Patent Term Extensions for New Pharmaceutical Formulations

The Australian Patents Act 1990 (Cth) provides a regime for extending the term of a pharmaceutical patent by up to five years beyond the standard patent term. However, to obtain an extension:

• one or more pharmaceutical substances per se must in substance be disclosed in the complete specification of the patent and, in substance, fall within the scope of the claim or claims of the patent specification; or
• one or more pharmaceutical substances when produced by a process that involves the use of recombinant DNA technology, must be so disclosed.

There have been a number of court decisions about the ambit of the term "pharmaceutical substance per se". It is clear that processes for the manufacture of a pharmaceutical substance and methods of treatment do not fall within the definition of a pharmaceutical substance per se and, therefore, patents for such inventions are incapable of extension beyond the standard patent term.

There is considerable debate, however, as to whether the term of formulation patents is capable of being extended in Australia.

The term "pharmaceutical substance" is defined in Schedule 1 of 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 physico-chemical interaction, with a human physiological system; or

(b) action on an infection agent, or on a toxin or other poison, in a human body;

(c) but does not include a substance that is solely for use in in vitro diagnosis or in vitro testing".

The term "therapeutic use" is, in turn, defined in relation to the definition of "pharmaceutical substance" as use for the purpose of:

(a) "preventing, diagnosing, curing or alleviating a disease, ailment, defect or injury in persons; or

(b) influencing, inhibiting or modifying a physiological process in persons; or

(c) testing the susceptibility of persons to a disease or ailment".^[1]

The rationale for implementing the extension of term provisions relating to pharmaceutical substances per se was to encourage investment in the research and development of new chemical entities by giving to patentees adequate compensation for the huge cost involved in bringing a new drug to market. But what of the position in respect of a new formulation of an old or known drug? Should a patent relating to a new formulation be entitled to the benefit of up to an extra five years of patent monopoly?

On 24 November 2005, the Advocate General of the European Court of Justice ("ECJ") published an opinion arising out of the refusal of the German Patent and Trade Mark Office to grant a supplementary protection certificate for a pharmaceutical product known as Gliadel ("the Gliadel case"). This product consisted of an active ingredient and a polymeric biologically degradable excipient. In Europe, a pharmaceutical patent term extension (in the form of an Supplementary Protection Certificate ("SPC")) is only available in respect of a "product" which is defined to mean:

"the active ingredient or combination of active ingredients of a medicinal product" [emphasis added].^[2]

The term "medicinal product" is defined:

"any substance or combination of substances presented for treating or preventing disease in human beings or animals and any substance or combination of substances which may be administered to human beings or animals with a view to making a medical diagnosis, or to restoring, correcting or modifying physiological functions in humans or in animals".^[3]

The essential questions that were referred to the ECJ in the Gliadel case were:

• Does the concept of "combination of active ingredients of a medicinal product" in the definition of 'product' in the relevant EU regulation mean that the components must all be active ingredients with a therapeutic effect; and
• Is there a "combination of active ingredients of a medicinal product" where one component is a known substance with a therapeutic effect for a specific indication and the other component renders possible a pharmaceutical form of the medicinal product that brings about a changed efficacy of the medicinal product for this indication'.

In the Gliadel case, the combination of the active ingredient and the particular excipient given the active ingredient entirely new properties in terms of efficacy and safety of use.

The Advocate General stated that a combination did not have to comprise two active ingredients in order to obtain an SPC but that it was permissible that there be an active, and an excipient which modulates the efficacy of the active, in other words, where a substance does not exert a pharmacological effect, but is required for the active ingredient to exert its therapeutic effect, then the combination falls within the definition of "product" and an SPC may be granted for the patent in respect of that combination.

The wording of the definition of "product" for the purposes of the EU SPC regulation can be contrasted with the definition of "pharmaceutical substance" in the Act. In the latter, there is reference to the fact that the substance may be a mixture or compound of substances for therapeutic use. There is no reference to the mixture or compound necessarily having to be a mixture of active ingredients only, but it must be borne in mind that an extension of patent term is only available in Australia in respect of patents for pharmaceutical substances "per se". The question is whether these extra words import a requirement that the mixture or compound of substances must be a mixture or compound of active ingredients in order for a patent term extension to be available.

The Advocate General's opinion in relation to Gliadel appears to be quite limited in operation and could be confined to the situation where the excipient has a modifying effect indirectly on the operation of the active. However, a more liberal interpretation might be that, to require all components of a product to be therapeutically active ingredients, would exclude from patent term extension new and effective drug formulations that had been the subject of extensive research and development.

It remains to be determined whether an Australian court would follow a line of reasoning similar to that expressed in the Advocate General's opinion in relation to formulation patents generally. Pharmaceutical companies may be interested to know that a closely related issue has just been argued before the Federal Court of Australia, (relating to whether a product by process claim is capable of extension), and judgment is currently eagerly awaited.^[4]

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.