Mumbai, June 19 -- In late May, Dr. Reddy's Laboratories, a pharmaceutical company from Hyderabad, sprang a surprise. It filed a patent challenge against Novo Nordisk, a Danish company, for its popular weight loss drug semaglutide.

Novo Nordisk filed for two patent applications in India-in 2006, which expired in September 2024, and another in 2007, which is set to expire in March 2026. Dr. Reddy's has challenged the second patent, contending that it lacks novelty.

Pharma companies often file follow-on patents with claims of modifications to the original compound and its derivative forms. The follow-on patents allow drug developers to extend their market monopoly and halt generic competition for longer. Generic versions are cheaper copie...