United States Patent 8,759,393: Dimethyl Fumarate Microtablet Claims, Patent Scope and Generic-Entry Risk

US Patent 8,759,393 protects pharmaceutical preparations containing dimethyl fumarate in microtablet form. The strongest commercial coverage is directed to enteric-coated microtablets with an approximately 2,000-micrometer mean diameter, a 10-mg-to-300-mg dimethyl fumarate load, and capsule delivery. The patent does not claim dimethyl fumarate generally, a method of treating multiple sclerosis, or every delayed-release dimethyl fumarate formulation.

The patent is associated with Biogen's Tecfidera product and has a reported nominal expiration date of June 1, 2028, subject to any applicable patent-term adjustment or pediatric extension reflected in FDA records.[1][2]

What does US Patent 8,759,393 cover?

The patent covers a dosage-form architecture rather than dimethyl fumarate as a chemical compound.

Its independent claims require:

Claim	Required subject matter	Principal scope
1	A pharmaceutical preparation comprising dimethyl fumarate in microtablet form	Broadest independent composition claim
8	A pharmaceutical preparation in microtablet form where dimethyl fumarate is the active ingredient	Requires dimethyl fumarate to be the active ingredient
13	Dimethyl fumarate, carriers and excipients, 10-300 mg DMF, microtablets with approximately 2,000-micrometer mean diameter	Narrowest but most commercially specific claim

The claims use different transition language:

Claim 1 uses "comprising," which generally permits additional ingredients or active substances unless another limitation excludes them.
Claim 8 states that the active ingredient "consists of dimethyl fumarate," which narrows the active-ingredient requirement.
Claim 13 uses "consisting essentially of," which permits ingredients that do not materially alter the claimed pharmaceutical preparation.

The patent therefore targets the physical presentation of dimethyl fumarate, including the size and, in some claims, the enteric coating and capsule format.

How do the claims of Patent 8,759,393 differ?

Claim 1: broad microtablet claim

Claim 1 requires only:

A pharmaceutical preparation;
Dimethyl fumarate; and
Microtablet form.

It does not require:

Enteric coating;
A specific microtablet diameter;
A particular dose;
Capsule packaging;
A particular therapeutic indication;
A particular excipient;
A specific release profile.

A competing product could face literal infringement under claim 1 if its dimethyl fumarate dosage form uses microtablets, even if the microtablets are not enteric coated or are packaged in a different dosage form.

The central legal issue is whether the product's units qualify as "microtablets." A product composed of pellets, granules, beads, particles, or conventionally compressed tablets may avoid literal infringement if those units do not meet the claim construction applied by a court.

Claim 2: enteric-coated microtablets

Claim 2 adds an enteric coating. The coating must function as an enteric coating, generally meaning that it resists release in the stomach and permits release at a higher intestinal pH.

A non-enteric-coated microtablet product would not literally meet claim 2, although claim 1 could remain relevant.

Claims 3 and 4: microtablet diameter

Claim 3 requires a mean diameter from 300 micrometers to 2,000 micrometers, excluding the coating.

Claim 4 narrows the range to a mean diameter "about 2,000 μm," also excluding the coating.

The phrase "exclusive of any coating" is important. A manufacturer cannot increase the measured diameter by relying on the enteric coating. The relevant measurement is the underlying microtablet core.

The term "about" creates a claim-construction and infringement issue. It does not necessarily require exactly 2,000 micrometers. The permitted variation depends on the patent specification, prosecution history, technical context, and court construction.

Claims 5, 6 and 7: dose and capsule limitations

These claims add:

10 mg to 300 mg of dimethyl fumarate;
Approximately 120 mg of dimethyl fumarate; and
Microtablets contained in one or more capsules.

The 120-mg limitation is relevant to the lower-strength Tecfidera presentation. The capsule limitation applies only to claim 7 and does not restrict claims 1 through 6 unless those claims are also asserted through dependency.

Claims 8 through 12: active-ingredient and capsule structure

Claim 8 is an independent claim requiring a pharmaceutical preparation in microtablet form with dimethyl fumarate as the active ingredient.

Claim 12 requires:

Dimethyl fumarate as the active ingredient;
Microtablets;
Enteric coating; and
One or more capsules.

This claim is narrower than claim 1 but maps more closely to a conventional delayed-release dimethyl fumarate capsule.

Claim 13: commercially focused combination

Claim 13 combines the most important product limitations:

Dimethyl fumarate as the active ingredient;
One or more carriers and excipients;
10 mg to 300 mg of dimethyl fumarate;
Microtablet form; and
Approximately 2,000-micrometer mean diameter excluding coating.

Claim 13 does not expressly require enteric coating or capsule containment. A product could therefore fall within claim 13 without satisfying the enteric-coating limitation in claim 12.

What formulations are protected by Patent 8,759,393?

The clearest protected formulation is a delayed-release capsule containing enteric-coated dimethyl fumarate microtablets approximately 2,000 micrometers in mean core diameter.

The claim set can be mapped as follows:

Formulation characteristic	Claim coverage
Dimethyl fumarate microtablets	Claims 1 and 8
Enteric-coated microtablets	Claim 2 and claim 12
Mean diameter of 300-2,000 μm	Claim 3
Approximately 2,000 μm mean diameter	Claims 4, 9 and 13
10-300 mg dimethyl fumarate	Claims 5, 10 and 13
Approximately 120 mg dimethyl fumarate	Claims 6 and 11
Capsule containment	Claim 7 and claim 12
DMF as the only active ingredient	Claims 8 and 12
DMF, excipients and approximately 2,000-μm microtablets	Claim 13

The claims do not expressly require dimethyl fumarate to be fumaric acid ester of a particular polymorph, nor do they claim a particular coating polymer or coating thickness. Those details may appear in the specification or related patents, but they are not apparent limitations of the claims supplied.

Does Patent 8,759,393 cover Tecfidera?

Yes. The claim structure is directed to the type of pharmaceutical preparation used for Tecfidera, which is marketed as delayed-release dimethyl fumarate capsules in 120-mg and 240-mg strengths.[3]

The patent does not necessarily cover every attribute of Tecfidera. A product can be covered by multiple patents at the same time, with separate patents addressing:

The active compound or chemical composition;
Treatment of multiple sclerosis;
Delayed-release delivery;
Microtablet size;
Enteric coating;
Capsule formulation;
Dosing schedules;
Manufacturing processes; and
Specific excipient systems.

Patent 8,759,393 is best characterized as a formulation and dosage-form patent.

When does Patent 8,759,393 lose exclusivity?

The reported nominal expiration date is June 1, 2028.[1][2]

A six-month pediatric exclusivity period, if applicable to the relevant approved product and patent listings, could extend the effective FDA exclusivity period to approximately December 1, 2028. Pediatric exclusivity is separate from the underlying patent term and must be confirmed against the FDA's current Orange Book patent and exclusivity data.[2]

The relevant timeline is:

Event	Date
Earliest reported priority date	June 1, 2008
US patent application filing	December 16, 2011
US publication	2012
Patent issued as US 8,759,393 B2	June 24, 2014
Tecfidera approval	March 27, 2013
Nominal patent expiration	June 1, 2028
Potential pediatric-extension endpoint	Approximately December 1, 2028

The patent term is generally calculated from the earliest effective nonprovisional filing date in the relevant priority chain, not from the issue date. The patent's publication, grant and expiration dates should therefore be evaluated through the complete USPTO file history and current Orange Book record.

What is the Orange Book status of Patent 8,759,393?

The patent has been associated with Tecfidera's FDA patent listings. The Orange Book is the controlling commercial source for determining whether a patent is listed against a specific NDA and whether an ANDA applicant must address that listing through a certification.[2]

For a listed formulation patent, an ANDA applicant generally must submit one of the following:

Paragraph I certification, if no patent information has been submitted;
Paragraph II certification, if the patent has expired;
Paragraph III certification, accepting approval after patent expiration; or
Paragraph IV certification, asserting that the patent is invalid, unenforceable or not infringed.

The practical importance of Patent 8,759,393 depends on:

Whether it remains listed against the relevant Tecfidera NDA;
Whether the generic applicant's product uses microtablets;
Whether the generic applicant certifies non-infringement or invalidity;
Whether Biogen files an infringement action within the statutory period; and
Whether a settlement permits an earlier launch.

An Orange Book listing does not establish patent validity. It creates an ANDA certification and litigation pathway.

Which companies have challenged Tecfidera patents?

Generic manufacturers, including Mylan and other ANDA sponsors, challenged Tecfidera's patent estate through Paragraph IV litigation and related federal-court proceedings. The best-known litigation involved Biogen's treatment patent US 8,399,514, not solely the microtablet claims of US 8,759,393.

In Biogen International GmbH v. Mylan Pharmaceuticals Inc., the Federal Circuit affirmed the invalidity of the '514 patent based on lack of written description for the claimed dosage range.[4] That decision materially reduced Biogen's protection for the broad treatment method claims associated with Tecfidera. It did not automatically invalidate every separate formulation patent in Biogen's portfolio.

The existence of litigation involving the '514 patent should not be treated as a ruling that claims 1-13 of the '393 patent are invalid. Patent validity is assessed claim by claim and patent by patent.

What patent litigation affects US Patent 8,759,393?

The commercial litigation risk around the '393 patent arises from ANDA products that use a microtablet architecture similar to Tecfidera.

Potential litigation issues include:

Claim construction of "microtablets"

The principal technical dispute is likely to concern the difference between:

Microtablets;
Mini-tablets;
Pellets;
Granules;
Spheroids;
Beads; and
Coated particles.

The patent claims do not define the term in the text supplied. The specification and prosecution history may therefore control how a court distinguishes a compressed microtablet from another multiparticulate dosage form.

Mean diameter testing

Claims 3, 4, 9 and 13 depend on mean diameter. A dispute may concern:

The number of units tested;
Sampling methodology;
Whether diameter is measured before or after coating;
Whether outliers are included;
Whether mean, median or another statistical measure is used; and
The permissible range for "about 2,000 μm."

Enteric coating

Claims 2 and 12 require enteric coating. A coating that produces delayed release through a mechanism other than pH-dependent enteric protection may avoid those limitations while still raising issues under claim 1 or claim 13.

Doctrine of equivalents

A product that falls outside a literal size range could still face a doctrine-of-equivalents argument. The scope of that argument may be limited by prosecution-history estoppel if Biogen narrowed the claims during examination to obtain allowance.

How strong is the patent estate for dimethyl fumarate?

Patent 8,759,393 has moderate formulation-specific strength and limited standalone breadth.

Strengths

Claim 1 does not require a particular dose, coating or capsule.
The patent targets a commercially relevant multiparticulate formulation.
Claims 3, 4, 9 and 13 provide multiple size-based positions.
Claims 5, 6, 10 and 11 correspond to commercially meaningful dose ranges.
Claim 13 combines dose, dosage form and size limitations in a single claim.

Weaknesses

The patent does not broadly claim dimethyl fumarate as a molecule.
It does not claim all delayed-release dimethyl fumarate products.
It does not expressly require a specific therapeutic use.
Infringement may be avoided by using a formulation that does not contain microtablets.
"Microtablets" and "about 2,000 μm" may create technical claim-construction disputes.
A generic manufacturer can design around the patent by changing the multiparticulate structure, unit size, release technology or dosage form.

The patent is stronger against a copycat formulation using enteric-coated dimethyl fumarate microtablets than against a generic product using a materially different delayed-release technology.

What generic launch scenarios exist for dimethyl fumarate?

Scenario 1: Same microtablet architecture

A generic product using approximately 2,000-micrometer dimethyl fumarate microtablets, particularly enteric-coated units in capsules, presents the highest infringement risk. A Paragraph IV certification could trigger litigation and a 30-month stay under the Hatch-Waxman framework if the statutory conditions are met.[5]

Scenario 2: Different multiparticulate architecture

A product using pellets, granules or substantially smaller or larger units may avoid some claims. Claim 1 remains the principal risk if the units are legally characterized as microtablets.

Scenario 3: Non-capsule dosage form

A tablet, sachet, suspension or other dosage form may avoid claims 7 and 12. It could still implicate claims 1, 3, 4, 8, 9 or 13 if the product uses the claimed microtablet structure.

Scenario 4: Post-expiration launch

After expiration of the patent and any enforceable extension, the '393 patent should no longer block an otherwise approvable generic product. Other Orange Book-listed patents, regulatory exclusivities, settlements or product-specific litigation could still affect the launch date.

What manufacturing and IP barriers does the patent create?

The patent can increase development risk even when a generic company does not intend to copy Tecfidera exactly. The main barriers are:

Producing uniform microtablets at the claimed size;
Applying a consistent enteric coating without changing the core-size measurement;
Controlling dose uniformity across capsule fills;
Demonstrating delayed-release performance;
Establishing that a substitute multiparticulate unit is not a microtablet;
Generating analytical evidence for Paragraph IV certification; and
Preserving a non-infringing design through scale-up and commercial manufacturing.

The patent does not appear, from the supplied claims, to claim a manufacturing process. Its commercial leverage comes from the product configuration. A design-around therefore must focus on the final dosage form, not only on manufacturing equipment or process parameters.

How does Patent 8,759,393 compare with Tecfidera's treatment patents?

Issue	US 8,759,393	US 8,399,514
Patent category	Pharmaceutical formulation	Method of treatment
Core subject	Dimethyl fumarate microtablets	Treatment regimen or therapeutic use
Requires microtablets	Yes	No
Requires specific dose form	Yes	Generally no
Main infringement evidence	Product composition and physical testing	Label, prescribing information and use
Design-around path	Change dosage-form architecture	Change indication, dosing or labeling where legally feasible
Public litigation significance	Formulation-specific	Major Federal Circuit validity decision
Commercial relevance	Protects a Tecfidera-type delivery format	Protects therapeutic use claims

The invalidation of the '514 patent materially changed the Tecfidera landscape, but it did not eliminate the formulation-specific risk created by the '393 patent.[4]

Are biosimilars relevant to dimethyl fumarate?

No. Dimethyl fumarate is a chemically synthesized small molecule, not a biologic. Competitors enter through the ANDA generic-drug pathway rather than the biosimilar pathway under section 351(k) of the Public Health Service Act.

The relevant regulatory issues are:

ANDA approval;
Paragraph IV patent certifications;
Therapeutic equivalence;
Bioequivalence;
Delayed-release performance; and
Product-specific formulation characterization.

"Biosimilar risk" is therefore not the correct competitive framework for Tecfidera. Generic substitution and formulation patent litigation are the relevant risks.

What licensing deals affect Patent 8,759,393?

Biogen acquired Fumapharm AG and related fumarate assets in 2006. That transaction provided Biogen with rights connected to fumarate products and intellectual property later associated with Tecfidera.[6]

The '393 patent should be evaluated within that broader acquisition and licensing chain. Publicly available materials identify Biogen as the commercial sponsor and patent owner or controlling entity associated with Tecfidera's US patent estate. A separate public license specifically covering US 8,759,393 is not apparent from the patent claims or standard FDA product records.

What is the geographic coverage of Patent 8,759,393?

US 8,759,393 provides rights only in the United States. Its international significance depends on corresponding applications in the patent family.

Jurisdiction	Effect
United States	Direct enforceability under US patent law
European countries	Requires separately validated national patents
Canada	Requires a Canadian family member
Japan	Requires a Japanese family member
Other markets	Requires jurisdiction-specific patent rights

A generic company can face different launch dates by country because patent scope, validity, litigation, regulatory exclusivity and settlement terms differ across jurisdictions.

Key Takeaways

US 8,759,393 is a formulation patent focused on dimethyl fumarate microtablets.
Claim 1 is the broadest claim because it requires microtablets and dimethyl fumarate but no specified dose, coating or capsule.
Claims 3, 4, 9 and 13 create size-based protection centered on a 300-to-2,000-micrometer range and approximately 2,000-micrometer microtablets.
Claims 2 and 12 add enteric coating; claims 7 and 12 add capsule containment.
Claims 5, 6, 10, 11 and 13 cover commercially relevant dimethyl fumarate amounts, including approximately 120 mg.
The patent does not broadly cover dimethyl fumarate as a molecule or all delayed-release dimethyl fumarate products.
The reported nominal expiration date is June 1, 2028, with a possible pediatric extension to approximately December 1, 2028.
The principal generic risk is highest for products using enteric-coated dimethyl fumarate microtablets in capsules.
Tecfidera is subject to generic-drug competition, not biosimilar competition.
The Federal Circuit's decision invalidating Biogen's US 8,399,514 treatment patent did not automatically invalidate US 8,759,393.

FAQs About US Patent 8,759,393

Can a generic avoid Patent 8,759,393 by using pellets instead of microtablets?

Potentially. The answer depends on whether the product's units are construed as pellets or microtablets and whether any claim limitations are met. Product characterization and claim construction would be central.

Does Patent 8,759,393 cover the 240-mg Tecfidera capsule?

The claims cover preparations containing 10 mg to 300 mg of dimethyl fumarate, which includes 240 mg. Coverage still requires the applicable microtablet, size and other limitations.

Does the patent cover a dimethyl fumarate tablet without enteric coating?

Claim 1 does not require enteric coating. Claims 2 and 12 do. A non-enteric-coated product could therefore remain exposed to claim 1 while avoiding the coating-dependent claims.

Can a generic use a different capsule color or capsule shell to avoid the patent?

No. Capsule color and shell appearance are not the material limitations in the supplied claims. The relevant issues are the presence of dimethyl fumarate microtablets, unit size, coating, dose and capsule containment where required.

Is Patent 8,759,393 a composition-of-matter patent?

No. It is a pharmaceutical preparation and formulation patent. It does not claim dimethyl fumarate as a chemical compound.

References

United States Patent and Trademark Office. (2014). US Patent No. 8,759,393 B2: Pharmaceutical preparation comprising dimethyl fumarate.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2013). FDA approves new treatment for multiple sclerosis.
United States Court of Appeals for the Federal Circuit. (2022). Biogen International GmbH v. Mylan Pharmaceuticals Inc., 18 F.4th 1333.
Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j).
Biogen Idec. (2006). Biogen Idec to acquire Fumapharm AG and fumarate-related assets.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	1131065	⤷ Start Trial	C300675	Netherlands	⤷ Start Trial
European Patent Office	1131065	⤷ Start Trial	CA 2014 00036	Denmark	⤷ Start Trial
European Patent Office	1131065	⤷ Start Trial	PA2014023	Lithuania	⤷ Start Trial
European Patent Office	1131065	⤷ Start Trial	92488	Luxembourg	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Summary for Patent: 8,759,393