Intellectual Property Office of New Zealand - Patents Decisions
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Last Updated: 16 October 2008
P21/2007
IN THE INTELLECTUAL
PROPERTY OFFICE OF
NEW
ZEALAND
IN THE MATTER of the Patents Act 1953
AND
IN THE MATTER of an application for Letters Patent No 313576 in the name of BERNARD CHARLES SHERMAN
Applicant
AND
IN THE MATTER of opposition to said application under section 21 by MERCK & CO, INC
Opponent
Hearing: 21 June 2007
A Brown QC, P Jones and K Murdoch for the Applicant
G Arthur and K
McHaffie for the Opponent
Decision
BACKGROUND
New Zealand Patent Application No. 313576 was filed by Bernard Charles Sherman as the New Zealand national phase of International Application No. PCT/CA96/00513. The application has an effective New Zealand filing date of 30 July 1996, and claims priority under international convention from United States (US) Patent Application Serial No. 08/511,297 dated 4 August 1995.
Acceptance of application 313576 was advertised in the Intellectual Property Office of New Zealand (IPONZ) Journal No. 1440 which issued on 28 May 1999.
The issues to be decided in this case are those of prior publication and obviousness based on prior publication. No other ground of opposition is being pursued.
EVIDENCE
In support of the opposition, as evidence in chief, were filed affidavits of:
Thomas Harold SYDDALL, Solicitor and Patent Attorney at A J Park, of Wellington, New Zealand;
Alister BROWN, Managing Director of Merck Sharp & Dohme (NZ) Limited, of Auckland, New Zealand;
George CRANK, Independent Consultant in Chemistry and Toxicology, of Engadine, New South Wales, Australia;
Gerard M DEVLIN, Attorney in the Intellectual Property Litigation group for Merck Sharp & Dohme Co Inc, of Rahway, New Jersey, US;
Peter James STEWART, Head of Department of Pharmaceutics and Associate Dean (Graduate Studies), Victoria College of Pharmacy at Monash University, of Parkville, Victoria, Australia;
Rachel Anna DE VRIES, Secretary at A J Park, Solicitors and Patent Attorneys, of Wellington, New Zealand; and
Michael Brian McGUINESS, Director of Pharmaceutical Manufacturing for Merck Sharp & Dohme Technology Singapore PTE Limited, of Singapore.
In support of the application, as evidence in chief, were filed statutory declarations of:
Ian George TUCKER, Professor (Pharmaceutical Sciences) and Dean of the School of Pharmacy at the University of Otago, of Dunedin, New Zealand;
Ian George TUCKER;
Nicole Lyndal WATLING, Patent Attorney at Freehills Patent & Trade Mark Attorneys, of Melbourne, Australia;
Paul William JONES, Registered New Zealand and Australian Patent Attorney and Partner of Freehills Patent & Trade Mark Attorneys, of Melbourne, Australia;
Paul William JONES;
Robert S LANGER, an Institute Professor at the Massachusetts Institute of Technlogy, of Newton, Massachusetts, US;
Robert A McCLELLAND, Professor Emeritus of the University of Toronto, of Thornhill, Scotland;
James B HENDRICKSON, Professor of Chemistry, Brandeis University, of Waltham, Massachusetts, US;
Zak T CHOWAN, Independent Consultant in the field of Pharmaceutical Development, of Gaithersburg, Maryland, US; and
Istvan TOTH, Chair of Biological Chemistry at the School of Molecular and Microbiological Sciences and Professor in the School of Pharmacy, at the University of Queensland, of Brookfield, Queensland, Australia.
In support of the opposition, as evidence in reply, were filed affidavits of:
George CRANK;
Craig Robert BUNT, Senior Lecturer in Pharmaceutics at the School of Pharmacy, University of Auckland, of Auckland, New Zealand; and
Peter James STEWART.
THE LAW
Opposition proceedings should only succeed in clear cases, as in Saxpack Foods v Watties Canneries (M 454/85, High Court, Wellington Registry, 11 July 1988), where at pages 8-9 Ongley J stated:
I approach the proceedings upon the basis that the purpose of opposition proceedings is to clear the register of patents which are manifestly untenable. It is not to provide a method of disposing of truly contentious cases...
The applicant drew on Beecham Group Limited v Bristol Myers Company (No2) [1979] NZLR 629 at 632 where Davison CJ referred to the nature of opposition proceedings both under the New Zealand Patents Act 1953 and the equivalent United Kingdom (UK) Patents Act 1949 as follows:
The function of the Assistant Commissioner in dealing with an application for Letters Patent where opposition proceedings have been filed has been clearly laid down. It is to determine “shall there be a grant of the patent?”. The proceedings are not intended to finally determine questions of validity of a patent if granted. Their purpose is to avoid the registration of patents that are clearly defective. If a patent is granted, the opponent will still be entitled to apply to the Court for revocation or to seek revocation by counterclaim in an infringement action.
After referring to a number of English and Australian authorities, Davison CJ stated at 634:
The same principles to which I have just referred are applied in England in dealing with applications for grants of patents. Perhaps the most helpful expression of opinion by an English Court is to be found in the General Electric Company’s Application [1964] RPC 413 from the judgment of Lord Diplock at p453:
The right principle is that if on the face of the written evidence filed there appears to be a bona fide conflict of fact or credible expert opinion upon a question on the answer to which the existence or non-existence of the ground for refusal specified in s 14(1) (e) depends, the [Commissioner] should not exercise his jurisdiction to refuse the grant unless, after cross-examination of the witness if he thinks fit to order it, the conflict is clearly resolved in favour of the party opposing the grant.
The applicant referred to the UK text, T A Blanco-White, Patents for Inventions, Fourth Edition, at pages 236 to 237:
The value of this right of opposition is limited. The benefit of any doubt must be given to the applicant for a patent or patentee: for an unsuccessful opponent has another chance to make out his case, in proceedings before the High Court after grant [pursuant to section 41], whilst an unsuccessful applicant has no second chance. The question to be decided is, in effect, whether the specification opposed “must necessarily be invalid.” Thus it is a difficult matter to secure refusal of grant (or revocation), if the opposition is contested, and whilst most oppositions secure at least amendment of the specification to meet the attacks made by the opponent most such amendments strengthen and not weaken the patent. Even the insertion of a specific reference, normally regarded as a defeat for the applicant, is a defeat only in relations to prestige: such references also tend to strengthen and not weaken the patent in whose specification they occur...
The applicant pointed out that the standard of proof to be applied is the ordinary civil standard, nonetheless what needs to be borne in mind is the threshold issue, as in Sealed Air New Zealand Ltd v Machinery Developments Ltd (unreported, HC WN CIV-2003-485-2274, 25 August 2004, MacKenzie J) paragraphs 10 and 11:
[10] ... The standard of proof to be applied is the ordinary civil standard, namely that any matters requiring to be proved must be established on the balance of probabilities. However, although the standard of proof is the civil standard, namely on the balance of probabilities, it is necessary to bear in mind the questions which the Assistant Commissioner at first instance, in this Court on appeal, must address in opposition proceedings. The opposition is a means of dealing with applications which clearly should not proceed. The question is, as it is put by Barker J in the passage from Beecham v Bristol-Myers (No.2) which I have cited, and by Ongley J in Saxpack Foods Limited v J Wattie Canneries Limited (M 454/85, High Court, Wellington Registry, 11 July 1988) whether the application is “manifestly untenable”. That procedure is not a method of disposing of truly contentious cases. For such cases, the procedure of a revocation action under s 41 is appropriate...
[11] That is not to impose upon the opponent a higher standard of proof than proof on the balance of probabilities, but the threshold which the opponent must reach, on the balance of probabilities is a high one.
THE INVENTION
The specification is entitled:
Stable solid formulations of enalapril salt and process for preparation thereof
The background to the invention (as it is to be amended) is described as:
New Zealand patent no 192312 discloses the compound enalapril maleate, which is a drug useful to treat hypertension. This patent also discusses methods of formulating drugs into pharmaceutical compositions such as tablets and capsules, but discloses no example of a tablet or capsule containing specifically enalapril maleate.
In order to manufacture pharmaceutical tablets, it is necessary to mix the active ingredient with inactive ingredients which may serve as binders, fillers, disintegrating agents, lubricants, and colorants or have other purposes. Inactive ingredients are also known as “excipients”.
The final mixture of active ingredient and excipients is made into tablets on a tablet press. The processes of preparing the mixture and making tablets are well known to those skilled in the art of pharmaceutical formulation.
One of the requirements for an acceptable pharmaceutical composition is that it must be stable, so as not to exhibit substantial decomposition of the active ingredient during the time between manufacture of the composition and use by the patient. Surprisingly, it has been found that enalapril maleate is not compatible with most of the usual excipients, including most of those mentioned in New Zealand patent no 192312. Decomposition of enalapril maleate is accelerated by most of those excipients, thus making it very difficult to formulate a stable tablet containing enalapril maleate.
The difficulty of formulating a stable tablet containing enalapril maleate is confirmed by United States patent no 5,350,582. That application discloses that a stable formulation can be made by suspending enalapril maleate in water, and adding an alkaline sodium compound, whereupon an acid-base reaction occurs to convert the enalapril maleate into enalapril sodium salt (hereinafter referred to as “enalapril sodium”) plus maleic acid sodium salt, thereby forming a clear solution. Other excipients are then added the mixture is dried, and the dry powder processed into tablets. Stability data contained in this patent application demonstrates that the final composition contained enalapril sodium mixed with maleic acid sodium salt and other ingredients is more stable than a similar composition containing enalapril maleate.
However, the formulations of United States patent no 5,350,582 have the disadvantage of requiring the step of suspending the enalapril maleate in water, adding the alkaline sodium compound, and mixing until the acid-base reaction is complete.
This requires the use of more equipment than would otherwise be needed for the manufacture of tablets. Also, because the enalapril sodium is in aqueous solution during the process, significant hydrolysis can occur by which some enalaprilat is formed, thus reducing the purity of the product.
Although the prior art discloses that stable tablets comprising enalapril maleate can be made if excipients are restricted to those which do not cause decomposition, this approach makes it difficult to produce tablets exhibiting good hardness.
In the light of the foregoing, the object of the invention is to enable production of tablets through a process whereby enalapril maleate is converted to the more stable sodium salt without requiring the steps of suspending the enalapril maleate in water, adding the alkaline sodium compound, and mixing until the reaction is complete and a clear solution is formed.
The amendments replace the original references to US patent no 4374829 by the equivalent New Zealand patent no 192312, and the original references to the unavailable document European patent application number 92119896.6 with the available US patent no 5,350,582. These amendments satisfied the opponent’s objections to the specification made under ground (g) of section 21(1).
The summary of the invention begins:
It has surprisingly been found that enalapril maleate can be converted to the stable enalapril sodium salt by mixing the enalapril maleate with an alkaline sodium compound and other excipients in dry form, adding sufficient water to moisten same, and thereafter drying, thus avoiding the need to suspend the enalapril maleate in water and to produce a solution of enalapril sodium in water.
There are three specific Examples in the specification. Example 1 uses a mixture of enalapril maleate (50g) and lactose monohydrate powder (1660g) to which was added sodium hydroxide (12.2g) dissolved in 400g water. The resulting wet mass was mixed well and then dried overnight at 500C. The dried mix was passed through a #40 screen and starch (75g) and magnesium stearate (8.3g) were added and mixed in, before compressing the final mix into capsules.
In Example 2, to enalapril maleate (100g), lactose monohydrate powder (1600g) and red iron oxide (5g) was added sodium carbonate (32.3g) dissolved in 400g water, before mixing well and drying overnight at 500C. As before, starch (73g) and magnesium stearate (8.6g) were added to the screened dried mix, and the resultant mixture compressed into tablets.
In Example 3, which is particularly relevant as it uses sodium bicarbonate, a mixture of enalapril maleate (50g), sodium bicarbonate (25.6g and lactose monohydrate powder (1650g) has added to it 400g water, before mixing well and drying overnight at 500C. As before, starch (75g) and magnesium stearate (8.8g) were added to the screened dried mix, and the resultant mixture compressed into tablets.
In each Example the ratio of enalapril maleate to water is 1 to 8 on a weight to weight basis.
The claims defining the invention, as they are to be amended, read:
i) a) mixing enalapril maleate with an alkaline sodium compound and at least one other excipient, adding water sufficient to moisten, and mixing to achieve a wet mass, or
thereby to achieve an essentially complete reaction without converting the enalapril maleate to a clear solution of enalapril sodium and maleic acid sodium salt in water,
ii) drying the wet mass, and
iii) further processing the dried material into tablets.
3. A process as in claim 1 or 2 wherein the excipient is lactose.
4. A process as in any of claims 1 to 3 which further
comprises addition of a lubricant.
5. A process as in claim 4 wherein the lubricant is a metal stearate.
6. A process as in claim 5 wherein the metal stearate is magnesium stearate.
7. A process as in any of claims 1 to 6 which further comprises the addition of a disintegrant.
8. A process as in claim 7 wherein the disintegrant is starch.
9. A process as in any one of claims 1 to 8 wherein the water or solution of an alkaline sodium compound in water is sufficient to render the mass very moist.
PRIOR PUBLICATION
Section 21(1)(b) states:
That the invention, so far as claimed in any claim of the complete specification, has been published in New Zealand before the priority date of the claim —
(i) In any specification filed in pursuance of an application for a patent made in New Zealand and dated within 50 years next before the date of filing of the applicant’s complete specification:
(ii) In any other document (not being a document of any class described in
subsection (1) of section 59 of this Act)
The usual test for prior
publication is that set forth in the judgment of the English Court of Appeal by
Sachs LJ in The General Tire & Rubber Company v The Firestone Tyre
and Rubber Company Limited and Others [1972] RPC 457 at 485 to 486:
When the prior inventor’s publication and the patentee’s claim have respectively been construed by the court in light of all properly admissible evidence as to technical matters, the meaning of words and expressions used in the art and so forth, the question whether the patentee’s claim is new for the purposes of section 32(1)(e) falls to be decided as a question of fact. If the prior inventor’s publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent, the patentee’s claim will have been shown to lack the necessary novelty, that is to say, it will have been anticipated. The prior inventor, however, and the patentee may have approached the same device from different starting points and may for this reason, or it may be for other reasons, have so described their devices that it cannot be immediately discerned from a reading of the language which they have respectively used that they have discovered in truth the same device; but if carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated.
If, on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee’s claim, but would be at least as likely to be carried out in a way which would not do so, the patentee’s claim will not have been anticipated, although it may fail on the ground of obviousness. To anticipate the patentee’s claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented ... A signpost, however clear, upon the road to the patentee’s invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee.
The applicant drew attention to the General Tire dictum having been followed by the Court of Appeal in Beecham Group Ltd v Bristol-Myers Company [1981] 1 NZLR 600, 606. The opponent noted that the formulation was endorsed by the Supreme Court of New Zealand in Peterson Portable Sawing Systems Limited v Lucas [2006] NZSC 20.
The opponent drew on Merrell Dow Pharmaceuticals Inc v H N Norton & Co Ltd [1995] UKHL 14; [1996] RPC 76 at 89/15 where Lord Hoffmann said an invention is:
part of the state of the art if the information which has been disclosed enables the public to know the product under a description sufficient to work the invention
and at 90/8:
if the recipe which inevitably produces the substance is part of the state of the art, so is the substance as made by that recipe
The applicant pointed out that it is the ‘the invention’ which is to be prior published. This was the basis of the approach to prior publication taken in Beecham Group Ltd v Bristol-Myers Company [1981] 1 NZLR 600 at 606:
It is true that the OMP patent does not expressly tell the reader to prepare the epimer separately by firstly resolving the starting acid, but merely describes the making of the DL mixture with racemic acid. We are not to be taken as ruling that counsel for Beecham is wrong in his argument that this point is decisive. But we find the liberalism of that test unattractive and prefer in relation to semi-synthetic chemical compounds a more direct approach to whether the invention claimed has been “published” in New Zealand previously. If such a compound has not been made before, its properties often cannot be predicted with any confidence; and where that is the case we do not consider that the invention claimed can fairly or accurately be described as “published”, even if a skilled chemist would realise that to make the compound by routine means would be practicable. A making of the compound and a discovery of its properties is necessary before the “invention” has occurred and can be “published”.
The Integers to be found in the prior art document are:
a process of manufacture of a pharmaceutical solid composition comprising enalapril sodium, which process comprises the steps of
i) a) mixing enalapril maleate with an alkaline sodium compound and at least
one other excipient, adding water sufficient to moisten,
and mixing to achieve a
wet mass,
or
i) b) mixing enalapril maleate with at least one excipient other than an alkaline sodium compound, adding a solution of an alkaline sodium compound in water, sufficient to moisten, and mixing to achieve a wet mass,
thereby to achieve an essentially complete reaction without converting the enalapril maleate to a clear solution of enalapril sodium and maleic acid sodium salt in water,
In effect the conversion of enalapril maleate to enalapril sodium takes place in the wet mass while the step of wet granulation is proceeding. The conversion is complete or substantially complete.
International Patent Application Publication No. WO 94/01093 (Rork & Haslam) (‘Rork’)
This publication was said to be available at IPONZ from 28 February 1994.
The publication relates to a ‘controlled porosity osmotic enalapril pump’. The specification refers to drawings, Figures 1 and 2, which were never attached to the application. The application did not proceed past the application stage. Hence there would appear to be no source from which to obtain these Figures.
Rork describes enalapril as an angiotensin-converting enzyme inhibitor prodrug which is administered orally. The pump system has an inner core compartment of osmotically active composition surrounded by an enclosing wall. The core is said to comprise enalapril, sodium bicarbonate and lactose. The wall constitutes a layer of controlled porosity that is substantially permeable to both the external fluid from the environment of use and the aqueous solution which forms within the core.
Enalapril, sodium bicarbonate, and the osmotically active excipient are said to be released from the osmotically activated system in a nearly pH independent manner by external fluid imbibition through the wall into the inner core compartment at a rate controlled by the thickness and degree of porosity of the wall. A solution containing the components of the core is released through the wall at a controlled rate.
In a brief description of the missing drawings, missing Figure 1 was said to show an embodiment of the osmotic pump where the core element was in the form of a tablet having a microporous rate controlling wall surrounding the core. The core was said to comprise enalapril, sodium bicarbonate and lactose as well as other tableting excipients. Missing Figure 2 was said to show embodiments of the osmotic pump in multi-particulate form.
In the detailed description of the invention the core was said to comprise a therapeutically effective amount of enalapril, sodium bicarbonate and lactose surrounded by a rate controlling water-insoluble fluid-permeable wall. The detailed description then describes the cores of missing Figures 1 and 2 as being comprised of a mixture of enalapril maleate, sodium bicarbonate, lactose and other inert pharmaceutically acceptable excipients, which may be osmotically effective agents. The excipients are said to be combined with the enalapril maleate, sodium bicarbonate and lactose to give the desired manufacturing and delivery characteristics.
The osmotic pressure developed by a solution of the core is said to be about 50 atmospheres developed from the mixture of enalapril maleate, lactose and sodium bicarbonate, however osmotic pressures greater that zero are said to be within guidelines. The combination of enalapril, as the active agent, and an effective amount of sodium bicarbonate, lactose and excipients is said to have the desired solubility, osmotic pressure, density, stability, and manufacturing characteristics.
The effective amount of sodium bicarbonate is said to be an amount sufficient to provide greater than 50% of the drug release zero order and stabilise the enalapril maleate of the core composition. The sodium bicarbonate, therefore, appears to play a major role in drug release rate.
The publication defines what it means by ‘enalapril’. It is (S)-1-[N-[1-(ethoxycarbonyl)-3-phenylpropyl]-L-alanyl]-L-proline and any of its pharmaceutically active salts such as the maleate salt, hydrates and crystal forms.
Rork then states that in preparing the granulation of the core composition about three moles of sodium bicarbonate are said to be added to the granulation for each mole of enalapril when enalapril maleate is used. In the presence of the granulating solvent, water, the sodium bicarbonate reacts with the acidic functional groups of the enalapril maleate, and carbon dioxide is released. I note that the three moles of sodium bicarbonate to one mole of enalapril maleate is the stoichiometric ratio of sodium bicarbonate to enalapril maleate to convert all the maleate salt to the sodium salt of enalapril.
The lower limit ratio of enalapril and sodium bicarbonate to other inert pharmaceutically acceptable carriers is said to be dictated by the desired osmotic activity of the core composition, the desired time span of release, and the pharmacological activity of the active agent.
The solubilised constituents of the core are said to create a water activity gradient across the wall of missing Figure 1, resulting in osmotically actuated fluid movement constituting the osmotic pump action of the invention. Since missing Figure 1 is purported to relate to the tablet form of the core, this could be a suggestion that there is a slow reaction over time between enalapril maleate and sodium bicarbonate in the core after administration of the pump to a patient.
The publication then states, as a specific embodiment of the invention, that the enalapril maleate is present in the tablet core at between about 1 and about 50mg and the sodium bicarbonate in the core is between about 5 μg and about 25mg. In another specific embodiment of the invention in the publication the enalapril maleate in the multiparticles is said to be between 1 and about 20% of the total multiparticulate care mass and the sodium bicarbonate is between about 0.0075% and about 10% of the total multiparticulate core mass. (‘Core mass’ is defined as the mass of the particle disregarding the mass of the coating.) At the upper end of both sets of ranges the molar ratio of enalapril maleate to sodium bicarbonate is 1 to 3, but at the lower end of both sets of ranges the molar ratio of sodium bicarbonate to enalapril maleate is much lower.
Ten pages of the 22 page description of Rork are then devoted to discussing the make up of the porous wall.
Example 1 describes the making of a multiparticulate formulation of enalapril maleate using a mole ratio of enalapril maleate to sodium bicarbonate of 1:3. Enalapril maleate (120g) was placed in a beaker and a slurry of sodium bicarbonate (62.4g) and water (300ml) was slowly added. The mixture was allowed to stir until neutralisation was complete (as evidenced by no further evolution of carbon dioxide). Lactose (360g), corn starch (150g) and a commercial microcrystalline cellulose (450g) were mixed in a planetary mixer for 5 minutes. The solution was added to the mixed solids and mixed, with additional water being added until an appropriate consistency was obtained. The mix was then extruded, spheronised and the resulting beads dried overnight at room temperature at 20% relative humidity, then sized. The multiparticulate beads as in Example 1 were then coated. Examples 2 to 5 used beads, prepared in the same way as in Example 1, with different coatings. Example 6 was the same as Example 1 except that 30g of enalapril maleate, 15.6g of sodium bicarbonate and 450g of lactose were used to make the particulate formulation.
The heading of the table of release rates for these Examples is ‘Enalapril Maleate Release Times’. However, it is accepted by the parties that in the foregoing Examples 1 to 6 the enalapril maleate has been completely converted by the sodium bicarbonate into enalapril sodium. Thus, it is enalapril sodium that is in the particulates and it is this sodium salt which is released from the osmotic pump. The opponent points out the use of the terminology ‘enalapril maleate’ when referring to what has in effect become enalapril sodium.
In Examples 1 to 6 the enalapril maleate is converted to enalapril sodium prior to the wet granulation stage hence these Examples, and the publication as it relates to the making of cores containing microparticles, does not prior publish the applicant’s claimed invention.
Example 7 describes the preparation of enalapril maleate tablet cores for controlled release osmotic pumps. The ingredients for the tablet cores prepared in Example 7 were enalapril maleate (5, 10 and 20mg per tablet) and sodium bicarbonate (2.5, 5 and 10mg, respectively, per tablet), ie in a molar ratio of 1:3. Also present was lactose (198 to 154mg per tablet), starch (22.8 to 22mg per tablet), pregelatinised starch (5 to 2.2mg per tablet), iron oxide colorants (q.s.), magnesium oxide (0.9 to 1.1mg per tablet), and water (q.s.).
The ingredients, except for the magnesium stearate and water were mixed in appropriate batch sizes in a high intensity mixer. The water was added at 850C, with mixing, at a spray rate sufficient to add all the water in 1 to 1.5 minutes. The material was mixed for 4 minutes. The material was discharged into a fluidised bed drier and dried at 500C until the moisture content was less than 1%. The dried material was milled, then blended with the magnesium stearate, screened and compressed to make extended release core tablets.
Examples 8 to 12 describe the application of different slow release coatings to the core tablets prepared by the method of Example 7. In Example 8 the core tablet is said to contain enalapril maleate. Examples 9 to 12 do not disagree with this statement.
The heading of the table of release rates for Examples 8 to 12 is again ‘Enalapril Maleate Release Times’. However, it is not accepted by the applicant that in the process of Example 7 the enalapril maleate is converted to any great degree, if at all, by the sodium bicarbonate into enalapril sodium. Thus, the applicant is of the view that enalapril maleate is present in the core tablets rather than enalapril sodium.
The view of the opponent is that during the preparation of the mixture in Example 7 the sodium bicarbonate converts the enalapril maleate to enalapril sodium.
The well qualified experts who have given detailed evidence on this document are divided as to what is the actual composition of the finished core in Example 7 of Rork. The experts for the applicant state that little if any conversion of enalapril maleate to enalapril sodium will take place. The experts for the opponent say that the enalapril maleate is converted to enalapril sodium at this stage, an implication of their evidence being that there is more or less full conversion. The case law states that where, on the face of the written evidence filed, there appears to be a bona fide conflict of fact or credible expert opinion then the Commissioner should not refuse the grant unless the conflict is clearly resolved in the opponent’s favour: On this basis I cannot decide that the document clearly prior publishes the applicant’s claimed invention.
With regard to Rork, the applicant says in its submissions:
The opponent says of Rork in its submissions:
The argument of the opponent and its experts on Rork, and its Example 7 in particular, appears to include:
The view of the applicant and its expert witnesses on Rork and its Example 7 is:
The opponent says that, whether or not it is apparent to the experts that a reaction took place, the question is whether carrying out the directions in Rork will inevitably result in something being done which, if the Sherman patent were valid, would constitute an infringement of Sherman’s claims. This is the true test.
It seems to me that the best that can be understood from Rork on the evidence before me is that some reaction will take place between enalapril maleate and sodium bicarbonate in the mixing step of Example 7. As I see it, there is, however, no clear description of the complete or substantially complete conversion of enalapril maleate to enalapril sodium in a wet granulation process as required by claim 1 of the present application. There appears to be less water in the wet granulation in Rork than in the Examples of the application in suit. Rork contains no clear description of, or clear instructions to do or make, something that would infringe the applicant’s claim if carried out after the grant of the applicant’s patent. There are signposts in Rork, however, as I understand them, they are not pointing to a clear end. Where the signposts are pointing is the subject of opposing opinions by the experts for the parties. At least there must be a doubt as to what Rork teaches regarding the making of tablets and the benefit of this doubt must be given to the applicant.
The ground of prior publication is not made out.
OBVIOUSNESS - section 21(1)(e)
Section 21(1)(e) reads:
That the invention, so far as claimed in any claim of the complete specification is obvious and clearly does not involve any inventive step having regard to matter published as mentioned in paragraph (b) of this subsection, or having regard to what was used in New Zealand before the priority date of the applicant’s claim
The opponent submitted that there are two leading New Zealand appellate authorities on obviousness. These are Ancare v Cyanamid [2001] RPC 335 (upheld in a judgment of the Privy Council at [2003] RPC 139) and Peterson Portable Sawing Systems Ltd v Lucas [2006] NZSC 20. These cases hold that under New Zealand law the principles of obviousness ‘are the same as those adopted in England and applicable still under the Patents Act 1977 (UK)’ (per Peterson para 54).
The Supreme Court in Peterson confirmed that the test for obviousness is that set out in Windsurfing International Inc v Tabur Marine (Great Britain) Ltd [1985] RPC 59 at 73-74 and this test was followed in Ancare v Cyanamid [2000] 3 NZLR 299 at 309 (CA). Oliver J in Windsurfing at 73-74 states:
There are, we think, four steps, which require to be taken in answering the jury question. The first is to identify the inventive concept embodied in the patent in suit. Thereafter, the court has to assume the mantle of the normally skilled but unimaginative addressee in the art at the priority date and to impute to him what was, at that date, common general knowledge in the art in question. The third step is to identify what, if any, differences exist between the matter cited as being “known or used” and the alleged invention. Finally the court has to ask itself whether, viewed without any knowledge of the alleged invention, those differences constitute steps which would have been obvious to the skilled man or whether they require any degree of invention.
The test was approved by the New Zealand Court of Appeal in Ancare v Cyanamid [2000] 3 NZLR 299 at 309, Gault J stating:
[43] ... the test [for obviousness] is well established. It postulates a person (or, where appropriate, a team), skilled in the field but not inventive, invested with the common general knowledge available in the field at the priority date, presented with the prior knowledge or prior use relied upon. Prior documents may be looked at together if that is what the skilled person or team would do. It asks whether to that person or team the alleged inventive step would be obvious and would be recognised, without bringing to bear any inventiveness, as something that could be done or is at least worth trying. That is a question of fact. If any embodiment within the scope of the claim is obvious the claim is invalid. These propositions are helpfully expanded upon in the recent English cases which are still applicable though under the 1977 Act; see the Windsurfing International case, Hallen Co v Brabantia (UK) Ltd [1991] RPC 195 at p 211, and Molnlycke AB v Procter & Gamble Ltd [1994] RPC 49 at p 112.
[44] As Mr Henry emphasised, the element of inventiveness necessary to resist attack was not high. He referred to the need only for a “scintilla” of invention ... He referred also to the need to avoid the influence of hindsight and stressed the secondary consideration indicative of invention - the commercial success of the patented invention.
The applicant pointed out that the Windsurfing test is based on revocation proceedings before the High Court under section 41. In the context of opposition proceedings obviousness under section 21(1))(e) is based on:
(a) matter published as set out in section 21(1)(b) [ie published in New Zealand], or
(b) what was used in New Zealand,
before the priority date.
The applicant also pointed out a further difference. This was that the Windsurfing test refers to the ‘inventive concept’ whereas section 21 specifically addresses the ‘invention so far as claimed in any claim of the complete specification’.
As noted above, obviousness by way of prior publication only is being pursued in these proceedings.
In terms of the present case, the Windsurfing test becomes:
The applicant pointed out that the fundamental yardstick is the wording in section 21(1)(e), and that many judicial dicta have been developed over the years in order to aid Assistant Commissioners and the Courts. The applicant submitted, therefore, that there is always a risk of elevating dicta in judge-made concepts into substitutes for the statutory word themselves As Sachs LJ stated in The General Tire & Rubber Company Limited and Others v The Firestone Tyre and Rubber Company Limited and Others [1972] RPC 457 at 497:
“Obvious” is, after all, a much-used word and it does not seem to us that there is any need to go beyond the primary dictionary meaning of “very plain”.
When the Court comes to consider the question of obviousness, it is critical that the dangers of hindsight are avoided, it being all too easy to view something as obvious once the solution is known and understood. The applicant again noted that the fourth step in Windsurfing International Inc v Tabur Marine (Great Britain) Ltd [1985] RPC 59 at 73-74 is:
Finally the court has to ask itself whether, viewed without any knowledge
of the alleged invention, those differences constitute steps which would
have been obvious to the skilled man or whether they require any degree of
invention.
(applicant’s emphasis added)
The applicant drew on Tompkins J in Smale v North Sails Ltd [1991] 3 NZLR 19 at 42-44 where the Windsurfing test was adopted; the notional addressee was said to be well informed in the art in question and to possess all the relevant skills, but was incapable of even a scintilla of invention; and the cases were said to be replete with warnings against being wise after the event as the result of ex post facto analysis. The New Zealand Courts, as with the Courts in the UK and Australia, strongly warned against applying hindsight, as in Smale v North Sails at 43:
The cases are replete with warnings against being wise after the event as the result of ex post facto analysis. In Non-Drip Measure Co Ltd v Strangers Ltd (1943) 60 RPC 135, Lord Russell of Killowen at p 142 observed that nothing is easier than to say, after the event, that the thing was obvious and involved no invention. He referred to Fletcher- Moulton LJ in British Westinghouse Electric and Manufacturing Co Ltd v Braulik (1910) 27 RPC 209, 230 where he said:
I confess that I view with suspicion arguments to the effect that a new combination, bringing with it new and important consequences in the shape of practical machines, is not an invention, because, when it has once been established, it is easy to show how it might be arrived at by starting from something known, and taking a series of apparently easy steps. This ex post facto analysis of invention is unfair to the inventors, and in my opinion it is not countenanced by English Patent Law.
The test for obviousness invests the skilled addressee with the common general knowledge available in the field at the time. The applicant listed the characteristics to be imputed to the ‘normally skilled but unimaginative addressee in the art’ as set out by Barker J in Beecham Group Ltd v Bristol-Myers Co (No 2) [1980] 1 NZLR 192 at 232:
(i) He is presumed to be a skilled technician, knowledgeable in the relevant literature, including patent specifications, but incapable of a “scintilla of invention”: Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd [1972] RPC 346, 355.
(ii) He may be an individual or a research team: Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1070] RPC 157, 184.
(iii) He will seek advice on aspects with which he is not personally familiar: Tetra Molectric Ltd v Japan Imports Ltd [1076] RPC 547, 583.
(iv) He will believe that what he reads in documentation is true: May & Baker Ltd v Boots Pure Drug Co Ltd (1950) 67 RPC 23, 36.
The applicant drew to my attention the attributes of this fictional person as analysed by Laddie J in Pfizer Ltd’s Patent [2000] EWHC 49; [2001] FSR 16 at paragraph 62:
The question of obviousness has to be assessed through the eyes of the skilled but non-inventive man in the art. This is not a real person. He is a legal creation. He is supposed to offer an objective test of whether a particular development can be protected by a patent. He is deemed to have looked at and read publicly available documents and to know of public uses in the prior art. He understands all languages and dialects. He never misses the obvious nor stumbles on the inventive. He has no private idiosyncratic preferences or dislikes. He never thinks laterally. He differs from all real people in one or more of these characteristics. A real worker in the field may never look at a piece of prior art - for example he may never look at the contents of a particular public library - or he may be put off because it is in a language he does not know. But the notional addressee is taken to have done so. This is a reflection of part of the policy underlying the law of obviousness. Anything which is obvious over what is available to the public cannot subsequently be the subject of valid patent protection even if, in practice, few would have bothered looking through the prior art or would have found the particular items relied on. Patents are not granted for the discovery and wider dissemination of public material and what was obvious over it, but only for making new inventions. A worker who finds, is given or stumbles upon any piece of public prior art must realise that that art and anything obvious over it cannot be monopolised by him and he is reassured that it cannot be monopolised by anyone else.
The opponent criticised the deponent Professor Tucker in that it was not Professor Tucker’s practice, at least up to the priority date, to read or consider the patent literature in the pharmaceutical formulation field. This must affect his ability to know the art at the priority date as most of the research and development on drugs is carried out by the pharmaceutical industry and the information therefrom is usually first disclosed in patent specifications. It is much later that such information might appear in textbooks. Deponent Dr Crank, however, does not explain his own position relating to reading and considering patent literature. Deponent Dr Stewart says that in academic institutions there would be a tendency not to consult patent literature all that much. He does not explain his own practice in this regard. There is some doubt, therefore, in my mind as to the ability of such deponents to state the common general knowledge at the priority date of the claims.
The applicant noted that the element of inventiveness to resist an attack on the ground of obviousness is not high. A ‘scintilla’ of inventiveness is sufficient, as in Samuel Parkes v Cocker Bros (1929) 46 RPC 241 at 248:
The truth is that ... it is, I think, practically impossible to say that there is not present that scintilla of invention necessary to support the Patent.
Section 42 is worded slightly differently from section 41, placing a higher onus on the opponent under section 42 (and section 21) than under section 41. As Tompkins J observed in Smale v North Sails Ltd at 42:
As [Barker J in Beecham] points out at p.230, s.21(1)(e) is worded
slightly differently from para.(f) of s.41(1) referring as it does to the
invention clearly not involving any inventive step. As a consequence
that section involved the higher onus on an opponent in opposition proceedings
than in an application for revocation [before a court under section
41].
[emphasis added]
The benefit of any doubt has to be given to the applicant, in General Electric Co (Cox’s) Patents [1977] RPC 421 at 437 it being stated:
It seems to me that the test can be stated, perhaps more simply, in these terms: Is it clear on the evidence before the Comptroller that, if the issue of obviousness (assuming that to be the ground relied on) were fought out in a full scale revocation action, the claims would be held bad for obviousness? If the answer is affirmative, then it is right that the patent should be killed in its infancy. If the answer is negative, the patentee should not be deprived of his patent without the protection of a full scale action. In other words, section 33, like section 14, is designed to clear the register of patents which are manifestly untenable. It is not intended to provide a method of disposing of truly contentious cases.
The applicant relied particularly on the observations of Lord Diplock in General Electric Company’s Application [1964] RPC 413 (mentioned above):
The right principle is that if on the face of the written evidence filed there appears to be a bona fide conflict of fact or credible expert opinion upon a question on the answer to which the existence or non-existence of the ground for refusal specified in s 14 (1) (e) depends, the [Commissioner] should not exercise his jurisdiction to refuse the grant unless, after cross-examination of the witness if he thinks fit to order it, the conflict is clearly resolved in favour of the party opposing the grant.
The opponent quoted as the classic statement of what constitutes common general knowledge The General Tire & Rubber Company Limited and Others v The Firestone Tyre and Rubber Company Limited and Others [1972] RPC 457 at 482:
The common general knowledge imputed to such an addressee must, of course, be carefully distinguished from what in patent law is regarded as public knowledge. This distinction is well explained in Halsbury’s Laws of England, Vol. 29, para. 63. As regards patent specifications it is the somewhat artificial (see per Lord Reid in the Technograph case [1971] F.S.R. 188 at 193) concept of patent law that each and every specification, of the last 50 years, however unlikely to be looked at and in whatever language written, is part of the relevant public knowledge if it is resting anywhere in the shelves of the Patent Office. On the other hand, common general knowledge is a different concept derived from a commonsense approach to the practical question of what would in fact be known to an appropriately skilled addressee - the sort of man, good at his job, that could be found in real life. ... it is clear that individual patent specifications and their contents do not form part of the relevant common general knowledge, though there may be specifications which are so well known amongst those versed in the art that upon evidence of that state of affairs they form part of such knowledge, and also that there may occasionally be particular industries (such as that of colour photography) in which the evidence may show that all specifications form part of the relevant knowledge.
The features of the invention as claimed in claim 1 are:
enalapril maleate is mixed with an alkaline sodium compound and at least one other excipient, water sufficient to moisten the mixture is added, then the whole is mixed to achieve a wet mass,
or
enalapril maleate with at least one excipient other than an alkaline sodium compound, has added to it a solution of an alkaline sodium compound in water, sufficient to moisten the mixture, then the whole is mixed to achieve a wet mass;
the result of either of these wet granulation processes is an essentially complete reaction of the enalapril maleate to the sodium salt without converting the enalapril maleate to a clear solution of enalapril sodium and maleic acid sodium salt in water; and
the completed reaction product is then dried and formed into tablets.
US Patent No. 5530582 (Marjo Merslavic et al) (‘Merslavic’)
This was said to be available at IPONZ from 27 October 1994. This specification corresponds to European patent application no. 92119896.6 (now to be amended to U S Patent No 5530582 in the complete specification) discussed in the background part of the Sherman specification.
Merslavic, in its Examples (using for illustration purposes the details of Example 1), teaches suspending enalapril maleate (250g) in demineralised water (800ml) and adding a solution of sodium hydroxide (60g in 400ml of demineralised water). A clear solution of enalapril sodium results.
Corn starch (400g) and dye stuff (30g) were added and the whole stirred to a homogeneous colour. Lactose (3125g) was then added and the wet mass dried at 40 to 500C. Corn starch (125g), talc (150g) and magnesium stearate (43g) were added and the mixture homogenised for 15 to 30 minutes. The homogenate thus prepared was used to make tablets.
Column 1, lines 30 to 55, shows enalapril maleate reacting with a stoichiometric amount of a sodium compound, such as sodium carbonate, sodium hydrogen carbonate or sodium hydroxide, to form enalapril sodium. Formulating additives are then added, the whole is homogenised and formulated.
The opponent says that the reaction disclosed in Merslavic is conceptually the same as disclosed in the claims in suit. In both processes a dissolved sodium compound (sodium hydroxide, sodium hydrogen carbonate or sodium carbonate) reacts with enalapril maleate to produce enalapril sodium.
The opponent says that the claims in suit require that there be at least one other excipient present with the mix of enalapril maleate and the sodium compound. The function of the excipient, says the opponent, is related to tablet formulation and it does not affect the reaction to produce enalapril sodium, neutralisation reactions not being inhibited or suppressed by the presence of a neutral non-reactive ingredient.
The opponent submits that the presence of an excipient in the wet granulation process will not significantly affect the reaction process. Although some lactose will be dissolved in the water there would still be water available to facilitate reaction between the enalapril maleate and the sodium compound.
The applicant’s contrasting view is that the added excipients will have important effects. Their presence will affect the kinetics of the reaction between enalapril maleate and sodium bicarbonate. There is the physical interference in the reaction, caused by the additional moieties present in the mix, reducing the rate of enalapril maleate/sodium compound interactions. There is the ‘soaking up’ of the water by the added excipients making the water less available as a medium for the enalapril maleate/sodium compound reaction. These would be understood by the unimaginative skilled addressee.
The opponent says that to avoid prior publication with Merslavic which discloses that the reaction proceeded to form a clear solution, claim 1 of the application in suit has been worded so as to include the limitation that there is a reaction without the conversion of enalapril maleate to a clear solution of enalapril sodium and maleic acid sodium salt.
The applicant’s view on this point is that there is a different process involved. Merslavic describes a two step reaction with the first being conversion of enalapril maleate to enalapril sodium taking place in solution, followed by wet granulation. However, in the applicant’s claims the reaction is a one step wet granulation step wherein the conversion of enalapril maleate to enalapril sodium takes place during the wet granulation step. The applicant also points out that some of the enalapril sodium in solution in Merslavic will convert to enalaprilat by hydrolysis. This conversion is due to the large amount of water present. This conversion, it is submitted by the applicant, does not occur in the moist granulation conditions of the applicant’s claimed invention.
The opponent says that the skilled addressee knows of wet granulation, knows from Merslavic of the formation of enalapril sodium, recognises that in a wet granulation process enalapril maleate will be combined with sodium bicarbonate and water, and hence it will be obvious to the skilled addressee that the enalapril maleate will react with the alkaline sodium compound in a wet mix to form enalapril sodium.
The applicant submits that the prior art process of Merslavic is not the wet granulation process of the claims in suit. There are differences. The applicant says that the unimaginative skilled addressee would understand that wet granulation is expected to take place without any reaction between the ingredients of the mixture. The applicant submits that normally wet granulation is expected to produce a pharmaceutical composition that has the active ingredient in unchanged form, so that the unaltered active agent will be administered to a patient. Thus, it will not be obvious to the skilled reader that in a wet granulation process reactions would occur.
The opponent submitted that, with the skilled addressee recognising the procedural disadvantage of suspending the enalapril maleate in water, adding the alkaline compound dissolved in water, and mixing until the acid-base reaction is complete, as disclosed in Merslavic, and the stability advantages of enalapril sodium, it is obvious and clearly does not involve an inventive step to perform the same reactive process in a wet mix rather than in a full solution. The opponent submitted that the skilled addressee will choose a one-step process over the Merslavic two-step process.
The applicant’s view is that for the skilled addressee to recognise these points requires inventive capacity. In addition, the applicant was the one to recognise that that enalapril sodium is hydrolysed in water to the unwanted enalaprilat.
The opponent discussed the contention of the witnesses in support of the application that Merslavic does not teach a reaction during the wet granulation process. However, the opponent says, the skilled addressee knows (at least from Merslavic) of the enalapril maleate/sodium compound reaction, the skilled addressee knows of wet granulation, the skilled addressee knows reactions can occur during wet granulation and there is no suggestion that the neutral excipient in wet granulation will affect the reaction. It is therefore clearly obvious to conduct the reaction during wet granulation rather than by forming a solution.
The applicant contends that in wet granulation it is expected that there will be no reactions, and that the skilled addressee would not know what effect the presence of neutral excipients would have on reactions and their rates. It appears that in the last paragraph the opponent really shows that the skilled addressee would need at least a scintilla of invention to put together the various integers as suggested by the opponent. I note that a one step process was not mentioned by Merslavic.
The applicant submitted that at column 3 lines 39 to 68 of Merslavic the specification discloses that the enalapril sodium prepared in situ (ie as per Merslavic) is more stable in pharmaceutical formulations than is the case when only physical mixing of enalapril maleate and sodium bicarbonate is used, indicating a teaching away from wet granulation.
As discussed in the present specification, the process described in Merslavic requires more water and requires more equipment than would be required in the present claims. The present applicant also discovered that the presence of the aqueous solution (as in Merslavic) leads to significant hydrolysis of the active to enalaprilat. This conversion is said to be avoided in the present application by not allowing a solution of enalapril sodium to form. Further, the process of the present claims has the advantage of being a one step process. The applicant also found that an essentially complete reaction of maleate to sodium salt is achieved despite the fact that there is a relatively small amount of water present and despite the relatively large amount of lactose present.
Dr Crank contends that the only difference between the opposed application and Merslavic is the amount of water and this he says is a factor that could be examined by routine experiments. As I see it, the skilled addressee has firstly to conceive of a process using less water.
The evidence for the application is that the deponents would not have expected a complete reaction of enalapril maleate to the sodium salt in wet granulation and this outcome seems to have been counterintuitive. Further, the normal expectation of wet granulation is that it is a purely physical process designed to bind the ingredients of the formulation in a homogeneous mixture.
Merslavic would not appear to motivate a skilled addressee to attempt to achieve an essentially complete reaction of enalapril maleate to enalapril sodium in a wet granulation type formulation process in the presence of a large excess of excipient.
International Patent Application Publication No. WO 94/01093 (‘Rork’)
This document is discussed above under Prior Publication. Rork relates to the preparation of osmotic pump formulations of enalapril sodium. The rationale of such pumps is to supply a zero order, that is a constant, release of the active at the predetermined dosage. Rork describes the preparation of core tablet formulations for use in the pumps. All the tablet cores are coated with a rate controlling water-insoluble wall to allow osmotic pressure to develop within the core. One of the roles of the sodium bicarbonate, says the applicant, is as an osmogent to ‘propel’ the drug out through the coating of the tablet at a controlled rate.
The opponent submits that Rork discloses all aspects of the invention claimed. The basic concept of a wet granulation process producing an enalapril sodium tablet is said to be fully disclosed. The opponent submits that, if Rork does not prior publish the present claimed invention, then Example 1 teaches the formulation of enalapril sodium tablets by forming enalapril sodium as a solution and then using a wet granulation process to make the tablets. The chemistry of the two processes is the same. The only difference, submits the opponent, is that the claims in suit use different amounts of water than Example 1 of Rork, and include an excipient. The opponent submits that the change in amount of water and the addition of a neutral excipient is not an invention. It appears to me that neither of these changes have been shown to be obvious to the unimaginative skilled addressee and hence there appears to be at least a scintilla of invention. At least there is a doubt.
The applicant submits that as enalapril maleate is both sparingly soluble in water and weakly acidic these make it less likely that a reaction would occur between enalapril maleate and sodium bicarbonate under unfavourable low water conditions of a wet granulation.
I also note that there appears to be a greater ratio of water to enalapril maleate used in the Examples of the application in suit compared to that used in Example 7 of Rork.
It appears to me that the opponent has not made out a case of obviousness. In any event, there must at least be a doubt and this doubt must be exercised in favour of the applicant in these proceedings. It seems to me, especially with the conflict of credible expert opinion, and particularly the conflict of expert opinion as to what is happening in the wet granulation stage of Example 7 of Rork, that the matter cannot be resolved other than in the applicant’s favour.
The ground of obviousness is not made out.
DECISION
I find that the grounds are not made out. Once the amended pages are inserted in the specification letters patent are to be sealed. I note that amended pages have been supplied, these being amended pages 1 and 2 filed on 11 April 2005 and amended pages 11 and 12 filed on 14 June 2007.
COSTS
Pursuant to section 95(1), each party is to meet its own costs in relation to the hearings on the allowability of the amendment proposals (the applicant having been partly successful) and in relation to the substantive hearing (the opposition resulting
in amendment of the invention claimed), the opponent is to pay the applicant the sum of $1310-00 in relation to the hearing on obtaining, and the opponent is to pay the applicant the sum of $1035-00 in relation to the hearing concerning striking out of clauses from the opponent’s statement of case.
IPONZ is to reimburse the opponent its $4000-00 security for costs once the opponent has paid the costs to the applicant.
Dated this 13th day of August 2007
____________________________
A Hazlewood
Assistant Commissioner of
Patents
Freehills Patent & Trade Mark Attorneys for the Applicant
A J Park for
the Opponent
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