In a separate efficacy study conducted by our partner Pfizer, NGD 96-3 significantly reduced the length of time required for healthy subjects to fall asleep.

Development Status
Pfizer is currently evaluating NGD 96-3, which entered Phase I clinical studies in the first quarter of 2002. Pfizer has now completed three single dose studies exploring the safety, pharmacokinetics and preliminary efficacy of NGD 96-3 and is further assessing the safety profile and commercial potential of the compound.

In a Phase I, placebo-controlled, single rising dose study of the safety and pharmacokinetics of NGD 96-3, the compound was well-tolerated in healthy volunteers. Reports of sleepiness by treated subjects in this study were consistent with the expected action of the drug.

Pfizer has also performed a separate human efficacy study of two dose levels of NGD 96-3 in healthy volunteers using the marketed drug zolpidem (Ambien®) and placebo as controls. In that study, when compared to subjects taking a placebo, both doses of NGD 96-3 significantly reduced the latency (or length of time) required for healthy subjects to fall into an EEG-defined sleep state during the day.

To further assess the safety profile of NGD 96-3, Pfizer has also conducted an additional single dose study in healthy volunteers. Given the broad patient population eligible for treatment and the availability of existing therapies, assessing the safety profile is a critical step in the development of drugs for the treatment of insomnia.

Neurogen and Pfizer are currently continuing discussions to explore various options to advance the clinical development of NGD 96-3.

Neurogen announced on December 20, 2004 that Phase I human testing had commenced with our leading proprietary drug candidate for insomnia, NG2-73.