Neurogen Corporation announced that Merck & Co. Inc., through an affiliate, has begun a phase II proof of concept clinical trial to study MK-2295 (NGD-8243) for the treatment of post-operative dental pain. MK-2295 is one of several drug candidates Merck is developing as part of its exclusive worldwide alliance with Neurogen to develop oral medicines targeting the VR1 receptor.

The initiation of the phase II study triggers a $3 million milestone payment from Merck to Neurogen. Through the alliance, Neurogen and Merck have generated a broad spectrum of chemical intellectual property and several leading drug candidates, including MK-2295. The companies will select the most promising of the lead candidates for further development once proof-of-concept has been established.

The phase II proof-of-concept trial is a randomized, double-blind, placebo controlled study, designed to determine the efficacy of MK-2295 in the treatment of post-operative dental pain. In single ascending dose phase I trials conducted to date, MK-2295 was potent and active at the VR1 target and generally well tolerated with no serious adverse events. Multiple ascending dose studies are ongoing.

"VR1 receptor antagonists have the potential to alleviate pain, including pain from inflammatory states," said William H. Koster, PhD, president and CEO of Neurogen. "We look forward to learning more about this promising new mechanism as clinical development continues."


Neurogen's exclusive worldwide alliance with Merck to research, develop and commercialize next-generation drugs for the treatment of pain and other disorders began in January 2004. The partnership enabled Merck and Neurogen to pool drug candidates targeting the type 1 vanilloid receptor (VR1), a key integrator of pain signals in the nervous system, and combine their ongoing VR1 programs to form a global research and development collaboration.