Endo Pharmaceuticals Inc, a wholly owned subsidiary of Endo Pharmaceuticals Holdings Inc, has reached agreement with the US FDA as to the design of a new clinical trial to provide additional safety and efficacy data of oxymorphone extended-release tablets (oxymorphone ER) in support of the company's New Drug Application (NDA) for this developmental product, a company release said.

Endo had submitted the trial protocol to FDA under the Special Protocol Assessment (SPA) process. Under the terms of the SPA, Endo will initiate a 12-week, multi-centre, double-blinded, placebo-controlled trial of oxymorphone ER.

As previously disclosed on October 20, 2003, the FDA issued an approvable letter for Endo's oxymorphone ER NDA but had requested that Endo address certain questions and provide additional clarification and information, including some form of additional clinical trial to further confirm the safety and efficacy of this product. Also as previously announced, the FDA, following a meeting with Endo in early May, indicated its concern that the outcome of two of the three phase III efficacy trials submitted in the NDA that met their predefined primary end-points may have been favourably biased by the statistical handling of data from patients who did not complete the trials. The design of this additional clinical trial is intended to address this issue, the release says.

"We are extremely pleased that we have reached agreement with the FDA and are able to initiate this clinical trial, which we believe will complement the already successful phase III clinical trial that we believe the FDA has accepted as demonstrating efficacy in the intended patient population. Based on the duration of the trial and the number of patients to be enrolled, we believe that, assuming the data are favourable, we will be in a position to finish the study and submit the complete response to the FDA in the late third quarter or early fourth quarter of 2005," said Carol A Ammon, chairman and chief executive officer. "At that point, the FDA will have six months to act on this complete response to its October 2003 approvable letter. We look forward to working with the FDA to complete this process and bring this important new pain medication to market," he added further.

As previously disclosed on March 31, 2004, the FDA indicated that more safety and efficacy information from patients receiving repeated doses of oxymorphone immediate-release tablets (oxymorphone IR) would be required. Endo has submitted to the FDA under the SPA process its proposed protocol for a short-term repeat-dose study for oxymorphone IR.

A wholly owned subsidiary of Endo Pharmaceuticals Holdings, Endo Pharmaceuticals Inc is a fully integrated specialty pharmaceutical company with market leadership in pain management products.