Dublin, Ireland-based speciality pharma Endo International is withdrawing its US application to add abuse deterrent labelling to its long-acting opioid Opana ER.

The company said the move follows discussions with the US Food and Drug Administration, and that it now plans to continue collecting and analysing epidemiological data relating to its drug before taking another run at approval.

"We anticipate the generation of additional data and we will seek collaboration with FDA to appropriately advance Opana ER," said Sue Hall, chief scientific officer and global head of R&D and Quality at Endo.

"We believe in the ability of Opana ER to continue making a difference in the lives of appropriate patients and remain committed to safely and effectively addressing the needs of the pain patient community".

The drug is already on the US market for the management of pain severe enough to require daily, around-the-clock opioid treatment and for which alternative treatment options are inadequate. But sales have taken a downturn, slipping 11 percent in the second quarter compared to a year ago.

The supplemental New Drug Application submission included studies designed to evaluate the abuse deterrence of the formulation, produced with INTAC Technology that increases tablet hardness using a high molecular weight polymer.