June 21, 2006

Merck sleep drug shows promise in small studies

By Bill Berkrot

NEW YORK -- An experimental insomnia drug being developed by Merck & Co. and Danish drug maker H. Lundbeck A/S showed promise in helping patients achieve deep sleep in small mid-stage clinical studies, the companies said on Wednesday.

Statistically significant increases in deep sleep were seen with gaboxadol at all four tested doses compared to a placebo, but the drug appeared to be more effective at the higher 10 milligram, 15 mg, and 20 mg than at the lowest 5 mg dose, researchers said.

"What's most interesting is we have consistent effects on slow-wave sleep with gaboxadol. That is something unlike all the other treatments currently on the market," Stephen Deacon, head of clinical development, sleep disorders, for Lundbeck and a lead investigator of one of the studies, said in an interview.

Slow-wave activity is associated with deep and/or restorative sleep.

"The higher the dose the more slow-wave sleep you get," added Deacon, who presented the data at the Associated Professional Sleep Societies meeting in Salt Lake City, Utah.

He cautioned that the effectiveness of the drug and the data from these studies needs to be confirmed in more, much larger trials.

Gaboxadol is already undergoing large, late-stage clinical trials and Merck said it expects to file an application seeking approval from U.S. regulators in the first quarter of 2007.


Separate two-night studies were conducted to treat patients with primary and transient insomnia. The drug, which represents a new class of sleep medicines, was better than placebo on both types of patients.

Transient insomnia is short-term sleep problems of the type associated with jet lag. Primary, or chronic, insomnia involves trouble with sleep initiation or sleep maintenance and interferes with daytime functioning.

In one 40-patient primary insomnia study, those who received 20 mg of gaboxadol recorded a 54 percent increase in slow-wave activity compared to a placebo, while 10 mg patients saw a 33 percent increase.

In a second primary insomnia study with 26 patients, slow-wave activity increased 21 percent at 15 mg of gaboxadol versus placebo but there was no significant effect at 5 mg.

The 109-patient transient insomnia studies looked at time it took to fall asleep and overall sleep time as measured both by instruments and patient self reporting.

Patients taking 10 mg and 15 mg of gaboxadol reported an average of 29.2 minutes and 32.2 minutes to fall asleep compared with an average of 44.4 minutes in the placebo group. The 5 mg dose was not effective.

However, all three doses improved patient-reported overall sleep time by a statistically significant 6 percent at 5 mg, 7 percent at 10 mg and 9 percent at 15 mg. At the highest dose, patients slept for an average of 426.8 minutes compared with 391.2 minutes for the placebo group.

All three doses also achieved statistical significance compared to placebo in total sleep time as measured by polysomnographic instruments.

There were no serious adverse events and no consistent next-day residual effects seen with gaboxadol. Residual effects, or hangover-like symptoms, have been seen with some sleep aids currently on the market.