in the United States and Japan.