United States Patent 5,776,885: Claim Scope, Expiration, and Sustained-Release Peptide Patent Landscape

U.S. Patent 5,776,885 covers biodegradable sustained-release compositions containing a water-insoluble peptide pamoate salt dispersed in polylactide, poly(lactic-co-glycolic acid), or a mixture of those polymers. The claims are directed principally to injectable microparticles, solid rods, and parenteral implants that release peptide continuously for at least one week and maintain peptide activity for at least one month.

The patent is expired and does not create current U.S. patent exclusivity. Its historical scope remains relevant for freedom-to-operate analysis because it illustrates the claim architecture used for long-acting peptide depots: active-agent salt selection, PLGA or PLA matrix composition, particle or rod geometry, gamma sterilization, burst-release limits, and sustained biological activity.

What does U.S. Patent 5,776,885 protect?

The patent protects a drug-delivery composition rather than a particular approved drug product. Its core technical combination has four components:

A biodegradable polymer, consisting of polylactide, a lactic acid-glycolic acid copolymer, or a mixture.
A therapeutically active peptide in a water-insoluble pamoate salt form.
A sustained-release performance profile.
In certain claims, a specific physical form, sterilization process, or administration route.

The broadest principal claim is claim 1. It requires:

Claim element	Requirement
Dosage form	Dry pharmaceutical composition
Active ingredient	Therapeutically active peptide as a pamoate salt
Polymer	Polylactide, poly(lactic-co-glycolic acid), or mixture
Release period	Continuous release for at least one week
Biological performance	Maintenance of peptide activity for at least one month
Environment	Aqueous physiological environment

The claim does not require a specific peptide sequence, particle size, polymer molecular weight, lactide:glycolide ratio, manufacturing process, injection route, or dosing interval unless those limitations appear in a dependent claim.

How broad is claim 1 of U.S. Patent 5,776,885?

Claim 1 is compositionally broad but functionally constrained. A potentially infringing composition would need to satisfy all of the following limitations:

It must be dry before administration or use.
The peptide must be present as a pamoate salt.
The matrix must contain PLA, PLGA, or both.
The formulation must release peptide continuously for at least one week.
Peptide activity must remain effective for at least one month after placement in an aqueous physiological environment.

The release and activity limitations are important. A PLA or PLGA depot containing a peptide pamoate would not necessarily fall within claim 1 unless the required release and activity profile could be demonstrated.

The phrase “maintenance of activity of the peptide for at least one month” is narrower than a simple requirement that peptide remain physically present. The formulation must maintain biological activity, which creates an analytical issue for infringement and validity. The relevant assay could involve receptor binding, endocrine activity, in vivo pharmacology, or another activity measurement depending on the specification and prosecution history.

The phrase “continuous manner” also limits the claim. A formulation that releases peptide only during discrete pulses, or that produces a substantial inactive interval, may fall outside the literal scope even if the total delivery period exceeds one month.

What peptides and peptide salts are covered?

Claim 2 expressly covers pamoate salts of LHRH and synthetic LHRH analogues. Claim 4 narrows the scope to the pamoate salt of D-Trp6-LHRH. Claim 5 identifies a second specific peptide:

D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2.

Claim 3 lists a broad group of peptide classes, including:

Oxytocin
Vasopressin
ACTH
Calcitonin
Epidermal growth factor
Prolactin
Inhibin
Interferon
Somatostatin
Insulin
Glucagon
Atrial natriuretic factor
Endorphin
Renin inhibitors
Growth hormone-releasing hormone
Peptide T
Synthetic analogues

Because claim 3 depends on claim 1, the listed peptide must still satisfy the pamoate-salt limitation inherited from claim 1. The claim therefore does not automatically cover every pharmaceutically acceptable salt of every listed peptide. It requires the combination of the listed peptide category, the pamoate salt, the specified polymer, and the claimed release profile.

What formulations and dosage forms are protected?

Microparticles and microspheres

Claim 6 covers particles ranging from 1 to 500 micrometers. This range is consistent with injectable biodegradable microspheres and microparticles used for subcutaneous or intramuscular depot administration.

The claim does not require the particles to be spherical. A formulation using irregular particles could fall within the claim if the particle-size limitation and other elements are met.

Solid rods

Claim 7 covers a solid rod sterilized by gamma radiation. Claim 9 further identifies the rod as a parenteral implant.

The rod claims are narrower than claim 1 because they require a particular physical configuration. They may cover implants designed for subcutaneous or other parenteral placement, including systems that deliver peptide over a month or longer.

Polymer-dispersed peptide

Claim 11 requires the peptide salt to be dispersed within solid particles of the polymer. Claim 12 narrows the formulation to:

Pamoate salt of D-Trp6-LHRH
D,L-lactide and glycolide polymer
Peptide salt dispersed within solid polymer particles

Claim 12 is technically specific and historically important for PLGA microsphere formulations containing a defined LHRH analogue.

What is the difference between claims 1 and 10?

Claims 1 and 10 are separate independent claims with overlapping subject matter.

Issue	Claim 1	Claim 10
Dry composition	Expressly required	Not expressly stated in the claim text
Peptide	Water-insoluble peptide pamoate salt	Therapeutically active peptide in water-insoluble pamoate salt form
Polymer	PLA, PLGA, or mixture	PLA, PLGA, or mixture
Release profile	At least one week of continuous release and one month of activity	Same
Gamma sterilization	Not required by claim 1	Required
Carrier	Not required	Must be suspended in pharmaceutically acceptable carrier
Particle dispersion	Not required	Added in dependent claim 11

Claim 10 may be broader than claim 1 regarding the “dry” limitation, but it adds two substantial requirements: gamma sterilization and suspension in a pharmaceutically acceptable carrier. A product that satisfies claim 1 but is not gamma sterilized would not satisfy claim 10.

How strong is the patent estate for U.S. Patent 5,776,885?

The patent’s historical estate was technically meaningful but dependent on a narrow combination of features.

Strengths

It claimed both composition and physical dosage-form characteristics.
It covered a broad class of biodegradable polymers.
It targeted water-insoluble pamoate salts, which can improve depot formation for peptide drugs.
It included specific LHRH analogues and a defined PLGA system.
The release profile captured long-acting formulations rather than merely identifying a polymer-drug mixture.

Potential claim vulnerabilities

The breadth of claim 1 created several potential validity issues:

Enablement. The claims list numerous peptide classes with substantially different molecular weights, solubilities, stabilities, and biological activities. A challenger could argue that the disclosure does not enable the full genus without undue experimentation.
Written description. The specification would need to support the full scope of pamoate salts across the listed peptide classes, not merely the exemplified LHRH analogues.
Obviousness. PLA and PLGA peptide depots were established drug-delivery technologies. The patentability question would focus on whether the pamoate salt selection and claimed release/activity profile produced an unexpected result.
Functional limitations. “Continuous” release and “maintenance of activity” may create claim-construction disputes if the patent does not define testing conditions, assay methods, or acceptable variability.
Reproducibility. Release behavior depends on polymer molecular weight, lactide:glycolide ratio, particle size, porosity, drug loading, residual solvent, sterilization dose, and storage conditions. These variables may complicate both infringement testing and enablement analysis.

The patent’s expiration eliminates the commercial impact of these issues for new U.S. products, but they remain relevant to historical validity reviews and patent-landscape studies.

When did U.S. Patent 5,776,885 lose exclusivity?

U.S. Patent 5,776,885 is expired. The patent therefore does not currently block manufacture, sale, or use in the United States based solely on the claims quoted above.

Patent term is generally governed by 35 U.S.C. § 154, subject to transitional rules, patent-term adjustment, terminal disclaimers, and any patent-term extension under 35 U.S.C. § 156. The USPTO patent record should be treated as the controlling source for the recorded expiration and legal-status history.[2][3]

The expiration of this patent does not eliminate separate protection that could exist for:

A specific peptide active ingredient
A proprietary drug product
A later formulation
A manufacturing process
A device or applicator
A method of treatment
A later patent family claiming improved release, stability, or sterilization

What is the Orange Book status of U.S. Patent 5,776,885?

The patent is not, on the information provided, an Orange Book drug-substance or drug-product patent listing. Its claims cover a general sustained-release peptide composition and implant technology rather than a clearly identified FDA-approved drug product.

The Orange Book lists patents submitted by approved NDA holders for approved drug products. A patent does not become an Orange Book patent merely because it covers a pharmaceutical composition. The listing must be tied to an approved product and satisfy FDA listing requirements.[4]

The practical consequences are:

The patent should not automatically create a Paragraph IV barrier.
A generic applicant would need to assess current Orange Book listings for the relevant approved peptide product.
A 505(b)(2) applicant may face separate formulation, method-of-use, or product patents even though U.S. Patent 5,776,885 has expired.

Are there Paragraph IV challenges or generic-entry risks?

No current Paragraph IV challenge can be attributed to U.S. Patent 5,776,885 solely from the claims supplied. Because the patent is expired, it is not a viable current Paragraph IV barrier.

Generic-entry analysis depends on the product category:

Product type	Likely FDA pathway	Principal patent risk
Small-molecule peptide product with an ANDA-eligible reference	ANDA under section 505(j)	Current Orange Book patents and exclusivity
Complex injectable depot	Often 505(b)(2) or product-specific pathway	Formulation, device, manufacturing, and clinical bridging patents
Peptide biologic or biologic-like product	BLA or abbreviated biologic pathway where applicable	Product, process, formulation, and interchangeability issues
Implant or drug-device combination	NDA, 505(b)(2), or combination-product review	Device and manufacturing patents

For long-acting PLGA products, regulatory substitutability can be more difficult than chemical equivalence. Particle-size distribution, polymer degradation, peptide integrity, burst release, residual solvent, injectability, and pharmacokinetic variability may require substantial comparative data.

Does U.S. Patent 5,776,885 create biosimilar risk?

The patent itself presents no current biosimilar risk because it is expired. The relevant distinction is between the patent and the regulatory classification of the active peptide.

Some peptide products are regulated as drugs, while others may fall within biologic frameworks depending on molecular structure, product history, and FDA classification. A follow-on product could therefore proceed through an ANDA, 505(b)(2), or biologics pathway depending on the reference product.

For a long-acting peptide depot, the principal commercial barriers are likely to be:

Demonstrating comparable drug release
Matching peptide exposure over the full dosing interval
Showing comparable local tolerability
Reproducing polymer degradation behavior
Establishing manufacturing consistency
Addressing device or implant administration requirements

These issues are separate from the expired patent.

What patent litigation and licensing issues affect the patent?

The claims supplied do not identify litigation, settlement agreements, assignments, or licensing terms. No license right should be inferred from the claim language.

Any historical transaction analysis would need to distinguish:

Ownership of U.S. Patent 5,776,885
Licenses to the patent family
Licenses to particular LHRH analogues
Product-specific development agreements
Patent settlements involving later patents
Manufacturing or technology-transfer agreements

An expired patent generally has no continuing exclusionary value for new U.S. commercial activity, although contractual obligations, know-how rights, confidential manufacturing information, or foreign counterparts may remain relevant.

How does the patent compare with later sustained-release peptide patents?

U.S. Patent 5,776,885 is an early platform-style patent. Its claims emphasize the combination of:

A water-insoluble pamoate salt
A biodegradable PLA or PLGA matrix
Continuous release
Sustained biological activity
Microspheres or implants

Later patent estates in the long-acting peptide sector commonly shift toward narrower technical variables, including:

Specific polymer molecular-weight ranges
Defined lactide:glycolide ratios
Peptide loading percentages
Controlled initial burst release
Particle morphology
Solvent-extraction methods
Spray drying or phase-separation processes
Gamma-irradiation dose ranges
Stabilizers and buffering agents
Injection-device characteristics
Specific treatment regimens

Those later claims can remain enforceable even when the foundational platform patent has expired.

What generic launch scenarios exist?

The most realistic launch scenarios are:

An applicant uses a non-pamoate salt. This may avoid the literal pamoate limitation but requires separate assessment of formulation behavior and other patents.
An applicant uses a different biodegradable matrix. A polymer outside PLA, PLGA, or their mixture may avoid the composition limitation, subject to later patent claims.
An applicant develops a shorter or differently characterized release profile. A product that does not release continuously for one week or maintain activity for one month may avoid the functional limitations, although it may not provide equivalent clinical performance.
An applicant uses a different dosage form. A conventional injectable solution, implant material, or delivery device may fall outside the particle and rod claims.
An applicant relies on the expired status of the patent. This is the simplest U.S. position unless a related, unexpired patent covers the product.

What geographic coverage remains?

The U.S. patent has no current U.S. exclusionary term. Foreign counterparts must be reviewed independently because patent expiration dates, maintenance requirements, claim scope, and prosecution histories differ by jurisdiction.

A global freedom-to-operate review should identify:

PCT applications associated with the invention
European, Japanese, Canadian, and Australian counterparts
National-phase grants
Continuations and divisionals
Terminal disclaimers
Patent-term adjustments or extensions
National maintenance-fee status
Later patents covering specific commercial products

The U.S. expiration does not establish that every foreign family member has expired.

Key Takeaways

U.S. Patent 5,776,885 covers biodegradable PLA or PLGA sustained-release compositions containing water-insoluble peptide pamoate salts.
Claim 1 is the principal broad composition claim.
Claims 6 through 9 address particle size, gamma-sterilized rods, and parenteral implants.
Claims 10 through 12 add gamma sterilization, carrier suspension, polymer-particle dispersion, and specific peptide/polymer combinations.
The patent is expired and does not provide current U.S. exclusivity.
It is not, based on the supplied claims, a product-specific Orange Book barrier.
Current generic or follow-on risks would arise from later patents, FDA product classification, manufacturing complexity, and formulation comparability.
The principal historical validity issues concern enablement, written description, obviousness, and interpretation of the release-performance limitations.
Foreign counterparts and later continuation or improvement patents require separate review.

FAQs

Does U.S. Patent 5,776,885 cover all PLGA peptide microspheres?

No. The claims require a water-insoluble pamoate salt and specified release and biological-activity characteristics. PLGA microspheres using another salt or another release profile may fall outside the claims.

Does the patent cover leuprolide depot products?

The quoted claims expressly identify LHRH and synthetic analogues, including D-Trp6-LHRH. Coverage of a particular leuprolide product would require confirming the peptide identity, salt form, polymer system, release profile, and any applicable later patents.

Can a company commercialize a PLGA peptide implant in the United States?

U.S. Patent 5,776,885 itself is expired. Commercialization still requires review of later patents, FDA approval requirements, manufacturing controls, device issues, and product-specific intellectual property.

Does gamma sterilization alone create infringement under claim 7?

No. Gamma sterilization is only one limitation. Claim 7 also requires the claimed sustained-release peptide composition in solid-rod form, including the polymer and pamoate-salt elements inherited from claim 1.

Is the pamoate salt limitation required for the peptides listed in claim 3?

Yes. Claim 3 depends on claim 1. The listed peptide must therefore satisfy the pamoate-salt, polymer, release, and activity requirements inherited from claim 1.

References

United States Patent No. 5,776,885, “Sustained Release Pharmaceutical Composition,” issued July 7, 1998. U.S. Patent and Trademark Office.
United States Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/
35 U.S.C. §§ 154, 156.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8722134	Sep 21, 1988

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	397035	⤷ Start Trial
Austria	A223488	⤷ Start Trial
Australia	2232688	⤷ Start Trial
Australia	611944	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,776,885

Summary for Patent: 5,776,885