Ranbaxy laboratories welcomed a ruling by a US district court that said the company's generic version of anti-viral drug Valcyte did not infringe Swiss pharma firm Roche's patent.

"We welcome the positive development," a Ranbaxy spokesperson said.

According to reports, the District Court of New Jersey has ruled that Ranbaxy's generic version did not infringe Roche's patented crystalline valganciclovir, the active ingredient in anti-viral drug Valcyte. The court, however, held Roche's patent on the product as valid.

Ranbaxy had filed an Abbreviated New Drug Application (ANDA) on amorphous form of valganciclovir with the US Food and Drug Administration (FDA) in 2006. This was challenged by Roche saying the amorphous form of valganciclovir would change to crystalline form and, thus, will infringe the patent.

The Ranbaxy spokesperson declined to comment on the company's marketing plans after the ruling of the court.