List of Excipients in Branded Drug COLAZAL

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Salix Pharmaceuticals Inc	COLAZAL	balsalazide disodium	65649-101	MAGNESIUM STEARATE
Salix Pharmaceuticals Inc	COLAZAL	balsalazide disodium	65649-101	SILICON DIOXIDE

Last updated: August 12, 2026

Colazal, the brand name for balsalazide disodium, is a colon-targeted oral prodrug whose commercial performance depends more on capsule design, excipient control, and generic execution than on a durable patent barrier. The product’s principal opportunity is a low-cost, differentiated generic or reformulated presentation that preserves delayed colonic drug release while improving swallowing, pediatric use, stability, or manufacturing efficiency.

Colazal Excipient Strategy and Commercial Opportunities for Balsalazide Disodium

What is Colazal and how does its formulation work?

Colazal contains balsalazide disodium, a 5-aminosalicylic acid, or 5-ASA, prodrug approved for the treatment of mildly to moderately active ulcerative colitis. The product is administered as an oral capsule and is designed to deliver mesalamine to the colon.

Balsalazide consists of mesalamine linked through an azo bond to an inert carrier molecule. Colonic bacteria reduce the azo bond, releasing mesalamine locally in the large intestine. This mechanism limits reliance on gastric or small-intestinal dissolution controls that are central to conventional enteric-coated mesalamine products.

The commercial formulation has three functional components:

Component	Commercial function
Balsalazide disodium	Active pharmaceutical ingredient and colon-targeted mesalamine prodrug
Capsule shell	Provides oral presentation, handling, identification, and patient acceptability
Internal excipients	Support powder flow, capsule filling, dispersion, disintegration, stability, and manufacturability

The Colazal prescribing information identifies inactive ingredients including colloidal silicon dioxide, FD&C Blue No. 2, gelatin, magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate, and titanium dioxide.[1]

What excipients are used in Colazal capsules?

The listed Colazal excipients are conventional oral solid-dose materials. Their value lies in controlling the physical performance of the capsule rather than creating a separate drug-release mechanism.

Microcrystalline cellulose

Microcrystalline cellulose is commonly used as a diluent and compression or filling aid. In a capsule product, it can improve bulk density, powder flow, and content uniformity. Its level may affect capsule fill weight and the rate at which the formulation disperses after the gelatin shell opens.

A generic manufacturer must control particle-size distribution, moisture, bulk density, and supplier variability. These attributes can affect encapsulation performance even when the qualitative excipient composition is unchanged.

Povidone

Povidone can function as a binder, wetting aid, or dispersion-support excipient. It may improve powder cohesion and reduce segregation during high-speed encapsulation. Excessive binder content can slow dispersion, while insufficient binder may increase fines and manufacturing losses.

Sodium starch glycolate

Sodium starch glycolate is a superdisintegrant. It promotes rapid breakup of the capsule fill after the capsule shell dissolves. For balsalazide, the objective is not rapid release in the stomach but reliable dispersion of the prodrug without compromising its transit to the colon.

The development target is a balanced disintegration profile. A formulation that disintegrates too slowly may create variable exposure. A formulation that disperses too aggressively may increase process sensitivity or produce unacceptable powder behavior.

Colloidal silicon dioxide

Colloidal silicon dioxide improves flow and reduces cohesion in powders. It can be important for consistent capsule filling, particularly where the active ingredient has poor flow or a broad particle-size distribution.

Overuse can increase dusting, reduce capsule-fill efficiency, or alter powder density. The grade and level should be treated as material attributes rather than interchangeable commodity choices.

Magnesium stearate

Magnesium stearate is a lubricant used to limit adhesion to manufacturing equipment. Its mixing time and concentration require control. Excessive lubrication may reduce wetting or slow dispersion, while inadequate lubrication can cause sticking, weight variation, and equipment downtime.

Gelatin, titanium dioxide, and FD&C Blue No. 2

These materials are associated primarily with the capsule shell and product identification. Capsule color can support brand recognition and reduce medication-selection errors. A reformulator can evaluate HPMC or other non-gelatin shells for vegetarian, religious, allergen, or supply-chain positioning, but any shell change requires comparative performance and regulatory assessment.

What excipient strategy best supports a generic Colazal product?

A successful generic strategy should preserve the reference product’s critical quality attributes while creating controlled differences in manufacturability, patient use, or supply economics.

Strategy 1: Qualitative and quantitative excipient alignment

The lowest regulatory and technical risk generally comes from matching the reference product’s excipient types and, where available, their levels. This approach reduces the probability that excipients will alter dissolution, disintegration, stability, or capsule performance.

The formulation team should prioritize:

• Comparable capsule rupture and fill dispersion
• Comparable dissolution across physiologic pH conditions
• Consistent dose uniformity
• Moisture protection
• Equivalent appearance and capsule identification
• Stable performance across the proposed shelf life

Strategy 2: Improve powder processability

Balsalazide disodium products may offer manufacturing savings through improved particle engineering, excipient grade selection, and optimized lubrication. Opportunities include:

• Narrower active-ingredient particle-size distribution
• Improved bulk density
• Reduced segregation during blending
• Lower lubricant exposure
• Higher capsule-filling speed
• Reduced weight variability
• Fewer in-process rejects

These changes can improve gross margin without changing the patient-facing product.

Strategy 3: Reduce excipient complexity

A manufacturer may attempt to reduce the number of excipients or replace multiple excipients with a multifunctional excipient. This could lower material and testing costs, but it creates higher development risk. The formulation must continue to meet performance requirements for capsule opening, powder dispersion, dose uniformity, and stability.

A simplified formulation may also have commercial value if it reduces allergen concerns or removes artificial colorants.

Strategy 4: Use a non-gelatin capsule shell

An HPMC capsule could support vegetarian and religious-diet positioning. It may also reduce dependence on gelatin supply chains. The main technical issue is shell behavior under storage and gastrointestinal conditions. Shell composition, moisture content, brittleness, oxygen transmission, and disintegration must remain suitable for the product.

This is a potential line-extension strategy rather than the lowest-risk first generic.

What formulations are protected by the Colazal product design?

The core formulation concept is colon delivery through bacterial cleavage of the balsalazide azo bond. The capsule itself does not appear to depend on a complex enteric coating system. This limits the value of simply adding a conventional enteric coat, because the product’s differentiation comes from the prodrug chemistry and colonic bacterial activation.

Potential formulation claim areas include:

1. Specific excipient combinations that improve powder flow or content uniformity.
2. Capsule-shell compositions with defined moisture or disintegration properties.
3. Particle-size distributions for balsalazide disodium.
4. Manufacturing processes that reduce degradation or improve yield.
5. Alternative dosage forms, including multiparticulates, sachets, dispersible granules, or pediatric presentations.
6. Combination products pairing balsalazide with another anti-inflammatory or microbiome-directed component.

The commercial enforceability of these claims depends on whether a competitor must practice the claimed excipient ratio, process step, particle-size range, or delivery format. Broad claims covering ordinary capsule excipients are generally more vulnerable than narrow claims linked to measurable performance or a specific manufacturing problem.

When does Colazal lose exclusivity?

Colazal’s principal small-molecule exclusivity period has largely elapsed. Balsalazide disodium is a mature active ingredient, and generic competition has existed in the U.S. market.

The commercial exclusivity profile is therefore driven by:

Protection category	Current commercial relevance
New chemical entity exclusivity	Expired
Brand product exclusivity	Expired or no longer the primary barrier
Formulation patents	Potentially relevant only if unexpired and listed or enforceable
Method-of-use patents	Limited value where the approved ulcerative-colitis indication is established
Regulatory exclusivity	Not expected to block ordinary ANDA competition for the mature product
Trade secrets	Relevant to manufacturing efficiency and supplier qualification
Trademark and brand recognition	Residual value, particularly in prescribing and pharmacy substitution

Patent expiry dates must be determined from the specific patent family, terminal disclaimers, patent-term adjustments, and Orange Book listing history. The core commercial conclusion is clear: a new entrant is more likely to compete on cost, supply reliability, formulation convenience, or distribution than on broad compound-patent protection.

What is the Orange Book and FDA status of Colazal?

The reference product is associated with FDA-approved labeling for Colazal capsules under NDA 020610. The labeled indication covers mildly to moderately active ulcerative colitis in adults and pediatric patients five years of age and older.[1]

FDA approval of generic balsalazide products is generally pursued through the abbreviated new drug application, or ANDA, pathway. A generic applicant must demonstrate pharmaceutical equivalence and bioequivalence to the reference listed drug under applicable FDA requirements.[2]

For a mature oral prodrug such as balsalazide, the regulatory focus includes:

• Active ingredient identity and strength
• Capsule dosage form
• Assay and impurities
• Content uniformity
• Dissolution and disintegration
• Stability
• Microbiological quality
• Bioequivalence
• Manufacturing controls

The Orange Book remains the authoritative source for current reference-product listings, therapeutic-equivalence codes, patent listings, and exclusivity information.[3] A commercial diligence review should distinguish patents listed for the reference drug from expired patents, unlisted formulation know-how, and patents covering products that are no longer commercially relevant.

How strong is the Colazal patent estate?

The patent estate is commercially weaker than the estates around newer small molecules, biologics, and proprietary delivery systems. Balsalazide is an established prodrug, and the basic commercial opportunity is exposed to generic substitution.

Patent strength is likely to be highest where claims cover:

• A narrowly defined manufacturing process
• A specific impurity profile
• A particle-engineered form
• A differentiated pediatric or sprinkle dosage form
• A controlled-release or multiparticulate system with demonstrated clinical or pharmacokinetic value
• A combination product with a separate inventive contribution

Patent strength is lower where claims cover routine capsule excipients, common lubricants, standard disintegrants, or broad use of balsalazide for ulcerative colitis.

A Paragraph IV challenge would be most commercially relevant if an unexpired patent remains listed in the Orange Book and the generic applicant certifies that the patent is invalid, unenforceable, or will not be infringed. For a mature Colazal product, the expected litigation risk is lower than for a recently launched product, but a specific line extension could create a new patent dispute.

What generic entry risks exist for Colazal?

The principal risks are technical and commercial rather than patent-driven.

Technical risks

A generic formulation can fail to match the reference product because of:

• Different particle-size distribution
• Excessive hydrophobic lubrication
• Inadequate or excessive disintegration
• Capsule-shell moisture variation
• Poor powder flow
• Blend segregation
• Inconsistent assay across the capsule fill
• Stability loss under elevated humidity

The drug’s colon-targeted mechanism increases the importance of demonstrating consistent performance through the upper gastrointestinal tract and reliable bacterial conversion in the colon.

Commercial risks

The market has several structural constraints:

• Balsalazide competes with generic mesalamine products.
• Physicians may select mesalamine based on familiarity, payer coverage, or dosing frequency.
• Ulcerative-colitis treatment is increasingly segmented by disease severity and biologic use.
• A capsule product may be less attractive for patients with swallowing difficulty.
• Low unit pricing can compress margins quickly after multiple ANDA entrants.

The strongest generic business case is likely a low-cost, reliable product supported by broad wholesaler access and consistent pharmacy supply.

What commercial opportunities exist for Colazal excipient innovation?

Pediatric and swallowing-friendly presentations

The FDA-approved pediatric indication creates a potential opportunity for a more patient-friendly presentation. Candidates include:

• Sprinkle capsules
• Mini-capsules
• Granules
• Sachets
• Powder for extemporaneous dispersion
• Lower-strength capsules for flexible dosing

Each format must preserve the colon-targeted mechanism. A liquid formulation is technically challenging because balsalazide stability, taste, microbial control, and dose uniformity become more difficult.

Colorant-free and gelatin-free capsules

A colorant-free product can appeal to patients and institutions seeking simpler excipient profiles. A gelatin-free capsule can support vegetarian or religious-diet requirements. These changes are commercially differentiated but may not command a large price premium in a heavily genericized market.

Manufacturing-cost reduction

The most immediate opportunity is process economics. A formulation that uses readily available excipient grades, fewer manufacturing steps, faster encapsulation, and lower rejection rates can improve profitability without changing the approved therapeutic positioning.

Global supply and regional licensing

Balsalazide products may be attractive in markets where mesalamine access is limited or expensive. Licensing opportunities could involve:

• Regional ANDA or equivalent registrations
• Contract manufacturing
• Private-label supply
• Hospital and tender channels
• Pediatric line extensions
• Non-gelatin capsule presentations

Geographic value depends on local ulcerative-colitis prevalence, reimbursement, regulatory requirements, and the availability of competing 5-ASA products.

How does Colazal compare with other mesalamine products?

Product category	Active approach	Delivery concept	Excipient opportunity
Colazal	Balsalazide disodium prodrug	Bacterial azo-bond cleavage in colon	Capsule flow, disintegration, shell, pediatric formats
Delayed-release mesalamine	Mesalamine	Enteric coating and pH-triggered release	Coating polymers, coat weight, dissolution control
Extended-release mesalamine	Mesalamine	Extended intestinal release	Matrix and multiparticulate systems
Sulfasalazine	Mesalamine prodrug	Bacterial cleavage of azo bond	Tolerability, dose size, alternative dosage forms
Topical rectal mesalamine	Mesalamine	Direct local delivery	Vehicle, retention, patient convenience

Colazal’s principal differentiation is the prodrug-based colon-delivery mechanism. Its formulation strategy is less dependent on an elaborate coating platform than delayed-release mesalamine. That can reduce manufacturing complexity, but it also narrows the scope for a formulation patent based solely on routine excipients.

What licensing and acquisition opportunities exist?

Licensing value is most credible in three areas.

First, an owner of an approved balsalazide product can offer regional commercialization rights where the licensee has established gastroenterology distribution.

Second, a formulation developer can license a pediatric or swallowing-friendly presentation that improves administration without changing the active ingredient.

Third, a contract manufacturer can offer a lower-cost, qualified supply platform based on process optimization, dual sourcing, and improved capsule filling.

An acquisition centered only on the legacy Colazal brand would face limited exclusivity and generic price pressure. An acquisition that includes manufacturing know-how, regulatory approvals in multiple jurisdictions, and differentiated dosage forms would have stronger strategic value.

Key Takeaways

• Colazal contains balsalazide disodium, a colon-targeted prodrug that releases mesalamine through bacterial azo-bond cleavage.
• The listed excipients are conventional capsule ingredients: microcrystalline cellulose, povidone, sodium starch glycolate, colloidal silicon dioxide, magnesium stearate, gelatin, titanium dioxide, and FD&C Blue No. 2.
• Generic competition is the central commercial reality because the product is mature and broad exclusivity has largely expired.
• The highest-value excipient opportunities involve process efficiency, capsule-shell redesign, pediatric administration, and improved powder handling.
• Conventional excipient patents are unlikely to create strong barriers unless linked to a specific performance advantage or manufacturing problem.
• The most attractive commercial opportunities are low-cost generic supply, private-label manufacturing, pediatric formats, and regional licensing.
• A new formulation must preserve consistent capsule performance and colonic delivery while meeting ANDA pharmaceutical-equivalence and bioequivalence requirements.

FAQs

Can Colazal be reformulated as a liquid?

A liquid formulation is possible in principle but presents substantial challenges involving taste, stability, microbial control, dose uniformity, and reliable delivery of balsalazide to the colon. Granules, sachets, or sprinkle capsules are more practical starting points.

Which Colazal excipient is most important for capsule performance?

Sodium starch glycolate is important for internal disintegration, while colloidal silicon dioxide and magnesium stearate strongly affect powder flow and manufacturing consistency. Capsule-shell moisture and disintegration are also critical.

Does Colazal require an enteric coating?

The product’s colon-targeting mechanism is based primarily on bacterial cleavage of balsalazide rather than a conventional pH-dependent enteric coating. An enteric coating could be used in a reformulated product, but it would introduce new dissolution and regulatory requirements.

Is a gelatin-free Colazal generic commercially viable?

A gelatin-free product could support vegetarian, religious-diet, and institutional procurement requirements. Its commercial viability would depend on manufacturing cost, pharmacy substitution, reimbursement, and whether the presentation offers a meaningful supply or patient-use advantage.

Can a generic manufacturer patent a new Colazal excipient combination?

A manufacturer may seek patent protection for a novel excipient combination if it produces a non-obvious and measurable technical benefit. Routine substitution of common capsule excipients is less likely to support a strong patent position.

References

1. U.S. Food and Drug Administration. (2019). Colazal (balsalazide disodium) capsules prescribing information. Salix Pharmaceuticals.

2. U.S. Food and Drug Administration. (2024). Abbreviated new drug application process. FDA.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

4. U.S. Food and Drug Administration. (2024). Inactive ingredient database. FDA.

5. DailyMed. (2024). Balsalazide disodium capsule and Colazal labeling. National Library of Medicine.