Neurogen suspends adipiplon in insomnia

US drug developer Neurogen says that, as planned, it commenced a Phase II/III clinical trial in chronic insomnia patients with its insomnia agent, adipiplon and that, based upon reports from initial dosing of a higher-than-anticipated rate of unwanted next day effects, the company has suspended dosing in the study. Neurogen believes that the bilayer tablet formulation of adipiplon being used in the study may not be performing as expected.

The company plans additional investigation of the bilayer tablet before proceeding further. In prior studies Neurogen has simultaneously administered various doses of both immediate- and controlled-release forms of adipiplon. The current study is the first in which it has used the two forms laminated together into one bilayer tablet. In previous testing in over 600 subjects, adipiplon has been well tolerated.

"We are disappointed by this setback," said Stephen Davis, Neurogen's chief executive. "We do not yet know whether there is a path forward with lower doses of the existing formulation or whether further formulation development would be required. Until we further assess the situation and determine whether there is a path forward we can and should take, we will carefully limit our resource commitments to this program. We remain focused on our ongoing Phase II studies with our dopamine partial agonist, aplindore, in Parkinson's disease and in restless legs syndrome," Mr Davis continued.