A US Court of Appeals has ruled that Dr Reddy’s Laboratories Ltd infringed on the patent of insomnia drug Lunesta of Sunovion Pharmaceuticals.

It also quashed an earlier judgment given by a New Jersey Court on non-infringement by the Hyderabad-based pharma major in the dispute which dates back to 2009.

The case was filed against about 10 generics companies, including Dr Reddy's, after they filed Abbreviated New Drug Applications (ANDAs) for generic versions of Lunesta.

Dr Reddy’s filed its ANDA with the US Food and Drug Administration in December 2008 seeking approval for generic eszopiclone products with some specifications which was later contested.

Early this year, the New Jersey federal judge observed that Dr Reddy's didn't infringe the patent of the drug belonging to Sunovion, finding that the Indian drug maker's proposed generic version of the sleep aid is chemically different.

Lunesta (eszopiclone) is a blockbuster drug of Sunovion, an arm of Dainippon Sumitomo Pharma.

It generated $136 million revenues in North America and Chinese markets in the April-June quarter of the current fiscal.

When contacted a spokesperson of Dr Reddy’s refused to comment on the implications of the judgment for the company.

Dr Reddy’s scrip was down 1.81 per cent on Friday on the BSE to end at Rs 2,411.40.