Authorities worry about abuse potential as OxyContin patent expires

NEW YORK — Purdue Pharma's patent for OxyContin expired Tuesday, opening up the opioid painkiller to generic competition, but authorities have raised concerns about what they call the potential for generic versions to be abused.

Purdue's branded version of the drug, known generically as oxycodone extended-release tablets, contains abuse-deterrent mechanisms designed to thwart crushing the tablets into a powder, which abusers of the drug usually do in order to snort or inject it; the company introduced the abuse-deterrent version of the drug in August 2010. But there are concerns about whether generic versions of the drug will include such features because current Food and Drug Administration regulations don't require them.

According to IMS Health, OxyContin has annual U.S. sales of about $3 billion, and companies that have lined up to market generic versions include Teva Pharmaceutical Industries and Endo Pharmaceuticals, though Endo's own branded opioid painkiller, Opana ER (oxymorphone), also includes anti-tampering properties.

The FDA approved OxyContin in 1995, and it became a drug of choice for drug abusers and a frequent target in pharmacy-related crime. The agency approved a version with abuse-deterrent features in April 2010, and Purdue stopped shipping the original version four months later, but authorities have warned that the reformulated version is still susceptible to abuse and misuse despite the reduced risk. According to the Substance Abuse and Mental Health Services Administration, about 500,000 people ages 12 years and older became abusers of the drug in 2008.

In a letter to Food and Drug Administration commissioner Margaret Hamburg last month, attorneys general of 46 states and the territories of Puerto Rico and Guam, writing on behalf of the National Association of Attorneys General, wrote that people who abuse opioid painkillers are turning to those that lack tamper-resistant features, and the attorneys general expressed concerns that future generic versions of OxyContin may not include those features unless the FDA requires them. Sen. Charles Schumer, D-N.Y., also has expressed concern about the potential for generic versions of OxyContin to be abused.

But in early January, the FDA released draft guidance for drug companies aimed to encourage abuse-deterrent painkillers. The guidance explains the agency's current thinking about the studies it said companies should conduct to demonstrate that a given formulation of an opioid drug has abuse-deterrent properties, how the agency would evaluate the studies and what labeling claims may be approved. "The agency believes that new technologies that are effective to reduce abuse are very important for us to incentivize," FDA Center for Drug Evaluation and Research deputy director for regulatory programs Warren Throckmorton said in a conference call with reporters at the time.