Pfizer and partner Acura Pharmaceuticals are celebrating after regulators in the USA gave the green light to the firms' Oxecta, an abuse-resistant form of the controversial opioid painkiller oxycodone.

The US Food and Drug Administration has approved Oxecta tablets for the management of acute and chronic moderate to severe pain where the use of an opioid analgesic is appropriate. It is the first immediate-release oxycodone medicine that applies technology designed to discourage common methods of tampering associated with opioid abuse and misuse.

That technology, known as Aversion "is a unique composition of commonly- used pharmaceutical ingredients", Pfizer says. It licensed the technology in Oxecta from Acura, which will now bank a $20 million fee following the FDA approval.

Getting that approval has been a tough task. Acura and King Pharmaceuticals, which Pfizer acquired in March, originally developed the drug (then known as Acurox) which combined oxycodone with niacin, which causes unpleasant side effects, including skin flushing. However, the FDA issued a complete response letter almost two years ago, saying it was not convinced by the potential abuse deterrent benefits and niacin was pulled from the formulation.

The agency has also stopped well short of saying that the product reduces drug abuse. The patient information states that "there is no evidence that Oxecta has a reduced abuse liability compared to immediate-release oxycodone" and users are warned to keep the drug, which "may be abused by crushing, chewing, snorting or injecting", in "a locked cabinet, drawer or medicine safe so that it will not be stolen".