The Food and Drug Administration (FDA)’s Anesthetic and Analgesic Drug Products Advisory Committee (AADPAC) and Drug Safety and Risk Management Advisory Committee voted against the approval (0 ‘yes’, 27 ‘no’) of oxycodegol (formerly NKTR-181; Nektar Therapeutics) for the treatment of chronic low back pain in adult patients with pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate.

Oxycodegol is a novel, oral, long-acting selective mu opioid receptor agonist that according to the developer, is associated with fewer CNS-mediated adverse effects due to a slower rate of brain entry across the blood brain barrier. Because of these characteristics, the product had not been formulated with any abuse-deterrent ingredients. 

In meeting documents, the committees pointed out several areas of the application that required further discussion and investigation. These included the proposed indication, which limits the product for use in only chronic low back pain, and the lack of a second well-controlled efficacy study. The panelists could also not determine based on the available data whether higher doses oxycodegol could potentially result in hepatic injury, as few patients in the study received doses above the proposed range. 

Moreover, results from human abuse potential studies showed that the oral abuse potential of the investigational treatment was similar to that of oxycodone; data to assess the abuse potential of oxycodegol via intravenous or intranasal administration were found to be inadequate. 

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As a result of the vote, Nektar has decided to withdraw the New Drug Application for oxycodegol and to cease further development of the product. 

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