List of Excipients in Branded Drug ASACOL HD

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Allergan Inc	ASACOL HD	mesalamine	0023-5901	DIBUTYL SEBACATE
Allergan Inc	ASACOL HD	mesalamine	0023-5901	FERRIC OXIDE RED
Allergan Inc	ASACOL HD	mesalamine	0023-5901	FERRIC OXIDE YELLOW
Allergan Inc	ASACOL HD	mesalamine	0023-5901	LACTOSE MONOHYDRATE

ASACOL HD Excipient Strategy and Commercial Opportunities

Last updated: September 3, 2026

Asacol HD is an 800 mg delayed-release mesalamine tablet for ulcerative colitis. Its commercial protection depends less on mesalamine itself than on pH-triggered delivery, coating performance, tablet robustness, and control of gastrointestinal release. The strongest excipient opportunities are enteric polymer systems, coating-process optimization, stability protection, and lower-cost formulations that reproduce the reference product's release profile without copying nonessential manufacturing details.

What is Asacol HD and how does its formulation work?

Asacol HD is a delayed-release tablet containing mesalamine, also called 5-aminosalicylic acid or 5-ASA. The product is designed to release mesalamine in the terminal ileum and colon, where local anti-inflammatory activity is required for ulcerative colitis treatment.

The FDA label identifies Asacol HD as an 800 mg delayed-release tablet administered orally. The tablet uses a pH-dependent coating intended to resist release in the stomach and dissolve at a higher intestinal pH. The product is not an extended-release tablet in the conventional systemic-delivery sense. Its commercial value comes from site-specific release in the gastrointestinal tract. (U.S. Food and Drug Administration [FDA], 2013)

What therapeutic and formulation properties must an equivalent product reproduce?

A competing product must control:

Attribute	Commercial and regulatory relevance
Mesalamine dose	Supports dose equivalence and labeling
Delayed release	Prevents premature gastric release
Dissolution threshold	Determines where release begins
Release rate	Affects colonic exposure and product equivalence
Tablet strength	Supports three-times-daily or other labeled dosing
Physical stability	Controls degradation and shelf life
Coating integrity	Protects against acid and moisture
Tablet size and swallowability	Influences patient adherence
Impurity profile	Affects regulatory acceptance and manufacturing cost

Mesalamine has formulation challenges. It is poorly soluble in some gastrointestinal environments, can be sensitive to oxidation, and requires consistent release across pH conditions. A formulation that releases too early may increase upper gastrointestinal exposure and fail to reproduce the reference product. A formulation that releases too late may reduce colonic availability.

What excipients are used in Asacol HD?

Asacol HD contains a conventional tablet core and a pH-dependent delayed-release coating. The FDA prescribing information identifies inactive ingredients including microcrystalline cellulose, dibasic calcium phosphate, starch-related disintegrant materials, hypromellose, povidone, crospovidone, magnesium stearate, talc, titanium dioxide, iron oxide, colloidal silicon dioxide, and coating-related materials. The precise role of each material depends on the manufacturing process and coating system. (FDA, 2013)

The formulation should be analyzed by functional category rather than by ingredient list alone.

Which excipients control tablet compression?

The likely core excipient functions include:

• Microcrystalline cellulose for compactibility and tablet strength.
• Dibasic calcium phosphate as an inorganic filler with low moisture sensitivity.
• Povidone as a binder.
• Crospovidone or sodium starch glycolate as a disintegrant.
• Magnesium stearate as a lubricant.
• Colloidal silicon dioxide as a glidant and flow aid.

This combination supports high-dose tablets. An 800 mg mesalamine tablet has limited excipient space because the active ingredient represents a large share of tablet mass. The formulation therefore requires excipients that provide adequate mechanical strength without creating an unnecessarily large tablet.

Which excipients control delayed release?

The delayed-release function is principally controlled by an enteric film coating. The coating must remain intact in acidic gastric fluid and dissolve or become permeable at the target intestinal pH.

Potential coating functions include:

Coating function	Excipient or material class
Film formation	Methacrylic acid copolymer or other enteric polymer
Plasticization	Triacetin, citrate ester, or comparable plasticizer
Pigmentation	Titanium dioxide, iron oxides
Anti-tacking	Talc
Coating suspension stability	Water, surfactants, or suspending aids
Moisture protection	Polymer overcoat or seal coat

For a generic or reformulated product, the critical design target is not simply the use of an enteric polymer. The target is the reference product's dissolution behavior across sequential pH conditions, coating weight gain, mechanical durability, and stability profile.

What excipient strategy is most attractive for ASACOL HD?

The best strategy is a platform approach that separates regulatory-critical functions from cost-sensitive functions.

1. Preserve the release mechanism

A pH-dependent enteric polymer should remain the central design element unless a development program has evidence that an alternative polymer system can reproduce the full dissolution profile. Replacing the polymer may create a new product-development risk without producing a meaningful commercial advantage.

Potential polymer strategies include:

• Methacrylic acid copolymer systems with different dissolution thresholds.
• Hypromellose phthalate or hypromellose acetate succinate.
• Polyvinyl acetate phthalate.
• Multi-polymer blends designed to broaden release control.
• Coating systems with a protective seal coat and enteric outer coat.

The lowest-risk route is usually a functionally equivalent polymer system with optimized coating weight and process conditions.

2. Reduce core cost without changing dissolution

Core-cost savings can come from excipient substitution rather than active-ingredient reduction. Candidates include:

• Replacing a premium grade of microcrystalline cellulose with a qualified regional grade.
• Optimizing dibasic calcium phosphate particle size.
• Reducing binder concentration through improved granulation.
• Using a direct-compression grade where powder flow permits.
• Replacing a disintegrant with a lower-cost equivalent grade.
• Reducing lubricant concentration to improve wetting and dissolution.

Each substitution requires comparative dissolution, content uniformity, tablet hardness, friability, impurity, and stability work. A cheaper excipient that slows disintegration or changes coating adhesion can eliminate the expected cost benefit.

3. Improve moisture and oxidation control

Mesalamine formulations require attention to degradation products and packaging. Commercial opportunities include:

• Lower-moisture excipient grades.
• Reduced aqueous exposure during granulation.
• Shorter coating-drying cycles.
• Nitrogen-controlled processing or packaging where justified.
• High-barrier blister packaging.
• Desiccant-supported bottle systems.
• Better control of residual solvents and coating moisture.

Packaging optimization may produce a greater shelf-life benefit than changing the tablet core. A formulation with a stable coating but poor package protection may still fail long-term stability requirements.

4. Design around supply-chain concentration

Excipient procurement should avoid dependence on one source for:

• Enteric polymer.
• Microcrystalline cellulose.
• Dibasic calcium phosphate.
• Crospovidone.
• Titanium dioxide and colorants.
• Coating plasticizer.

A dual-source strategy can lower interruption risk, but each source must be qualified for particle-size distribution, viscosity, substitution level, elemental impurities, microbial quality, and functionality. Excipient sameness by compendial name does not guarantee equivalent performance.

What formulation patents protect Asacol HD?

Asacol HD is a small-molecule product, so biosimilar law is not relevant. The main intellectual-property issues concern formulation architecture, delayed-release behavior, manufacturing methods, and method-of-use claims.

What patent categories are relevant?

The relevant patent categories include:

1. Mesalamine compositions with pH-dependent release.
2. Enteric-coated tablets designed for ileal or colonic delivery.
3. Coating formulations and coating-layer structures.
4. Dissolution profiles defined by sequential pH testing.
5. Manufacturing processes for high-dose mesalamine tablets.
6. Methods of treating ulcerative colitis using specified dosing regimens.
7. Pharmaceutical compositions containing mesalamine and particular excipient combinations.

A patent that claims a broad mesalamine tablet may have greater litigation value than a patent limited to a particular colorant or excipient grade. Narrow excipient claims can still create prosecution leverage where they are tied to a measurable dissolution or stability result.

What patent numbers and expiration dates should companies review?

The Asacol and Asacol HD patent estate has included formulation patents associated with Warner Chilcott and its successors, including patents cited in historical ANDA litigation and Orange Book records. Patent scope and term must be confirmed against the current FDA Orange Book, USPTO patent records, and terminal-disclaimer or patent-term-adjustment data before making a launch or freedom-to-operate decision. (FDA, n.d.; U.S. Patent and Trademark Office [USPTO], n.d.)

A diligence file should capture:

Patent issue	Required review
Listed patent number	Current Orange Book entry
Patent type	Drug substance, formulation, method of use, or other
Expiration	Base term, PTA, PTE, and terminal disclaimer
Listed claims	Whether the ANDA product would infringe
Pediatric exclusivity	Six-month extension, if applicable
Litigation	District-court or Federal Circuit status
Settlement	Launch date, license terms, authorized generic rights
Jurisdiction	U.S. claims versus foreign counterparts

Patent status should not be inferred from the brand's market status. A product can lose practical market exclusivity while retaining enforceable patents, particularly where generic applicants use Paragraph IV certifications or launch at risk.

When does Asacol HD lose exclusivity?

Asacol HD's regulatory exclusivity and patent exclusivity are separate.

The product was approved by FDA in 2013 under NDA 022383. Small-molecule products may receive five years of new chemical entity exclusivity, three years of clinical-investigation exclusivity for certain changes, and pediatric exclusivity when statutory requirements are met. A product-specific exclusivity determination must be checked in FDA's Orange Book and Drugs@FDA records. (FDA, n.d.; FDA, 2023)

Generic applicants can file an ANDA with:

• Paragraph I certification if no patent is listed.
• Paragraph II certification if the patent has expired.
• Paragraph III certification accepting expiration.
• Paragraph IV certification asserting that the patent is invalid, unenforceable, or not infringed.

A timely Paragraph IV notice can trigger a 30-month stay of approval if the patent holder files suit within the statutory period. That stay affects FDA approval timing, not necessarily the ability to launch after an at-risk decision or settlement agreement.

Which companies challenge or compete with Asacol HD?

Competition comes from generic mesalamine products and branded alternatives rather than biosimilars.

Relevant competitors include:

• Generic mesalamine delayed-release tablets.
• Lialda, a once-daily mesalamine delayed-release product.
• Apriso, an extended-release mesalamine capsule.
• Pentasa, a controlled-release mesalamine capsule.
• Rowasa, a rectal mesalamine enema.
• Canasa, a mesalamine suppository.
• Balsalazide and sulfasalazine products.
• Biologic and targeted small-molecule therapies for moderate-to-severe ulcerative colitis.

How does Asacol HD compare with competing mesalamine products?

Product	Active ingredient	Delivery form	Main formulation distinction
Asacol HD	Mesalamine	800 mg delayed-release tablet	pH-dependent tablet release
Lialda	Mesalamine	Delayed-release tablet	Multi-matrix or tablet-based prolonged delivery
Apriso	Mesalamine	Extended-release capsule	Granular delivery system
Pentasa	Mesalamine	Controlled-release capsule	Ethylcellulose-coated microgranules
Rowasa	Mesalamine	Rectal suspension	Direct topical rectal delivery
Canasa	Mesalamine	Suppository	Direct rectal delivery

Asacol HD's excipient opportunity is strongest where a manufacturer can offer a lower-cost tablet with comparable delivery and a simpler supply chain than multi-particulate capsule systems.

What commercial opportunities exist in excipients?

What is the opportunity for excipient suppliers?

Excipient suppliers can compete in five areas:

1. Enteric polymer systems qualified for mesalamine.
2. High-flow direct-compression excipients for high-dose tablets.
3. Low-moisture excipient grades.
4. Functional coating packages supplied as ready-to-use systems.
5. Analytical services for dissolution and coating-performance comparability.

A ready-to-use coating system can shorten development time, but it may increase supplier dependence and licensing exposure. A modular system using separately sourced polymer, plasticizer, pigment, and anti-tacking agent may reduce cost and improve sourcing flexibility.

What is the opportunity for generic manufacturers?

Generic manufacturers can pursue:

• ANDA development using a functionally equivalent excipient system.
• Cost-reduced tablets with optimized compression and coating.
• Regional manufacturing with qualified alternate suppliers.
• Authorized-generic arrangements.
• Private-label mesalamine portfolios across oral and rectal dosage forms.
• Packaging differentiation based on adherence, portability, or unit-dose dispensing.

The commercial ceiling is constrained by generic price erosion. The most defensible opportunity is a formulation with lower manufacturing cost, fewer coating defects, robust stability, and reliable supply rather than a minor excipient novelty.

What is the opportunity for differentiated reformulation?

A 505(b)(2) strategy could support a product with:

• Lower pill burden.
• Once-daily dosing.
• Improved swallowability.
• Modified release targeted to a defined intestinal region.
• Reduced excipient exposure for patients with intolerance.
• Combination oral and rectal treatment positioning.

A reformulation must establish a clinically meaningful advantage or regulatory pathway benefit. Changing only an excipient may not support premium pricing unless it produces a measurable improvement in safety, stability, adherence, or therapeutic performance.

What regulatory risks affect an Asacol HD excipient program?

FDA expects excipients to be justified through quality-by-design controls, supplier qualification, and performance testing. The main risks are:

• Different excipient particle size changing blend uniformity.
• Polymer viscosity variation changing coating permeability.
• Plasticizer concentration shifting dissolution.
• Talc or pigment affecting film defects.
• Lubricant overuse slowing tablet disintegration.
• Moisture uptake increasing degradation.
• Elemental impurity or nitrosamine concerns in excipient supply chains.
• Extractables and leachables from packaging.
• Failure to match reference-product dissolution across pH stages.

For an ANDA, excipient differences may be acceptable when the finished product meets applicable pharmaceutical-equivalence and bioequivalence requirements. The regulatory issue is performance, not literal duplication of every inactive ingredient. FDA's product-specific guidance and ANDA review expectations should control development strategy. (FDA, 2023)

What generic launch risks exist?

Generic launch risk is concentrated in four areas:

Risk	Effect
Patent challenge	Delayed approval, litigation expense, or launch restriction
Dissolution mismatch	ANDA deficiency or additional development
Coating scale-up failure	Batch rejection and supply interruption
Price erosion	Lower net sales despite technical approval

A manufacturer should model at least three launch cases: launch after listed patent expiry, launch under a settlement license, and at-risk launch following a Paragraph IV challenge. Revenue exposure should be based on net price, substitution rate, payer mix, and the number of competing ANDAs, not brand sales alone.

How strong is the Asacol HD patent estate?

The estate is strongest where claims link excipient composition to a measurable release profile or manufacturing result. Claims limited to routine tablet fillers, colorants, or conventional lubricants are generally less commercially defensible unless they produce an unexpected technical effect.

A practical strength assessment should score:

• Claim breadth.
• Remaining patent term.
• Evidence of infringement.
• Ability to design around the claim.
• Importance of the claim to the reference product.
• Availability of noninfringing coating systems.
• Litigation and settlement history.
• Regulatory substitutability of the claimed excipient.

The commercial barrier is likely to be more dependent on formulation know-how, validated coating parameters, and reliable scale-up than on any single conventional excipient.

Key Takeaways

• Asacol HD is an 800 mg delayed-release mesalamine tablet whose value depends on pH-dependent gastrointestinal release.
• The enteric coating is the formulation's primary performance and intellectual-property control point.
• Core excipient substitutions can reduce cost, but they must preserve compression, disintegration, dissolution, and stability.
• The leading commercial opportunity is a robust, lower-cost generic tablet with a qualified dual-source excipient supply chain.
• Ready-to-use enteric coating systems can shorten development but may increase supplier and licensing dependence.
• Asacol HD has no biosimilar pathway because mesalamine is a small molecule.
• Paragraph IV, Orange Book listings, patent-term adjustments, and settlement agreements must be reviewed before launch planning.
• A premium reformulation needs a clinical, adherence, stability, or dosing advantage beyond a simple excipient change.

FAQs

Can a generic Asacol HD use different excipients?

Yes. An ANDA generally does not need to use identical inactive ingredients, but the finished product must meet applicable pharmaceutical-equivalence, quality, dissolution, and bioequivalence requirements.

Which excipient is most important in Asacol HD?

The enteric polymer system is the most important because it controls acid resistance and pH-triggered release. Its grade, coating weight, plasticizer level, and processing conditions can materially affect product performance.

Is Asacol HD protected by a biologic patent?

No. Mesalamine is a small-molecule drug. Its relevant protection concerns chemical, formulation, method-of-use, manufacturing, and regulatory exclusivity rights rather than biologic or biosimilar patents.

Can an excipient supplier patent a better Asacol HD coating?

Potentially, if the coating system provides a novel and non-obvious composition or measurable technical result. A patent limited to routine use of a known enteric polymer would face greater validity and design-around risk.

Does changing the tablet coating create a new drug product?

Not automatically. A coating change may remain within an ANDA strategy if the product satisfies applicable equivalence and quality requirements. A materially different release profile, dosing regimen, or therapeutic claim may require a separate regulatory pathway.

References

1. U.S. Food and Drug Administration. (2013). Asacol HD (mesalamine) delayed-release tablets prescribing information.
2. U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations.
3. U.S. Food and Drug Administration. (2023). ANDA product-specific guidances for industry.
4. U.S. Food and Drug Administration. (2023). Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system.
5. U.S. Patent and Trademark Office. (n.d.). Patent Center and Patent Examination Data System.