Teva Pharmaceutical Industries has received a major boost after a US court backed the Israeli firm in a patent dispute concerning its multiple sclerosis blockbuster Copaxone.

A court in New York has found in favour of Teva in the company’s patent infringement lawsuit against Momenta Pharmaceuticals and Novartis' Sandoz unit, plus Mylan and Natco Pharmaceuticals. Teva had filed suit for infringement of multiple patents covering the chemical composition of Copaxone (glatiramer acetate), plus methods of using the product and processes for manufacturing.

The judge rejected Momenta/Sandoz and Mylan/Natco’s claims that the Copaxone patents are invalid and unenforceable and found that the those firms' generic versions infringe those patents. Teva noted that this ruling should prevent the US Food and Drug Administration from approving copycat versions until May 2014, and believes they are unlikely to appear before September 2015 when the process patent expires.

News of the case sent Teva shares up nearly 12% now it looks as though Copaxone will continue being a cash cow for a few more years. First-quarter sales reached $909 million, up 8%, and last month Teva said turnover from the drug should come in at around $3.80 billion this year.

Jeremy Levin, Teva’s chief executive, noted that the firm is confident Copaxone "will remain a proprietary, global market-leading product…given the strength of its intellectual property rights". Earlier this month, the firm unveiled promising Phase III data on a longer-acting version of the drug.

However this may not be the end of the story as Momenta said it intends to appeal as "we remain confident in our legal position". Chief executive Craig Wheeler said "we are disappointed that the court determined that Teva's patents were valid and infringed, and we look forward to reading the full opinion to understand its reasoning".