Israeli drugmaker Teva Pharmaceutical has reported that a clinical trial indicated that Copaxone, the company's multiple sclerosis (MS) medication, was shown to be effective in patients who had stopped responding to Avonex, a competing drug made by Biogen Idec. The results of the study were published in the European Journal of Neurology.

The study, which involved 85 patients who had been treated with Avonex for at least 18 months, found that Copaxone reduced the annual relapse rate of MS by an additional 57 percent over Avonex.

Sales of Copaxone rose 29 percent in the first quarter of the year to $329 million, said Teva.