Days after getting the green light in the USA for Oxecta, Pfizer's bid to get a second abuse-resistant form of the controversial opioid painkiller oxycodone approved, Remoxy, has failed.

The US Food and Drug Administration has issued Pfizer and partners Pain Therapeutics and Durect Corp with another complete response letter on the resubmission to the New Drug Application for Remoxy (oxycodone) extended-release capsules. The agency previously rejected the drug in December 2008 and it was refiled two years later by King Pharmaceuticals, which was acquired by Pfizer in February this year.

Pfizer is saying very little about why the regulator has turned down Remoxy this time, merely saying it "is working to evaluate the issues described in the CRL and plans to have further discussions with FDA around them". The firm's general manager for primary care, Olivier Brandicourt, added that "we share the concern about misuse and abuse of opioid medicines and are committed to being part of the solution".

Observers believe that the problem could be to do with the FDA's concerns about the manufacturing of Remoxy, which is oxycodone in liquid form and uses technology developed by Durect. Pfizer had previously mentioned that manufacturing was an issue.

The US government is very concerned about prescription painkiller abuse, but the rejection of Remoxy comes at the end of a week when the FDA approved Pfizer and Acura Pharmaceuticals' oxycodone-based drug Oxecta. The latter is a tablet made up of "a unique composition of commonly- used pharmaceutical ingredients" designed to discourage tampering.