Details for Patent: 6,096,342

Summary for Patent: 6,096,342

Title:	Dosage forms of risedronate
Abstract:	The present invention is directed to a novel enteric-coated oral dosage form of a risedronate active ingredient comprised of a safe and effective amount of a pharmaceutical compostion which is comprised of a risedronate active ingredient and pharmaceutically-acceptable excipients. Said dosage forms prohibit the exposure of the risedronate active ingredient to the epithelial and mucosal tissues of the buccal cavity, pharynx, esophagus, and stomach and thereby protects said tissues from erosion, ulceration or other like irritation. Accordingly, the said dosage forms effect the delivery to the lower intestinal tract of said human or other mammal of a safe and effective amount of the risedronate active ingredient, and substantially alleviate the esophagitis or esophageal irritation which sometimes accompanies the oral administration of risedronate active ingredients.
Inventor(s):	Richard John Dansereau, Russell Youker Mosher, Douglas Wayne Axelrod, William Kendall Sietsema
Assignee:	Warner Chilcott Co LLC
Application Number:	US09/303,466
Patent Claim Types: see list of patent claims	Composition; Compound;

US Patent 6,096,342: Risedronate Formulation Scope, Claim Analysis, and Patent Landscape

US Patent 6,096,342 covers solid pharmaceutical compositions containing risedronate and four specified excipients: lactose monohydrate, microcrystalline cellulose, crospovidone, and magnesium stearate. The claims are formulation claims, not claims to risedronate itself, its therapeutic use, or a manufacturing process. The patent’s standard 20-year term would have ended in December 2018, subject to any patent-term adjustment or other statutory extension. The claims therefore have no current exclusionary value in the United States unless an unusual term adjustment or related enforceable right applies. [1]

What does US Patent 6,096,342 protect?

The patent protects a pharmaceutical composition that meets four core requirements:

1. It contains risedronate as the active ingredient.
2. Risedronate represents 0.15% to 40.00% by weight of the composition.
3. The excipient portion represents 60.00% to 99.75% by weight.
4. The excipient system includes lactose monohydrate, microcrystalline cellulose, crospovidone, and magnesium stearate.

The claims use the transitional term “comprising.” That term generally permits the presence of additional ingredients, excipients, coatings, processing aids, or other components, provided the claimed ingredients and percentage limitations are present. A product containing the four listed excipients plus additional excipients could therefore fall within the literal scope if all other limitations are satisfied.

The claim language does not expressly require:

• A tablet;
• A particular risedronate salt;
• A specific dosage strength;
• A particular dissolution profile;
• A particular particle size;
• A specific compression force;
• A coating;
• A particular method of manufacture; or
• Treatment of osteoporosis or another disease.

The scope is consequently defined primarily by composition and weight percentage.

How do the three claims differ?

Claim	Risedronate content	Excipient content	Key limitation
1	0.15% to 40.00% by weight	60.00% to 99.75%	Requires all four named excipients
2	0.5% to 30.00% by weight	70.00% to 99.5%	Narrows the percentage ranges
3	11.76% by weight	88.24% by weight	Claims a specific composition ratio

Claim 2 is narrower than claim 1 because its risedronate and excipient ranges fall within the broader ranges of claim 1. Claim 3 is narrower in percentage terms but retains the ingredient requirements of claim 1.

The percentages appear to treat the active ingredient and excipients as the principal composition categories. A product analysis would need to determine whether the percentages are calculated against the total finished composition, the uncoated tablet core, or another defined unit. The claim language supplied does not resolve that issue. Coating materials, water, processing residues, and the chemical form of risedronate could affect the calculation.

What formulations are protected by US 6,096,342?

A formulation is within the literal scope of claim 1 if it contains all four specified excipients and risedronate in the claimed range. Examples include:

• A tablet containing 10% risedronate, 20% lactose monohydrate, 40% microcrystalline cellulose, 20% crospovidone, and 10% magnesium stearate.
• A tablet containing 0.5% risedronate and the four excipients in an aggregate amount of at least 70%.
• A composition containing 11.76% risedronate and 88.24% total excipients, if the excipient fraction includes all four named materials.

The claims do not require a specific ratio among lactose monohydrate, microcrystalline cellulose, crospovidone, and magnesium stearate. A composition could therefore use a very small amount of one listed excipient and still potentially satisfy the claim, subject to claim construction and enablement issues.

The use of “comprising” also means that a formulation with additional binders, disintegrants, lubricants, fillers, coatings, or stabilizers could remain within scope. Omitting one of the four named excipients is a more direct design-around than adding another ingredient.

How strong are the claims under patentability and infringement analysis?

The claims have a relatively narrow ingredient fingerprint but broad internal formulation flexibility.

Literal infringement risk

Literal infringement would generally require proof that the accused product contains:

• Risedronate;
• Lactose monohydrate;
• Microcrystalline cellulose;
• Crospovidone;
• Magnesium stearate; and
• The specified weight percentages.

A product that uses all four excipients but falls outside the claimed active-ingredient range would not literally infringe. A product that replaces lactose monohydrate with anhydrous lactose, calcium phosphate, mannitol, or another filler would have a potential noninfringement position because the claim identifies lactose monohydrate specifically.

The same analysis applies to substitutions for microcrystalline cellulose, crospovidone, and magnesium stearate. The chemical identity of each excipient matters. Pharmaceutical equivalents are not automatically claim equivalents.

Doctrine of equivalents

A patentee could argue that a substituted excipient performs substantially the same function in substantially the same way to obtain substantially the same result. That argument would face limits where the patent prosecution history distinguished the claimed excipients from alternatives or where the substitute would vitiate an express claim limitation. The absence of prosecution-history analysis prevents a definitive assessment of equivalents risk.

Written description and enablement

Claim 1 covers a wide range of risedronate concentrations and potentially numerous relative proportions of the four excipients. The patent’s specification and prosecution history would determine whether the full scope was adequately described and enabled. A broad claim can be vulnerable if the disclosure supports only a limited number of examples or a specific tablet formulation.

Claim 3 is more resistant to breadth-based written-description objections because it identifies a precise composition ratio. Its vulnerability would instead depend on prior art, support in the specification, and whether the claimed ratio produces a disclosed technical benefit.

When did US Patent 6,096,342 lose exclusivity?

The patent issued on August 1, 2000. For a post-1995 US utility application, the ordinary patent term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment and possible statutory extensions. The patent is associated with a December 1998 nonprovisional filing timeline, producing a standard expiration in December 2018. [1][2]

Risedronate products also had separate patent and regulatory exclusivity issues. Expiration of US 6,096,342 did not by itself terminate all risedronate protection. Other patents could have covered:

• The risedronate compound;
• Specific dosage regimens;
• Once-weekly or intermittent dosing;
• Pharmaceutical salts;
• Methods for treating osteoporosis;
• Delayed-release or enteric formulations; and
• Specific tablet or packaging configurations.

The relevant commercial question was therefore the combined estate, not this formulation patent in isolation.

What was the Orange Book status of the patent?

A patent is relevant to the Hatch-Waxman process only if it is properly listed for an approved drug product and remains relevant under FDA listing rules. The Orange Book can identify patents submitted by the NDA holder, but listing status does not establish validity or infringement. [3]

For risedronate products such as Actonel, the principal reference-product sponsor was Procter & Gamble, with later commercial rights and product activities involving Warner Chilcott and Allergan-related entities. The Orange Book history for risedronate products should be separated into:

• Active listings during the generic-challenge period;
• Expired listings;
• Delisted patents;
• Method-of-use patents;
• Drug-substance patents; and
• Formulation patents.

US 6,096,342 should not be treated as an active Orange Book barrier after its expiration. An expired listed patent cannot support a current 30-month stay for a Paragraph IV challenge. [3][4]

Which companies challenged risedronate patents?

Risedronate faced generic competition through ANDA filings and patent certifications directed at the broader Actonel patent estate. The relevant challengers varied by product strength, dosage regimen, and formulation. Typical generic entrants included major ANDA sponsors such as Teva, Mylan, Watson/Actavis, and other manufacturers active in bisphosphonate products.

A Paragraph IV certification against an unexpired Orange Book patent can trigger patent litigation and, if the NDA holder sues within the statutory period, a 30-month stay of ANDA approval. The expiration of US 6,096,342 removed this particular formulation claim from the basis for future Paragraph IV litigation. [4]

The commercial launch date for a generic risedronate product depended on the complete patent and exclusivity profile, not solely on the expiration date of this patent. Settlement agreements, first-filer status, pediatric exclusivity, and other listed patents could alter the timing.

Did US 6,096,342 protect a method of use or a biologic?

No. The supplied claims are composition claims. They do not require administration to a patient or recite osteoporosis, Paget’s disease, bone density, fracture prevention, or another therapeutic indication.

The patent also does not concern a biologic. Risedronate is a small-molecule bisphosphonate. Biosimilar pathways under the Biologics Price Competition and Innovation Act are irrelevant. Competitive entry occurs through the generic-drug framework, generally via an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act. [4][5]

What design-around options exist?

A generic or follow-on manufacturer could reduce literal infringement risk by adopting one or more of the following approaches:

Design-around	Potential effect
Omit lactose monohydrate	Removes an express claim limitation
Replace microcrystalline cellulose	Removes an express claim limitation
Replace crospovidone	Removes an express claim limitation
Replace magnesium stearate	Removes an express claim limitation
Use a different dosage form	May avoid the composition if the product does not meet the claimed formulation
Move outside the percentage ranges	Avoids literal percentage limitations
Use a different active form or salt	Depends on construction of “risedronate active ingredient”
Use a liquid or suspension	May avoid a tablet-oriented formulation, although the claim itself is not expressly limited to tablets
Use a different manufacturing platform	Relevant only if separate process claims exist

A formulation using all four excipients at the claimed concentrations would create a higher historical risk profile. A formulation that omits one named excipient offers a clearer literal noninfringement position, although equivalence and other patents would still require review.

How does this patent compare with the broader risedronate estate?

Protection category	Covered by US 6,096,342?	Commercial relevance
Risedronate molecule	No	May have been covered by separate composition-of-matter patents
Risedronate sodium	Not expressly established by supplied claims	Depends on claim construction and other patents
Tablet formulation	Yes, if all listed ingredients and ranges are present	Main subject of this patent
Method of treating osteoporosis	No	Separate method-of-use patents may apply
Dosing regimen	No	Separate regimen patents may apply
Manufacturing process	No claim supplied	Separate process patents may apply
Biologic or biosimilar product	No	Not relevant
Packaging or device	No	Separate rights may apply

The patent’s historical value was concentrated in formulation replication. Its current value is primarily analytical: it identifies one formulation architecture that may have influenced branded or generic risedronate tablets.

What is the current generic entry risk?

For US 6,096,342 alone, current generic entry risk is not constrained because the ordinary patent term expired in 2018. The remaining risks would arise from other unexpired patents, regulatory exclusivity, product-specific patents, litigation settlements, or confidential commercial agreements.

The patent does not create a current manufacturing barrier. Lactose monohydrate, microcrystalline cellulose, crospovidone, and magnesium stearate are standard pharmaceutical excipients with broad commercial availability. Their use does not ordinarily create a supply-chain barrier or a meaningful trade-secret barrier.

Key Takeaways

• US 6,096,342 is a risedronate formulation patent.
• Claims 1 through 3 require risedronate plus lactose monohydrate, microcrystalline cellulose, crospovidone, and magnesium stearate.
• Claim 1 covers 0.15% to 40.00% risedronate by weight.
• Claim 2 narrows the active range to 0.5% to 30.00%.
• Claim 3 covers a specific 11.76% risedronate composition.
• The claims use “comprising,” permitting additional ingredients.
• The claims do not cover risedronate as a molecule, treatment methods, dosing schedules, or biologics.
• The ordinary US patent term ended in December 2018.
• The patent no longer presents a current US formulation exclusivity barrier.
• Historical infringement risk centered on products using all four named excipients within the claimed percentage ranges.
• The broader risedronate patent estate, Orange Book history, ANDA certifications, and settlement agreements remained more important to actual generic launch timing.

FAQs About US Patent 6,096,342

Does US 6,096,342 cover Actonel itself?

It does not claim Actonel as a brand or risedronate as a chemical compound. It covers qualifying risedronate compositions containing the four specified excipients and claimed weight percentages.

Can a generic use three of the four listed excipients?

A formulation omitting one required excipient has a strong literal noninfringement position against the supplied claims. Other patents and an equivalents analysis could still affect the overall risk.

Does claim 3 cover an 11.76% risedronate tablet?

It can, if the composition also contains the four excipients required by claim 1 and the claimed 88.24% excipient fraction is satisfied.

Is a Paragraph IV certification still relevant to this patent?

Not as a current patent-term barrier after expiration. Paragraph IV practice would have mattered while the patent was unexpired and properly listed for the relevant approved product.

Are risedronate biosimilars affected by this patent?

No. Risedronate is a small-molecule drug, so generic competition proceeds through the ANDA pathway rather than the biosimilar pathway.

References

1. United States Patent and Trademark Office. (2000). U.S. Patent No. 6,096,342.
2. United States Code, 35 U.S.C. § 154.
3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
4. United States Code, 21 U.S.C. § 355(j).
5. U.S. Food and Drug Administration. (2018). Abbreviated new drug application submissions: Refuse-to-receive standards.

Drugs Protected by US Patent 6,096,342

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 6,096,342

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	195075
Australia	3060492
Australia	661080
Brazil	9206797
Canada	2122479