Evergreening of patents is done by

Evergreening of patents is a strategic practice, primarily in the pharmaceutical industry, used to extend the monopoly over a product beyond the initial 20-year patent term [4]. This is achieved by filing secondary patents for minor modifications, such as new formulations, delivery systems, or citing another use of the same product [4]. While the original patent on the chemical compound may expire, these secondary patents on 'new uses' or 'new forms' create a 'patent thicket' that delays the entry of affordable generic drugs [1]. In India, Section 3(d) of the Patent Act 1970 specifically restricts evergreening by requiring that new versions of known substances demonstrate significantly enhanced therapeutic efficacy to be patentable [3]. Therefore, citing a new use for an existing product is a classic method used to trigger a new patent cycle and maintain market exclusivity.

Sources

1. [4] https://en.wikipedia.org/wiki/Evergreening
2. [1] Indian Economy, Vivek Singh (7th ed. 2023-24) > Chapter 13: International Organizations > 13.8 Intellectual Property Rights (IPR) > p. 386
3. [2] https://www.congress.gov/crs-product/R46679
4. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC3680578/