New Delhi, April 16 -- Shares of Indian pharmaceutical majors Lupin Ltd. and Zydus Lifesciences Ltd. declined sharply on April 16 after a US Federal Court ruled in favour of Astellas Pharma in a key patent litigation case. The ruling blocks the two companies from selling their generic versions of Mirabegron, the bioequivalent of Astellas' overactive bladder drug, Myrbetriq, in the United States - dealing a serious blow to their US market ambitions and triggering investor concerns.

According to the judgment, the Delaware District Court upheld the validity of Astellas Pharma's Patent 780 and dismissed the invalidity arguments presented by Lupin and Zydus. Astellas had sued both companies for allegedly infringing on its patent by planning t...