In recent years, the Federal Circuit has reviewed a number of “second generation” patents that are directed toward new discoveries related to previously known, and often commercially viable, drugs. These inventions include new salt forms or stereoisomers, new diseases to be treated and improved drug formulations. Provided they represent improvements within fields of study that are frequently very crowded, these developments often result in patents that provide additional protection for drugs that are covered by soon-to-expire, “first generation” patents.
A tally of court of appeals cases in which these patents are scrutinized, however, shows many being held as invalid. In these decisions, the court regularly views these “discoveries” as obvious variations of what would have been known to one of skill in the art. See, e.g., Pfizer v. Apotex (2007), Aventis v. Lupin (2007), In re Kao (2011), and Tyco v. Mutual Pharma (2011). In spite of this trend, two recent court of appeals cases show that improvement patents are not automatically dismissed by the court as lacking obviousness.
When filing a New Drug Application for this formulation (Fortical), Unigene demonstrated bioequivalence with Miacalcin, another formulation comprising salmon calcitonin. The Fortical and Miacalcin formulations use different components to act as both an absorption enhancer and a surfactant—Fortical relies on 20 mM citric acid for this function, while Miacalcin uses benzalkonium chloride (BZK).
Referring to the Miacalcin formulation as the “reference composition,” the court held that one of skill in the art would have had no motivation to replace BZK with 20 mM citric acid. In its review of certain secondary references, the court noted that one U.S. patent disclosed solid, not liquid, oral dosage forms, as well as concentrations of citric acid that were much higher than what was claimed. Another publication disclosed the use of citric acid in liquid nasal sprays, but as a “pH adjuster or buffer,” not a surfactant or preservative. The court also proposed that yet another U.S. patent taught away from the use of citric acid, as it disclosed a study in which citric acid yielded “discouraging” test results.