Last updated: February 19, 2026
This analysis details the patent litigation between Horizon Medicines LLC and Ajanta Pharma Ltd. concerning Horizon's drug Vimovo. The core of the dispute centers on alleged infringement of U.S. Patent Nos. 8,492,370 and 9,095,517, both covering Vimovo. Ajanta Pharma's Abbreviated New Drug Application (ANDA) for a generic version of Vimovo triggered this litigation.
What are the Patents in Dispute?
The litigation involves two Horizon Medicines patents protecting Vimovo (naproxen/esomeprazole magnesium):
- U.S. Patent No. 8,492,370: Titled "Naproxen-Esomeprazole Magnesium Compositions." This patent issued on July 23, 2013. The claims relate to specific formulations of naproxen and esomeprazole magnesium.
- U.S. Patent No. 9,095,517: Titled "Naproxen-Esomeprazole Magnesium Compositions." This patent issued on August 4, 2015. Its claims also pertain to naproxen and esomeprazole magnesium compositions, likely representing a continuation or improvement on the earlier patent.
What is Vimovo and What is its Indication?
Vimovo is a prescription medication approved for the relief of signs and symptoms of osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis in patients who require management with NSAIDs. It combines naproxen, a nonsteroidal anti-inflammatory drug (NSAID), with esomeprazole magnesium, a proton pump inhibitor (PPI), to reduce the risk of developing gastric ulcers associated with NSAID use.
What is Ajanta Pharma's Generic Product?
Ajanta Pharma Ltd. sought to market a generic version of Vimovo. Filing an Abbreviated New Drug Application (ANDA) with the U.S. Food and Drug Administration (FDA) indicates Ajanta's intent to introduce a bioequivalent version of the branded drug.
What are the Key Allegations in the Litigation?
Horizon Medicines alleged that Ajanta Pharma's ANDA and proposed generic product infringe U.S. Patent Nos. 8,492,370 and 9,095,517. Horizon sought to prevent Ajanta from launching its generic product until these patents expire or are invalidated. Ajanta Pharma, in turn, would argue non-infringement or invalidity of the asserted patents.
What is the Legal Framework for ANDA Litigation?
The Hatch-Waxman Act (Drug Price Competition and Patent Term Restoration Act of 1984) governs the abbreviated approval of generic drugs. When a generic manufacturer files an ANDA, they certify that their product does not infringe existing patents listed in the FDA's Orange Book. If the ANDA applicant certifies that a listed patent is invalid, unenforceable, or will not be infringed (a Paragraph IV certification), the patent holder is typically notified and has a limited window to file an infringement lawsuit. This lawsuit triggers an automatic 30-month stay on FDA approval of the generic drug, unless the litigation is resolved sooner.
What Was the Timeline of the Litigation?
- October 29, 2019: Horizon Medicines LLC filed suit against Ajanta Pharma Ltd. in the United States District Court for the District of Delaware, alleging infringement of U.S. Patent Nos. 8,492,370 and 9,095,517. This filing was triggered by Ajanta Pharma's Paragraph IV certification [1]. The case number is 1:19-cv-01814.
What Were the Key Legal Arguments?
Horizon Medicines argued that Ajanta Pharma's proposed generic Vimovo product would infringe one or more claims of its asserted patents. Ajanta Pharma's defense likely involved challenging the validity and/or enforceability of the asserted patents, or arguing that its product does not fall within the scope of the patent claims (non-infringement). Common invalidity arguments include obviousness, anticipation, lack of enablement, or indefiniteness of patent claims.
What Was the Outcome of the Litigation?
On October 19, 2023, the District Court issued a Markman Order, construing claims 1-7 and 10-13 of the '370 patent and claims 1-9 of the '517 patent. The court’s claim constructions are critical for determining infringement and validity.
Following the Markman ruling, the parties engaged in further proceedings. On November 1, 2023, a Joint Stipulation of Dismissal with Prejudice was filed, indicating a settlement between Horizon Medicines and Ajanta Pharma. This means that both parties agreed to resolve their disputes, and the case was dismissed from court. The terms of the settlement are confidential and were not disclosed.
What Are the Implications of the Settlement?
The settlement between Horizon Medicines and Ajanta Pharma means that the litigation over U.S. Patent Nos. 8,492,370 and 9,095,517 concerning Vimovo has concluded. The specific terms of the settlement would dictate the timeline for Ajanta Pharma's generic launch. Settlements in ANDA litigation often involve a licensing agreement, allowing the generic manufacturer to launch its product on a specific date, often before the patent expiration but after a negotiated period. This avoids further costly litigation and provides certainty for both parties. The 30-month stay on FDA approval is lifted upon dismissal of the case, although the FDA may still take time to review the ANDA based on its own procedures.
Key Takeaways
- Horizon Medicines LLC defended its patents U.S. Patent Nos. 8,492,370 and 9,095,517 for Vimovo against Ajanta Pharma Ltd.'s generic entry.
- The litigation, filed in October 2019, concluded with a settlement and a Joint Stipulation of Dismissal filed on November 1, 2023.
- The District Court issued a Markman Order on October 19, 2023, construing key patent claims, which likely informed the settlement negotiations.
- The confidential settlement terms will dictate the market entry of Ajanta Pharma's generic Vimovo product.
Frequently Asked Questions
1. When was the lawsuit filed?
The lawsuit was filed on October 29, 2019.
2. What were the asserted patent numbers?
The asserted patent numbers were U.S. Patent No. 8,492,370 and U.S. Patent No. 9,095,517.
3. Did the court rule on patent validity or infringement?
The court issued a Markman Order construing patent claims on October 19, 2023. However, the case was subsequently settled before a final ruling on validity or infringement.
4. What does a "Joint Stipulation of Dismissal with Prejudice" mean?
This stipulation means both parties agreed to resolve the dispute and have the case terminated. "With prejudice" means that Horizon Medicines cannot refile the same lawsuit against Ajanta Pharma based on these patents and allegations.
5. When can Ajanta Pharma launch its generic Vimovo?
The specific launch date is governed by the confidential terms of the settlement agreement and is not publicly disclosed.
Citations
[1] Complaint for Patent Infringement, Horizon Medicines LLC v. Ajanta Pharma Ltd., No. 1:19-cv-01814 (D. Del. Oct. 29, 2019).
