United States Patent 4,515,805: Scope, Claim Construction, Expiration and Patent Landscape for Sodium Cromoglycate Compositions

U.S. Patent No. 4,515,805 covers a fast-dissolving oral sodium cromoglycate composition built on sucrose particles. The claims require defined particle-size ranges, a sucrose-to-drug ratio, and deposition of fine sodium cromoglycate on the surface of larger sucrose particles. The patent also claims certain unit-dose, low-moisture and sachet presentations, plus a manufacturing method.

The patent issued on May 7, 1985. Its original 17-year patent term therefore ended on May 7, 2002, absent an unusual term adjustment or terminal-disclaimer issue. The patent is no longer an enforceable U.S. exclusion right under the ordinary statutory term rules applicable to the application. Its commercial importance is historical rather than current. [1][2]

What does U.S. Patent 4,515,805 protect?

The patent protects a physical formulation architecture rather than sodium cromoglycate as a chemical compound.

The claimed product has four central features:

A water-soluble pharmaceutical carrier consisting essentially of sucrose.
Sucrose particles measuring 200 to 1,000 microns.
Sodium cromoglycate particles with a mass median diameter of 2 to 30 microns.
Sodium cromoglycate deposited as a coating or surface layer on the sucrose particles, at a sucrose-to-drug weight ratio of 2:1 to 20:1.

Claim 1 is the broadest composition claim. Claims 2 through 7 narrow the formulation by adding tighter particle-size ranges, dosage, packaging, moisture and excipient limitations.

Claims 8 through 10 are process claims. They require depositing the specified sodium cromoglycate particles as a surface layer on the sucrose carrier to produce an increased dissolution rate in cold water.

Patent identification

Item	Data
Patent	U.S. Patent No. 4,515,805
Likely title	Pharmaceutical compositions
Patent type	Formulation and manufacturing-process patent
Active ingredient	Sodium cromoglycate, also called cromolyn sodium
Assignee shown in the patent record	Fisons Limited
Issue date	May 7, 1985
Original patent term	17 years from grant for this pre-June 8, 1995 patent
Ordinary expiration date	May 7, 2002
Current enforceability	Expired by term
Main dosage concept	Water-soluble oral powder or granule composition
Main commercial objective	Rapid dissolution in cold water

How should claim 1 be construed?

Claim 1 is a combination claim. A product must contain every material limitation to infringe literally.

Required carrier

The carrier must be water-soluble, pharmaceutically acceptable and composed essentially of sucrose. The phrase “consisting essentially of” generally permits components that do not materially alter the basic and novel characteristics of the composition. The claim therefore has less flexibility than an “ comprising” limitation but is broader than a strict “consisting of” limitation.

A formulation based on lactose, mannitol, sorbitol, maltodextrin or another soluble carrier would not literally satisfy the sucrose carrier limitation. A composition containing sucrose plus a minor processing aid could raise a “consisting essentially of” issue, depending on whether the additional material changes the claimed coating or dissolution characteristics.

Required sucrose particle size

The sucrose carrier must have a particle size of 200 to 1,000 microns. Claim 2 narrows the range to 200 to 500 microns.

The patent does not merely claim sucrose as a diluent. Particle size is a mandatory claim limitation. A formulation using sucrose outside the claimed range would have a noninfringement position under the literal claim language, subject to measurement methodology and possible doctrine-of-equivalents arguments.

Required sodium cromoglycate particle size

The drug must have a mass median diameter of 2 to 30 microns. Claim 2 narrows the range to 2 to 10 microns.

Mass median diameter is a distribution metric, not simply the size of an individual particle. Particle-size testing technique, sample preparation, agglomeration and instrument selection could materially affect infringement analysis. A technical comparison would need to use a reproducible method consistent with the patent specification and the accused product’s manufacturing controls.

Required surface coating

The sodium cromoglycate must form a coating or surface layer on the sucrose particles. This limitation distinguishes the patent from a simple physical blend of sucrose and cromolyn sodium.

The coating requirement is likely the principal structural limitation. Evidence relevant to infringement would include:

Scanning electron microscopy.
Cross-sectional imaging.
Particle morphology.
Distribution of sodium cromoglycate on sucrose surfaces.
Granulation or layering process records.
Dissolution behavior in cold water.
Batch manufacturing instructions.

A product containing the same ingredients and ratio but manufactured as a homogeneous blend may avoid literal infringement if the drug does not form a surface layer.

Required weight ratio

The carrier-to-sodium cromoglycate ratio must be 2:1 to 20:1. Claim 3 narrows that range to 5:1 to 12:1.

The ratio is expressed as parts by weight of carrier to drug in the coated particles. The relevant calculation may exclude or include other components depending on the claim construction and the formulation’s actual composition. Because claim 7 excludes other excipients, the patent provides a particularly narrow embodiment in which sucrose is the only excipient.

Which dependent claims add the most commercial significance?

Claims 2, 3 and 4 are the most commercially relevant narrowing claims. They describe a practical dosage-form window rather than merely theoretical boundaries.

Claim	Added limitation	Commercial implication
1	Sucrose carrier, particle sizes, surface coating, 2:1 to 20:1 ratio	Core formulation
2	Drug 2-10 microns; sucrose 200-500 microns	Tighter dissolution-oriented particle ranges
3	Sucrose-to-drug ratio 5:1 to 12:1	Preferred formulation ratio
4	Unit dose with 50-300 mg sodium cromoglycate	Patient-use dosage presentation
5	Water-resistant sachet	Moisture-protective packaging
6	Less than 2% water	Stability and powder-flow limitation
7	No excipient other than soluble carrier	Narrow excipient profile

Claim 5 is directed to packaging rather than the drug product alone. A sachet made of material that prevents water ingress must contain the claimed composition, but the patent does not claim every moisture-resistant package for sodium cromoglycate.

Claim 6 may have been intended to address the hygroscopic or moisture-sensitive behavior of the powder. It creates a measurable but potentially variable limitation. Testing the finished product’s water content would be central to any enforcement analysis.

Claim 7 is narrow because many commercial oral powders use flow agents, sweeteners, flavorants, buffers or other excipients. A product with any additional excipient may fall outside claim 7 even if it satisfies claim 1.

What formulations are protected by U.S. Patent 4,515,805?

The strongest claimed embodiment is a sachet containing 50 to 300 mg of sodium cromoglycate, fine drug particles in the 2-10 micron range, sucrose particles in the 200-500 micron range, a sucrose-to-drug ratio of 5:1 to 12:1, less than 2% water and no excipient other than sucrose.

The patent therefore targets a dry, rapidly dissolving oral powder intended to be dispersed in cold water before administration. It does not broadly cover:

All sodium cromoglycate products.
All oral cromolyn sodium products.
Inhaled cromolyn products.
Nasal cromolyn products.
Liquid cromolyn solutions.
Tablets or capsules lacking the claimed sucrose coating.
Sucrose-free formulations.
Formulations with materially different particle sizes.
Formulations in which sodium cromoglycate is blended rather than surface-deposited.

The claims do not cover the active ingredient itself. Sodium cromoglycate was known before this patent, and the claimed advance concerns dissolution and formulation engineering.

How do the method claims differ from the product claims?

Claims 8 through 10 require a method of preparing the composition by depositing fine sodium cromoglycate on larger sucrose particles.

A process may infringe claim 8 if it performs the specified deposition steps and produces the claimed particle and ratio characteristics, even if the resulting product is sold in a different presentation. Claim 8 also recites an “increased rate of dissolution in cold water,” which may create an evidentiary issue concerning the comparator and test conditions.

The method claims are vulnerable to several noninfringement positions:

Use of a different granulation or agglomeration process.
Dry blending without surface deposition.
Use of a carrier other than sucrose.
Use of particle sizes outside the claimed ranges.
Use of a ratio outside 2:1 to 20:1.
Failure to achieve the claimed dissolution result.

The process claims could have mattered during the patent term to manufacturers whose formulation was difficult to distinguish analytically from the claimed product. They have no current blocking effect because the patent has expired.

When did U.S. Patent 4,515,805 lose exclusivity?

The patent’s ordinary term ended on May 7, 2002, 17 years after issuance. This term rule applies to U.S. patents issued from applications filed before the transition to the modern 20-year-from-earliest-effective-filing-date regime. [2]

The practical timeline is:

Event	Date
Patent issued	May 7, 1985
17-year term begins for term calculation	May 7, 1985
Ordinary expiration	May 7, 2002
Current status	Expired

The patent therefore cannot block a current generic, reformulator or manufacturer based solely on the expired claims. Patent expiration does not eliminate other possible rights, such as trademarks, trade secrets, regulatory exclusivity, manufacturing know-how or later patents covering a different formulation.

What is the Orange Book status of the patent?

U.S. Patent No. 4,515,805 is not an operative Orange Book patent right today because it expired in 2002. Orange Book listing is product- and NDA-specific, and a patent number does not establish that it was listed against every cromolyn sodium product.

Cromolyn sodium has been marketed in multiple FDA dosage forms, including oral and inhaled products. Gastrocrom is an FDA-approved oral cromolyn sodium product, while Intal was associated with inhaled cromolyn sodium therapy. The claimed sucrose-coated oral powder is materially different from an inhalation aerosol or nebulized formulation. [3][4]

Any historic Orange Book listing would have depended on whether the patent claimed the approved NDA product and whether the NDA holder submitted it for listing. The expired status means that no current paragraph IV certification or 30-month stay can preserve exclusivity under this patent.

Were there Paragraph IV challenges or generic-entry disputes?

No current Paragraph IV dispute can arise from U.S. Patent No. 4,515,805 because the patent expired more than two decades ago. A generic applicant today would not need to wait for this patent to expire and would not obtain a litigation stay based on it.

The patent’s claims also would not automatically be relevant to every abbreviated new drug application for cromolyn sodium. Relevance would depend on the proposed product’s dosage form and whether the ANDA product uses the claimed sucrose-particle architecture.

For a current oral powder, a historical freedom-to-operate review should separate:

Expired patent 4,515,805.
Later patents on cromolyn formulations.
Manufacturing-process patents.
Device or packaging patents.
FDA labeling and product-specific requirements.
Trade-secret process information held by current or former manufacturers.

How strong was the patent estate?

The patent had moderate technical specificity but limited breadth.

Strengths during the patent term

It claimed both product and manufacturing method.
It used several measurable formulation parameters.
It focused on a practical dissolution problem.
The coating limitation could distinguish a routine physical mixture.
The dependent claims captured a commercially plausible unit-dose product.

Weaknesses during the patent term

The claims were narrowly tied to sucrose.
Particle-size and mass-median measurements could create reproducibility disputes.
The surface-coating limitation required specialized evidence.
The active ingredient was old and not protected by the patent.
Alternative carriers, dosage forms and manufacturing processes were outside the core claim set.
Claim 7 was particularly narrow because it barred other excipients.

The patent was therefore a formulation patent with meaningful design-around potential. A competitor could investigate alternative soluble carriers, different particle-size distributions, additional excipients, liquid dosage forms or a noncoating manufacturing route.

What generic-entry risks exist today?

Patent risk from this patent is zero as a matter of current term status. Commercial and regulatory risks may remain independent of the expired patent.

Potential current barriers include:

FDA requirements for an oral cromolyn sodium product.
Demonstrating pharmaceutical equivalence and bioequivalence where applicable.
Manufacturing reproducibility for a powder or reconstituted solution.
Stability under moisture exposure.
Product liability and labeling requirements.
Brand, trade dress or trademark rights.
Later formulation patents not addressed by this patent.
Limited market size and uncertain reimbursement.

The patent itself does not create a current generic-launch obstacle.

Which companies held or commercialized the relevant rights?

The patent identifies Fisons Limited as the patent assignee. Fisons was historically associated with cromolyn sodium products, including Intal and oral cromolyn products. Corporate ownership and product rights later changed through pharmaceutical portfolio transactions and corporate acquisitions.

The patent record alone does not establish a continuing license, settlement, covenant not to sue or current ownership interest. No current licensing or settlement right should be inferred from the expired patent.

How does this patent compare with competing cromolyn sodium patent strategies?

Strategy	Covered by 4,515,805?	Commercial effect
Sucrose-coated oral powder	Yes, if all limitations are met	Core target
Oral liquid solution	Generally no	Different formulation platform
Inhaled cromolyn aerosol	No	Separate dosage form
Nasal cromolyn spray	No	Separate delivery system
Tablet with non-sucrose excipient	Generally no	Potential design-around
Simple sucrose-drug blend	Not necessarily	Coating limitation is material
Process using alternative carrier	No literal coverage	Manufacturing design-around
Product with added excipients	May avoid claim 7; not necessarily claim 1	Depends on “consisting essentially of”

Key Takeaways

U.S. Patent 4,515,805 claims a sucrose-based, surface-coated sodium cromoglycate powder.
The core numerical limitations are sucrose particles of 200-1,000 microns, sodium cromoglycate particles of 2-30 microns, and a 2:1 to 20:1 carrier-to-drug ratio.
Claims 2-7 narrow the invention through preferred particle sizes, dosage, packaging, moisture content and excipient restrictions.
Claims 8-10 cover the deposition process used to prepare the coated particles.
The patent issued May 7, 1985 and ordinarily expired May 7, 2002.
It has no current blocking effect against generic or reformulated cromolyn sodium products.
The patent never broadly covered cromolyn sodium as an active ingredient or all cromolyn dosage forms.
The principal historical design-arounds were alternative carriers, different particle sizes, added excipients, liquid formulations and noncoating processes.
Current commercial diligence must focus on later patents, FDA requirements, manufacturing know-how and market economics rather than this expired patent.

FAQs

Does U.S. Patent 4,515,805 cover Gastrocrom?

It may have been relevant to an oral sodium cromoglycate powder concept, but the patent does not automatically cover every Gastrocrom presentation. Product coverage depends on the approved formulation and whether it contains the claimed sucrose-coated particles.

Can a company manufacture a sucrose and cromolyn sodium powder today?

Yes, the expired patent does not prevent manufacture. A current product would still require compliance with FDA requirements and review of later patents, trademarks, trade secrets and product-specific regulatory obligations.

Is sodium cromoglycate the same drug as cromolyn sodium?

Yes. Sodium cromoglycate is commonly called cromolyn sodium in the United States. The patent uses sodium cromoglycate terminology.

Does a moisture-resistant sachet alone infringe the patent?

No. The sachet limitation appears in claim 5, which depends on the claimed composition and unit-dose limitations. Packaging alone is insufficient.

Can a liquid cromolyn sodium product infringe this patent?

A liquid product would generally not satisfy the claimed particulate sucrose carrier and surface-coating limitations. Separate patents or regulatory rights could still apply to the liquid product.

References

United States Patent No. 4,515,805, “Pharmaceutical compositions,” issued May 7, 1985, U.S. Patent and Trademark Office.
35 U.S.C. §§ 154, 156, 271, 282. United States Code.
U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs, cromolyn sodium products.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book.

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8035457	Nov 05, 1980

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	530962	⤷ Start Trial
Australia	7712781	⤷ Start Trial
Belgium	891013	⤷ Start Trial
Canada	1166571	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,515,805

Summary for Patent: 4,515,805