Orexigen Therapeutics, Inc. presented data showing successfully achieved key objectives in two phase I clinical trials of Contrave(R) (naltrexone SR / bupropion SR).

The key objectives - slowing the drug’s entry into the bloodstream (Tmax) and reduction of peak concentration in the blood (Cmax) to improve tolerability of the drug - were achieved in two phase I clinical trials.

Relative bioavailability was assessed in 40 patients randomized to naltrexone SR 40 mg or naltrexone immediate release (IR) 36 mg in a single dose. Analysis indicated that SR formulation showed lower Cmax and Tmax but comparable area under the curve (AUC) to the IR formulation.

Further, to evaluate apparent improvements in tolerability associated with naltrexone SR, pooled 24 week data from the Phase II NB-201 trial was compared with the 24 week blinded data from a series of four Phase III trials, consisting of nearly 4,000 patients, all employing naltrexone SR. The Phase III trials all had varying designs, doses and patient populations; and discontinuation due to adverse event rates associated with them ranged from 13.8% to 22.8%.

Compared to the Phase II trial experience, lower rates of nausea were found in all four pooled Phase III trials. Further, in study NB-301, the trial with dosing most similar to the Phase II NB- 201 trial, nausea, headache, or dizziness were all less frequent than in the prior Phase II trial, as was the overall rate of early discontinuation due to any adverse event (13.8% versus 16.0%).

Obesity is a disorder which afflicts more than 75 million Americans. The company expects to receive data from the first Contrave(R) Phase III trials in January of 2009 and the remaining three trials by the middle of 2010.

Results from this series of investigations have been selected for presentation at The Obesity Society Annual Scientific Meeting.

Source: Orexigen Therapeutics, Inc.