GlaxoSmithKline has filed a lawsuit against Dr Reddy's Laboratories in the US District Court of New Jersey alleging patent infringement of its branded drug Zofran. According to a press release issued by Dr Reddy's, the Hyderabad-based bulk drug manufacturing company, it had filed an Abbreviated New Drug Application (ANDA) for Ondansetron HCl tablets equivalent to 16mg base, with a paragraph IV certification on the four Orange Book patents.

Ondansetron HCl is the generic version of GlaxoSmithKline's Zofran. The 16mg dose is not currently marketed by GlaxoSmithKline. While filing the lawsuit, GlaxoSmithKline alleged patent infringement on three of the four Orange Book patents as well as a process patent not listed in the Orange Book.

Zofran is indicated for the prevention of post-operative nausea and vomiting, cancer chemotherapy induced nausea and vomiting and radiotherapy induced nausea and vomiting. The brand has annual sales in the United States of approximately $900 million for all dosage forms and strengths.