Effexor Patent Denied Priority Date


Sigma Pharmaceuticals (Australia) Pty Ltd v Wyeth [2011] FCAFC 132


Applicants should always ensure that the specification currently on file tracks developments. For example, when it becomes clear that a preferred formulation is no longer specifically described, action should be taken immediately so as not to lose the ability to protect that formulation. Failure to do so could result in the public release of the formulation before an amendment or a divisional is filed, leading to disastrous consequences, such as the inability to enforce the patent.


This is an appeal from the case before a single judge of the Federal Court, reported by me on 16 November 2010.

This case is complex, but raises some important points in connection with priority dates. In particular it provides a good example of how the Full Federal Court allocates effective dates to material in a patent document.

Here, a provisional patent application was filed on 25 March 1996, a grandparent application on 20 March 1997, a parent application on 10 October 2000 and a child application on 30 October 2003. The child application was amended on 20 December 2006, and, when granted to Wyeth was used as the basis of an action for infringement against Sigma.

The 2006 amendment introduced material that was not specifically described in the specification prior to the amendment. It was necessary for Wyeth to show that the specification, as amended, did not "travel beyond the disclosure" in the child application in order for infringement to be found. In other words, the parent application had to provide basis for the claims subsequent to amendment so that those claims could capture the alleged infringement.

Wyeth attempted to argue that a method involving the use of an encapsulated extended release formulation as opposed to the formulation itself was sufficient to cover the use of such a formulation in the form of a hydrogel tablet formulation. However, the provisional specification made no mention of such a formulation per se. Indeed, the provisional described how attempts to produce such tablets by hydrogel technology were unsuccessful.

The problem prior to the invention defined in the provisional was that instant release formulations in multiple daily doses gave unwanted side-effects. Wyeth's case was that the solution it invented was the appreciation that the answer to the problem was a formulation that provided a therapeutic level over a 24-hour period and an ER formulation with the prescribed plasma profile. But the court determined that the invention was a successful formulation, overcoming the lack of utility of previous unsuccessful formulations, including those of hydrogel tablet technology. The related method claims therefore included the formulation, as described in the associated description, as an essential integer, making the method dependent on the formulation.

The following statement by Bennett J. is particularly apposite: "A skilled reader reading the whole of the Priority Document would be left in no doubt that the methods ... refer to the use of an encapsulated, ER formulation.  In order to know how to work the method of those claims, the reader would have to turn to the body of the specification which provides that formulation.  Otherwise, claims ... would be to a goal and not to a patentable invention that is a manner of manufacture and useful and where sufficient instruction is given to enable the skilled worker to work the claimed method."

For us practitioners, heed should be taken of the following:

 "To ascertain the nature of the Amended Patent, I am assisted by the way in which the patentee describes:

  • the invention;
  • what is said about the problem faced by the patentee; and
  • the advance over matters previously known."

The court said that, properly construed, the claims of the provisional could not encompass a hydrogel tablet formulation. The claims must be read as part of the specification as a whole; if there were any ambiguity or uncertainty on the part of the skilled reader as to the scope of the formulation described in the claims, a reading of the specification would make it clear that it did not extend to hydrogel tablet formulations.


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