Teva Pharmaceuticals and Endo Pharmaceutical Holdings Inc will halt sales of generic OxyContin (oxycodone) by the end of this year under a settlement agreement resolving patent disputes with Purdue Pharma. Under the terms of the agreement, the generic companies will not be held liable for any past or future infringement of Purdue's patents for the painkiller.

The settlements mark the latest in a series of legal twists that began with a June 2005 ruling that several OxyContin patents were unenforceable because of misrepresentations by the patentee. That decision opened the door for the marketing of generic versions of the drug, but that opportunity evaporated when the courts reconsidered the case and sent the case back to trial for further review.