The US patent of anti-psychotic medication Abilify has been upheld by a federal court, preventing the sale of generic versions in the country until April 2015.
The ruling will come as a blow to Teva Pharmaceuticals and Novartis AG;s Sandoz unit, who sought to market generic versions of Abilify.
US district judge Mary Cooper said that generic manufacturers had failed to provide convincing evidence that the patent should be invalidated, adding that developer Otsuka is entitled to a permanent injunction against infringement of its patent.
The blockbuster medication has proved to be one of the largest revenue sources for Bristol-Myers Squibb, who jointly market Abilify with Otsuka. Sales totalled $1.86bn in the first nine months of 2010.