Background

The Indian Patent Office has revoked Patent No. 281489, Application No. 201641013880 (relating to a Linezolid manufacturing process) following a post-grant opposition by Symed Labs.

Granted in March 2017, the patent was revoked for lack of inventive step, non-patentability under Section 3(d), and failure to disclose foreign filings under Section 8. Linezolid, used for drug-resistant TB and other infections, is under NPPA price control.

Abbott’s challenge to the price cap was rejected in October 2024. The revocation underscores the need for rigorous scrutiny of pharma patents, particularly to prevent evergreening.

OPPOSITION DETAILS

• • Filed by: Symed Labs
  • Filing Date: 5 March 2018
  • Hearing Held: June 2024

Key Developments

• • Multiple rounds of evidence submissions
  • Patentee filed writ in Madras HC for new Opposition Board (2023)
  • Amendment request via Form 13 remained undecided pending opposition outcome

GROUNDS OF OPPOSITION (Under Section 25(2))

• • Anticipation by Prior Publication
  • Anticipation by Prior Claiming
  • Obviousness / Lack of Inventive Step
  • Not Patentable under Section 3(d)
  • Failure to Disclose Information (Section 8)

SECTION 25(2)(B) - Anticipation by Prior Publication

• • Opponent cited abandoned/refused earlier patents by same applicant
  • Patentee claimed different intermediates + use of sodium hydride
  • Decision: Anticipation not established — cited docs lacked detailed embodiment or parameters

SECTION 25(2)(C) - Anticipation by Prior Claming

• • Opponent’s Argument: Relied on documents already cited under Section 25(2)(b)
  • Issue: Cited documents were published before the patentee’s priority date
  • Legal Requirement: Section 25(2)(c) applies to claims published after the patentee’s priority date but with an earlier filing date
  • Decision: Patent Office rejected the ground as the cited documents did not meet the statutory criteria

SECTION 25(2)(E) - Obviousness / Inventive Step

Opponent’s Claim  -

• Patent was a mere “workshop improvement” using known techniques
• Cited patents:
  • • No. 449110 (Benova Labs)
    • No. 213062 (Symed Labs)
• Prior art disclosed safe, cost-effective inorganic bases (e.g., sodium/potassium bases)
• No technical advantage shown by the patentee

Patentee’s Argument

• • Process results in faster reaction, better yield and purity
  • Sodium hydride not taught in the same context in prior art
  • Reagent used in commercial manufacturing safely

Patent Office Conclusion

• • Process is known based on cited prior art
  • Did not provide detailed reasoning
  • Section 3(d) objection upheld – patent lacks novelty or enhanced efficacy

SECTION 25(2)(H) - Failure to Disclose Foreign Applications

Under section 8 of the Patents Act, the patentee is mandated to disclose foreign applications.

The patent office had noted that till the time of hearing the patentee has not taken any steps to disclose the same.

Further adding that the disclosure under Form 18A cannot be equated with the disclosure under Form 3 for foreign application disclosures. Therefore, holding this ground to be maintainable.

WAY FORWARD

The decision appears to have fairly considered arguments from both sides before revoking the patent. However, it is notable that the Patent Office overlooked key procedural requirements, particularly the mandatory disclosure under Section 8 via Form 3. This oversight raises concerns about the level of scrutiny during the grant stage. Similarly, the grounds of obviousness and Section 3(d), supported by clear prior art, should have been more rigorously examined early on. Given the public health implications of pharmaceutical patents, stricter and more careful evaluation under Section 3(d) is essential.