Low-dose doxepin demonstrated efficacy in its primary endpoint, wake time during sleep (WTDS) at all doses studied (1mg, 3mg and 6mg). Low-dose doxepin also demonstrated efficacy in all secondary sleep maintenance endpoints as well as patient reported outcomes.
In all dose groups, there were no differences in adverse events and no statistically significant next day residual effects with low-dose doxepin versus placebo.
On the basis of these results, coupled with positive data from a similar dose-finding study reported earlier this year, Somaxon is preparing to evaluate low-dose doxepin in phase III trials. The company expects the first phase III trial to commence by the middle of 2005.
Doxepin HCL is a tricyclic compound currently approved for the treatment of depression, with a recommended daily dose for the treatment of depression ranging from 75mg to 300mg. Unlike all FDA approved products for the treatment of insomnia, Doxepin is not a Schedule IV controlled substance.