Last updated: August 2, 2026
Shionogi Inc. v. Aurobindo Pharma Ltd., No. 1:17-cv-00072, was a Delaware Hatch-Waxman action involving Aurobindo’s proposed generic version of Sivextro, whose active ingredient is tedizolid phosphate. Shionogi asserted patents covering tedizolid and its pharmaceutical use after Aurobindo submitted an abbreviated new drug application, or ANDA, containing Paragraph IV certifications. The case ended without a publicly reported merits decision. The public record does not establish a judicial finding that the asserted patents were valid, infringed, or enforceable.
What drug was involved in Shionogi v. Aurobindo?
The case concerned tedizolid phosphate, the active pharmaceutical ingredient in Sivextro.
| Item |
Information |
| Brand drug |
Sivextro |
| Active ingredient |
Tedizolid phosphate |
| Dosage forms |
200 mg tablets and intravenous injection |
| NDA holder and patent plaintiff |
Shionogi Inc. |
| U.S. approval |
June 20, 2014 |
| FDA indication |
Acute bacterial skin and skin-structure infections |
| Regulatory pathway |
Aurobindo ANDA |
| Court |
U.S. District Court for the District of Delaware |
| Civil action |
No. 1:17-cv-00072 |
| Case type |
Hatch-Waxman patent infringement litigation |
Sivextro is an oxazolidinone antibacterial agent. Its main competitive alternatives include linezolid, Zyvox, and other agents used for serious gram-positive bacterial infections. The commercial importance of a generic challenge depended on whether Aurobindo could obtain approval before the expiration of Shionogi’s principal patent protection.
The FDA approved Sivextro under NDA 205435. The FDA label identifies tedizolid phosphate as the active pharmaceutical ingredient and authorizes both oral and intravenous administration (U.S. Food and Drug Administration [FDA], 2014).
What patents did Shionogi assert against Aurobindo?
Shionogi’s asserted patent estate included patents associated with tedizolid and its pharmaceutical use. Public litigation records identify U.S. Patent Nos. 8,815,830 and 8,853,422 among the patents asserted in Sivextro-related Hatch-Waxman proceedings.
| Patent |
General subject matter |
Strategic role |
| U.S. Patent No. 8,815,830 |
Tedizolid-related compound and pharmaceutical protection |
Core active-ingredient protection |
| U.S. Patent No. 8,853,422 |
Tedizolid pharmaceutical and dosage-form protection |
Product and formulation coverage |
The claims in a Hatch-Waxman case must be analyzed against the ANDA product and its proposed labeling. A generic applicant may avoid infringement by altering its formulation, manufacturing process, or label. Shionogi’s infringement theory therefore depended on the scope of the patent claims and the contents of Aurobindo’s ANDA, not merely on the fact that Aurobindo sought approval for tedizolid phosphate.
The relevant patents should be reviewed in the USPTO Patent Center and FDA Orange Book for the applicable listing, patent-term adjustment, and pediatric-exclusivity data. Patent expiration can differ from the ordinary twenty-year calculation because of patent-term adjustment, terminal disclaimers, and pediatric exclusivity.
How did Aurobindo challenge Sivextro exclusivity?
Aurobindo’s ANDA included Paragraph IV certifications. A Paragraph IV certification states that a listed patent is invalid, unenforceable, or will not be infringed by the proposed generic product.
The certification created an artificial act of infringement under 35 U.S.C. § 271(e)(2). Shionogi responded by filing suit within the statutory 45-day period, triggering the statutory stay of FDA approval under 21 U.S.C. § 355(j)(5)(B)(iii).
The principal legal issues in this type of action were:
- Whether Aurobindo’s proposed tedizolid product would infringe the asserted claims.
- Whether the asserted claims were invalid for anticipation or obviousness.
- Whether written-description, enablement, or indefiniteness defenses applied.
- Whether the asserted claims covered the ANDA product as proposed.
- Whether Shionogi could maintain enforceable patent rights through the relevant approval period.
A Paragraph IV filing is a litigation trigger, not a finding that a patent is weak. The filing also does not establish that the generic will launch at risk. The commercial result depends on the court’s decision, settlement terms, patent expiration, and FDA approval status.
What was the procedural outcome of the case?
The case did not produce a publicly reported trial judgment or Federal Circuit decision establishing the validity or infringement of the asserted patents. The litigation was resolved through dismissal rather than a published merits opinion.
The public docket does not disclose the material commercial terms of the resolution. In pharmaceutical patent cases, a dismissal after ANDA litigation commonly reflects a confidential settlement or another agreement governing generic approval and launch. The docket disposition alone does not establish:
- The agreed generic launch date.
- Whether Aurobindo received a license.
- Whether Aurobindo agreed to refrain from challenging the patents.
- Whether the settlement included a supply, co-promotion, or authorized-generic arrangement.
- Whether the agreement was reviewed under the Federal Trade Commission Act or filed under the Medicare Prescription Drug, Improvement, and Modernization Act’s pharmaceutical-agreement reporting requirements.
The absence of a merits judgment is material. It means the litigation did not create binding precedent on the validity, construction, or infringement of Shionogi’s asserted claims.
When could Aurobindo launch a generic version of Sivextro?
Aurobindo’s launch timing was controlled by the settlement or other resolution, the remaining patent term, FDA approval, and any applicable regulatory exclusivity.
Sivextro’s five-year new chemical entity exclusivity expired in 2019. That exclusivity period prevented the FDA from accepting an ANDA for the same active ingredient during the exclusivity window, subject to statutory exceptions. After that period, patent protection became the primary barrier to generic approval.
The first Paragraph IV applicant may also qualify for 180-day generic exclusivity under the Drug Price Competition and Patent Term Restoration Act. The first-filer analysis cannot be determined solely from the Aurobindo docket because other ANDA applicants may have filed earlier, shared first-filer status, forfeited eligibility, or resolved their cases separately.
A generic launch scenario would require all of the following:
| Launch condition |
Relevance |
| FDA approval |
Aurobindo must obtain final ANDA approval |
| Patent resolution |
Settlement, judgment, license, or patent expiration must remove the approval barrier |
| Regulatory exclusivity |
Any remaining exclusivity must expire or be otherwise addressed |
| Settlement compliance |
Aurobindo must comply with the agreed launch date and product restrictions |
| Commercial readiness |
Manufacturing, inventory, distribution, and reimbursement must be in place |
The case therefore created a potential route to market but did not itself guarantee an early launch.
What is the Orange Book status of Sivextro?
Sivextro was listed in the FDA Orange Book with patents associated with tedizolid phosphate. Orange Book listings provide the statutory basis for ANDA patent certifications and Hatch-Waxman litigation.
The listing analysis should distinguish among:
- Active-ingredient patents.
- Formulation or composition patents.
- Method-of-use patents.
- Patents with expiration dates later than the principal composition patent.
- Patents that may be subject to a section viii “skinny label” carve-out.
A method-of-use patent does not necessarily block approval of a generic product if the relevant indication can be omitted from the proposed labeling. A compound or formulation patent generally presents a more substantial barrier because the generic product may infringe regardless of the label.
Sivextro’s label includes both oral and intravenous administration. A generic applicant could seek approval for one or both dosage forms, creating separate infringement and commercial analyses. A product that avoids one asserted formulation claim may remain exposed to claims directed to tedizolid itself.
How strong was Shionogi’s patent estate?
Shionogi’s estate had meaningful commercial strength because it combined product-specific protection with pharmaceutical-use and dosage-form coverage. The strength of the estate was not established by a final judgment in this action.
Core strengths
The central strength was protection tied to tedizolid, the ingredient responsible for Sivextro’s therapeutic activity. If a valid claim covered the compound or its required pharmaceutical form, design-around options would be limited.
The estate also had potential layering value. Multiple patents can delay generic entry when each patent presents a separate infringement or validity issue. A generic applicant must defeat all blocking claims or obtain a license covering the relevant claims.
Key vulnerabilities
The estate faced ordinary Hatch-Waxman validity risks:
- Prior-art challenges based on earlier oxazolidinone compounds.
- Obviousness challenges based on medicinal-chemistry disclosures.
- Claim-construction disputes over the chemical structure and pharmaceutical form.
- Enablement and written-description challenges.
- Arguments that the ANDA product did not meet one or more claim limitations.
- Potential limitations associated with specific dosage forms or uses.
Without a merits decision, the case does not support a definitive probability assessment. The settlement preserved the patents from invalidity findings but also prevented Shionogi from obtaining a court judgment confirming infringement.
Did the case affect generic competition for tedizolid?
The case was one component of the broader competitive landscape for tedizolid. Aurobindo’s challenge indicated that generic manufacturers considered the product commercially viable despite Sivextro’s smaller market relative to broader antibacterial franchises.
The principal competitive risks were:
- Entry by Aurobindo under a negotiated date.
- Parallel challenges by other ANDA filers.
- Price erosion after the first generic launch.
- Substitution between tedizolid and linezolid.
- Hospital and infectious-disease formulary decisions.
- Different launch timing for tablets and injection.
- Potential authorized-generic competition.
Tedizolid has clinical and commercial differentiation from linezolid, including a shorter labeled course for the approved skin-infection indication. Those advantages may support branded pricing, but they do not prevent ordinary generic substitution after FDA approval.
What litigation and settlement risks remain?
The case did not eliminate future patent or regulatory risk. Aurobindo or another generic applicant could pursue later litigation involving:
- A different ANDA formulation.
- A new Paragraph IV certification.
- A later-filed patent.
- A separate dosage form.
- A manufacturing-process patent.
- A declaratory-judgment action after a change in regulatory posture.
Shionogi could also assert patents not included in the original action if those patents were properly listed and applicable to a later ANDA. Conversely, a generic applicant could use a section viii statement to omit a patented method of use where the statutory requirements are satisfied.
The principal business risk for Shionogi was revenue erosion following the first approved generic. The principal risk for Aurobindo was delayed approval, litigation expense, possible damages exposure, and breach risk if the settlement imposed a restricted launch date.
How does Shionogi v. Aurobindo compare with ordinary Hatch-Waxman cases?
The case followed the standard structure of an ANDA patent dispute:
- A generic applicant filed an ANDA.
- The applicant submitted Paragraph IV certifications.
- The brand company sued under section 271(e)(2).
- FDA approval was subject to the statutory litigation stay.
- The parties resolved the dispute without a reported merits judgment.
The case is commercially important because settlement, rather than invalidation, preserved the appearance of patent strength while leaving the actual generic launch terms confidential. Investors and licensing counterparties should therefore avoid treating the dismissal as either a confirmed win for Shionogi or a confirmed loss for Aurobindo.
Key Takeaways
- Shionogi Inc. v. Aurobindo Pharma Ltd., No. 1:17-cv-00072, involved Aurobindo’s proposed generic tedizolid phosphate product for Sivextro.
- The action was a Delaware Hatch-Waxman case triggered by Paragraph IV certifications.
- U.S. Patent Nos. 8,815,830 and 8,853,422 were among the patents associated with the asserted Sivextro estate.
- The case ended without a publicly reported merits judgment.
- The public docket does not establish the settlement’s launch date or commercial terms.
- Sivextro’s NCE exclusivity expired in 2019, leaving patent term and settlement restrictions as the principal barriers to generic entry.
- The estate had layered product, formulation, and use coverage, but no final decision confirmed its validity or infringement.
- The main commercial exposure was post-entry price erosion in the tedizolid market.
FAQs About Shionogi v. Aurobindo
Was Shionogi v. Aurobindo a Paragraph IV lawsuit?
Yes. The case was a Hatch-Waxman patent action arising from Aurobindo’s ANDA and Paragraph IV certifications for a proposed generic version of Sivextro.
Did Aurobindo win the Sivextro patent case?
No merits victory was publicly reported. The case was dismissed without a published decision holding that Shionogi’s patents were invalid or not infringed.
What is Sivextro’s generic name?
Sivextro is the brand name for tedizolid phosphate, an oxazolidinone antibacterial drug.
Did the litigation involve a biosimilar?
No. Sivextro is a small-molecule drug subject to the ANDA pathway, not a biologic subject to the biosimilar pathway under the Public Health Service Act.
What should investors examine when valuing Sivextro patent risk?
Investors should examine the Orange Book listings, patent-term adjustment, other ANDA litigations, settlement launch provisions, approved generic products, and any later patents covering tedizolid formulations or manufacturing.
References
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U.S. Food and Drug Administration. (2014). Sivextro (tedizolid phosphate) prescribing information. FDA.
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U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
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Shionogi Inc. v. Aurobindo Pharma Ltd., No. 1:17-cv-00072 (D. Del. 2017). Public docket and case filings.
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21 U.S.C. § 355(j).
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35 U.S.C. § 271(e)(2).
