The patent in question claims a controlled release formulation of the opioid oxycodone, which is a well-known pain relief drug.
The formulation, marketed as “OxyContin”, controls the release of the oxycodone into the patient’s blood plasma over a period of time.
This decision is one of a series of recent decisions addressing whether a patent claiming a new formulation of a known drug is eligible for a patent term extension.
Extension of term of standard patents relating to pharmaceutical substances
Under the Australian Patents Act 1990 certain pharmaceutical patents can be granted a patent term extension if specific criteria are met. In this case, the criterion under consideration was whether or not the claims defined “one or more pharmaceutical substances per se”
Spirit Pharmaceuticals contended the patent term extension as they believe that the patent does not disclose a pharmaceutical substance per se.
A pharmaceutical substance is defined in the act as a substance (including a mixture or compound of substances) for therapeutic use whose application (or one of whose applications) involves:
(a) a chemical interaction, or physicochemical interaction, with a human physiological system; or
(b) action on an infectious agent, or on a toxin or other poison, in a human body;
but does not include a substance that is solely for use in in vitro diagnosis or in vitro testing.
The Court’s conclusion as to the meaning of the term “pharmaceutical substance per se”
The court considered that the use of the expression of “pharmaceutical substance” in the Act when read with its definition meant a substance, including a mixture, that involves a chemical interaction with a human physiological system to achieve the “therapeutic use”.
- The court rejected Spirit’s submission that the construction of the expression “pharmaceutical substance per se” meant only the active pharmaceutical ingredient, in this case oxycodone.
The court considered how the controlled release formulation OxyContin worked when the formulation is taken orally and ingested. In particular, the Court considered that there are at least two chemical interactions in the human physiological system for the OxyContin formulation to have the therapeutic use.
The first is a gastro-intestinal (GI) tract interaction where the formulation breaks down in a way that gradually causes the oxycodone in the mixture to leach into the GI tract.
Once released into the GI tract, the oxycodone passes into the bloodstream and eventually leads to the second interaction, the nerve interaction to relieve pain.
The court decided that the patent term extension was valid.
This decision highlights that patents claiming new formulations of known drugs can be eligible for a patent term extension in certain circumstances.
Based on this decision, it appears that to be considered a “pharmaceutical substance per se” the formulation needs to result in a new chemical interaction, or physicochemical interaction, with the patient resulting in a difference compared to known formulations of the drug.
However, it appears from the decision that a merely formulating a known drug in a new way would not be enough.
This decision has now been appealed to the Full Court of the Federal Court.