US Patent 10,736,866: Scope, Claim Construction, Expiration, and Sodium Oxybate Patent Landscape

US Patent No. 10,736,866 protects a once-nightly, dual-release gamma-hydroxybutyrate formulation that combines immediate-release and modified-release sodium oxybate with viscosity control and acidification. The patent is closely associated with Avadel Pharmaceuticals' Lumryz, an extended-release sodium oxybate product approved by the FDA in 2023 for cataplexy or excessive daytime sleepiness in narcolepsy. Its strongest protection is directed to the combined formulation architecture, not to sodium oxybate, narcolepsy treatment, or generic controlled release in isolation.[1][2]

The claims create multiple overlapping protection layers:

A dual-release sodium oxybate formulation.
A defined immediate-release-to-modified-release drug ratio.
Specific suspending or viscosifying agents and acidifying agents.
Dry particulate or powdered dosage forms mixed with liquid before administration.
Dissolution and pharmacokinetic performance limits.
Once-nightly treatment of narcolepsy.
Modified-release particles or coatings containing hydrophobic compounds with melting points of at least 40°C.

What does US Patent 10,736,866 cover?

The patent covers a formulation containing two physically or functionally distinct gamma-hydroxybutyrate populations:

An immediate-release portion.
A modified-release portion.
A suspending or viscosifying agent.
An acidifying agent.
A gamma-hydroxybutyrate ratio of 10/90 to 65/35 between the immediate-release and modified-release portions.

The core independent claim is claim 1. Claims 20, 39, 40, 41, 42, and 43 through 52 provide alternative independent claim formats that vary the added limitations.

The invention is designed to reproduce, through one nighttime dose, selected exposure characteristics associated with two equally divided doses of an immediate-release sodium oxybate liquid. The commercial objective is to avoid the second nighttime administration required by Xyrem and other immediate-release sodium oxybate regimens.

What are the independent claims in US 10,736,866?

Claim	Principal subject matter	Key additional limitation
1	Dual-release formulation	Defined excipient lists, acidifying-agent list, and 10/90 to 65/35 drug ratio
20	Once-nightly narcolepsy formulation	3.0 g to 12.0 g sodium oxybate equivalent; cataplexy or EDS treatment
39	Functional formulation	Viscosity and pourability after mixing; release profile remains unchanged for at least 15 minutes
40	Functional once-nightly formulation	Excipient percentages, sodium oxybate dose range, and narcolepsy use
41	Coated modified-release formulation	Hydrophobic coating compound with melting point of at least 40°C
42	Coated once-nightly formulation	Dose, use, excipient percentages, and hydrophobic coating
43	Bioavailability formulation	Relative bioavailability greater than 80% versus divided immediate-release dosing
44	Once-nightly bioavailability formulation	Dose, narcolepsy use, and relative bioavailability greater than 80%
45	Exposure-duration formulation	Mean AUC8h/AUCinf greater than 0.80
46	Once-nightly exposure-duration formulation	Dose, narcolepsy use, and AUC8h/AUCinf limitation
47	Tmax formulation	Median Tmax within 150 minutes of the comparator
48	Once-nightly Tmax formulation	Dose, narcolepsy use, and Tmax limitation
49	Concentration-profile formulation	Later concentration greater than comparator and later concentration below comparator
50	Once-nightly concentration-profile formulation	Dose, narcolepsy use, and concentration-profile limitation
51	Exposure and concentration formulation	AUCinf greater than 80% and C8h below 95% of comparator
52	Once-nightly exposure and concentration formulation	Dose, narcolepsy use, and combined PK limitations

Claims 2 through 19, 21 through 38, and the dependent claims associated with the later independent claims add narrower formulation, dose, coating, dissolution, or pharmacokinetic limitations.

How does claim 1 define the protected formulation?

Claim 1 requires every element below:

Required element	Scope
Active ingredient	Gamma-hydroxybutyrate, including sodium oxybate under claim 7
Release structure	Immediate-release portion plus modified-release portion
Suspending or viscosifying agent	One or more agents from a closed list
Acidifying agent	One or more agents from a closed list
Structural separation	Suspending/viscosifying and acidifying agents must be separate and distinct from the immediate- and modified-release portions
Drug ratio	Immediate-release drug to modified-release drug of 10/90 to 65/35

The ratio is particularly important. It permits an immediate-release fraction from 10% through 65%, with the balance in the modified-release fraction. A formulation with a 20/80, 40/60, or 65/35 distribution could fall within the express numerical range if the other limitations are met.

The claim does not require a specific manufacturing process, capsule, sachet, liquid volume, particle size, polymer molecular weight, or coating thickness. That broadens literal product coverage but leaves potential validity and infringement disputes focused on claim construction, enablement, written description, and the meaning of “portion.”

What excipients are protected by the patent?

The principal suspending or viscosifying-agent list includes:

Xanthan gum
Carrageenan gum
Gellan gum
Guar gum
Sodium alginate
Calcium alginate
Agar
Sodium carboxymethyl cellulose
Microcrystalline cellulose
Hydroxyethyl cellulose
Hydroxypropylmethyl cellulose

The acidifying-agent list includes:

Malic acid
Citric acid
Tartaric acid
Adipic acid
Boric acid
Maleic acid
Phosphoric acid
Ascorbic acid
Oleic acid
Capric acid
Caprylic acid
Benzoic acid

Claim 3 narrows the excipient combination to either:

Xanthan gum, carrageenan gum, and hydroxyethylcellulose; or
Xanthan gum and carrageenan gum,

combined with malic acid or tartaric acid.

Claims 2 and 20 impose concentration ranges of 1% to 15% for the viscosifying agent and 1.2% to 15% for the acidifying agent. These percentage limitations are calculated by weight of the formulation and may create design-around opportunities if a competing product uses different concentrations or a nonlisted excipient.

What formulations are protected by claims 5, 24, and 39 through 42?

The patent has substantial coverage for dry oral products that are mixed with liquid before administration.

Claim 5 covers a dry particulate or powdered formulation. Claims 24 and 39 through 42 provide related coverage, with claims 39 and 40 expressly linking the excipient system to post-reconstitution viscosity, pourability, and release-profile stability.

The “separate and distinct” language is commercially important. It indicates that the suspending or viscosifying agent and acidifying agent are not merely generic ingredients in a homogeneous formulation. The claim language requires them to be distinct from the immediate-release and modified-release drug portions. A product using separate immediate-release particles, coated modified-release particles, and an external excipient matrix is more likely to implicate this limitation than a single matrix tablet in which all components are inseparably combined.

Claims 41 and 42 separately target a modified-release portion having a coating that includes a hydrophobic compound with a melting point of at least 40°C. The claim does not identify a closed list of hydrophobic coating materials. Potential materials could include hydrophobic lipids, waxes, fatty compounds, or related high-melting-point coating agents, subject to the patent's specification and claim-construction record.

What doses and administration methods are covered?

Claims 6 and 25 identify 4.5 g, 6.0 g, 7.5 g, and 9.0 g of gamma-hydroxybutyrate. Claims 20, 40, 42, 44, 46, 48, 50, and 52 broaden the sodium oxybate-equivalent dose range to 3.0 g through 12.0 g.

The treatment claims require a formulation designed for once-nightly oral administration to treat:

Cataplexy in narcolepsy.
Excessive daytime sleepiness in narcolepsy.

This is narrower than a formulation-only claim because it incorporates dose and intended therapeutic use. A competing formulation that satisfies the physical composition limitations but is not labeled or marketed for these indications could present a different infringement analysis. The formulation claims remain the principal commercial barrier because they do not depend on a method-of-treatment limitation.

What pharmacokinetic performance does the patent require?

Claims 9 through 13 and claims 28 through 32, 43 through 52 claim defined pharmacokinetic outcomes. The principal benchmarks are:

Parameter	Claimed threshold
Relative bioavailability	Greater than 80% versus equal-dose immediate-release sodium oxybate given at t0 and t4h
AUC8h/AUCinf	Greater than 0.80
Median Tmax	Within 150 minutes of the comparator Tmax
Late concentration profile	C6h or C7h greater than comparator and C10h less than comparator
Total exposure	Mean AUCinf greater than 80% of comparator
Late exposure	Mean C8h less than 95% of comparator

The comparator is not a simple single-dose immediate-release product. Several claims compare the patented formulation with an equal total dose of immediate-release liquid sodium oxybate administered in two equally divided doses at t0 and t4h, approximately two hours after a standardized evening meal.

These limitations can strengthen patentability by tying the formulation to a defined pharmacokinetic result. They can also complicate enforcement. An infringement case would likely require product testing under the specified fed conditions, dose, sampling schedule, and statistical definitions.

Claim 49 as supplied contains “mean C0,” while the corresponding claim 12 language uses “mean C4h.” That discrepancy should be checked against the issued patent PDF, certificate of correction, and prosecution history before relying on the supplied transcription.

What dissolution profiles are protected?

Claims 14 through 19 and claims 33 through 38 define dissolution behavior under USP Apparatus 2 conditions.

Portion or formulation	Dissolution requirement
Full formulation	At least 80% released at three hours in pH 6.8 phosphate buffer
Full formulation	10% to 65% released at one hour and three hours in 0.1 N hydrochloric acid
Modified-release portion	Greater than 80% released at three hours in pH 6.8 phosphate buffer
Modified-release portion	Less than 20% released at one hour in 0.1 N hydrochloric acid
Modified-release portion	Greater than 80% released at three hours after a two-hour acid stage followed by pH 6.8 buffer
Immediate-release portion	Greater than 80% released at one hour in 0.1 N hydrochloric acid

The dissolution claims are technically specific. They define medium, volume, pH, temperature, paddle speed, and apparatus. The modified-release portion must resist release in acid but release rapidly after transition to near-neutral phosphate buffer. That profile corresponds to a dosage form intended to pass through the stomach with limited release and then release in intestinal conditions.

A competing product could attempt to avoid these claims by changing the release mechanism, using a different pH response, adopting a different release window, or using a different combination of immediate- and modified-release units. Such changes would not necessarily avoid the broader composition claims.

When does US Patent 10,736,866 expire?

The patent issued on August 11, 2020. Its reported patent-term expiration is in March 2036, subject to any applicable patent-term adjustment, terminal disclaimer, correction, or later USPTO record.[1]

Event	Date
Patent issued	August 11, 2020
Patent number	US 10,736,866
Reported expiration	March 2036
Regulatory product associated with the estate	Lumryz, extended-release sodium oxybate
FDA approval of Lumryz	May 2023

The exact Orange Book expiration entry should control for regulatory exclusivity analysis. Patent expiration does not itself establish FDA exclusivity, and FDA regulatory exclusivity can expire on a different date.

What is the Orange Book status of US 10,736,866?

US 10,736,866 is associated with the Lumryz patent estate and has been reported as an Orange Book-listed patent for the product. The relevant commercial effect is that an ANDA applicant seeking approval for a product referencing Lumryz may need to address the listed patent through a Paragraph IV certification, a Paragraph III certification, or a statement that the applicant will not market until patent expiry, depending on the applicant's proposed label and product design.[2][3]

The Orange Book listing does not mean every claim is necessarily infringed by every sodium oxybate product. The listed claims are formulation-specific. A generic applicant must assess whether its product contains:

Both immediate- and modified-release sodium oxybate portions.
The claimed excipient system.
The claimed drug ratio.
The claimed coating or dissolution profile.
The claimed pharmacokinetic performance.

A product referencing Lumryz may face a more direct patent challenge than a product referencing Xyrem or Xywav because the product design itself is based on once-nightly extended release.

Have Paragraph IV challenges or litigation affected the patent?

The principal Paragraph IV risk is an ANDA or other abbreviated application directed to Lumryz. A Paragraph IV certification could trigger a patent infringement action under the Hatch-Waxman framework and a potential 30-month FDA approval stay if the statutory conditions are met.[3]

The relevant litigation questions are:

Whether an ANDA product uses the same dual-release architecture.
Whether the generic product's immediate-release fraction falls within 10% to 65%.
Whether the formulation uses a listed viscosity agent and acidifying agent.
Whether the modified-release component meets the hydrophobic-coating or dissolution limitations.
Whether the generic applicant's proposed label induces use for narcolepsy indications.
Whether the listed claims are valid under Sections 101, 102, 103, and 112.

No conclusion about a particular Paragraph IV certification or settlement should be inferred from the patent claims alone. A complete litigation assessment requires the FDA Orange Book record, ANDA notices, district-court complaints, docket activity, and any settlement or license agreements.

Which companies compete with Avadel in sodium oxybate?

Company	Product	Release pattern	Commercial relevance
Avadel Pharmaceuticals	Lumryz	Once-nightly extended release	Closest product to the claimed formulation
Jazz Pharmaceuticals	Xyrem	Immediate-release oral solution, generally divided dosing	Original branded sodium oxybate benchmark
Jazz Pharmaceuticals	Xywav	Once-nightly? No. Immediate-release mixed-cation oxybate solution with divided dosing	Competes on lower-sodium formulation and established Jazz distribution
Generic manufacturers	Sodium oxybate products	Primarily immediate-release or reference-product-dependent	Potential price competition; formulation-specific patent risk varies

Lumryz's differentiator is once-nightly administration. Xyrem and Xywav rely on divided nighttime dosing, although Xywav addresses sodium burden through a mixed-cation formulation. Those products may compete clinically and commercially without practicing every claim of US 10,736,866.

How strong is the patent estate for Lumryz?

US 10,736,866 has meaningful claim breadth but is not a standalone monopoly over sodium oxybate.

Strengths

Multiple independent claims cover the same commercial concept through different legal structures.
The claims combine composition, release architecture, dissolution, pharmacokinetic, and therapeutic-use limitations.
The 10/90 to 65/35 ratio directly targets the pharmacologic design of a dual-release once-nightly product.
Claims 41 and 42 add coating-based protection.
Claims 39 and 40 address reconstitution behavior, including viscosity, pourability, and release stability.

Vulnerabilities

Many claims depend on functional pharmacokinetic or dissolution testing that may produce litigation over methodology and reproducibility.
The excipient lists are closed in several claims, creating design-around opportunities.
A competitor could use a different modified-release mechanism or a different ratio.
Prior-art risk may arise from earlier controlled-release oxybate, multiparticulate, hydrophobic-coating, or reconstitutable-powder disclosures.
The “separate and distinct” limitation may become central if a competing product uses a single matrix or a different particle architecture.
The specification must support the full breadth of the numerous excipient combinations, dose ranges, ratios, and performance outcomes under Section 112.

The estate is strongest against a product that copies the commercial formulation architecture: dry multiparticulate sodium oxybate, a defined immediate-release fraction, hydrophobic modified-release particles, xanthan/carrageenan-based suspension control, and acidification with malic or tartaric acid.

What generic launch risks exist?

A generic launch could follow several paths:

Launch scenario	Patent risk
Copy of Lumryz release architecture	High risk under composition and dissolution claims
Same dose but different release mechanism	Moderate risk; depends on ratio and functional results
Immediate-release sodium oxybate	Lower risk under this patent, but other patents and regulatory requirements apply
Modified-release sodium oxybate without listed viscosity system	Reduced risk under narrow excipient claims; broader claims still require review
Product outside the 10/90 to 65/35 ratio	Potential design-around, subject to doctrine-of-equivalents arguments
Product without hydrophobic coating	Avoids claims 41 and 42 but not claims 1, 20, 39, or 40 if other elements remain
Product with a different acidifier	May avoid closed-list claims, depending on the independent claim asserted
Product marketed for a non-narcolepsy indication	May avoid method-of-use limitations but not formulation claims

FDA approval risk is separate from patent risk. A formulation may avoid infringement while still requiring a new drug application, a 505(b)(2) application, or another regulatory pathway rather than a conventional ANDA.

Does US 10,736,866 cover biosimilars?

No. Sodium oxybate is a small-molecule active pharmaceutical ingredient, not a biologic. Biosimilar provisions under the Public Health Service Act do not apply. The relevant competitors are ANDA applicants, 505(b)(2) applicants, and potentially new drug applicants.[3]

What manufacturing and IP barriers does the patent create?

The key manufacturing barrier is the need to produce reproducible populations of immediate-release and modified-release gamma-hydroxybutyrate while maintaining:

The claimed drug ratio.
Particle or granule integrity.
Controlled acid-stage release.
Rapid post-acid release.
Stable viscosity after reconstitution.
Pourability from the delivery container.
Dose uniformity across high sodium oxybate loads.
Pharmacokinetic consistency under fed conditions.

These requirements can create process know-how that is not fully visible from the issued claims. Even if a competitor designs around the patent, it may face development and scale-up challenges in matching a once-nightly exposure profile without excessive early exposure or inadequate late-night concentrations.

What licensing and settlement issues should investors monitor?

The most important commercial documents are:

Avadel's licenses and development agreements relating to FT218 or Lumryz.
Jazz settlement agreements with generic sodium oxybate applicants.
Orange Book patent listings and delistings.
Paragraph IV notices concerning Lumryz.
District-court litigation involving US 10,736,866 and related patents.
Any covenant not to sue, supply agreement, or authorized-generic transaction.

A settlement involving Xyrem or Xywav does not necessarily resolve US 10,736,866. The Avadel and Jazz patent estates protect different product architectures and should be analyzed separately.

Key Takeaways

US 10,736,866 is a formulation patent directed to once-nightly extended-release gamma-hydroxybutyrate, particularly sodium oxybate.
The central architecture is a 10% to 65% immediate-release fraction combined with a 35% to 90% modified-release fraction.
Claims also require specific suspending or viscosifying agents and acidifying agents in several independent claim formats.
Claims 39 through 42 add reconstitution, viscosity, pourability, release-stability, and hydrophobic-coating limitations.
Claims 43 through 52 protect defined bioavailability, AUC, Tmax, concentration, and dissolution outcomes.
The patent is associated with Avadel's Lumryz and has a reported expiration in March 2036.
The patent does not cover all sodium oxybate products or biosimilars.
A direct Lumryz copy presents the highest infringement risk. Immediate-release products, alternative release mechanisms, different excipients, and out-of-range drug ratios offer potential design-around strategies.
Paragraph IV, Orange Book, litigation, and settlement analysis must be performed at the patent-family and product-label level, not from the patent claims alone.

FAQs About US Patent 10,736,866

What drug is protected by US Patent 10,736,866?

The patent protects formulations containing gamma-hydroxybutyrate, including sodium oxybate, with combined immediate-release and modified-release portions. It is associated with Lumryz.

Is US 10,736,866 a method-of-use patent?

Most claims are formulation claims. Claims 20, 40, 42, 44, 46, 48, 50, and 52 include once-nightly treatment of cataplexy or excessive daytime sleepiness in narcolepsy.

Can a generic sodium oxybate liquid infringe US 10,736,866?

A conventional immediate-release sodium oxybate liquid would generally lack the claimed dual-release formulation architecture. It may still face other patents, regulatory requirements, or product-specific claims.

What is the most important limitation in claim 1?

The combination of a separate immediate-release portion, a separate modified-release portion, the 10/90 to 65/35 drug ratio, and the specified viscosity and acidification system is the central limitation.

Does patent expiry automatically permit generic Lumryz launch?

No. A generic applicant must address all relevant unexpired patents, regulatory exclusivity, FDA approval requirements, and any litigation or settlement restrictions.

References

United States Patent and Trademark Office. (2020). US Patent No. 10,736,866, gamma-hydroxybutyrate formulations. U.S. Department of Commerce.
U.S. Food and Drug Administration. (2023). Lumryz (sodium oxybate) extended-release oral suspension: Prescribing information. FDA.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2023). Lumryz approval announcement and regulatory materials. FDA.
Congress of the United States. (1984). Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Avadel Cns	LUMRYZ	sodium oxybate	FOR SUSPENSION, EXTENDED RELEASE;ORAL	214755-001	May 1, 2023		RX	Yes	Yes	10,736,866	⤷ Start Trial	Y				⤷ Start Trial
Avadel Cns	LUMRYZ	sodium oxybate	FOR SUSPENSION, EXTENDED RELEASE;ORAL	214755-002	May 1, 2023		RX	Yes	No	10,736,866	⤷ Start Trial	Y				⤷ Start Trial
Avadel Cns	LUMRYZ	sodium oxybate	FOR SUSPENSION, EXTENDED RELEASE;ORAL	214755-003	May 1, 2023		RX	Yes	No	10,736,866	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	109376	⤷ Start Trial
Australia	2017300845	⤷ Start Trial
Australia	2020231916	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 10,736,866

Which drugs does patent 10,736,866 protect, and when does it expire?

Summary for Patent: 10,736,866