Product-by-Process: Perception by Indian Patent Law

14 November 2023

by Pranjal Dhiman Archana Viswanathan

This article aims to explore the scope of patentability and infringement concerning product-by-process claims with a specific emphasis on the recent two decisions of the Delhi High Court, passed by the learned Single Judge and the Division Bench of the Delhi High Court in the case of CS(COMM) 261/2021 and connected matters.

These suits were filed by Vifor against the Defendants i.e., (i) MSN Laboratories Private Limited and (ii) MSN Life Sciences Pvt. Ltd. (collectively referred to as “MSN”) in CS(COMM) 261/2021; Dr. Reddy’s Laboratories Limited (“DRL”) in CS(COMM) 265/2021; and (i) Corona Remedies Private Limited and (ii) Virchow Biotech Private Limited (“CRPL and VBPL”) in CS(COMM) 448/2022. The fourth suit was filed by CRPL and VBPL against Vifor in CS(COMM) 450/2022.

In a detailed judgement discussing whether an interim injunction should be granted against the Defendants, the Single Judge of the Delhi High Court permitted the Defendants to launch their product, with a caveat that Defendants shall not use a process/set of processes which infringes the Suit Patent. However, the Division Bench has placed a stay on said order.


-    The Suit Patent in question, IN 221536 (“IN’536”) is held by Vifor (International) Ltd. (“Plaintiff”) and is titled ‘Water Soluble Iron Carbohydrate Complex and A Process for Producing Water Soluble Iron Carbohydrate Complex’. The Suit Patent relates to FERRIC CARBOXYMALTOSE (“FCM”) which can be used for intravenous treatment of iron deficiency. The said patent has expired recently on 20th October 2023.

-    According to the Plaintiff, claim 1 of IN’536 is a product by process type of claim and recites water-soluble iron carbohydrate complexes, whereas the claims 2-6 recite a process for producing aforesaid iron carbohydrate complex. In furtherance to this, the claims 7-8 recite a medicament containing an aqueous solution of an iron carbohydrate complex and claim 9 recites water-soluble iron carbohydrate complexes for therapy.

-    In December 2020, Vifor found out about the intention of MSN to launch a generic version of FCM. Similarly, in May 2021, Vifor learnt that DRL was manufacturing FCM and was expected to release a generic version of FCM. Further, VBPL via letter dated 17 June 2022 informed Vifor that they were manufacturing FCM. The defendants claimed that their respective processes to manufacture FCM are novel and therefore, they are not infringing IN’536.

Common initial submissions by Vifor:

-    Vifor asserted that the claim 1 of IN’536 is a product claim for FCM wherein process elements are used to describe the final product as it was not easy to describe the product due to its large or complex molecular composition. Further, it mentioned that the process elements present in the claims represent an exemplary process to prepare FCM and in no way preparation of FCM can be limited to the given process. In summation, the Plaintiff emphasised that, what is claimed is the product with definite and distinctive technical features, such as average molecular weight between 80 kDa and 400 kDa, regardless of the process employed for its preparation.

-    Vifor referring to Section 2(1)(j) of the Patents Act, 1970 (“Act”) asserted that only “product” and “process” are considered as allowable/patentable subject matter and any third category such as ‘product-by-process’ does not have a statutory recognition. It also referred to the guidelines followed by IPO in examining patent applications according to which a ‘product-by-process’ claim should disclose a novel and inventive product per se and patentability cannot depend on novelty and non-obviousness of the process limitation alone. It further stated that IN’536, containing a claim in the ‘product-by-process’ format, has been allowed in India, thereby indicating that the product as such is novel and inventive independent of process features.

-    To further support that the claim 1 of IN’536 relates to a product, Vifor placed reliance on INN assigned by WHO to Vifor’s invention and that US 7612109 (corresponding US patent to Suit Patent) covering FCM, has been mentioned in the US Food and Drug Administration’s (‘US FDA’) Orange Book as the “Drug substance (DS)”.

-    Vifor indicated the strength of their patent by mentioning that patents corresponding to the Suit Patent have been granted globally in 57 countries which include major patent jurisdictions as well, such as the US and EU. It was also mentioned that no pre-grant or post-grant opposition was filed challenging the validity of the Suit Patent in the period of last 20 years.

Submissions by Defendants:

Scope of Claim 1:

-    The Defendants contended that the scope of the claim 1 of the Suit Patent is limited to a product obtained by or through the specific process provided therein, i.e., oxidation of maltodextrin using aqueous hypochlorite in alkaline pH range. The Defendants further asserted that the step of oxidation of maltodextrin using aqueous hypochlorite is an essential feature which imparted novelty and inventiveness to the claim 1 of the Suit Patent and it does not cover any or all processes that may be used to obtain FCM, or any or all processes for oxidation of maltodextrin.

-    The Defendants also mentioned that in ‘product-by-process’ claims, the claims are deemed to be novel and inventive because of the characteristic features imparted by the process to the product and the claims are never construed as product claims per se but are inextricably tied to the process of which they are the outcome/result.

-    The Defendants further relying upon Hospira UL Limited[1] and Terrel on the Law of Patent, 18th Ed., Chapter 9, Section 8, stated that in a ‘product-by-process’ claim, the product will only be infringed when the product is manufactured by the process recited in the claim of the Suit Patent and thus, to make a case of infringement, Vifor needs to show as to how the process of the Defendants maps with the process claimed in Suit Patent.

-    The Defendants asserted that Vifor’s product FCM is an iron carbohydrate complex which would include any molecule consisting of iron ions and a carbohydrate shell and such a molecule is already recognized in the industry by several other names.

Reliance on the prosecution history by the Defendant:

Referring to the prosecution history of the Suit Patent and the corresponding applications, the Defendants made following assertions:

-    Vifor has admitted multiple times in the opposition filed by them to IN3474/CHE/2013 that claim 1 of IN’536 is a process claim.

-    In the response filed by Vifor during the prosecution of EP1554315B1 (hereinafter referred to as EP’315), it was specifically mentioned that the claim 1 of EP’315 is different from the cited prior art disclosing oxidation of dextrin and dextran because of employing aqueous hypochlorite in EP’315, thereby admitting that the only feature which distinguishes the claim 1 from the prior art is the step of oxidation of maltodextrins using aqueous hypochlorite in alkaline pH range.

-    During the prosecution of IN’536 in India, when a document disclosing iron carbohydrate complex was cited, Vifor argued that its product was novel in view of the cited document because of using ‘oxidised maltodextrin’ in the process.

Infringement analysis:

The Defendants stated that their process is different from the process of Vifor and hence, not infringing the Suit Patent. The differences as submitted by the Defendants are summarised below:

-    The process employed by MSN and DRL for the manufacture of FCM involves use of oxone, as a maltodextrin-oxidising agent, instead of aqueous hypochlorite as used by Vifor, wherein the chemical and the physical properties of oxone and sodium hypochlorite are distinct and use of oxone provides the additional advantage of increasing the yield and purity of iron (III) carboxymaltose by decreasing the amount of unwanted chlorinated by-products, inorganic impurities such as metal bromides, chlorides and carbonates.

-    VBPL and CPL use starch hydrolysate as the reactant instead of maltodextrin as employed by Vifor. Thus, the product of the Defendants consists of a carbohydrate shell made of starch and iron being placed at the centre, prepared from hydrolysed starch having DE value of higher than 20 which is different from maltodextrin.

Final submissions by Vifor:

-    Vifor submitted that the three essential elements of claim 1 of IN’536 are iron carbohydrate complex having (i) an iron (III) core; (ii) an average molecular weight in the range of 80 kDa-400 kDa; and (iii) using oxidized maltodextrin as ligand. Vifor asserted that all the Defendants’ products contain each of the three essential elements of IN’536 and the difference in oxidizing agent as mentioned by the Defendants is not an essential element of the claim 1 of Suit Patent.

-    Vifor further referred to the paragraph 147(i) in Hospira UL Limited (supra), wherein Justice Birss recognises that when a claim relates to a new product, scope of the claims reciting the terms ‘obtainable’ and ‘obtained’ would be different. In this view, FCM is a new product and the term recited ‘obtainable from’ would not limit its scope to any specific method/process. Vifor concluded that the defendants cannot avoid infringement of the product FCM by merely asserting that their process is different.

Court’s view (Single Judge):

The Court referring to the ‘Guidelines for Examination of Patent Applications in the Field of Pharmaceuticals’, firstly stated that the IPO acknowledges product-by-process type of claims and secondly, the patentability of product-by-process claim depends upon the product itself if it does not depend upon the method of production, which highlights that process terms in such claims are limitations and not additional features of the product. Thirdly, the Court further made clear that one cannot compare the assessment of novelty and infringement as they are unrelated and have to be analysed separately.  

Scope of Claim:

-    The Court analysed the scope of claim while discussing claim construction. The Court stated that the Claim 1 is not a ‘product claim’ as a product needs to be characterized by its physical and chemical composition as well as physical and chemical structure, and shall not to be restricted by a method/process.

-    The Court further stated that the Claim 1 of the Suit Patent recites ‘water-soluble iron carbohydrate complexes’ wherein ‘obtainable from’ is the transition phrase and the process features recites the limitations to the preamble. The Court mentioned that the claimed process resulted in iron carbohydrate complexes with an average molecular weight between the range of 80 kDa to 400 kDa, i.e., the unique and characteristic property of FCM is due to the process employed by Vifor. Thus, the essence of the claimed invention of the Suit Patent is in preparing iron carbohydrate complexes starting from maltodextrin as the reactant and/or oxidation of maltodextrin via aqueous hypochlorite solution.

In view of the above reasonings, the Court concluded that the scope of Claim 1 of IN’536 is limited to a product obtained through a specific process feature identified therein and cannot cover any and all processes that may be used by a third party to produce FCM and it is thus held that Claim 1 is a product-by process claim and not a pure product claim.

Infringement analysis:

-    The Court relied upon the US concept of “Markman Hearing” and the principles of claim construction as laid down in the case of in F. Hoffmann-La Roche Ltd. & Anr., to conduct the infringement analysis. Such infringement analysis was conducted by a two-fold step; first, by determining the meaning and scope of the claims of the Suit Patent; and second, comparing the allegedly infringing products/process.

The Court opined that the infringement analysis is to be made by focussing on the process as a limitation and the product would be considered to be infringed only by a product made by the same process.

The Court also referred to CS(OS) 1206/2015 filed by Vifor, wherein the Defendants were allowed to prepare FCM of Suit Patent by employing a different method which did not infringe the patent of Vifor thereby indicating that IN’536 is a product-by-process patent, otherwise the Court would have granted injunction.

-    While comparing Vifor’s process and that of the Defendants, the Court noted that the essential features of IN’536 are: (a) iron (III) core; (b) oxidized maltodextrin having DE value between 2-20; (c) pH value within the alkaline range; (d) end product with average molecular weight 80-400 kDa; and (e) oxidation of maltodextrin is carried out using ‘sodium hypochlorite’ as oxidizing agent. The Court stated that VBPL and CRPL use starch hydrolysate as a reactant for the reaction wherein the DE value is more than 20, and MSN and DRL manufacture FCM by using oxone as an oxidizing agent. The Court also noted the physical/chemical properties of oxone and sodium hypochlorite being different and the advantages of using oxone as highlighted by the Defendants.

In view of the above, the Single Judge order concluded that the process employed by the Defendants to produce FCM is outside the limits of the scope of IN’536 as the Patent protection secured by product-by-process claim(s) is restricted by the process of preparing the product. The Court held that the impugned processes of MSN, DRL, CRPL and VBPL are non-infringing and further permitted the Defendants to launch their product, i.e., FCM, with a caveat that Defendants shall not employ the process as claimed under IN’536, which infringes the Suit Patent.

Court’s view (Division Bench):

The Division Bench set aside the directions in the Single Judge order and stated that they are unable to concur with the learned Single Judge who has understood it to be a product by process patent alone. The Division Bench stated the claim 1 of the Suit Patent recites a product and the claims 2 to 6 recites a process and further took note of Clause 7.9 of the “Guidelines for Examination of Patent Applications in the Field of Pharmaceuticals”. The Division Bench further acknowledged that the Defendants were unable to invalidate the claim of Suit Patent with respect to novelty.


The Division Bench of the Hon’ble High Court of Delhi supports the requirements defined by Clause 7.9 of the “Guidelines for Examination of Patent Applications in the Field of Pharmaceuticals” for product-by-process claims. The Division Bench’s order provided some degree of clarity regarding product-by-process claims. The order emphasized that the scope of such claims primarily pertain to the product itself, with the process elements not imposing a limitation on the product. Consequently, the patentability and infringement analysis for product-by-process claims should predominantly focus on the product feature stated in the claim. The Division Bench also acknowledged the delay in judgment, i.e., more than 7 months due to which several technical documents were not taken in consideration. Thus, importantly, this order is a re-assessment of the product-by-process claims as per Indian Patent Law.

[The authors are Associate and Principal Associate, respectively, in IPR practice of Lakshmikumaran & Sridharan Attorneys, New Delhi]



[1] “143. However, a question not focused upon by Lord Hoffmann in Kirin- Amgen is whether the rule that the process feature is irrelevant for novelty is a rule of law of novelty or a rule of mandatory claim interpretation. To be novel, a claim of erythropoietin made by the expression of a gene in a host cell had to be different from known urinary erythropoietin. But assuming that the claim was novel, was it infringed by erythropoietin which had not been made by the expression of a gene in a host cell?

Now the House of Lords also decided that the defendant’s rEPO did not infringe the patent because it was not the product of the expression of a gene in a host cell (see paragraphs 13 onwards, ending at paragraph 85 which finds no infringement of any claim). Thus Lord Hoffmann was applying the process feature as a relevant limitation which was not satisfied for the purposes of (non- )infringement but ignoring it for the purposes of novelty. That can only be on the basis that the product by process rule is a rule of novelty law, not claim construction.”

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