Evergreening - the FDA help on making old drug get new patent

"‘Evergreening’ is the term used to describe the process by which the innovator patents trivial modifications of already-existing drugs which, in turn, extends their monopolies beyond the 20-year period granted for the original patent. It is a common practice in the pharmaceutical industry."

This is from The Economic Times. On this article it's explained how Wyeth have received a new patent to their blockbuster antibiotic Zozin that will expire in 2023 just by adding a purifying agent to its molecule.
Three companies, one from India have taken legal action against Wyeth.

"According to USFDA rules, a company is allowed to withdraw a product from the market only for reasons related to safety and efficacy. In case the product is withdrawn from the market, it is subsequently removed from the approved drugs’ reference list, and therefore no pharmaceutical company can market a generic version of this same drug.

"Zosyn is a safe and efficient drug. This is just a move to extend the patent life of the drug and prevent the entry of generic players in the market," K Raghavendra Rao, managing director, Orchid Chemicals & Pharmaceuticals, told ET."

FDA response to the Citizen's Petition (CP) filed by Orchid Chemicals in response to accusations of 'evergreening' related to Wyeth's re-formulated Zosyn (piperacillin/tazobactam):

10/30/2006

2006P-0442

Orchid Healthcare/Determine that Wyeth Pharmaceuticals, Inc. discontinued its previously-approved formulation of the Reference Listed Drug Zosyn (piperacillin and tazobactam for injection), 40.5 gram pharmacy bulk via

Interim Response 04/23/2007

It's amazing that FDA has so little concern in promoting health and a huge concern with pharmaceutical industries profit.