Oxycodone alleviates pain ... and weakens the Spirit

Date: 2013-08-14
Author: James Cherry

Spirit Pharmaceuticals Pty Ltd v Mundipharma Pty Ltd [2013] FCA 658

This recent decision by the Federal Court confirms that patents claiming new pharmaceutical formulations of known active agents may be eligible for an extension of term.

Mundipharma owns Australian Patent No. 657027 which relates to a controlled release oxycodone formulation marketed as “OxyContin”. The patent’s expiry date was extended in 2000 from 25 November 2012 to 23 July 2014.

In seeking to market its own generic version of OxyContin, Spirit Pharmaceuticals challenged the extension of the patent’s term on the basis that it was not validly granted because, inter alia, the controlled release oxycodone formulation claimed is not a “pharmaceutical substance per se” as required under s 70(2)(a) of the Patents Act 1990 (the Act).

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 a physico-chemical interaction, with a human physiological system; …"

Spirit Pharmaceuticals argued that it is the application of oxycodone per se, not the controlled release formulation comprising oxycodone in combination with various excipients, whose application involves an interaction with a human physiological system.

However, the Federal Court dismissed this argument, reasoning that the application of the controlled release oxycodone formulation involves two separate interactions within a human physiological system – firstly, the interaction within the gastrointestinal tract during which the formulation breaks down to controllably release the oxycodone for absorption into the blood plasma, and secondly, the nerve interaction during which the oxycodone in the blood plasma interacts with nerve cell receptors in the spinal chord and brain to alleviate pain.

Accordingly, the Federal Court concluded that the controlled release oxycodone formulation is a “pharmaceutical substance per se” and hence the extension of the patent’s term was validly granted. Spirit Pharmaceuticals have appealed this decision.

We will likely learn the outcome of the appeal in mid- to late-2014. But, in the meantime at least, this decision is a pertinent reminder that “pharmaceutical substance per se” is not to be interpreted as being limited to an active agent.