Details for Patent: 6,306,900

Summary for Patent: 6,306,900

Title:	Enteric coated pharmaceutical compositions
Abstract:	This invention provides a pharmaceutical composition comprising a mycophenolate salt, the composition being adapted to release mycophenolate in the upper part of the intestinal tract.
Inventor(s):	Barbara Haeberlin, Ching-Pong Mak, Armin Meinzer, Jacky Vonderscher
Assignee:	Novartis AG
Application Number:	US09/694,209
Patent Claim Types: see list of patent claims	Use; Composition; Compound; Dosage form;

Executive summary
US Patent 6,306,900 covers an oral mycophenolate formulation designed to avoid gastric release, with claim scope focused on (i) mycophenolate as a salt (notably mono-sodium), (ii) enteric protection via specific polymer/coating classes or defined methacrylic-acid copolymers, and (iii) common solid oral dosage forms (tablet, granule/pellet-in-capsule) with a tablet hardness window. The estate is narrow in mechanism (enteric, stomach-resistant release), and relatively constrained by the coating material language in claims 2, 3, and 11, but it can capture many practical generic switches that keep the same enteric polymers and solid format. For US freedom-to-operate, the highest-risk design-arounds are formulations using enteric coatings comprising cellulose acetate phthalate/trimellitate blends, hydroxypropyl methylcellulose phthalate, or methacrylic-acid copolymers at ≥40% methacrylic acid.

What is the scope of US Patent 6,306,900 for mycophenolate enteric-coated formulations?

What do the claims cover at the highest level? (independent claim scope)

US 6,306,900 claim 1 is directed to a pharmaceutical composition comprising a mycophenolate salt adapted to prevent release of mycophenolate in the stomach. That is the core claim theme: stomach-resistance for an orally administered mycophenolate salt.

Everything else in claims 2–14 adds limitations around enteric-coating composition, dosage form, tablet hardness, salt identity (mono-sodium), crystallinity, and dosing amount ranges.

Claim 1 (broadest anchor):

• Mycophenolate salt
• Composition adapted to prevent release of mycophenolate in the stomach
• No explicit enteric polymer specified in claim 1
• No explicit dosage form specified in claim 1

Claims 2 and 11 (enteric coating composition is the key narrowing feature):

• Enteric coating present
• Coating must comprise one of the enumerated polymer systems:
  • cellulose acetate phthalate and trimellitate, or
  • methacrylic acid copolymers containing at least 40% methacrylic acid, or
  • hydroxypropyl methylcellulose phthalate

Claims 4–7 (solid dosage form coverage):

• Tablet form (claims 4–5)
• Granule or pellet form contained in capsule (claims 6–7)

Claims 5 and 13 (tablet hardness):

• Hardness between 10 and 70 N

Claims 8–9 and 12 (salt identity and crystallinity):

• Mono-sodium salt (claims 8 and 11)
• Crystalline form (claims 9 and 12)

Claims 10 and 14 (dose amount range):

• About 50 mg to 1.5 g of a pharmaceutically acceptable mycophenolate salt

What does “adapted to prevent release… in the stomach” mean for claim construction?

In practical formulation terms, this is an enteric-release requirement: the composition must resist dissolution in gastric conditions and release in the intestine. Claim 1 itself does not name the coating, but claims 2 and 11 do, which tends to inform how a court would map the “adapted” language to known enteric systems.

For design-around, the operative lever is whether the formulation is truly “adapted” to prevent gastric release. If the dosage form uses non-enteric gastric protection (for example, different pH-responsive systems outside the enumerated polymer families) it may avoid claims 2/11, but claim 1 could still be asserted if a patentee argues the system still prevents stomach release.

How do the dependent claims tighten the patent’s practical capture range?

The dependent claims narrow scope to specific implementation details that are common in enteric coating practice, which can make at-risk designs broadly aligned with generic commercial realities.

Coating polymer language is the central risk driver

For claims 2 and 11:

• cellulose acetate phthalate and trimellitate (as a coating comprising that combination)
• or methacrylic acid copolymers with ≥40% methacrylic acid
• or hydroxypropyl methylcellulose phthalate

This is a classic claim drafting approach that covers multiple polymer options while still anchoring to a limited list of enteric materials and a numerical threshold for methacrylic acid copolymers.

Tablet hardness adds a manufacturing-parameter limitation

Hardness between 10 and 70 N (claims 5 and 13). This can act as a partial carve-out if a competitor targets a tablet hardness outside that window, but it also creates evidence issues tied to measured test results and product specification controls.

Salt form adds crystallinity and mono-sodium identity

Mono-sodium salt (claims 8 and 11) plus crystalline form (claims 9 and 12). If a competitor uses a different counterion or an amorphous form, it can fall outside these dependent claims. Claim 1 is not limited to mono-sodium, so the counterion swap only helps against claims that explicitly require mono-sodium.

Dose amount range likely maps to label strengths

The “about 50 mg to 1.5 g” range (claims 10 and 14) is broad, spanning typical mycophenolate salt unit and daily amounts in transplant regimens. For generics, most standard strength tablets/capsules likely land within the range.

Which enteric coating systems are explicitly protected by US 6,306,900?

What polymers are named in the claims? (direct list)

Claims 2 and 11 require an enteric coating comprising at least one of:

1. Cellulose acetate phthalate and trimellitate
   • The language reads as a coating comprising cellulose acetate phthalate and trimellitate.
2. Methacrylic acid copolymers containing at least 40% methacrylic acid
   • This includes a numeric threshold (≥40% methacrylic acid) that can be used to test whether a coating polymer qualifies.
3. Hydroxypropyl methylcellulose phthalate

Is methacrylic acid copolymer coverage expanded by claim 3?

Yes. Claim 3 narrows claim 2 to “methacrylic acid copolymers containing at least 40% methacrylic acid.” Claim 3 functions as an additional anchor showing the patentee contemplated this class as a distinct and important embodiment.

How do these specific polymer lists affect generic design-around strategy?

• High risk: formulations using enteric polymers that match any named polymer family (and for methacrylic acid copolymers, meeting the ≥40% requirement).
• Intermediate risk: formulations that use different enteric polymers may avoid claims 2/3/11, but may still implicate claim 1 if they still prevent gastric release of mycophenolate salt.
• Lower risk: formulations that alter the “salt” definition (non-mono-sodium), or deliver mycophenolate without the enteric stomach-protection concept, could reduce literal infringement exposure, though claim 1’s “adapted to prevent release in the stomach” can be broad.

How strong is the patent estate for mycophenolate stomach-resistant release in the US?

What portion of scope is likely to be enforceable via literal infringement?

Based solely on the provided claim text, literal infringement exposure is strongest when a competitor’s formulation matches:

• mycophenolate as a salt
• an enteric-coated solid dosage form
• with enteric polymer using one of the enumerated materials or meeting the methacrylic-acid copolymer threshold
• and, for dependent claims, mono-sodium crystalline form, tablet hardness, and dosage range

Because many marketed enteric coatings use cellulose acetate phthalate, HPMCP, or methacrylic acid copolymers, the practical reach can be broad across typical enteric design templates.

Where are the clear narrowing “escape hatches”?

• Use of a non-enumerated enteric polymer family to avoid claims 2/11 (though claim 1 may still be asserted).
• Avoiding mono-sodium salt (and crystallinity) to avoid claims 8/9/11/12.
• Choosing tablet hardness outside 10–70 N (for tablet versions) to avoid claims 5/13.
• Changing the dosage amount so it is outside the “about 50 mg to 1.5 g” range (unlikely for standard strength ranges, but conceptually available).

What does claim 1 imply about risk even if coating differs?

Claim 1 does not name coating polymers. If a competitor uses any mechanism that prevents gastric release of mycophenolate salt, claim 1 may still be asserted. Coating polymer differences mainly help defeat dependent claims 2/11, but they may not defeat claim 1 if the stomach-release prevention is functionally achieved.

What generic entry risks exist for competitors targeting mycophenolate enteric-coated products?

How would an ANDA or generic formulation design map to the claim structure?

A generic marketer would typically ensure bioequivalence while copying:

• the salt form or closely related salt
• the enteric coating technology
• the release profile (gastric resistance)
• solid dosage characteristics

The highest literal infringement risk aligns with matching the claim’s enumerated coating materials. The fastest path to risk is a “same polymer set” generic.

Tablet versus capsule-in-granule/pellet

• Tablet forms are directly covered (claims 4–5).
• Capsule containing granules/pellets are also covered (claims 6–7). If a competitor chooses a different physical dosage form, claim 4–7 may fall away, but claim 1 (and claim 2/11 if coating applies) can still capture the composition if it prevents gastric release and includes the enumerated enteric coating polymers.

What about changing tablet hardness?

Hardness between 10 and 70 N is a measurable parameter. Competitors can target different compression forces and excipient systems to push hardness outside this window. The risk becomes evidentiary: specification vs batch results, and whether the marketed product is manufactured to stay within the claimed range.

What about changing salt crystallinity?

Claims 9 and 12 require crystalline form when the salt is mono-sodium. If a competitor uses a non-crystalline form or different solid-state form, it can avoid those dependent claims. Again, claim 1 is not limited to crystalline form and can still be asserted depending on whether the “salt” and stomach-release function match.

How does US 6,306,900 compare with other mycophenolate enteric-release IP in the US?

Comparison framework (claim-by-claim)

Because only this patent’s claims are provided, the most actionable comparison framework is architectural:

• This patent’s signature: enteric-coated stomach-resistant release of a mycophenolate salt with specific polymer options (CAP/trimellitate, HPMCP, and ≥40% methacrylic acid copolymers), plus mono-sodium crystalline and tablet hardness-dependent narrowing.
• Competing estates typically differ by:
  • active ingredient polymorph/crystal forms
  • specific process for making the salt or coating
  • alternative enteric polymer systems and thresholds
  • combination products or dosage regimens

For a freedom-to-operate assessment, mapping a competitor to which of these “architecture elements” they match is more useful than a generic “similarity” analysis.

Patent landscape and related US enforcement considerations

What litigation and Orange Book status are implicated?

No Orange Book listings, associated FDA references (brand/RLD), prosecution history, or current litigation status are included in the provided material. As a result, a complete US landscape cannot be generated without introducing unsupplied facts.

What can be stated from the claim set alone

• The claim structure targets a formulation class that is compatible with multiple mycophenolate products that use enteric protection.
• The strongest enforceability angle is when an accused product uses the enumerated enteric polymers and is an orally administered solid dosage that prevents gastric release.
• Dependent claims create additional “checkpoints” (mono-sodium crystalline, tablet hardness, dosage amount range) that can be used to narrow infringement theories or to craft design-arounds.

Key Takeaways

• US 6,306,900 is fundamentally a stomach-release prevention patent for oral mycophenolate salts, with claim 1 setting the functional stomach-resistance concept and dependent claims specifying enteric coatings.
• The enumerated enteric polymers are the highest-value scope: CAP/trimellitate, HPMCP, and methacrylic-acid copolymers with ≥40% methacrylic acid.
• Tablet hardness (10–70 N) and mono-sodium crystalline form create additional dependent-claim constraints that can be targeted via formulation and solid-state controls, but claim 1 still carries functional scope risk.
• Dosage amount language (about 50 mg to 1.5 g) is broad and likely aligns with typical marketed strengths, so it is less likely to be a meaningful design-around lever in practice.

FAQs

Does US 6,306,900 require an enteric coating in the broadest claim?

No. Claim 1 requires a mycophenolate salt adapted to prevent gastric release, but it does not specify the coating composition or even name an enteric coating.

Which dependent claims specify the exact enteric polymer systems?

Claims 2 and 11 specify enteric coatings comprising cellulose acetate phthalate and trimellitate, or methacrylic acid copolymers with ≥40% methacrylic acid, or hydroxypropyl methylcellulose phthalate.

Can a competitor avoid infringement by changing from tablet to capsule?

Claims 4–7 cover tablet and capsule with granules/pellets, but claim 1 (and claims 2/11 if the coating polymers are used) can still apply if the formulation is adapted to prevent gastric release.

How does tablet hardness factor into infringement risk?

Claims 5 and 13 require tablet hardness between 10 and 70 N. A competitor can attempt to manufacture outside that range to avoid those dependent claims, but claim 1 and other dependent claim elements may still be relevant.

Is mono-sodium crystalline form required for all claims?

No. Claims 8, 9, 11, and 12 require mono-sodium and crystalline form, but claim 1 only requires a mycophenolate salt.

References

1. United States Patent 6,306,900. “Pharmaceutical composition comprising a mycophenolate salt adapted to prevent release in the stomach.” (Claim set provided in prompt).

Drugs Protected by US Patent 6,306,900

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

Foreign Priority and PCT Information for Patent: 6,306,900

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	9607564	Apr 12, 1996
United Kingdom	9622028	Oct 24, 1996

International Family Members for US Patent 6,306,900

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	0892640		91094	Luxembourg
European Patent Office	0892640		300157	Netherlands
European Patent Office	0892640		CA 2004 00024	Denmark
European Patent Office	0892640		SPC/GB04/030	United Kingdom
European Patent Office	0892640		SPC017/2004	Ireland