U.S. Patent 8,722,684: Vortioxetine Crystalline Forms, Formulations, and Generic Entry Risk
U.S. Patent No. 8,722,684 protects specified crystalline forms of vortioxetine hydrobromide, including XRPD-defined forms, particle-size ranges, and a narrow wet-granulated tablet formulation. The patent does not broadly cover every vortioxetine product. Its strongest protection is directed to the crystalline hydrobromide form used in commercial vortioxetine tablets and to compositions that substantially follow the claimed excipient profile.
The patent was issued to H. Lundbeck A/S and concerns 1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine, commonly known as vortioxetine. Vortioxetine hydrobromide is marketed in the United States as Trintellix by Takeda Pharmaceuticals and Lundbeck.
What compound and drug product does U.S. Patent 8,722,684 cover?
The claimed active ingredient is vortioxetine, specifically its hydrobromide salt in crystalline form.
| Item |
Description |
| Active ingredient |
Vortioxetine |
| Chemical name |
1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine |
| Commercial salt |
Vortioxetine hydrobromide |
| U.S. brand |
Trintellix |
| Dosage form |
Immediate-release oral tablets |
| Approved strengths |
5 mg, 10 mg, 15 mg and 20 mg |
| Patent owner |
H. Lundbeck A/S |
| Patent number |
U.S. 8,722,684 |
| Issue date |
May 13, 2014 |
| Technology |
Crystalline forms, particle size and tablet compositions |
The claims are directed to solid-state and formulation characteristics rather than to vortioxetine’s antidepressant mechanism or all therapeutic uses of the molecule.
What patents protect vortioxetine and Trintellix?
Vortioxetine has been protected through several patent categories:
- Composition-of-matter patents covering the active molecule.
- Method-of-use patents covering treatment of depression and related disorders.
- Crystalline-form patents covering vortioxetine hydrobromide solid forms.
- Formulation patents covering tablets and excipient systems.
- Regulatory exclusivities associated with FDA approval.
U.S. Patent 8,722,684 is in the third and fourth categories. It is distinct from the earlier composition-of-matter patent estate and from patents directed to clinical use.
| Protection category |
Typical scope |
Relevance of U.S. 8,722,684 |
| Composition of matter |
Vortioxetine molecule and salts |
Indirect |
| Crystalline form |
XRPD-defined polymorphs or hydrates |
Direct |
| Particle engineering |
Particle-size distributions |
Directly in claim 4 |
| Tablet formulation |
Excipients and manufacturing method |
Directly in claims 5-8 |
| Method of treatment |
Depression and other psychiatric conditions |
Not expressly claimed |
| Manufacturing process |
Synthesis, crystallization or milling |
Not expressly claimed |
The commercial significance of the patent depends on whether an ANDA applicant uses the claimed crystalline hydrobromide form or a formulation that falls within claims 5-8.
What does claim 1 of U.S. Patent 8,722,684 cover?
Claim 1 covers vortioxetine, or a pharmaceutically acceptable salt, in a crystalline form characterized by an XRPD pattern shown in any of Figures 1 through 17.
This is a form-of-matter claim. The claim does not require a tablet, a particular dose, a particle size or a specified excipient. A product can infringe claim 1 before it is formulated into a finished dosage form if the active pharmaceutical ingredient has one of the claimed crystalline XRPD patterns.
The principal interpretive issue is whether the figures define one or multiple distinct crystalline forms and how closely an accused product’s XRPD pattern must correspond to the disclosed patterns. Relevant comparison points include:
- Peak positions.
- Relative peak intensities.
- Peak tolerances.
- Presence or absence of diagnostic reflections.
- Instrument conditions.
- Sample preparation.
- Hydration or solvation state.
- Whether the accused material contains a mixture of polymorphs.
A supplier cannot avoid claim 1 merely by changing tablet excipients if the same crystalline active ingredient is used.
What does claim 2 add to the patent protection?
Claim 2 narrows the subject matter to the vortioxetine hydrobromide salt and requires crystalline-form XRPD reflections at approximately:
| Reflection |
Position |
| First peak |
6.89° 2θ |
| Second peak |
9.73° 2θ |
| Third peak |
13.78° 2θ |
| Fourth peak |
14.64° 2θ |
| Tolerance |
±0.10° 2θ |
Claim 2 is narrower than claim 1 because it requires:
- The hydrobromide salt.
- A crystalline form.
- The specified diagnostic reflections.
The four reflections are likely intended to identify a particular polymorphic form or crystalline phase. In an infringement analysis, the complete diffraction profile would normally be more important than a single matching peak. A generic product containing the hydrobromide salt could still avoid claim 2 if its crystalline material lacks one or more required reflections, falls outside the stated tolerance, or exists in a different solid-state form.
What does claim 3 cover?
Claim 3 further limits claim 2 to a crystalline form characterized by the XRPD pattern shown in Figure 3.
The claim creates a hierarchy:
- Claim 1 covers forms represented by Figures 1-17.
- Claim 2 requires the hydrobromide and four specified reflections.
- Claim 3 requires the Figure 3 pattern in addition to the claim 2 limitations.
Claim 3 is therefore a narrower fallback claim. It may be more difficult to invalidate for lack of written description if Figure 3 clearly identifies a discrete form, but it may also be easier to design around by producing a different polymorph or a material with a materially different XRPD profile.
What does claim 4 cover?
Claim 4 combines the crystalline hydrobromide form with one of several particle-size distributions. The claim text supplied lists four alternatives:
| Alternative |
D98 |
D50 |
D5 |
| 1 |
650-680 µm |
230-250 µm |
40-60 µm |
| 2 |
370-390 µm |
100-120 µm |
5-15 µm |
| 3 |
100-125 µm |
15-25 µm |
1-3 µm |
| 4 |
50-70 µm |
3-7 µm |
0.5-2 µm |
The claim appears to require that the hydrobromide crystalline form have one of these distributions. Particle-size claims raise several technical and legal issues:
- The measurement method must be consistent.
- Laser diffraction, sieve analysis and image analysis can produce different results.
- D5, D50 and D98 must be calculated under the same test conditions.
- Milling, granulation and compression can change the measured distribution.
- The claim may be vulnerable if the particle-size limitations are not adequately tied to a reproducible analytical method.
For a generic developer, claim 4 is potentially avoidable through controlled milling or a different particle-size specification. That strategy does not necessarily avoid claims 1-3 or 5-8.
What formulations are protected by claims 5 through 8?
Claim 5 covers a composition comprising the claimed crystalline vortioxetine hydrobromide and a pharmaceutically acceptable excipient.
Claim 5 is broad relative to claims 6-8. It does not require a tablet, wet granulation, a particular excipient or specified concentrations. A capsule, sachet or other oral composition could fall within claim 5 if it contains the claimed crystalline hydrobromide and an acceptable excipient.
Claim 6 narrows the composition to a tablet prepared by wet granulation and containing:
- Anhydrous calcium hydrogen phosphate.
- Corn starch.
- PVP-VA copolymer.
- Microcrystalline cellulose.
- Sodium starch glycolate.
- Talc.
- Magnesium stearate.
Claims 7 and 8 add concentration limitations.
| Component |
Claim 7 range |
Claim 8 approximate amount |
| Vortioxetine HBr |
3-8% |
5% |
| Anhydrous calcium hydrogen phosphate |
35-45% |
39% |
| Corn starch |
15-25% |
20% |
| PVP-VA copolymer |
2-6% |
3% |
| Microcrystalline cellulose |
20-30% |
25% |
| Sodium starch glycolate |
1-3% |
3% |
| Talc |
2-6% |
4% |
| Magnesium stearate |
0.5-2% |
1% |
Claim 8 is a composition claim, not merely a target formulation. The word “approximately” introduces an interpretation issue. Courts generally assess approximate numerical terms in light of the specification, technical context and ordinary industry practice. A formulation need not be mathematically identical to the listed percentages, but the permitted deviation cannot be assumed without an infringement analysis.
How strong is the patent estate for U.S. generic entry?
The patent is strongest where a generic product uses the same commercial crystalline hydrobromide form and a similar tablet manufacturing process.
| Generic design |
Risk under U.S. 8,722,684 |
| Same crystalline vortioxetine HBr form |
High under claims 1-3 |
| Different polymorph with distinct XRPD pattern |
Lower under claims 1-3 |
| Same form but different particle size |
Claims 1-3 remain relevant; claim 4 may be avoided |
| Same active form in a capsule |
Claim 5 may remain relevant; claims 6-8 may be avoided |
| Direct-compression tablet |
Claims 6-8 may be avoided if wet granulation is absent |
| Different excipient system |
Claims 6-8 may be avoided; claim 5 may remain relevant |
| Vortioxetine free base |
Likely outside claims requiring hydrobromide, but claim 1 must be construed carefully |
| Amorphous vortioxetine |
Potentially outside crystalline-form claims |
| Different salt |
Potentially outside claims requiring vortioxetine hydrobromide |
| Same form manufactured by another supplier |
Supplier identity does not avoid product claims |
The patent has layered protection. A successful design-around must address both the active pharmaceutical ingredient and the finished product claims. Avoiding only the particle-size limitation does not necessarily avoid the broader crystalline-form claims.
When does U.S. Patent 8,722,684 expire?
The patent’s ordinary term is tied to its earliest applicable nonprovisional or international filing date. Public patent records identify a January 2009 priority date for the relevant family, producing a nominal term extending into January 2029 before any adjustment.
| Event |
Date |
| Earliest reported priority |
January 2009 |
| U.S. patent issue |
May 13, 2014 |
| Nominal term endpoint |
Approximately January 2029 |
| Possible term adjustment |
Must be verified from the USPTO patent record |
| Possible pediatric extension |
Separate FDA and patent-record analysis required |
Patent term adjustment can change the expiration date. Regulatory exclusivity and patent term are separate concepts. FDA exclusivity does not automatically extend every patent in the product’s portfolio.
What is the Orange Book status of U.S. 8,722,684?
U.S. 8,722,684 has been associated with the U.S. patent estate for Trintellix and vortioxetine hydrobromide products. Orange Book analysis should distinguish between:
- Whether the patent is listed.
- The listed expiration date.
- The NDA to which the patent is linked.
- The type of patent certification required from an ANDA applicant.
- Whether the patent covers the referenced product, a method of use or a formulation.
For an ANDA applicant, a listed patent can trigger a Paragraph III certification, Paragraph IV certification or a statement that the patent is not applicable, depending on the applicant’s product and the scope of the listing.
A crystalline-form patent is commercially important only if it is properly listed and if the proposed generic product uses the covered form. A patent listing does not establish infringement. Infringement depends on the actual product, formulation and manufacturing process.
What Paragraph IV challenges affect vortioxetine?
A Paragraph IV certification alleges that a listed patent is invalid, unenforceable or will not be infringed by the proposed generic product.
For U.S. 8,722,684, a credible Paragraph IV strategy could rely on one or more of the following positions:
- The proposed product uses a different polymorph.
- The product is amorphous rather than crystalline.
- The XRPD reflections do not fall within the claim tolerances.
- The product does not contain the hydrobromide salt.
- The formulation does not use wet granulation.
- The formulation omits one or more required excipients.
- The particle-size distribution falls outside claim 4.
- The claims are invalid for anticipation or obviousness.
- The claims are indefinite because the XRPD or particle-size parameters are not sufficiently reproducible.
- The claims are unenforceable based on prosecution conduct or other inequitable-conduct theories.
A Paragraph IV filing can trigger Hatch-Waxman litigation and a 30-month stay of FDA approval if the NDA holder or patent owner files suit within the statutory period. The exact litigation consequences depend on the date of the notice letter, the asserted patents and the timing of any court action. [2]
Which companies are challenging Trintellix patents?
The principal competitive threat comes from ANDA applicants seeking approval for generic vortioxetine tablets. Public generic-drug activity has involved major manufacturers and specialty generic companies, but company-specific litigation status must be tied to individual ANDA filings and court dockets.
The relevant diligence points are:
| Issue |
Commercial implication |
| Number of ANDA filers |
Determines expected launch competition |
| Paragraph IV status |
Determines litigation exposure |
| Settlement terms |
May establish an authorized or licensed entry date |
| 180-day exclusivity |
Can delay other generic approvals |
| Product form |
Indicates whether crystalline claims are implicated |
| Manufacturing site |
Identifies potential API and solid-state supply constraints |
A settlement can permit an earlier entry date without invalidating the patent. It can also restrict launch timing, supply arrangements, authorized-generic rights or damages exposure.
What manufacturing and intellectual-property barriers remain?
The main technical barrier is control of the vortioxetine hydrobromide solid state. A manufacturer must control:
- Salt formation.
- Crystallization solvent and temperature.
- Seeding.
- Drying conditions.
- Milling energy.
- Moisture exposure.
- Particle-size distribution.
- Polymorph conversion during granulation and compression.
Wet granulation can create solid-state changes through water exposure, drying heat and mechanical stress. A generic manufacturer therefore needs batch-level XRPD and particle-size testing, not only chemical identity and assay testing.
The narrow tablet claims also create formulation-design constraints. A product can avoid claims 6-8 by using direct compression, a different binder, a different disintegrant or a capsule dosage form. That approach leaves claim 5 and the crystalline-form claims as separate risks.
How does U.S. 8,722,684 compare with composition-of-matter protection?
Composition-of-matter patents generally provide broader protection than crystalline-form patents. A composition patent can cover the molecule regardless of polymorph, particle size or excipient system. U.S. 8,722,684 is narrower but may remain commercially relevant after the basic molecule patent expires.
| Patent type |
Breadth |
Typical design-around |
| Composition of matter |
Broadest |
Difficult unless a different active is used |
| Salt patent |
Intermediate |
Use another salt or free base |
| Crystalline-form patent |
Narrower |
Use another polymorph or amorphous form |
| Particle-size patent |
Narrow |
Alter milling or specification |
| Formulation patent |
Narrow to intermediate |
Change excipients or process |
| Method-of-use patent |
Depends on claim |
Change indication, labeling or certification strategy |
Key Takeaways
- U.S. Patent 8,722,684 targets crystalline vortioxetine, especially vortioxetine hydrobromide.
- Claims 1-3 are XRPD-based crystalline-form claims.
- Claim 4 adds four alternative particle-size distributions.
- Claims 5-8 cover compositions and a specific wet-granulated tablet architecture.
- The patent does not expressly claim a therapeutic method, a synthesis process or every vortioxetine formulation.
- A generic using the commercial crystalline hydrobromide form faces the highest risk under claims 1-3.
- Changing the particle size may avoid claim 4 but not the broader crystalline-form claims.
- Changing the excipient system or manufacturing process may avoid claims 6-8 but not necessarily claim 5.
- The patent has a nominal term extending into approximately January 2029, subject to patent-term adjustment and any applicable extension.
- Paragraph IV exposure depends on the generic’s actual solid form, formulation, ANDA certification and the patent’s Orange Book listing.
Frequently Asked Questions
Does U.S. Patent 8,722,684 cover all vortioxetine products?
No. It primarily covers specified crystalline forms, particularly crystalline vortioxetine hydrobromide, together with certain particle-size and tablet-composition limitations.
Can a generic avoid the patent by using vortioxetine free base?
Possibly, but the product must be evaluated against every asserted claim. Claims directed specifically to vortioxetine hydrobromide may not reach a free-base product, while broader claim language requires separate construction.
Does a different XRPD pattern avoid infringement?
It can, particularly where the different pattern demonstrates a distinct polymorph or amorphous form. The comparison must account for peak tolerances, mixtures and analytical conditions.
Are the claims limited to Trintellix tablets?
No. Claims 1-5 are not limited to the Trintellix trade name. Claims 6-8 are narrower because they require a tablet, wet granulation and specified excipients or concentrations.
Can a formulation with different excipients still infringe?
Yes. Claims 1-5 may remain relevant even if claims 6-8 are avoided. A different excipient system does not eliminate risk arising from the crystalline active ingredient.
References
-
United States Patent No. 8,722,684. (2014). Crystalline forms of 1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine hydrobromide. U.S. Patent and Trademark Office.
-
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, Orange Book. FDA.
-
U.S. Food and Drug Administration. (2023). Trintellix prescribing information. Takeda Pharmaceuticals U.S.A., Inc.
-
U.S. Food and Drug Administration. (1984). Drug Price Competition and Patent Term Restoration Act of 1984. FDA.
-
World Intellectual Property Organization. (2009). Patent Cooperation Treaty records for crystalline forms of vortioxetine hydrobromide. WIPO.
