US firm sues Cadila in patent row

Three Rivers Pharmaceuticals, a US-based speciality drug manufacturer, has sued Zydus Cadila (Cadila Healthcare) and its US subsidiary Zydus Pharmaceuticals (USA) for infringing on the former's patent on a process for manufacturing an anti-viral drug Ribavirin used in the treatment of Hepatitis C.

Three Rivers Pharma has alleged that Zydus Cadila infringed on its patent on an improved process for manufacturing Ribavirin pellets using wet granulation.

The lawsuit was filed in the district court of Virginia about a month ago to prevent Zydus Cadila from making, selling or importing finished dosage forms of ribavirin in the United States.

Ribasphere, Three Rivers' Ribavirin drug, was approved by the US Food and Drug Administration in April 2004. Ribavirine is an old-generation molecule used in the treatment of Hepatitis C as a combination therapy with drugs such as Roche's Pegasys.

Zydus Cadila declined to comment on the development. It also declined to reveal the abbreviated new drug applications (ANDA) with a Para IV certification filed in the US.

According to the US rules, ANDAs with Para IV certifications are a challenge on an innovator's drug patent. The challenge has to be notified to the innovator company, which in turn has to sue the challenger within 45 days of the notice.

"We expected Zydus to respect our intellectual property without the need for litigation. But they refused to provide us with any meaningful assurance that it had not used and would not use our patented process," Donald Kerrish, president and CEO of Three Rivers, stated on the company's website.

Zydus Cadila has around 27 approvals since the commencement of filing process with the US Food and Drug Administration (FDA) in 2003-04, and has filed over 60 ANDAs and 51 drug master files (DMFs). However, most of its ANDAs were for patent non-infringing processes.

Three Rivers Pharmaceuticals is a privately held company based in Cranberry Township, Pennsylvania, and focuses on specialised therapies.