US Drug Patent 8,426,389: Tedizolid Phosphate Crystal, Formulation and Manufacturing Claims
US Patent No. 8,426,389 protects crystalline tedizolid phosphate particles, specified particle-size distributions, an identified X-ray powder diffraction pattern, impurity limits, pharmaceutical compositions, bacterial-infection treatment methods and manufacturing steps. The patent is associated with tedizolid phosphate, the active pharmaceutical ingredient in Sivextro, marketed by Merck following its acquisition of Cubist Pharmaceuticals.
The core commercial value is the claimed crystalline form and its production process. The patent does not broadly cover every tedizolid phosphate molecule or every use of tedizolid. Infringement generally would require practicing the claimed solid-state, compositional or process limitations.
What drug does US Patent 8,426,389 protect?
US 8,426,389 covers crystalline particles of (R)-3-(4-(2-(2-methyltetrazol-5-yl)pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyl oxazolidin-2-one dihydrogen phosphate, commonly identified as tedizolid phosphate.
Tedizolid phosphate is an oxazolidinone antibacterial used for acute bacterial skin and skin-structure infections caused by susceptible Gram-positive bacteria. FDA approved Sivextro in 2014 as an intravenous and oral product containing tedizolid phosphate, equivalent to 200 mg of tedizolid once daily for six days [1].
| Item |
Detail |
| Active ingredient |
Tedizolid phosphate |
| Brand |
Sivextro |
| Developer |
Trius Therapeutics |
| Current commercial sponsor |
Merck & Co. |
| Drug class |
Oxazolidinone antibacterial |
| FDA approval |
June 20, 2014 |
| Approved forms |
200 mg tablet and intravenous formulation |
| Primary indication |
Acute bacterial skin and skin-structure infections |
| Patent at issue |
US 8,426,389 |
| Patent issue date |
April 23, 2013 |
| Named commercial relevance |
Crystalline tedizolid phosphate and related pharmaceutical compositions |
The chemical identity in the claims corresponds to the phosphate prodrug of tedizolid. The active antibacterial moiety is released after administration through conversion of the phosphate prodrug.
What are the core claims of US 8,426,389?
The broadest practical claim is claim 1. It requires a crystalline particle composition containing at least about 96% by weight of a specified crystalline tedizolid phosphate form, together with particle-size and X-ray diffraction limitations.
The principal limitations are:
- At least about 96% tedizolid phosphate by weight.
- A defined crystalline particle population.
- Particle-size characteristics, including a median volume diameter of at least about 1.0 micrometer and specified volume-distribution thresholds.
- An XRPD pattern with peaks at approximately:
- 14.7°
- 15.2°
- 16.6°
- 20.3°
- 26.8°
- 28.2°
- In dependent claims, specified impurity limits and thermal behavior.
The claims therefore combine chemical identity with solid-state identity. A competing product containing tedizolid phosphate could avoid claim 1 if it used a different polymorph, amorphous material, particle profile or diffraction pattern. That outcome would depend on claim construction and analytical testing.
What does claim 1 cover?
Claim 1 is directed to a crystalline particle composition rather than to tedizolid phosphate as a molecule. The claim is strongest against a product that contains the claimed crystal form and reproduces the specified XRPD pattern.
The phrase "at least about 96% by weight" provides a purity threshold. The remainder may include one or more specified compounds, although the supplied claim text omits part of the "consisting of" list. The omitted structures materially affect the exact scope of the claim.
The particle-size limitations are potentially important because they distinguish the claimed material from a chemically identical but physically different solid. Median volume diameter and volume-fraction measurements are normally established by laser diffraction or another validated particle-size method.
What do claims 2 through 8 add?
Claims 2 through 5 narrow the composition by imposing impurity restrictions and higher purity levels.
| Claim |
Main limitation |
| 2 |
Less than 1% of a specified chloromethyl oxazolidinone impurity |
| 3 |
At least about 97% tedizolid phosphate under claim 2 |
| 4 |
Less than 1% of another specified compound |
| 5 |
At least about 97% tedizolid phosphate under claim 4 |
| 6 |
Independent crystalline-particle claim with the specified XRPD pattern |
| 7 |
Median volume diameter of at least about 1.0 micrometer |
| 8 |
DSC endothermic peaks at approximately 255-258°C |
Claim 8 adds a thermal fingerprint. DSC data can support identification of the claimed crystalline form, but the exact evidentiary value depends on testing conditions, instrument calibration, heating rate and sample preparation.
The supplied text for claims 1, 4 and 6 omits chemical structures after the phrase "selected from the group consisting of." Those omissions prevent a complete determination of every alternative impurity or composition expressly recited in the issued claims.
What formulations are protected by US 8,426,389?
Claims 9, 10 and 26 cover pharmaceutical compositions containing the claimed crystalline particles and a pharmaceutically acceptable carrier, excipient or diluent.
Claim 10 identifies:
- Mannitol
- Polyvinylpyrrolidone
- Cross-linked polyvinylpyrrolidone
- Magnesium stearate
These excipients correspond to conventional solid-dose formulation components. The claim is not limited to a tablet unless other claim language or the specification imposes that restriction. Claim 26 separately covers compositions containing the crystalline particles of claim 6.
Claims 13 through 18 address a sodium-phosphate formulation pathway and compositions containing a salt of tedizolid phosphate. Claim 13 covers a lyophilisate of a reaction mixture involving the crystalline material and a base. Claim 14 covers a combination containing at least about 96% of the disodium phosphate form, with pharmaceutical excipients or specified salts of related compounds.
The supplied text omits the structural diagrams for several compounds in claims 14 through 18. Those claims cannot be evaluated at full chemical resolution from the text alone.
What methods of treatment are protected?
Claims 19, 20 and 27 cover methods of treating a bacterial infection by administering:
- The crystalline particles of claim 1;
- The pharmaceutical composition of claim 14; or
- The crystalline particles of claim 6.
These are composition-linked method-of-use claims. They do not appear to claim every antibacterial use of tedizolid independently. A method must include administration of the specified crystalline material or composition and treatment of a bacterial infection.
Because the approved Sivextro indication is acute bacterial skin and skin-structure infection, the treatment claims are commercially relevant to the approved product. Their enforceability against a generic product would depend on the product label, prescribing information, induced-infringement evidence and any applicable carve-out.
What manufacturing processes are protected?
Claims 21 through 25 cover processes for producing the claimed crystalline particles.
The process limitations include:
- Drying the crystalline particles.
- Filtering the particles from a supernatant before drying.
- Contacting a salt of crystalline tedizolid phosphate with an acid solution.
- Forming crystallized tedizolid phosphate before filtration.
- Using hydrochloric acid and ethanol, or hydrochloric acid and tetrahydrofuran.
These claims target solid-form isolation and purification rather than the complete synthesis of tedizolid. A manufacturer could face process-claim risk even if the final product is not sold under the Sivextro brand, provided the manufacturing route practices the claimed steps.
The process claims may be more difficult to detect than product claims because manufacturing records, batch records and process chemistry are usually required. The final product's XRPD pattern may establish product-claim risk but will not necessarily prove use of a specific acid-solvent crystallization process.
When does US Patent 8,426,389 expire?
The patent has a 20-year term measured from its earliest effective nonprovisional or international filing date, subject to patent-term adjustment and any applicable patent-term extension. Public patent records commonly associate the patent with a 2029 expiration period, with the nominal term generally reported as October 2029.
| Event |
Date or period |
| Patent issued |
April 23, 2013 |
| FDA approval of Sivextro |
June 20, 2014 |
| Nominal patent-expiration period |
October 2029 |
| Regulatory exclusivity |
Expired |
| Patent-term extension status |
Must be confirmed against the Orange Book entry and USPTO term calculation |
FDA approval exclusivity for Sivextro is no longer the principal barrier to generic entry. The remaining commercial barrier is patent protection, including this crystalline-form patent and other listed or potentially relevant tedizolid patents.
What is the Orange Book status of tedizolid phosphate?
Sivextro is an FDA-approved product listed in the Orange Book. FDA identifies patent information for approved products through the Orange Book patent listings and the product's approval history [2].
The relevant Orange Book analysis has four parts:
| Issue |
Assessment |
| Drug approval |
Sivextro is approved |
| Listed drug |
Tedizolid phosphate product marketed as Sivextro |
| Regulatory exclusivity |
Expired |
| Patent barrier |
Patent listings extend into the late 2020s, including crystalline-form protection |
An Orange Book listing does not establish that every listed claim is valid or infringed. It gives an approved-product sponsor a mechanism to receive notice of an ANDA applicant's Paragraph IV certification and, if suit is filed within the statutory period, obtain a potential 30-month stay of approval.
Which companies are challenging tedizolid patent rights?
No broadly established market entry by an approved generic tedizolid product is identified in the supplied record. The available information does not establish a final Paragraph IV judgment, a public settlement covering US 8,426,389, or an approved ANDA that has launched a competing tedizolid product.
A generic applicant seeking approval before listed patent expiry would ordinarily choose one of four paths:
- Paragraph III certification, accepting approval after patent expiry.
- Paragraph IV certification, alleging invalidity, unenforceability or noninfringement.
- A section viii statement carving out a patented method of use, where legally available.
- A formulation or product design that avoids the claimed crystalline form.
For this patent, a section viii strategy may be less useful if the generic product itself contains the claimed crystalline form. The principal risk is product-form and solid-state infringement, not only the treatment indication.
How strong is the patent estate for tedizolid?
The patent estate is strongest where a generic manufacturer uses the same tedizolid phosphate crystal form as the reference product. The asserted combination of XRPD, purity and particle-size limitations can make design-around more difficult if the commercial product requires that form for manufacturability or dosage-form performance.
Strengths
- Product claims cover a defined crystalline form.
- XRPD peaks provide a reproducible analytical fingerprint.
- Impurity limits support purity-based claim differentiation.
- Formulation claims cover conventional excipients used in oral dosage forms.
- Process claims target acid-mediated crystallization and drying.
- Treatment claims support infringement theories based on labeled use.
Limitations
- The claims do not appear to cover every tedizolid phosphate form.
- A different polymorph or amorphous form may avoid the XRPD limitation.
- Particle-size limitations can create noninfringement opportunities.
- Process claims may be difficult to enforce without access to manufacturing evidence.
- Several supplied claim structures are missing, limiting precise analysis of the full claim boundaries.
- Validity challenges could target written description, enablement, anticipation, obviousness or indefiniteness depending on the complete patent record.
How does US 8,426,389 compare with other tedizolid patents?
US 8,426,389 is a later-stage product and manufacturing patent. It is distinct from earlier composition-of-matter patents covering the tedizolid chemical entity.
| Patent category |
Subject matter |
Generic-entry relevance |
| Composition of matter |
Tedizolid or related oxazolidinone compounds |
Broadest chemical protection, usually earliest expiry |
| Crystalline form |
Defined tedizolid phosphate particles and XRPD pattern |
Direct product-form barrier |
| Formulation |
Tablets, lyophilisates, excipients and dosage forms |
Product-specific infringement risk |
| Manufacturing |
Crystallization, filtration and drying |
Process evidence required |
| Method of use |
Treatment of bacterial infections |
Label and prescribing conduct are relevant |
For generic litigation, the key question is cumulative exposure. A generic may avoid one patent while remaining blocked by another. Conversely, a successful invalidity or noninfringement ruling on a core crystal-form patent may materially reduce the practical barrier if other patents do not cover the proposed product.
What generic launch scenarios exist?
Launch after patent expiry
This is the lowest litigation-risk path. The applicant accepts the patent term and seeks approval timed to the end of the applicable Orange Book protection.
Paragraph IV challenge
A challenger could argue that its product does not contain the claimed crystalline form, does not meet the XRPD peaks, fails the particle-size thresholds or does not practice the claimed process. It could also challenge validity based on prior-art crystalline forms or obviousness.
Design-around formulation
A manufacturer could investigate:
- A different tedizolid polymorph;
- Amorphous tedizolid phosphate;
- Different particle-size distribution;
- A non-phosphate salt or alternative prodrug;
- A formulation that does not use the claimed excipient combination.
Each option introduces development, stability, bioequivalence and regulatory risks.
At-risk launch
An applicant could launch before final resolution of patent disputes. That would expose the company to damages, injunction risk and potential loss of market exclusivity if the patent is upheld.
What is the commercial exposure?
Sivextro's commercial exposure is concentrated in hospital and outpatient antibiotic channels. The product competes with other agents used for acute bacterial skin and skin-structure infections, including linezolid, vancomycin, dalbavancin, oritavancin and ceftaroline.
Tedizolid's once-daily six-day regimen is commercially relevant, but generic entry would likely put pressure on price, hospital formulary positioning and Merck's branded revenue. Precise current revenue exposure cannot be established from the patent text. Merck's public financial reporting should be used for product-level revenue where disclosed; Sivextro may be reported within a broader infectious-disease or hospital-products category rather than as a separately reported product [3].
Key Takeaways
- US 8,426,389 is principally a crystalline-form patent for tedizolid phosphate.
- Claim 1 combines chemical purity, particle-size and XRPD limitations.
- Claims 2 through 8 narrow the patent through impurity, purity and thermal specifications.
- Claims 9 through 18 cover pharmaceutical compositions, lyophilisates and sodium-phosphate formulations.
- Claims 19, 20 and 27 cover treatment of bacterial infections.
- Claims 21 through 25 cover crystallization, filtration and drying processes.
- The patent is associated with a nominal October 2029 expiration period.
- FDA exclusivity has expired, leaving patent rights as the principal US entry barrier.
- The most credible design-around strategies involve a different solid form, particle profile, salt or manufacturing route.
- The supplied claim text omits structural formulas for several alternatives, preventing complete evaluation of those specific chemical limitations.
FAQs About US Patent 8,426,389 and Tedizolid
Does US 8,426,389 cover tedizolid itself?
No. It primarily covers a specified crystalline form of tedizolid phosphate and related compositions, processes and treatment methods. Earlier patents may provide broader chemical protection.
Can a generic use tedizolid phosphate without infringing this patent?
Potentially, but only if the product avoids the claimed crystalline, particle-size, impurity or process limitations. Chemical identity alone does not determine infringement.
Is US 8,426,389 an Orange Book patent?
It is associated with the Sivextro patent estate and the relevant Orange Book protection should be confirmed against the current FDA listing. An Orange Book listing does not determine validity or infringement.
Can a generic avoid the patent by changing tablet excipients?
Changing excipients may avoid a formulation claim, but it may not avoid claims directed to the crystalline tedizolid phosphate particles themselves.
Is tedizolid a biologic subject to biosimilar competition?
No. Tedizolid phosphate is a small-molecule drug. Competition would proceed through the ANDA pathway, not the biosimilar pathway under the Public Health Service Act.
References
- U.S. Food and Drug Administration. (2014). Sivextro (tedizolid phosphate) prescribing information.
- U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
- Merck & Co., Inc. (2024). Annual report.
- U.S. Patent and Trademark Office. (2013). United States Patent No. 8,426,389: Crystalline forms of tedizolid phosphate and compositions and methods thereof.
