Sales in Teva Pharmaceutical Industries have been hit amid fears that generic competition to its multiple sclerosis blockbuster Copaxone is moving closer.

Such fears are growing after rival Mylan noted that a US court in New York has denied Teva's motion for a summary judgment finding of "no inequitable conduct" in relation to Copaxone (glatiramer acetate). The Israeli drugmaker had filed the motion in a bid to stop Mylan launching a generic version of the $3-billion-a-year drug.

The court has also set a start date of July 11 for the trial regarding Mylan's "inequitable conduct affirmative defence". The remaining issues will be tried beginning on September 7.

Teva believes the US patents on Copaxone are valid until 2014 and the Petah Tikva-headquartered firm has been fighting to protect the drug. As well as its battles with Mylan, it has repeatedly asked the US Food and Drug Administration through citizens petitions to refuse to approve any abbreviated New Drug Application for a “purported generic version” of Copaxone, including ANDAs from Momenta Pharmaceuticals and Novartis unit Sandoz.

Teva has previously spoken about “the inability to establish acceptable ‘sameness’ of the active ingredients” in the drug, due to “the complexity of the mechanism of action of a glatiramoid and the inapplicability of leveraging conventional pharmacokinetic and pharmacodynamic testing methods to demonstrate bioequivalence”.

The agency has turned down three citizens petitions so far; the last one was rejected on June 8.