By Swaraj Singh Raghuwanshi and Subhashree Priyadarshinee
Introduction
In the case of Frimline Private Limited & Anr. v. K-Smatco Lifesciences Private Limited & Ors.[1], the Hon’ble Delhi High Court examined the scope of patent protection where the claims employ the transitional term “comprising”. The decision reiterates settled principles relating to claim construction and provides guidance on how specifications may influence the interpretation of patent claims, particularly in pharmaceutical patents.
Brief facts of the case
In this case, the Indian Patent No. 382949 of patentee Frimline Private Limited (hereinafter referred to as the Appellant) titled “A Pharmaceutical Composition for Anaemia”, disclosed a pharmaceutical composition comprising a synergistic combination of Lactoferrin and Guanosine Nucleotide or its salts for the treatment of iron deficiency anaemia, anaemia of inflammation and certain neuro-degenerative disorders.
The Appellant is in the business of marketing products based on the patented invention under the brands FERRONEMIA, FERRONOMIC and allied products since 2018.
In July 2025, the Appellant discovered that FERROTOK PLUS, marketed by K-Smatco Lifesciences Private Limited and others (hereinafter referred to as the Respondent), allegedly incorporated the same active ingredient combination in its drug. Consequently, the Appellant instituted a suit seeking relief for patent infringement along with an application for interim injunction.
Claims in issue
- Claim 1 relates to a pharmaceutical composition comprising Lactoferrin and one or more Guanosine Nucleotide or a pharmaceutically acceptable salt thereof, with Lactoferrin present in specified weight percentages.
- Claim 2 limits the Guanosine Nucleotide may be selected from Guanosine monophosphate (GMP), Guanosine diphosphate (GDP), Guanosine triphosphate (GTP) or combinations thereof.
The Appellant claimed that the Respondents’ product contained Disodium Guanosine 5-Monophosphate (DGMP), which was not expressly named in either claim.
Issues Before the Court
- Whether the use of the term “comprising” in Claim 1 renders the claim open-ended and non-restrictive?
- Whether patent claims must be interpreted in conjunction with the specification?
- Whether the Appellant had made out a prima facie case of infringement?
Submissions on behalf of the Appellant
The Appellant submitted that the use of the term “comprising” in Claim 1 rendered the claim open ended and non-restrictive. It was argued that DGMP, being a salt of a Guanosine Nucleotide, fell within the scope of Claim 1.
It was further argued that claims could not be construed in isolation and must be read in conjunction with the complete specification. The detailed description of the Invention expressly referred to DGMP as one of the contemplated embodiments, and one of the working examples included a formulation containing DGMP.
The Appellant relied on the decision of the Division Bench of the Delhi High Court in the case of F. Hoffmann-La Roche Ltd. v. Cipla Ltd.[2] and on the excerpts from the Book- Terrell on the Law of Patents, to submit that the term “comprising” is enabling in nature and does not confine the claim to the elements specifically mentioned.
Submissions on behalf of the Respondents
The Respondents argued that DGMP was not specifically claimed and therefore fell outside the scope of the patents. It was contended that patent protection must be restricted to the subject matter expressly recited in the claims, and that extending protection to unclaimed compounds would amount to an impermissible expansion of the patent monopoly.
Findings of the Court
Interpretation of the Term “Comprising”
The Court held that the use of the term “comprising” in Claim 1 clearly indicated an open-ended claim. Relying on the decision in Roche v. Cipla[3], and standard patent law principles, the Court observed that the term permits inclusion of variants and salts falling within the invention as disclosed in the specification.
Claims Read in Conjunction with the Specification
Placing reliance on the Hon’ble Supreme Court’s decision in the case of Biswanath Prasad Radhey Shyam v. Hindustan Metal Industries[4] the Court reiterated that patent claims must be interpreted in conjunction with the complete specification.
Upon examining the Detailed Description of the Invention and the examples, the Court noted that DGMP was expressly disclosed as an embodiment of the invention. On this basis, the Court concluded that DGMP was covered by the suit patent notwithstanding its absence from Claim 2.
Prima Facie Case of Infringement
The Court mapped the constituents of the Respondent’s product against Claim 1 and found that FERROTOK PLUS contained Lactoferrin and DGMP, thereby satisfying the claim requirements. The Appellant was held to have established a strong prima facie case of infringement. Consequently, the Court granted an interim injunction restraining the Respondent from manufacturing, marketing, distributing or otherwise commercializing the infringing product during the subsistence of the patent.
Key takeaways
- The decision reiterates that the use of the term “comprising” in patent claims results in broader claim coverage and allows inclusion of variants disclosed in the specification.
- It reinforces the principle that claims must be read in conjunction with the specification and not in isolation.
- The ruling highlights the importance of careful claim drafting and comprehensive disclosure, particularly in pharmaceutical patents where multiple variants and salts may be commercially relevant.
Practical Considerations for Claim Drafting
The Frimline ruling highlights the strategic importance of open-ended transitional phrases like “comprising” in claim drafting. Unlike restrictive phrases such as “consisting of” or “consisting essentially of”, “comprising” signals that a claim is not limited to the listed elements alone. For instance, a claim drafted as “a pharmaceutical composition comprising compounds A, B, C, and D” protects formulations containing these compounds as well as additional variants, salts, or functional equivalents disclosed in the specification. Careful selection of transitional language can therefore significantly influence the breadth of protection, particularly in pharmaceuticals where minor modifications or salts may have substantial commercial relevance. Drafting claims with a clear understanding of open-ended phrasing ensures maximum coverage while maintaining clarity and enforceability.
Conclusion
The decision of the Delhi High Court in the instant case of Frimline v. K-Smatco Lifesciences reaffirms that:
- “Comprising” in patent claims confers broader protection than restrictive transitional terms.
- Claims must be read in conjunction with the specification to determine the full scope of the invention.
- Careful use of transitional language is critical to claim breadth and enforceability, particularly in industries like pharmaceuticals where minor variations carry commercial significance.
The ruling serves as a practical guide for patent drafters, patentees, and potential competitors alike, emphasizing that strategic language choices during claim drafting can materially affect the scope of patent protection in India.
[1] CS(COMM) 808/2025, decided on August 29, 2025
[2] 2015 SCC OnLine Del 13619
[3] ibid
[4] (1979) 2 SCC 511