Full Federal Court finds Effexor™ extended release patent invalid

In a unanimous decision, the Australian Full Federal Court has found Pfizer’s Effexor™ (venlafaxine) extended release patent invalid, reversing the decision at first instance where the patent was found valid and infringed (Sigma Pharmaceuticals (Australia) Pty Ltd v Wyeth [2011] FCAFC 132 (28 October 2011).

The claims as originally lodged claimed an encapsulated extended release formulation of venlafaxine containing, among other ingredients, hydroxyl propyl methyl cellulose (HPMC) in both the core and coating of the capsules. However, the claims were subsequently amended to claim any extended release venlafaxine formulation exhibiting, in use, a desired blood plasma concentration. The claims of the extended release patent as amended were found not to be fairly based on the specification as lodged and consequently lost their priority date. As a result, the claims were held to be not novel in the light of the original specification.

This is an important decision as Australian Patent Law is extremely liberal on amendments, which may be undertaken at any time during the life of the patent. The requirement that the amended claims be “in substance disclosed” in the specification as lodged has been has been interpreted very liberally. This decision brings the Australian law more in line with the position in other jurisdictions.

Pfizer/Wyeth has signalled it will seek special leave to appeal to the High Court. It will be interesting to see whether special leave is granted.

Contact: If you have any specific enquiries about this decision, or amendments more generally, please contact Paul Jones.