The Federal Court of Australia has recently issued a decision that has important implications for chemical patents in Australia, and especially for patents concerned with pharmaceutical substances.
Alphapharm Pty Ltd v H Lundbeck A/S  FCA 559, concerned a patent which discloses the (+)-enantiomer of the antidepressant drug known as citalopram. The patent claims (+)-citalopram and its non-toxic acid addition salts, pharmaceutical compositions containing them, and two processes for preparing (+)-citalopram. It discloses that the (+)-enantiomer is 100-fold more pharmaceutically active than the (-)-enantiomer. Racemic citalopram had been disclosed, claimed and published in another patent before the priority date. Both patents are owned by H Lundbeck A/S (“Lundbeck”).
The case involved four proceedings that were heard simultaneously by Lindgren J and involved
- issues of validity of the patent and infringement of some of its claims;
- the correctness or otherwise of a decision by the Commissioner of Patents to, in effect, cancel the grant of an extension of term of the patent; and
- a request by Lundbeck for an order that certain information that it had supplied to the Therapeutic Goods Administration (“TGA”) for the purpose of obtaining marketing approval for (+)-citalopram not be used, or be permitted to be used, by the Secretary of the Department of Health and Ageing when evaluating any application by a person other than Lundbeck Australia for the registration of therapeutic goods.
Infringement of the process claim
Claim 6 of the patent defines, in the alternative, two processes for obtaining (+)-citalopram. Infringement was argued in respect of one of these two processes. The claimed process starts with a diol precursor of citalopram and proceeds by resolving this diol into its enantiomers by forming an acid addition salt with an enantiomer of an optically active acid, forming a labile ester of the appropriate enantiomer of the diol at the primary hydroxyl group, then performing ring closure on the ester, so as to generate the (+)-enantiomer of citalopram.
Alphapharm Pty Ltd (“Alphapharm”) had imported (+)-citalopram which had been manufactured overseas. Lindgren J reaffirmed that it is an infringement of a process claim in an Australian patent to exploit, in Australia, a product that has resulted from the use of a process outside of Australia where, had that process been used within Australia, it would have infringed the Australian patent.
Alphapharm’s main defence, however, derived from the fact that in the process used by its supplier, a bromo-substituent was present in the diol precursor, in place of the cyano group in structure (II) shown above.
Lindberg J held that there had been infringement of the process claim, notwithstanding the difference between what is set out in the patent claim and the process steps actually followed.
Validity of the extension of term
Lundbeck had obtained an extension of the term of the patent, based on its having registered (+)-citalopram on the Australian Register of Therapeutic Goods (“ARTG”) on 16 September 2003. In the circumstances of the case, the Patents Act required an application for extension of term to be made not more than 6 months after the date of commencement of the first inclusion in the ARTG of goods that contain, or consist of, (+)-citalopram or a salt of (+)-citalopram. Lundbeck applied for the extension of term on 22 December 2003, and it was granted on 27 May 2004. However, racemic citalopram had been included on the ARTG on 9 December 1997. The Commissioner took the view that the racemate was “goods that contain (+)-citalopram” and determined that the application for an extension of term that had been filed on 22 December 2003 was made well outside the time permitted. Accordingly, the Commissioner decided that the Register of patents should be rectified by removing reference to any extension of term of the patent in suit.
Lundbeck appealed from the decision of the Commissioner to rectify the Register, but Lindberg J refused the appeal following various submissions made by Lundbeck to the effect that the racemate should not be considered to “contain” the (+)-enantiomer in the relevant sense, which his Honour described as an “ordinary English word”.
Claim 5 claimed a pharmaceutical composition in unit dosage form in which the active ingredient is present in an amount from 0.1 to 100 milligrams per unit dose. The evidence was that the minimum useful dose of (+)-citalopram is 5mg, and the maximum dose is 40mg. Lindgren J held that claim 5 claims quantities outside the useful range and thus is invalid by reason of inutility.
Novelty and inventiveness
After reviewing the available evidence Lindgren J concluded that the claim directed to (+)-citalopram as a matter of construction requires something different to that enantiomer as part of the racemate; his Honour did not find that it was necessary to construe (+)-citalopram as being at a certain level of purity and instead construed the term as being present other than in a racemate.
This finding was important for consideration of the novelty and inventiveness of the claim in the light of the prior publication of the racemate: Lindgren J held that claim 1 was both novel and involves an inventive step. This conclusion, reached only after lengthy consideration of the evidence, does not necessarily imply that a claim to any resolved enantiomer will be held to be both novel and inventive in the light of a prior disclosure of the corresponding racemate.
The process claim was only attacked on the ground of lack of inventive step. Lindgren J found that on the evidence a person skilled in the art would not, as a matter of routine and with the expectation of success, have been led to try the precursor diol route of the process claim and would not have thought of using chiral HPLC, as a means of resolving citalopram. Accordingly, the claim was held to involve an inventive step.
Infringement of the product claims
With regard to the product claims, it was admitted by Alphapharm that it had, inter alia, imported raw materials containing (+)-citalopram oxalate, conducted tests on it, and manufactured goods containing it. However, Alphapharm claimed a statutory defence against a finding of infringement.
The relevant statutory provision is (now) s 119A of the Patents Act which provides that it is not an infringement of a pharmaceutical patent to exploit the invention claimed in it solely for purposes connected with obtaining (a) inclusion in the ARTG of goods that are intended for therapeutic use (and are not medical devices or therapeutic devices) or (b) similar regulatory approval under a law of a foreign country.
Lindgren J noted Alphapharm’s statement to the effect that its exploitation of (+)-citalopram was solely for the purpose of obtaining inclusion of (+)-citalopram in the ARTG. In the result, Lindgren J accepted that Alphapharm’s defence was made out.
The “protected information” request of Lundbeck
“Protected information” under the Therapeutic Goods Act, is information in relation to therapeutic goods that cannot be used by the Secretary of the Department of Health and Ageing in assessing other therapeutic goods for registration.
Lundbeck’s request in this aspect of the case was in effect for a declaration that certain information it had supplied to the TGA was “protected information”. However, Lindgren J’s conclusion was that racemic citalopram “contains” the (+)-enantiomer and was therefore fatal to Lundbeck’s request because under the Therapeutic Goods Act, the period of protection of information is not more than 5 years from the date of first registration of goods containing the relevant pharmaceutical substance and racemic citalopram had been registered on the ARTG for more than 5 years.
The infringement finding
It appears that where a process claim includes one or more process steps involving a chemical structure having certain defined substituents, the claim can include within its scope processes in which the same step or steps is/are carried out on similar structures having variant substituents not defined in the claim, provided such substituents do not materially affect the way the process works.
The extension of term finding
It follows from this decision that an owner of a patent for a pharmaceutical substance needs to be vigilant to ensure not only that the relevant deadline for filing an application for extension of the term of the patent is recorded and acted on, once the pharmaceutical substance or goods containing it are first recorded on the ARTG, but also that any other substances, whether intended to be present or not, that are contained in the goods which have been registered, do not also give rise to deadlines for making application for extension of time in respect of other patents that the patentee owns.
The inutility finding
Although in this case is doubtful whether the patentee was particularly distressed about the revocation of claim 5, the same would not necessarily be so in other situations involving similar “unit dose” claims. This decision, if it is correct, implies that patentees need to be careful to limit such claims to ranges of doses that are known to be effective. It is somewhat unclear what is the position if the useful dosage range is unknown at the time of filing the relevant patent application; it appears that such claims may be vulnerable to revocation if it later transpires that the dosages which they recite go beyond the range of effective doses.
Author: Colin Bodkin
After a career in industrial research and development, Colin was a Principal of Spruson & Ferguson from 1995-2002. He is a Fellow of the Institute of Patent and Trademark Attorneys and has contributed to teaching in the Master of Industrial Property course at the University of Technology, Sydney. Colin is the author of the book "Patent Law in Australia", which was published in 2007. He is currently a consultant to Spruson & Ferguson.