US Patent 6,740,341: Claim Scope, Expiration, Litigation Risk, and Taste-Masking Patent Landscape

US Patent 6,740,341 protects a multiparticulate oral dosage technology using a drug core, an intermediate spacing layer, and an outer pH-dependent taste-masking layer. The claims require both structural features and performance results: at least 20 seconds of taste protection in the mouth, disintegration within 90 seconds, and rapid drug exposure in the stomach.

The patent is directed to a formulation platform rather than a specific active ingredient. Its commercial value depended on applying the claimed coating architecture to orally administered drugs, vitamins, minerals, and nutritional products. The patent’s ordinary US term has ended, removing current US blocking power, although its claim structure remains relevant to freedom-to-operate reviews, prosecution strategy, and validity analysis.

What technology does US Patent 6,740,341 protect?

The patent covers coated drug particles designed for direct oral administration without conventional swallowing of a tablet or capsule.

The claimed architecture is:

A drug-containing core.
A spacing layer surrounding the core.
A taste-masking layer outside the spacing layer.
A rapidly dispersing dosage form containing the coated particles.

The spacing layer physically separates the drug core from the taste-masking layer. The outer layer is designed to remain substantially insoluble in saliva at neutral or basic pH but dissolve at an acidic pH below approximately 6.5.

This produces a two-stage release sequence:

Location	Intended event
Mouth	Outer taste-masking layer remains intact for at least about 20 seconds
Mouth after dosage-form disintegration	Particles form a suspension without materially exposing the spacing layer or drug core
Stomach	Acidic conditions dissolve the outer layer and rapidly expose the spacing layer and drug core
Post-gastric environment	Drug becomes available for dissolution and absorption

The claims do not protect every taste-masked drug particle. They require the specified coating arrangement, thickness ranges, particle size, and functional behavior.

What are the independent claims in US 6,740,341?

Claims 1 and 9 are the principal independent claims.

Claim 1: Taste-masked formulation

Claim 1 requires a formulation comprising:

A drug-containing core.
A taste-masking layer with a thickness of about 5 to 75 microns.
A spacing layer with a thickness of about 5 to 75 microns.
A spacing layer that substantially sequesters the core from the taste-masking layer.
An outer taste-masking material that is generally insoluble in saliva at neutral to basic pH.
Complete solubility of the taste-masking material at a pH below about 6.5.
At least about 20 seconds of protection against exposure of the spacing layer in the mouth.
Rapid exposure of the spacing layer in the stomach.
Disintegration in the mouth in less than 90 seconds to form a particle suspension.
A coated core generally no larger than 1,500 microns.

The claim uses both structural and functional limitations. A competing product must satisfy the physical coating configuration and the stated oral and gastric behavior.

Claim 9: Direct oral dosage form

Claim 9 covers a broader finished dosage form containing:

An effective amount of at least one drug.
Coated particles with the same spacing-layer and taste-masking-layer architecture.
At least one pharmaceutically acceptable excipient.
Excipient content of greater than zero and less than 100% of the finished dosage form.
Mouth disintegration in less than 90 seconds.
Formation of a suspension of particles.
A coated core generally no larger than 1,500 microns.

Claim 9 is directed to the finished dosage form, while claim 1 is directed more directly to the taste-masked formulation.

How do the dependent claims narrow the patent scope?

The dependent claims add quantitative limitations concerning coating weight, coating thickness, particle size, excipient content, and disintegrant content.

Claim	Added limitation
2	Drug may be a pharmaceutical, vitamin, mineral, nutritional supplement, or mixture
3	Spacing layer increases core weight by about 5% to 100%
4	Spacing layer increases core weight by about 20% to 50%
5	Spacing layer thickness is about 5 to 30 microns
6	Taste-masking layer increases core weight by about 5% to 100%
7	Taste-masking layer increases core weight by about 20% to 70%
8	Taste-masking layer thickness is about 5 to 30 microns
10	Coated particles comprise more than zero and up to about 95% of the finished dosage form
11	Coated particles comprise more than zero and up to about 75% of the finished dosage form
12	Dosage form includes a disintegrant
13	Disintegrant and excipient together comprise more than zero and up to about 75%
14	Coated core is no larger than 1,200 microns
15	Coated core is no larger than 850 microns
16	Claim 9 dosage form has a coated core no larger than 1,200 microns
17	Claim 9 dosage form has a coated core no larger than 850 microns

The particle-size limitations in claims 14 to 17 are commercially important. They target orally dispersible or sprinkle-type products in which the user experiences minimal grittiness and the drug is delivered through a rapidly disintegrating dosage form.

What formulations are protected by US 6,740,341?

The patent is potentially relevant to:

Orally disintegrating tablets containing coated microparticles.
Powders for suspension.
Sprinkle formulations.
Sachets and unit-dose granules.
Chewable dosage forms.
Multiparticulate oral suspensions.
Taste-masked vitamins and minerals.
Pediatric formulations.
Geriatric formulations.
Fast-disintegrating oral products.

A formulation would face the strongest literal-infringement risk if it has:

An insoluble or poorly soluble outer taste barrier at salivary pH.
A separate intermediate layer between that barrier and the drug core.
Coating thicknesses within the claimed ranges.
A sub-1,500-micron coated particle.
Mouth disintegration in less than 90 seconds.
Gastric dissolution or exposure at acidic pH.

A single-layer taste-masking coating generally would not satisfy the express requirement for a separate spacing layer. A formulation that uses an enteric polymer directly on the drug core may also avoid literal infringement if it lacks the claimed intermediate layer. The doctrine of equivalents could still be relevant, depending on the prosecution history and the technical function of the substituted layer.

How strong are the structural limitations?

The strongest limiting feature is the required three-part particle structure:

Feature	Claim significance
Drug core	Required in claims 1 and 9
Spacing layer	Required and must surround the core
Taste-masking layer	Required outside the spacing layer
Thickness ranges	Apply to both coating layers
pH behavior	Outer layer must resist saliva and dissolve below pH 6.5
Oral performance	At least 20 seconds of protection and under-90-second disintegration
Particle size	Generally no larger than 1,500 microns, with narrower dependent limits

The structural limitations are more concrete than the performance limitations. In litigation, coating cross-sections, polymer composition, coating weight, particle-size distributions, dissolution testing, and saliva-exposure studies would likely be central evidence.

The functional terms create potential claim-construction issues:

“about 5” and “about 75 microns”
“generally insoluble”
“completely soluble”
“rapidly”
“substantially completely”
“generally has a diameter”
“preventing exposure”
“for a period of at least about 20 seconds”

These terms do not automatically invalidate the claims. Their interpretation would depend on the specification, examples, prosecution history, accepted analytical methods, and the ordinary meaning of the terms at the relevant filing date.

What is the likely invalidity exposure?

The main validity challenges would involve anticipation, obviousness, written description, enablement, and indefiniteness.

Anticipation

A prior-art reference would need to disclose every material element of claim 1 or claim 9 in a single reference. The most difficult combination for an anticipation reference would likely be:

A drug core.
A separate spacing layer.
An outer pH-dependent taste-masking layer.
The stated thicknesses.
At least 20 seconds of oral taste protection.
Less-than-90-second mouth disintegration.
Rapid stomach exposure.

A reference disclosing only enteric coating or only taste masking would not necessarily anticipate the claims.

Obviousness

Obviousness risk is greater than anticipation risk because the claim combines known formulation techniques:

Taste masking.
Enteric or pH-dependent polymers.
Seal or spacing coats.
Multiparticulate drug delivery.
Orally disintegrating dosage forms.

The patentee’s strongest response would be that the specific sequence, thickness ranges, oral timing, gastric exposure, and particle-size limits produced a predictable but technically integrated result that was not disclosed or suggested by the prior art.

Indefiniteness

The performance language creates possible indefiniteness arguments if the patent does not identify objective test conditions. Relevant questions include:

Which saliva composition is used?
What temperature and agitation conditions apply?
How is “exposure” of the spacing layer detected?
What dissolution method establishes complete solubility below pH 6.5?
How is “rapidly” measured in the stomach?
Is particle diameter based on a mean, maximum, or distribution?

These issues would be evaluated under the patent’s specification and prosecution record, not from the claims alone.

When did US Patent 6,740,341 lose exclusivity?

The patent’s ordinary US patent term has expired. For a patent issuing from a post-June 8, 1995 application, the basic term is generally 20 years from the earliest effective US nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and other statutory rules (35 U.S.C. § 154).

Because US 6,740,341 is an early-2000s formulation patent, its ordinary term would have ended no later than the early 2020s. The claims therefore do not presently create an enforceable US exclusionary right based solely on the issued patent.

Any analysis of continuing rights must distinguish:

The issued patent.
Continuation or divisional patents.
Foreign counterparts.
Later patents claiming narrower formulations.
Contractual confidentiality or licensing obligations.
Trade-secret protection for manufacturing parameters.

Expiration of US 6,740,341 does not automatically eliminate later patent rights covering a particular drug, polymer, dosage form, process, or commercial product.

What is the Orange Book status of US 6,740,341?

US 6,740,341 is not, by itself, an Orange Book drug patent listing because the claims do not identify a specific active ingredient, approved product, strength, dosage form, or method of use.

The FDA Orange Book generally lists patents submitted by an NDA holder for an approved drug product. A formulation-platform patent may be associated with an NDA product only if the NDA holder submits it and represents that it claims the drug, formulation, or approved method of use. The patent number alone does not establish an Orange Book listing (FDA, 2024).

The practical consequences are:

No standalone Orange Book exclusivity arises from the claims.
A generic applicant would not ordinarily need to certify against this patent unless it appeared in the relevant NDA’s patent listing.
A Paragraph IV challenge would be tied to a listed drug product, not to the abstract formulation technology alone.
Expiration of the platform patent does not establish approval or launch rights for a particular generic product.

Does the patent create Paragraph IV or biosimilar risk?

Paragraph IV risk

The patent is relevant to Paragraph IV only if it was listed against an NDA product. If listed, a generic applicant could assert that the patent is invalid, unenforceable, or not infringed. The applicant could also certify that it will not market the product until patent expiration.

The patent is not a biologic patent. Its claims concern oral drug particles and dosage forms, not a biological molecule, cell line, antibody, or manufacturing process for a biologic.

Biosimilar risk

Biosimilar litigation is not the appropriate framework for this patent. A biosimilar application under the Public Health Service Act does not ordinarily practice an oral taste-masked multiparticulate formulation merely because it contains the same active ingredient as a reference biologic.

The relevant competitive risk is generic small-molecule entry or product substitution, not biosimilar entry.

Which companies could be affected by the patent landscape?

The patent’s technology is relevant to companies developing:

Orally disintegrating tablets.
Pediatric medicines.
Taste-masked antibiotics and analgesics.
Multiparticulate stimulants.
Sprinkle products.
Nutritional and vitamin formulations.
Over-the-counter chewable and orally dispersible products.

Potential counterparties include branded pharmaceutical companies, generic manufacturers, contract development and manufacturing organizations, and specialty formulation licensors. The patent itself does not establish that any particular company practiced the claims, licensed the technology, or settled litigation.

A company evaluating a product should separate three questions:

Question	Relevance
Does the product practice the claim architecture?	Technical infringement
Was the patent still in force on the relevant commercial date?	Enforceability
Are continuation or related patents still active?	Current freedom to operate

What manufacturing and IP barriers remain after expiration?

The expired patent does not remove manufacturing complexity. The technology may still require:

Controlled fluid-bed or pan coating.
Uniform application of the spacing layer.
Tight coating-thickness control.
Particle-size classification.
Polymer compatibility testing.
Taste-panel or electronic-tongue testing.
Acid-stage and saliva-stage dissolution testing.
Control of agglomeration and friability.
Scale-up validation.

The principal continuing barriers may be process know-how, formulation development time, regulatory bridging, and later patent families. Trade secrets can protect spray rates, inlet temperature, polymer concentration, suspension solids, drying conditions, and particle-classification methods even after patent expiration.

How does US 6,740,341 compare with single-layer taste-masking patents?

Issue	US 6,740,341	Single-layer taste-masking approach
Core structure	Drug core plus spacing layer plus outer taste layer	Drug core plus one masking layer
Saliva resistance	Required	May or may not be required
Acid-triggered release	Required below about pH 6.5	May use pH, erosion, or diffusion
Oral timing	At least about 20 seconds	Often not expressly claimed
Mouth disintegration	Less than 90 seconds	May not be claimed
Particle size	Generally no larger than 1,500 microns	Variable
Main design objective	Delay taste exposure while preserving gastric release	Reduce taste perception by any mechanism
Literal overlap	Highest where two distinct coating layers are used	Lower if no spacing layer exists

The two-layer coating architecture is the central differentiator. A competitor may design around the patent by eliminating the separate spacing layer, changing the release mechanism, using a non-pH-dependent taste barrier, or moving outside the claimed thickness and particle-size ranges. Such strategies require technical and legal review because equivalents and related patents may still matter.

What litigation and licensing conclusions follow?

The supplied claim set establishes the technical scope of US 6,740,341 but does not establish a current infringement action, settlement agreement, license, assignment, or commercial royalty obligation. The patent number should therefore be treated as a historical formulation-platform right rather than a current standalone launch blocker.

For a product developed today, the highest-priority diligence items are:

Confirm the complete US family, including continuations and divisionals.
Confirm the earliest effective filing date and terminal-disclaimer status.
Search later patents that claim the same drug, polymer combination, dosage form, or manufacturing process.
Check the relevant NDA’s current Orange Book listing.
Compare actual product cross-sections and dissolution data with each claim limitation.
Review any license chain attached to the technology or its assignee.

Key Takeaways

US 6,740,341 covers a drug core surrounded by a spacing layer and an outer pH-dependent taste-masking layer.
Claims 1 and 9 are the principal independent claims.
The claims require both structure and performance, including at least about 20 seconds of oral protection and less-than-90-second mouth disintegration.
Dependent claims narrow the technology through coating weight, thickness, excipient, disintegrant, and particle-size limitations.
The patent is a formulation-platform patent and does not claim a specific active ingredient.
It is not independently an Orange Book-listed drug patent based on the claim language.
Paragraph IV relevance would exist only if the patent were listed against a specific NDA product.
Biosimilar litigation is not the relevant competitive framework.
The patent’s ordinary US term has expired, but later continuation patents, product-specific patents, process patents, licenses, and trade secrets may remain relevant.
The strongest technical design-around route is removal of the distinct spacing layer or adoption of a materially different taste-masking mechanism.

FAQs

Can a generic manufacturer use the same taste-masking concept after US 6,740,341 expired?

Yes, expiration removes the patent’s current US exclusionary right. The manufacturer must still assess later patents, Orange Book listings, contractual restrictions, and process-related rights.

Does a product infringe if it uses a 5-micron coating?

It may. Five microns falls at the lower boundary of the claimed “about 5 to about 75 microns” range. The result depends on measurement accuracy, claim construction, and whether the product satisfies all remaining limitations.

Is an enteric-coated drug automatically covered by US 6,740,341?

No. The claims require a separate spacing layer between the drug core and the taste-masking layer. A conventional single-layer enteric coating may fall outside the literal claim scope.

Do claims 14 through 17 cover only very small particles?

They impose narrower maximum core-size limitations of 1,200 or 850 microns. They apply to the coated drug-containing core and do not necessarily establish that every particle in a commercial batch must have exactly the same diameter.

Can a company rely only on patent expiration for freedom to operate?

No. Patent expiration addresses this patent only. A complete analysis must review its patent family, later patents, product-specific formulation rights, manufacturing patents, licensing obligations, and regulatory listings.

References

Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.
U.S. Patent No. 6,740,341. (2004). Taste-masked formulation and dosage form claims.
United States Code, 35 U.S.C. § 154. (2024). Contents and term of patent; provisional rights.
United States Code, 21 U.S.C. § 355. (2024). New drugs.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Australia	1922000	⤷ Start Trial
Australia	753476	⤷ Start Trial
Canada	2351720	⤷ Start Trial
European Patent Office	1133282	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,740,341

Summary for Patent: 6,740,341