You Are Feeling Very Sleepy

Today Somaxon announced more positive results for its Phase III insomnia drug low-dose doxepin (Silenor). This trial--a test of the drug in elderly patients with primary sleep maintenance insomnia (trouble staying asleep) was the third Silenor Phase III to read out and added more positive data to boost Somaxon's prospects. The results of the final Phase III for Silenor should be released in December.

Insomnia is a massive market and one that remains responsive to old-school boots-on-the-ground promotion and DTC-driven consumer awareness. Market growth has been largely fueld by Sanofi-Aventis' controlled-release zolpidem (Ambien) and to a lesser extent to Takeda's rozerem (Ramelton) and Sepracor's eszopiclone (Lunesta).

But it's also a space where Big Pharma thinks there's room for improvement--and isn't afraid to spend for a shot at the market. Pfizer bought into Neurocrine's indiplon in 2002 and the drug was widely expected to give Ambien a run for its money--but Pfizer wound up giving up on indiplon when the FDA raised questions about its higher, extended-release doses that basically sidelined the drug.

Somaxon hopes that Silenor can provide physicians and patients with the best of both worlds: GABA acting drugs like Ambien, Lunesta and indiplon are the most effective drugs on the market--but are so-called Schedule IV controlled substances according to the DEA, and thus are potentially addictive. Rozerem is not scheduled, but so far such melatonin agonists have not shown the same efficacy as GABA acting drugs.

If Silenor, an H1 receptor antagonist (and available as a generic antidepressant at higher doses), can demonstrate GABA-like efficacy and steer clear of DEA scheduling Big Pharma partners should be very receptive.