US Patent 8,394,407: Scope, Claims, Expiration, and Patent Landscape for Press-Coated Prednisone Tablets

US Patent 8,394,407 protects a press-coated, time-delayed tablet designed to release a glucocorticosteroid after approximately two to six hours. Its strongest protection is directed to a specific tablet architecture: a defined inner core, an asymmetric hydrophobic compression coating, a porous release region, and rupture-driven drug release. The patent is narrower than a general delayed-release or sustained-release claim because it requires both physical geometry and timed dissolution behavior.

The patent was granted on March 12, 2013, under the title "Press-coated tablet." The claim set covers the tablet, specified prednisone and related steroid formulations, dissolution performance, administration methods, and the manufacturing process used to press-coat the core.[1]

What does US Patent 8,394,407 protect?

The patent protects a press-coated tablet with four principal technical characteristics:

A defined core containing an active pharmaceutical ingredient.
A compression coating surrounding the core.
An asymmetric coating geometry, with greater thickness and lower density along the X-Y axis than along the orthogonal A-B axis.
A porous hydrophobic coating that permits water ingress and produces delayed release followed by rupture.

The central technical concept is not a conventional polymer film coating. It is a compressed outer layer whose thickness, density, porosity, and material composition are controlled to create a lag period followed by rapid release.

What is the broadest claim?

Claim 1 is the principal apparatus or composition claim. It requires:

Limitation	Scope
Dosage form	Press-coated tablet
Inner component	Defined core containing a pharmaceutically active agent
Outer component	Compression coating around the core
Geometry	Coating is thicker and less dense about X-Y than about orthogonal A-B
Material	Insoluble or poorly water-soluble hydrophobic material
Release mechanism	Aqueous ingress through the X-Y region followed by rupture
Timing	Release after approximately two to six hours
Exclusion	No swelling or gelling ingredients that create a diffusion barrier

Each limitation is material. A product that uses the same active ingredient but has a symmetric coating, a soluble film, or a swelling polymer barrier may avoid literal infringement of claim 1.

Which claims are independent?

The claim structure has three principal independent claim categories:

Claim	Subject matter	Practical significance
1	Press-coated tablet	Core composition and physical release architecture
18	Method of administering a glucocorticosteroid	Patient-use claim tied to the tablet of claim 7
19	Method of making the tablet	Granulation, core formation, and press-coating steps

Claims 2 through 17 depend from claim 1 directly or indirectly. Claim 18 depends on claim 7, making it specifically directed to administration of prednisone, prednisolone, or methylprednisolone. Claim 19 is directed to the manufacturing sequence rather than the final composition alone.[1]

How strong is the patent estate for US 8,394,407?

The patent has a focused but technically differentiated claim set. Its strongest features are the combination of physical structure and performance limitations.

Claim-strength assessment

Claim feature	Strength	Reason
Press-coated tablet	Moderate	Press coating is known in controlled-release dosage forms
Asymmetric X-Y/A-B geometry	Strong	Narrows the claim to a distinctive tablet architecture
Hydrophobic compression coating	Moderate	Several hydrophobic excipients and polymers are expressly listed
Rupture after a two-to-six-hour lag	Moderate to strong	Adds a timing and release-mechanism requirement
No swelling or gelling diffusion barrier	Strong against conventional matrix systems	Excludes common hydrogel-based approaches
2.2-2.6 mm and 1.0-1.6 mm thicknesses	Strong but narrow	Claim 2 creates a measurable design-around boundary
50% dibasic calcium phosphate and 40% glyceryl behenate	Very strong but narrow	Claim 9 is close to a specific formulation
80% release after 4.5 hours and 100% after 5 hours	Strong if reproducible	Functional limitations can create litigation issues over test conditions
Manufacturing sequence	Moderate	Potentially useful against a process that copies the granulation and press-coating steps

The patent is more defensible against a copycat product that reproduces the same geometry and release mechanism than against a competing delayed-release tablet using a membrane coating, osmotic system, enteric polymer, or swellable matrix.

Why the geometric limitation matters

Claim 1 requires the coating to be thicker and less dense about the X-Y axis than about the A-B axis. Claim 15 further specifies an X-Y to A-B coating-thickness ratio of 1.3:1 to 2.6:1. These limitations convert the patent from a broad delayed-release concept into a structural claim.

A competitor could seek to avoid infringement by using:

A substantially uniform coating thickness.
A coating thicker along the opposite axis.
A multiparticulate system rather than a single press-coated tablet.
A film-coated core.
A capsule containing coated particles.
A hydrophilic matrix that controls release by swelling.
An enteric coating that dissolves at a selected pH.
An osmotic delivery system.
A coating that erodes without rupture.

The design-around analysis must account for the doctrine of equivalents. A change in geometry that performs substantially the same function in substantially the same way may still create risk, although the prosecution history and claim amendments would control the analysis.

What formulations are protected by US 8,394,407?

The patent covers several active-ingredient classes, but the most commercially specific claims concern glucocorticosteroids and prednisone.

Prednisone formulation

Claim 9 identifies a 5 mg prednisone tablet with the following composition:

Component	Core percentage	Coating percentage
Prednisone	8.33%	Not specified
Lactose monohydrate	64.47%	Not specified
Povidone	6.67%	8.40%
Croscarmellose sodium	18.33%	Not specified
Dibasic calcium phosphate dihydrate	Not specified	50%
Glyceryl behenate	Not specified	40%

The claim requires the active ingredient and excipient percentages to be calculated separately based on the weight of the core and coating. A product need not use the exact claim 9 formulation to fall within claim 1, but claim 9 creates a narrower infringement position where the composition is replicated.

Other active ingredients

The claims expressly identify:

Prednisone.
Prednisolone.
Methylprednisolone.
Terbutaline sulfate.
Other sympathomimetic agents.

Claim 12 permits the sympathomimetic active agent to represent 1% to 50% of the core by weight. The breadth is materially greater than the prednisone claims because it is not limited to a single dosage strength or corticosteroid.

Excipients and coating materials

Claim 3 lists a broad group of hydrophobic or poorly soluble materials, including:

Alkylcellulose and related cellulose derivatives.
Hydroxypropyl cellulose.
Hydroxypropyl methylcellulose.
Carboxymethyl cellulose and derivatives.
Polymethacrylic polymers.
Polyvinyl acetate.
Cellulose acetate polymers.
Fatty acids and fatty acid salts.
Fatty acid esters.
Long-chain fatty alcohols.
Polyoxyethylene alkyl ethers.
Polyoxyethylene stearates.
Sugar esters.
Lauroyl macrogol-32 glyceryl.
Stearoyl macrogol-32 glyceryl.

Claim 4 focuses on calcium phosphate salt, glyceryl behenate, and povidone. The claim language contains an apparent spelling variation, "polyvinyl pyrollidone," while the formulation is conventionally known as polyvinylpyrrolidone or povidone. Patent interpretation would depend on the specification and prosecution record.

What dissolution profile does the patent require?

Claims 13, 16, and 17 define release performance. The specified test uses:

USP dissolution apparatus No. 2.
100 rpm.
500 mL purified water.
A median lag time of approximately four hours.
At least 80% release after 4.5 hours.
Approximately 100% release after five hours.

Performance limitation	Claim
Median lag time of about four hours	13
At least 80% release after 4.5 hours	13 and 16
About 100% release after five hours	13 and 17

These claims are useful only if the test method is reproducible and the accused product is tested under materially equivalent conditions. Small changes in tablet dimensions, agitation, vessel configuration, water quality, sampling time, or analytical method can affect the result.

The functional claims also create litigation exposure. A patentee would need to establish that the accused product meets the claimed release profile, while an accused infringer could challenge the meaning of "about," "median lag time," or "about 100%."

When does US Patent 8,394,407 lose exclusivity?

The patent's base term is generally calculated from the earliest effective nonprovisional filing date or applicable priority chain, subject to patent-term adjustment, terminal disclaimers, and any patent-term extension.[2]

The available patent record indicates a priority chain dating to the mid-2000s. On that basis, the ordinary 20-year term would place the projected expiration in 2024 or 2025, depending on the earliest effective filing date. The exact enforceable expiration date requires the USPTO patent-term calculation, including any patent-term adjustment.[1][3]

Event	Date or period
Earliest priority period	Mid-2000s
US grant	March 12, 2013
Ordinary 20-year term	Projected 2024-2025 range
Patent-term adjustment	Must be included in the final calculation
Patent-term extension	No drug-specific extension is established from the claim information
Post-expiration status	Claims cannot be enforced after the enforceable expiration date

Grant date does not determine expiration. A patent granted in 2013 can expire before 2033 if it claims priority to an earlier application.

What is the Orange Book status of US 8,394,407?

US Patent 8,394,407 should not be treated as an Orange Book-listed patent merely because it covers a pharmaceutical tablet. Orange Book listing is tied to an approved drug product and FDA-approved labeling, not to the patent's existence.[4]

The patent claims a delayed-release tablet architecture and glucocorticosteroid formulations. The claims do not, by themselves, establish that a corresponding FDA-approved product has been listed in the Orange Book.

For an ANDA applicant, the relevant questions would be:

Whether the reference listed drug is an FDA-approved delayed-release prednisone product.
Whether the patent is listed against that product.
Whether the applicant must make a Paragraph IV certification.
Whether the patent has expired by the date of ANDA approval.
Whether the proposed product uses the claimed tablet structure.

If the patent is not listed against the relevant reference product, it may still be asserted in district court, but it would not necessarily create a statutory 30-month stay based on an ANDA Paragraph IV notice.

Are there Paragraph IV challenges to the patent?

A Paragraph IV challenge requires an ANDA applicant to certify that a listed patent is invalid, unenforceable, or will not be infringed. The existence of US 8,394,407 does not establish that a Paragraph IV certification has been filed.

No publicly established Paragraph IV litigation can be inferred from the claim text alone. The patent's practical ANDA relevance depends on Orange Book listing, the identity of the reference product, and the applicant's certification strategy.[4][5]

Potential Paragraph IV defenses would include:

Lack of novelty based on an earlier press-coated dosage form.
Obviousness based on combining known press coating, hydrophobic excipients, and timed-release objectives.
Indefiniteness of the X-Y and A-B axes.
Indefiniteness or lack of enablement for the two-to-six-hour release period.
Failure to meet the claimed dissolution profile.
Noninfringement based on a symmetric coating or a different release mechanism.
Written-description challenges to the full genus of hydrophobic materials.

The patentee would likely rely on the specific combination of asymmetric geometry, porosity, rupture, and absence of a swellable diffusion barrier to distinguish prior art.

What patent litigation affects US 8,394,407?

The patent number alone does not establish a current infringement case, settlement, or license. No litigation or settlement should be attributed to this patent without a docket, complaint, judgment, or publicly reported agreement identifying US 8,394,407.

A litigation review should examine:

Issue	Relevance
ANDA litigation	Determines generic entry risk
Declaratory judgment action	Could establish noninfringement or invalidity
Claim-construction order	Important for X-Y/A-B geometry and "rupture"
Laboratory testing	Determines compliance with claims 13, 16, and 17
Prosecution history	May limit the scope of claim 1
Settlement agreement	Could impose a licensed entry date or product restrictions
Manufacturing discovery	Relevant to claim 19

The most important factual evidence would be tablet cross-sections, coating density measurements, excipient composition, dissolution data, and manufacturing batch records.

Which companies are challenging or commercializing this technology?

The patent claims do not identify a current commercial owner, licensee, generic challenger, or FDA-approved product. The public patent record should be reviewed for assignment transactions and maintenance-fee status before attributing the patent to a current rights holder.[1][3]

The competitive landscape includes four technology groups:

Competing technology	Risk to the patent
Hydrophobic press-coated tablets	Direct technical overlap
Polymer film-coated delayed-release tablets	May avoid the compression-coating limitation
Enteric-coated prednisone products	Usually use pH-dependent dissolution rather than timed rupture
Multiparticulate or capsule systems	May avoid the single press-coated tablet limitation
Swellable hydrophilic matrices	Potentially excluded by the claim's no-diffusion-barrier language
Osmotic tablets	Generally use a different release mechanism

The patent's commercial value is highest for a product requiring a single-unit, approximately four-hour lag followed by rapid corticosteroid release. Its value is lower against products that achieve delayed release through pH response, multiparticulates, or a conventional film membrane.

What manufacturing and intellectual-property barriers does the patent create?

Claim 19 covers a manufacturing sequence involving:

Formation of a first granulate containing coating material.
Formation of a second granulate containing core material.
Compression of the second granulate into a core.
Press coating of the first granulate around the core.

The process claim may be difficult to enforce without access to manufacturing records. The final tablet can reveal some structural features, but not necessarily the order of granulation or compression steps.

Manufacturing risk is highest where a producer uses:

The same core and coating excipients.
Similar tablet dimensions.
The same asymmetric press-coating tooling.
Equivalent granulation steps.
The same dissolution target.
The same 5 mg prednisone strength.

A producer using a different manufacturing process may avoid claim 19 while still facing claims 1 through 17 if the final tablet has the claimed structure and release profile.

How does US 8,394,407 compare with conventional delayed-release patents?

US 8,394,407 is structurally distinct from conventional delayed-release patents.

Feature	US 8,394,407	Conventional enteric tablet
Primary trigger	Water ingress and coating rupture	pH-dependent polymer dissolution
Coating	Compression coating	Film coating
Geometry	Intentionally asymmetric	Usually uniform
Core	Defined compressed core	Often coated tablet core
Lag mechanism	Porosity, thickness, density, rupture	Gastric resistance and intestinal pH
Key testing	Timed release in water	Dissolution across pH stages
Main design-around	Change geometry or mechanism	Use a different enteric polymer or coating process

The patent therefore has limited reach over products that are delayed-release only in a regulatory or commercial sense but do not use the claimed press-coated architecture.

Key Takeaways

US 8,394,407 is a formulation and drug-delivery patent, not a broad patent on prednisone.
Claim 1 requires an asymmetric hydrophobic compression coating, defined axes, timed water ingress, and rupture-driven release.
Claim 9 is the narrowest commercially relevant prednisone formulation, covering a 5 mg tablet with specified core and coating percentages.
Claims 13, 16, and 17 require a defined dissolution profile, including at least 80% release after 4.5 hours and approximately complete release after five hours.
Conventional enteric coatings, osmotic systems, multiparticulates, and many swellable matrices may avoid the principal structural limitations.
Claim 19 creates process risk where the accused manufacturer uses the same granulation and press-coating sequence.
The patent's ordinary term appears to fall in the 2024-2025 range based on its mid-2000s priority chain, subject to USPTO patent-term adjustment.
Orange Book listing, Paragraph IV activity, litigation, settlement terms, and current ownership require confirmation from the applicable FDA, USPTO, and court records.
The patent's strongest commercial position is against a single-unit, delayed-release corticosteroid tablet that copies the asymmetric press-coated architecture and approximately four-hour lag profile.

Frequently Asked Questions

Does US 8,394,407 cover all delayed-release prednisone tablets?

No. It covers a specific press-coated tablet structure and release mechanism. A prednisone tablet using an enteric film, multiparticulate coating, osmotic system, or different matrix may fall outside the claims.

Can a competitor avoid the patent by changing the coating thickness?

Possibly. A material change to the X-Y and A-B thickness relationship may avoid literal infringement, but the full claim language, prosecution history, and doctrine of equivalents would control.

Is a 5 mg prednisone tablet automatically infringing?

No. The 5 mg strength alone is insufficient. The product would need to satisfy the applicable structural, material, geometric, process, and release limitations.

Does patent expiration permit immediate generic entry?

Not necessarily. Generic entry also depends on FDA approval, applicable Orange Book listings, other patents, regulatory exclusivity, injunctions, and any settlement restrictions.

Does the patent cover a conventional hydrophilic matrix tablet?

The claims are less naturally directed to that technology because claim 1 excludes ingredients that swell and gel to create a diffusion barrier. A hydrophilic matrix could still require a detailed claim-by-claim analysis if it also has the claimed compression coating and other limitations.

References

United States Patent No. 8,394,407, "Press-coated tablet," issued March 12, 2013. Google Patents. https://patents.google.com/patent/US8394407B2/en
35 U.S.C. § 154. Patent term. https://www.law.cornell.edu/uscode/text/35/154
United States Patent and Trademark Office. Patent Center. https://patentcenter.uspto.gov/
U.S. Food and Drug Administration. Approved Drug Products with Therapeutic Equivalence Evaluations, commonly known as the Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
21 U.S.C. § 355(j). Abbreviated new drug applications and patent certifications. https://www.law.cornell.edu/uscode/text/21/355

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	0309342.4	Apr 24, 2003

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	512659	⤷ Start Trial
Australia	2004231362	⤷ Start Trial
Brazil	PI0409652	⤷ Start Trial
Canada	2523158	⤷ Start Trial
China	102525993	⤷ Start Trial
China	1777412	⤷ Start Trial
Cyprus	1111835	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,394,407

Summary for Patent: 8,394,407