In the billion dollar pain market, Endo Pharmaceuticals is fiercely defending their opiod painkiller market from generic competition, and has resorted to suing the FDA in order to delay generic competition. Endo's Opana ER, oxymorphone hydrochloride (HCl), patent expired in January 2013 and is facing generic competition from Impax Laboratories. Endo no longer markets the Impax non-tamper resistant formulation (TRF) of Opana ER after voluntarily withdrawing the product in place of their new crush resistant formulation (CRF) of Opana ER.

Endo's currently marketed CRF Opana ER has sustainable patent protection until 2029, while Impax has launched the previously marketed Opana non-TRF formulation in January 2013. This is the premise for Endo's legal action against the FDA. Endo had hoped to force a decision from the FDA (through a lawsuit) before the end of 2012, causing the FDA to block the Impax non-TRF Opana ER.

However, the FDA is constrained by its legal authority to stop generic entry of a product previously considered safe that must now be found unsafe upon introduction of a new "safer and less-abused" formulation. Endo was not able to invoke FDA action through their lawsuit, as the process to withdraw approval of a previously-approved generic is fraught with liability from the FDA's standpoint.

Another recent example is the case of AstraZeneca and their attempt to preserve their lucrative Seroquel franchise from generic erosion. Seroquel and Seroquel XR, an anti-psychotic drug prescribed to treat schizophrenia and bipolar disorder, is a multi-billion dollar drug that was responsible for approximately 18 percent of AstraZeneca's total prescription and over-the-counter revenue in 2011.

With patent expiry looming, AstraZeneca attempted to delay the inevitable launch of generic rivals by claiming that the drug's data exclusivity, which had not yet expired, protected the safety data that AstraZeneca had generated in clinical trials; therefore, a generic manufacturer could not rightfully include this side effect information on their label.