Vifor International Ltd (hereinafter referred to as Vifor) is a pharmaceutical company of Switzerland, incorporated in 1991. The company was granted a patent in India, patent no. IN 221536 titled ‘Water Soluble Iron Carbohydrate Complex and a process for producing Water Soluble Iron Carbohydrate Complex’, (hereinafter referred to as “IN’536”). The granted patent related to Ferric Carboxymaltose (hereinafter referred to as “FCM”) which is a water soluble iron carbohydrate of complex of iron and oxidation product of one or more maltodextrins. Application for the grant of a patent was filed in India on 25^th May 2005 which was granted on 25^th June 2008. Emcure Pharmaceuticals Ltd. of Pune, Maharashtra, India, entered into a non-exclusive Licence Agreement dated 25.01.2012 for commercialisation of FCM in India. 

FCM treats iron deficiency and is administered intravenously and thus is a very useful replacement when other treatments are ineffective. The prior art iron preparations were based on sucrose and dextran, stable up to 100ºC only, rendering their sterilisation difficult. Further, dextran based complexes could introduce anaphylactic shock. Thus, a need existed for an iron preparation which was free from the adversities of the prior art and FCM fulfilled that need.

In December 2020, Vifor came to know that MSN Laboratories Private Limited and (ii) MSN Life Sciences Pvt. Ltd. (hereinafter collectively referred to as “MSN”) were intending to launch a generic, infringing FCM. Vifor was also informed that MSN was manufacturing FCM, claiming their process to be novel and inventive and not infringing IN’536. It may also be stated that a patent application was also filed by Virchow Biotech Pvt Ltd (hereinafter VBPL) claiming a process for the preparation of FCM. Other companies like Dr. Reddy’s Laboratories Limited (hereinafter referred to as “DRL”) and Corona Remedies Private Limited were also allegedly infringing IN’536. Vifor filed suits before the High Court of Delhi at New Delhi, demanding interim injunction against all the companies alleging infringement of IN’536. The issues were decided by a common judgement delivered by the High Court of Delhi on 24^th July 2023 (CS(COMM) 261/2021 and connected matters).

Contention of the Plaintiff

Vifor claimed that Claim 1 of IN’536 is a product claim for FCM and could also be described as a ‘product-by-process’ claim, which was a common practice while drafting claims. The process elements are used to describe the end product which forms the subject matter of the claim and the process elements were not limiting. It averred that Claim 1 was a product per se claim and even if the product claimed is prepared using an alternative process, it would still amount to infringement as the process elements were claimed only for illustrative purpose. It tried to substantiate its stand that on the date of filing of the priority application in 2003, the product could not be structurally defined completely and therefore, the language of product-by-process claim was adopted.

Claim 1 IN’536 reads as follows “Water soluble iron carbohydrate complexes obtainable from an aqueous solution of iron (III) salt and an aqueous solution of the oxidation product of one or more maltrodextrins using an aqueous hypochlorite solution at a pH-value within the alkaline range, where, when one maltodextrin is applied, its dextrose equivalent lies between 5 and 20, and when a mixture of several maltodextrins is applied, the dextrose equivalent of the mixture lies between 5 and 20 and the dextrose equivalent of each individual maltodextrin contained in the mixture lies between 2 and 40, wherein the obtained iron complexes have an average molecular weight of 80 kDa to 400 kDa.

Vifor averred that FCM is a product covered directly under IN’536 and has definite and unique characteristic features, such as average molecular weight between 80 kDa and 400 kDa and manufacture by any unauthorised entity of a product which exhibits the same characteristics, would amount to infringement of IN’536, by virtue of Section 48 of the Indian Patents Act 1970. The products of the defendants fell within the claimed molecular weight range.  

Contention of the defendants

The defendants contended that the three prior art complexes identified in the suit patent are iron carbohydrate, iron-dextran, iron-pullulans or water soluble iron (III) hydroxide sucrose complex. Problems of the prior art identified in IN’536 are all process related, i.e., such prior art complexes are difficult to obtain and require production under pressure and high temperature and involve a hydrogenation step.

The defendants further averred that description is silent on head-to-head comparison between iron-dextran and FCM and there is no disclosure whatsoever as to the nature and character of the prior art iron-carbohydrate complexes and the problems which are overcome by FCM. The first paragraph on page 2 of IN’536 reflects that the problem(s) identified in the prior art is solved only by an iron (III) carbohydrate complex, which is obtainable using the oxidation products of maltodextrin and the only oxidation route identified is using aqueous hypochlorite.

Oxidation of maltodextrins yielding products in a molecular weight range of 80kDa to 400 kDa, was known in the prior art and the only novel and inventive step lies in the oxidation of maltodextrins using aqueous hypochlorite in the alkaline pH range. The contention of the plaintiff that irrespective of the process adopted, obtaining FCM through any other process would infringe IN’536, does not stand up to scrutiny. Further, opposition filed by the plaintiff in February, 2020 to the application no IN 3474/CHE/2013 admits in many places that claim 1 of IN’536 is a process claim.

Discussion and analysis

Though Indian Patents Act 1970 does not refer to the expression “product-by-process” but it finds mention in the Guidelines for examination of patent applications in the field of pharmaceuticals issued by the Indian patent office, with illustrative examples for determination of novelty for product-by-process claims. It lays down that a product-by-process claim must also define a novel and unobvious product and that its novelty cannot rest on the novelty and non-obviousness of the process alone. In other words, a product-by-process claim is to be tested on the anvil of novelty and inventiveness for the product and the novelty and inventiveness of the process.   

The High Court of Delhi averred that the preamble of Claim 1 of IN’536 recites ‘water-soluble iron carbohydrate complexes’ and ‘obtainable from’ is the transition phrase. The process steps claimed results in iron carbohydrate complexes with a defined average molecular weight between 80 kDa to 400 kDa. In case a product is claimed, it must be described by its composition and structure, both physical and chemical and should not be limited by a process. Vifor claims that claim 1 is a product claim without describing the product.  

There is an admission by Vifor that use of iron carbohydrate complexes is known and a water-soluble iron (III) hydroxide sucrose complex is a frequently and successfully used preparation. During prosecution in India, Vifor stated that the essence of invention resided in appropriately selecting suitable maltodextrins, having specific Dextrose Equivalent as defined in the claims and oxidizing them stereoselectively and regioselectively at the terminal aldehyde group and then by reacting them with iron (III) salts, as a result of which iron (III)-oxidized maltodextrin complexes are obtained, which are polynuclear complexes, having a specific high average molecular weight. The maltodextrins and the oxidation process are known, but the new feature of the present invention is that the obtained iron complexes are very stable to heat, have a very low toxicity, a low risk of anaphylactic shock, sterilized by heating and can be given intravenously. The process disclosed by the defendants included starch hydrolysate with dextan equivalent > 25 and therefore, the starting material itself was different from that used by the plaintiff. In another variation, oxidizing agent was oxone which was different from that used by the plaintiff. Iron carbohydrate complexes with a molecular weight ranging from 80 kDa to 400 kDa were known in the prior art. The process disclosed by the defendants appeared to be different from the process claimed by the plaintiff and also it appeared that the product claimed was known in the prior art. Therefore, the interim injunction against defendants was not granted. However, the defendants were directed to maintain the account books till the final adjudication.

It is felt that the battle for interim injunction was lost because of inadequate effort by the plaintiff for characterising the product and bringing out its novelty. As disclosed hereinabove, the product had a number of advantages over the prior art products and it would have been worthwhile to dwell on the product characterisation as well. It appears that Vifor failed to capitalize on this aspect.

In a concluding para of the judgment, the High Court of Delhi averred that in order to succeed in establishing its claim for infringement even at the prima facie stage, Vifor is required to show that the rival processes to manufacture FCM are identical, which burden Vifor has failed to discharge. The conclusion is at complete variance with the section 104A (1) of the Indian Patents Act 1970 which states that in case of suits concerning infringement of a patent, where the subject matter is a process for obtaining a product, the court may direct the defendant to prove that the process used by him is different from the patented product. Thus, it was the defendant who was to prove that alleged infringing process was different from that of the patented process. The burden of proof regarding a process related infringement lies with the defendant and not with the plaintiff.

It is re-iterated that there is no statute in the Indian Patents Act 1970 regarding product-by-process claims. Reference to the Guidelines for examination of patent applications in the field of pharmaceuticals, issued by the Indian Patents Office, can at best be considered persuasive. Nevertheless, it is perhaps for the first time that a judgement has dealt extensively on the subject matter of product-by-process claims.

Global perspective on product-by-process patent claims

It may be worthwhile to look at global perspective on these issues.

EPO accepts product-by-process claims only if the product is different form an existing product and the difference may not be describable in chemical and physical terms (Flavors & Fragrances Inc [1984] OJ EPO 309). The EPO's approach to such claims is settled today and are permitted only if there is no other way available to the inventor for defining the product.  

Donald Chisum in his ‘Chisum on Patents: A Treatise on the Law of Patentability, Validity and Infringement’ defines a product-by-process claim as one in which the product is defined at least in part in terms of the method or process by which it is made. This definition has been referred to by the Court of Appeals for the Federal Circuit of the United States in Atlantic Thermoplastics Co., Inc. v. Faytex Corporation, 970 F.2d 834. Thus, the process claims and product characteristics are integrated and are incomplete without each other.

The courts have also considered the thin line between: a) product ‘obtained by’ a process; and (b) a product ‘obtainable by’ a process (Hospira UL Limited v. Genentech Inc., [2014] EWHC 3857 (Pat). These two at-least prima-facie appear to be different. A product “obtained by” a process would be infringed only if a product was made that way in which it is claimed in the claim. If the product was made in any other way in the prior art, it would have no bearing on the process claimed. This was the view taken of product by process claims in the Court of Appeal in Kirin Amgen ([2002] EWCA Civ 1096, [2003] RPC 3). The word "obtainable by" was intended to claim a product irrespective of how it was made but with a particular product characteristic which is the same characteristic which results from using a given process (Johnson Matthey case cited in argument (T956/04). For example, if the distribution of catalyst particle size produced by a process, resulted in a beneficial catalytic property, it may not matter how the specific particle size was produced. In such a case, the particle size distribution process may have been claimed only for illustrative purpose and therefore ‘obtainable by’ word used. The view taken by the EPO in the 1980s (IFF / Claim Categories T150/82 and later cases T248/85 and T219/83) was firmly against that an old thing could be patented using a product by process language. If a product was known in the prior art, product-by-process language in the claims could confer novelty on the prior art product. The words “obtained by” and “obtainable by” were to be treated at par. If the process introduced specific characteristics in the product, then only it could be considered different from that in the prior art product.