King Pharmaceuticals and Acura are facing a deal in getting their painkiller Acurox onto the market after regulators in the USA issued a letter expressing concerns about the drug's abuse-deterrent properties.

The US Food and Drug Administration has issued a complete response letter regarding the New Drug Application for Acurox (oxycodone/niacin), an immediate release product intended for the relief of moderate-to-severe pain. King and Acura said that the letter raises issues “regarding the potential abuse deterrent benefits” of the drug, but believe that at this stage “they can respond to the issues raised without conducting any additional studies”. The companies added that they plan to meet with the FDA “following submission of their response”.

The FDA's response comes as no surprise as the comments it contains had already been sent to the companies in preliminary notes. Nevertheless it is a blow to King and Acura, especially as earlier this week, an agency advisory committee recommended banning drugs containing acetaminophen, such as Abbott Laboratories' Vicodin (acetaminophen/hydrocodone) and Endo Pharmaceuticals’ (acetaminophen/oxycodone), over the risk of potential liver damage.

Hopes were high for Acurox seeing as it contains niacin, which causes unpleasant side effects, including skin flushing, which may help deter abuse. The fact that the FDA is still concerned about such benefits, however, worried investors and both firms suffered share price declines.