US Patent 10,098,892: Suvorexant Amorphous Formulation Claims and Patent Landscape
US Patent 10,098,892 is a narrow formulation and manufacturing patent covering suvorexant in an amorphous form dispersed with copovidone and produced through hot-melt extrusion. It does not claim suvorexant as a chemical compound, orexin-receptor antagonism generally, or every suvorexant dosage form. The broadest independent claim requires four technical elements: amorphous suvorexant, copovidone, a pharmaceutical composition, and preparation by hot-melt extrusion of a mixture containing suvorexant and copovidone.
The patent’s commercial relevance is greatest for generic or follow-on products that replicate the Belsomra formulation architecture, particularly tablets containing amorphous suvorexant, copovidone, lactose monohydrate, microcrystalline cellulose, croscarmellose sodium and magnesium stearate. The principal design-around opportunities are use of crystalline suvorexant, a polymer other than copovidone, a manufacturing process other than hot-melt extrusion, or a materially different excipient system.
What does US Patent 10,098,892 protect?
The patent protects compositions containing amorphous suvorexant and copovidone when the composition is made using hot-melt extrusion. The claims combine product limitations with a manufacturing-process limitation.
| Claim group |
Scope |
Additional limitation |
| Claim 1 |
Amorphous suvorexant plus copovidone |
HME of a mixture containing suvorexant and copovidone |
| Claims 2-5 |
Claim 1 composition |
At least 90%, 95%, 98% or 99% amorphous suvorexant |
| Claims 6-9 |
Claim 1 composition |
Lactose, microcrystalline cellulose, croscarmellose sodium or magnesium stearate |
| Claim 10 |
Amorphous suvorexant, copovidone and four specified excipients |
HME of suvorexant and copovidone |
| Claims 11-14 |
Claim 10 composition |
At least 90%, 95%, 98% or 99% amorphous suvorexant |
| Claims 15-18 |
Claims 11-14 composition |
5 mg, 10 mg, 15 mg or 20 mg suvorexant |
The independent claims are claims 1 and 10. Claim 1 is the broader composition claim because it requires only amorphous suvorexant and copovidone, while claim 10 requires the complete excipient combination.
How broad is claim 1 of US 10,098,892?
Claim 1 is broad in excipient scope but narrow in solid-state and process scope.
A composition generally must satisfy all of the following limitations:
- It contains suvorexant.
- The suvorexant is in amorphous form.
- It contains copovidone.
- It is prepared by a process comprising hot-melt extrusion.
- The extruded mixture contains suvorexant and copovidone.
Claim 1 does not expressly require lactose, microcrystalline cellulose, croscarmellose sodium or magnesium stearate. It also does not specify a particular suvorexant dose, tablet weight, dissolution profile, polymer ratio or extrusion temperature.
The claim therefore reaches a range of amorphous suvorexant-copovidone dispersions, provided the claimed HME process is used. The absence of quantitative limits for copovidone concentration gives the claim potentially broad formulation coverage, subject to written-description, enablement and claim-construction limitations.
What formulations are protected by claims 10 through 18?
Claims 10 through 18 target a tablet-like formulation containing the excipient combination associated with a conventional immediate-release oral dosage form.
The required components are:
- amorphous suvorexant;
- copovidone;
- lactose monohydrate;
- microcrystalline cellulose;
- croscarmellose sodium; and
- magnesium stearate.
The composition must also be prepared using hot-melt extrusion of a mixture containing suvorexant and copovidone.
Claims 15 through 18 add the dose range corresponding to 5 mg, 10 mg, 15 mg or 20 mg of suvorexant. These claims are substantially narrower than claim 10 because they require a specified amorphous-content threshold and one of the listed doses.
| Claim |
Amorphous suvorexant threshold |
Dose limitation |
| 15 |
At least 90 wt.% |
5, 10, 15 or 20 mg |
| 16 |
At least 95 wt.% |
5, 10, 15 or 20 mg |
| 17 |
At least 98 wt.% |
5, 10, 15 or 20 mg |
| 18 |
At least 99 wt.% |
5, 10, 15 or 20 mg |
These claims are commercially important because a generic tablet could match the listed dose strengths and excipient system while avoiding the patent only if it also avoids one of the solid-state or process limitations.
How does the amorphous-form limitation affect infringement?
The amorphous-form limitation is central. A product consisting exclusively of a recognized crystalline suvorexant polymorph would not satisfy the express requirement for suvorexant in amorphous form. A product containing a mixture of amorphous and crystalline material may fall within claims 2 through 5 or 11 through 14 depending on the amount of amorphous material.
The nested thresholds operate as follows:
- Claim 2 and claim 11 require at least 90 wt.% amorphous suvorexant.
- Claim 3 and claim 12 require at least 95 wt.%.
- Claim 4 and claim 13 require at least 98 wt.%.
- Claim 5 and claim 14 require at least 99 wt.%.
The phrase “relative to other morphological forms of suvorexant” raises analytical questions. A patent dispute would likely focus on:
- the definition of “amorphous form”;
- the analytical method used to quantify amorphous material;
- whether the percentage is measured in the active ingredient or the entire composition;
- the treatment of partially crystalline or poorly ordered material; and
- the reproducibility of measurements after storage.
The claims do not specify XRPD, DSC, solid-state NMR, microscopy or another analytical technique. That omission can create evidentiary disputes over whether the claimed amorphous percentage is met.
Is the hot-melt-extrusion limitation important?
Yes. The HME limitation is a principal boundary of the patent.
Hot-melt extrusion typically combines an active pharmaceutical ingredient with a polymer under heat and shear to produce a solid dispersion or molecularly dispersed system. In these claims, the process must include extrusion of a mixture containing suvorexant and copovidone. The claims do not expressly specify:
- extrusion temperature;
- residence time;
- screw configuration;
- feed rate;
- drug-to-polymer ratio;
- solvent use;
- die geometry; or
- downstream milling or compression steps.
The absence of those parameters broadens the process language but may create questions about whether every claimed composition can be made across the full scope.
Under US product-by-process doctrine, a process limitation in a product claim can affect infringement analysis even when the claim is written as a composition claim. The Federal Circuit has treated product-by-process limitations as legally relevant limitations, although the application depends on the claim language, the accused product and the evidence of product identity or process performance. See Abbott Laboratories v. Sandoz, Inc., 566 F.3d 1282 (Fed. Cir. 2009).
A manufacturer using spray drying, solvent evaporation, freeze drying, co-precipitation or direct blending may have a non-infringement position if the resulting product is not made by the claimed HME process. That position is stronger when the final product has distinguishable structural or physical characteristics.
Which elements create the strongest design-around opportunities?
The most practical design-around routes are the following:
| Design-around route |
Potential effect |
| Use crystalline suvorexant |
Avoids the amorphous-form limitation |
| Use a polymer other than copovidone |
Avoids a required excipient in claims 1 and 10 |
| Use spray drying or solvent evaporation |
May avoid the HME limitation |
| Use direct compression of crystalline API |
Avoids both amorphous and HME limitations |
| Replace the listed excipient system |
Avoids claim 10 and claims 15-18, but not necessarily claim 1 |
| Use a dose outside 5-20 mg |
Avoids claims 15-18, but not claims 10-14 |
| Use amorphous content below 90% |
Avoids the percentage-dependent claims, but not necessarily claims 1 or 10 |
The most important distinction is between avoiding claims 15 through 18 and avoiding the independent claims. A product with a 25 mg dose, for example, could avoid the dose limitation in claims 15 through 18 but remain exposed to claim 10 if it contains the specified excipients and was made by HME.
What prior-art issues are most relevant to US 10,098,892?
The likely patentability pressure points are:
Amorphous drug-polymer dispersions
Amorphous solid dispersions using polymers to improve dissolution and bioavailability were established in the pharmaceutical literature before the patent’s filing. Prior art involving amorphous active ingredients with copovidone could be relevant to anticipation or obviousness.
Hot-melt extrusion
HME was a known technique for producing amorphous solid dispersions. The key issue is likely whether the prior art specifically disclosed suvorexant with copovidone, rather than HME generally.
Suvorexant solid-state forms
Earlier patents and publications concerning suvorexant may disclose crystalline polymorphs, amorphous material, salt forms, solvates, pharmaceutical compositions or methods for improving dissolution. The strength of the patent depends on whether the claimed combination of suvorexant, copovidone and HME was disclosed or would have been an obvious formulation choice.
Excipient combinations
Lactose monohydrate, microcrystalline cellulose, croscarmellose sodium and magnesium stearate are common tablet excipients. Their presence is less likely to provide substantial inventive distinction by itself. Claim 10’s defensibility is more likely to depend on the interaction between amorphous suvorexant, copovidone and HME than on the conventional excipient package.
How strong is the patent estate for suvorexant?
US 10,098,892 is best characterized as a targeted formulation patent rather than the core suvorexant patent.
| Estate category |
Relevance to this patent |
| Chemical compound patents |
Outside the claim scope |
| Orexin-receptor method patents |
Outside the direct claim scope |
| Crystalline polymorph patents |
Relevant as prior art and design-around barriers |
| Amorphous-form patents |
Directly relevant |
| HME and solid-dispersion patents |
Directly relevant |
| Tablet formulation patents |
Directly relevant to claims 10-18 |
| Method-of-use patents |
Separate protection layer |
| Manufacturing patents |
Potentially overlapping depending on process |
The estate’s practical strength is concentrated in products that reproduce the patented amorphous solid dispersion. It is weaker against a generic that uses a different solid-state form or manufacturing route. The patent does not prevent all suvorexant products from entering the market.
What is the FDA and Orange Book significance?
Belsomra, containing suvorexant, was approved by the FDA in 2014 for the treatment of insomnia characterized by difficulties with sleep onset and sleep maintenance. The approved strengths include 5 mg, 10 mg, 15 mg and 20 mg tablets (FDA, 2024).
For an ANDA applicant, Orange Book-listed patents can trigger certification obligations under the Hatch-Waxman framework. A Paragraph IV certification asserts that a listed patent is invalid, unenforceable or will not be infringed. If the patent owner brings suit within the statutory period, FDA approval may be subject to a 30-month stay under 21 U.S.C. § 355(j)(5)(B)(iii).
The existence of US 10,098,892 does not by itself establish that the patent is currently listed in the Orange Book for Belsomra. Orange Book listing is product-specific and depends on the patent holder’s submission and FDA’s listing records. The relevant regulatory analysis should distinguish:
- patents listed for the active ingredient;
- formulation patents;
- method-of-use patents;
- patents listed for specific strengths or dosage forms; and
- unlisted patents that may still be enforceable under 35 U.S.C. § 271(e)(2).
An unlisted patent can remain relevant to commercial litigation, but it does not create the same ANDA certification pathway as an Orange Book-listed patent.
When does US Patent 10,098,892 lose exclusivity?
The patent’s enforceable expiration date cannot be determined from the claim text alone. It depends on the patent’s earliest effective nonprovisional priority date, any patent-term adjustment, terminal disclaimer, patent-term extension and relevant prosecution history.
For a US utility patent, the baseline term is generally 20 years from the earliest effective US nonprovisional filing date, subject to statutory adjustments. The grant date, August 7, 2018, does not itself determine expiration. The patent should therefore be analyzed against:
- the front-page patent-term data;
- the USPTO Patent Center prosecution record;
- any continuation or divisional relationship;
- any terminal disclaimer;
- any patent-term adjustment calculation; and
- any Orange Book patent-term information.
A generic launch date cannot be projected reliably from the grant date alone. If the patent is Orange Book-listed and challenged through an ANDA, litigation timing and any settlement agreement may delay commercial entry beyond the nominal patent expiration.
Which companies are challenging the suvorexant patent estate?
The supplied claims do not identify an ANDA applicant, Paragraph IV certification, district-court action, or settlement agreement. No challenger, litigation date or settlement term can be inferred from US 10,098,892 itself.
The relevant sources for identifying challenges are:
- FDA Paragraph IV and exclusivity records;
- US district-court dockets;
- Delaware and New Jersey Hatch-Waxman complaints;
- Abbreviated New Drug Application litigation notices;
- PTAB inter partes review records; and
- SEC disclosures by Merck or generic applicants.
A Paragraph IV challenge would likely focus on claim construction of “amorphous form,” the meaning of “prepared by a process comprising hot melt extrusion,” enablement, written description and obviousness over prior amorphous solid-dispersion technology.
What is the generic-entry risk for Belsomra?
Generic-entry risk is product-design dependent.
High exposure
A generic is highly exposed if it:
- uses amorphous suvorexant;
- uses copovidone as the dispersion polymer;
- manufactures the dispersion by HME;
- uses the Belsomra-like excipient combination; and
- supplies 5 mg, 10 mg, 15 mg or 20 mg tablets.
Moderate exposure
Risk is moderate if the generic uses amorphous suvorexant and copovidone but uses a different manufacturing route, or uses HME but a different polymer system. The outcome would depend on whether the process and composition limitations are met and whether equivalent process evidence is available.
Lower exposure
Risk is lower where the product uses:
- a crystalline suvorexant form;
- a polymer other than copovidone;
- a non-HME manufacturing process; or
- a substantially different dosage form.
Lower exposure under this patent does not eliminate risk from separate compound, polymorph, method-of-use or formulation patents.
What is the commercial exposure?
Belsomra is the reference product for the claimed strengths. The claims therefore map directly onto the commercial tablet strengths approved by FDA. Revenue exposure depends on:
- whether the patent is Orange Book-listed;
- whether a generic applicant selects the same solid dispersion;
- whether other suvorexant patents remain enforceable;
- whether FDA grants 180-day first-filer exclusivity;
- whether litigation produces a launch-at-risk decision; and
- whether a settlement permits an agreed entry date.
The patent’s commercial value is higher if it is one of several mutually reinforcing patents covering the active ingredient, polymorph, formulation and use. Its standalone value is more limited because a technically credible alternative formulation may avoid the claims.
What geographic coverage does the patent provide?
US Patent 10,098,892 provides protection only in the United States. Corresponding international or foreign-family applications may protect similar subject matter in Europe, Japan, Canada, Australia and other markets, but foreign coverage cannot be assumed from the US patent number.
Foreign equivalents may differ materially in:
- claim scope;
- validity;
- prosecution amendments;
- patent-term dates;
- supplementary protection certificate eligibility;
- opposition history; and
- enforceability.
A global freedom-to-operate review must therefore examine the INPADOC or equivalent family, not only the US grant.
Key Takeaways
- US 10,098,892 is a formulation and process patent, not a basic suvorexant compound patent.
- Claim 1 requires amorphous suvorexant, copovidone and HME preparation.
- Claim 10 adds lactose monohydrate, microcrystalline cellulose, croscarmellose sodium and magnesium stearate.
- Claims 15 through 18 cover 5 mg, 10 mg, 15 mg and 20 mg products with at least 90%, 95%, 98% or 99% amorphous suvorexant, depending on the claim.
- The strongest design-around options are crystalline suvorexant, a polymer other than copovidone and a non-HME manufacturing process.
- The absence of specified analytical methods for amorphous content may create infringement and validity disputes.
- Orange Book listing, Paragraph IV activity, litigation and settlement status must be established from FDA and court records rather than inferred from the patent grant.
- The patent’s commercial strength depends on whether it operates with separate suvorexant compound, polymorph, method-of-use and formulation patents.
FAQs
Does US 10,098,892 cover Belsomra itself?
It may cover a Belsomra formulation only if the marketed product satisfies the claimed amorphous suvorexant, copovidone and HME limitations. The patent does not automatically cover every product containing suvorexant.
Can a generic avoid the patent by changing only the excipients?
Changing the excipients may avoid claim 10 and claims 15 through 18, but it may not avoid claim 1 if the product still contains amorphous suvorexant and copovidone and is made by HME.
Does a 20 mg suvorexant tablet automatically infringe claim 18?
No. The dose is only one limitation. The product must also meet the specified excipient, amorphous-content and HME requirements.
Does use of hot-melt extrusion alone create infringement?
No. HME alone is insufficient. The claimed composition must also contain amorphous suvorexant and copovidone, and the relevant mixture must be extruded under the claim language.
Can a patent challenge proceed through inter partes review?
Potentially. Patentability challenges based on printed prior art may be suitable for inter partes review, while some issues, including certain enablement and infringement disputes, are more commonly litigated in district court.
References
-
Abbott Laboratories v. Sandoz, Inc., 566 F.3d 1282 (Fed. Cir. 2009).
-
Food and Drug Administration. (2014). Belsomra (suvorexant) prescribing information. U.S. Department of Health and Human Services.
-
Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
-
U.S. Congress. (2012). 21 U.S.C. § 355: New drugs.
-
United States Patent and Trademark Office. (2018). U.S. Patent No. 10,098,892: Suvorexant pharmaceutical compositions. U.S. Department of Commerce.
