List of Excipients in Branded Drug CARDIZEM

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Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Bausch Health US LLC	CARDIZEM	diltiazem hydrochloride	0187-0771	CELLULOSE, MICROCRYSTALLINE
Bausch Health US LLC	CARDIZEM	diltiazem hydrochloride	0187-0771	D&C YELLOW NO. 10
Bausch Health US LLC	CARDIZEM	diltiazem hydrochloride	0187-0771	FD&C BLUE NO. 1
Bausch Health US LLC	CARDIZEM	diltiazem hydrochloride	0187-0771	HYDROXYPROPYL CELLULOSE

Cardizem Excipient Strategy and Commercial Opportunities in Diltiazem Formulations

Last updated: September 24, 2026

Cardizem is the brand name for diltiazem hydrochloride, a benzothiazepine calcium-channel blocker used for hypertension, angina, and selected supraventricular tachyarrhythmias. Its commercial opportunity is no longer based on primary-molecule exclusivity. It is based on formulation engineering, dose flexibility, modified-release performance, manufacturing efficiency, and differentiated generic or specialty products.

The strongest opportunities are extended-release oral products, low-cost immediate-release tablets, orally disintegrating or sprinkle-compatible dosage forms, and injectable presentations with improved handling and stability. Excipient selection is commercially important because diltiazem products compete primarily on bioequivalence, release profile, tolerability, manufacturing cost, and pharmacy substitution.

What is Cardizem and which diltiazem formulations are commercially relevant?

Cardizem products contain diltiazem hydrochloride. The principal dosage forms are:

Product category	Typical release profile	Commercial role	Key formulation issue
Immediate-release tablets	Immediate release	Hypertension, angina, rate control	Dose flexibility and low cost
Extended-release capsules	Once-daily or controlled release	Chronic hypertension and angina	Multiparticulate release control
Extended-release tablets	Once-daily controlled release	Chronic cardiovascular therapy	Matrix or coated-tablet performance
Injectable solution	Immediate parenteral delivery	Acute rate control and hospital use	Sterility, pH, preservative strategy
Generic diltiazem products	Multiple release profiles	Broad substitution market	Product-specific bioequivalence

Cardizem CD is an extended-release capsule product. Cardizem LA is an extended-release tablet product. Cardizem injection is an intravenous product. FDA labeling requires product-specific administration instructions because extended-release diltiazem formulations are not interchangeable solely on the basis of milligram strength or active ingredient content.[1-3]

The formulation platform matters more than the diltiazem molecule. Immediate-release and extended-release products can have materially different pharmacokinetics, dosing schedules, and substitution requirements.

What excipients are used in Cardizem and generic diltiazem products?

The exact excipient composition depends on the manufacturer, strength, dosage form, and product approval. Cardizem CD and Cardizem LA use different release technologies, while generic products may use alternative excipient systems if they satisfy pharmaceutical equivalence, bioequivalence, stability, and quality requirements.

Immediate-release tablet excipients

Immediate-release diltiazem tablets generally use conventional solid-dose excipients such as:

• Lactose or another diluent
• Microcrystalline cellulose
• Pregelatinized starch or corn starch
• Povidone or another binder
• Crospovidone or croscarmellose sodium as a disintegrant
• Colloidal silicon dioxide as a glidant
• Magnesium stearate as a lubricant
• Film-coating polymers, plasticizers, pigments, or opacifiers

The commercial objective is a robust, low-cost tablet with rapid disintegration and consistent assay uniformity. Because diltiazem hydrochloride is a potent active ingredient administered across multiple strengths, powder flow and content uniformity are important manufacturing variables.

Extended-release capsule excipients

Cardizem CD-type capsules use coated beads or multiparticulate units. A typical multiparticulate platform may include:

• Sugar or microcrystalline cellulose starter cores
• Povidone or hydroxypropyl cellulose binder
• Ethylcellulose or another water-insoluble release-controlling polymer
• Hypromellose as a film-forming or pore-forming polymer
• Triethyl citrate or another plasticizer
• Talc or colloidal silicon dioxide
• Gelatin capsule shells
• Titanium dioxide and approved colorants

The product-specific label should be used for the definitive inactive-ingredient list. FDA labeling for Cardizem CD identifies a multiparticulate extended-release system and instructs patients to swallow the capsule whole rather than crush or chew it.[1]

Multiparticulate technology creates several development advantages:

1. Release can be adjusted through coating thickness and polymer composition.
2. Dose strength can be changed by bead loading rather than redesigning the entire tablet.
3. Drug release may be less sensitive to localized tablet defects.
4. Sprinkle-capable products may be possible if the beads retain their release characteristics after administration with soft food.

The main risk is process variability. Coating weight gain, bead-size distribution, residual solvent, agglomeration, and dose uniformity can affect dissolution and bioequivalence.

Extended-release tablet excipients

Cardizem LA-type products use a controlled-release tablet architecture. A generic extended-release tablet may use:

• Hypromellose or another hydrophilic matrix polymer
• Lactose, microcrystalline cellulose, or dibasic calcium phosphate as a diluent
• Povidone as a binder
• Crospovidone or sodium starch glycolate as a disintegrant
• Magnesium stearate or sodium stearyl fumarate as a lubricant
• Film-coating polymers
• Plasticizers, pigments, and opacifiers

Hydrophilic matrix formulations are attractive because they avoid capsule filling and multiparticulate coating. They can reduce manufacturing steps and packaging costs. Their performance depends on polymer grade, viscosity, particle size, compression force, tablet hardness, and gastrointestinal hydration.

A matrix formulation must control dose dumping risk and maintain the target release profile across fed and fasted conditions. Alcohol-induced dose dumping, food effects, and sensitivity to gastrointestinal transit are important development considerations for controlled-release products.

Injectable excipients

Cardizem injection is an aqueous diltiazem hydrochloride solution for intravenous use. Injectable formulations generally prioritize:

• Water for injection
• pH adjustment
• Tonicity adjustment where required
• Container-closure compatibility
• Low particulate burden
• Sterility and endotoxin control

The product label should control the exact formulation and administration requirements. Parenteral diltiazem products may use different presentations and concentrations, so hospital purchasing decisions depend on vial size, ready-to-use status, dilution requirements, stability after preparation, and shortage history.[3]

What excipient strategy best fits a new Cardizem or generic diltiazem product?

A commercially effective strategy should match the dosage form to the target market rather than use one excipient platform for every product.

Target	Preferred formulation approach	Commercial rationale
Low-cost generic IR tablet	Direct compression or dry granulation	Low manufacturing cost and broad pharmacy demand
Once-daily product	Multiparticulate capsule or hydrophilic matrix tablet	Established patient need and differentiated dosing
Sprinkle-compatible product	Coated beads in capsule or sachet	Administration benefit for dysphagia populations
Hospital injectable	Ready-to-use sterile solution	Lower preparation burden and fewer medication errors
Brand-style authorized generic	Match reference-product release behavior	Easier substitution and commercial credibility
Specialty product	Taste-masked or patient-centric dosage form	Potentially stronger differentiation but higher regulatory burden

The most defensible formulation investment is usually an extended-release product with a clearly controlled dissolution profile and a manufacturing process that can support multiple strengths. Immediate-release tablets are technically easier but face intense price competition.

What formulation patents protect Cardizem and diltiazem products?

Most original Cardizem formulation patents are old relative to current pharmaceutical standards. Diltiazem was approved in the United States decades ago, and the primary active-ingredient patent estate no longer provides meaningful market exclusivity for ordinary generic development.

The remaining intellectual-property risk is more likely to arise from:

• Specific extended-release delivery systems
• Multiparticulate coating designs
• Release-rate control using particular polymer combinations
• Dose regimens or cardiovascular methods of use
• Manufacturing processes
• Drug-device combinations
• Pediatric or patient-specific dosage forms
• Improvement patents owned by generic or specialty manufacturers

Current patent status must be assessed against the FDA Orange Book, United States Patent and Trademark Office records, and relevant court dockets. An Orange Book listing does not itself establish that every claim is valid or enforceable. Conversely, an unlisted process or formulation patent may still create commercial risk outside the Orange Book framework.[4-6]

Does Cardizem have active Orange Book exclusivity?

Cardizem does not have the type of new chemical entity exclusivity associated with a recently approved drug. The commercial market is dominated by generic diltiazem products with multiple approved strengths and release profiles.

The relevant regulatory questions are:

• Which product is the reference listed drug?
• Is the generic approved under an ANDA or another pathway?
• Does the applicant need to certify against listed patents?
• Is the product eligible for AB or other therapeutic-equivalence coding?
• Are any listed patents still unexpired?
• Are there product-specific labeling restrictions?

Orange Book status can change as patents expire, are delisted, or are associated with new product approvals. A diligence review should use the current FDA electronic Orange Book rather than historical patent summaries.[4]

When does Cardizem lose exclusivity and what is the generic entry risk?

The original Cardizem exclusivity period has expired. Generic entry is already established across immediate-release tablets, extended-release capsules, extended-release tablets, and injectable products.

Generic entry risk varies by presentation:

Presentation	Generic competition	Entry barrier
Immediate-release tablets	High	Low to moderate
Extended-release capsules	High but formulation-specific	Moderate
Extended-release tablets	High but product-specific	Moderate to high
Injectable solution	Established	Moderate, depending on sterile capacity
Novel sprinkle or patient-centric product	Limited relative to standard tablets	Higher regulatory and manufacturing burden

For an ANDA applicant, the principal risks are not basic active-ingredient exclusivity. They are bioequivalence failure, dissolution mismatch, manufacturing scale-up, stability failure, and inability to reproduce the reference product's release profile.

Paragraph IV challenges may still arise if an applicant relies on a certification that a listed patent is invalid, unenforceable, or not infringed. For older diltiazem products, Paragraph IV risk is generally narrower than for newly approved products because the main molecule and early formulation patents have expired. The relevant exposure depends on the current Orange Book listing and the specific reference product.[4,7]

What manufacturing and excipient barriers affect diltiazem commercial entry?

Coated-bead manufacturing

Extended-release capsules require control of:

• Starter-core size distribution
• Drug-layer uniformity
• Coating weight gain
• Polymer permeability
• Plasticizer distribution
• Residual solvents
• Bead segregation during capsule filling

The manufacturing process may be protected even when the active ingredient is not. A company with fluid-bed coating capacity has an advantage over a tablet-only manufacturer when pursuing Cardizem CD-type products.

Matrix-tablet manufacturing

Extended-release tablets require control of:

• Polymer hydration
• Granule density
• Compression force
• Tablet hardness
• Lubrication time
• Dissolution across multiple pH conditions
• Food-effect performance

Hydrophilic polymers can create scale-up problems because mixing energy and granulation endpoint affect release. A formulation that works at laboratory scale may fail at commercial batch size.

Injectable manufacturing

Sterile diltiazem products require:

• Validated aseptic processing or terminal sterilization, where compatible
• Container-closure integrity
• Particulate control
• pH and osmolality control
• Stability after dilution
• Reliable supply of sterile-fill capacity

Hospital customers may favor ready-to-use presentations even when the active ingredient is generic because they reduce pharmacy compounding workload.

How does Cardizem compare with competing calcium-channel blockers?

Cardizem competes with verapamil and dihydropyridine calcium-channel blockers such as amlodipine and nifedipine. Its commercial position is differentiated by its use in both rate control and vasodilation.

Drug	Class	Main formulation opportunity	Competitive issue
Diltiazem	Non-dihydropyridine	Multiple ER technologies and injectable use	Complex release-profile competition
Verapamil	Non-dihydropyridine	ER tablets and capsules	Similar rate-control market
Amlodipine	Dihydropyridine	Simple once-daily tablets	Lower formulation complexity
Nifedipine	Dihydropyridine	Controlled-release tablets	Strong modified-release competition

Amlodipine is usually easier to manufacture and commercialize because once-daily immediate-release or simple tablet products can achieve broad use. Diltiazem offers more formulation differentiation, but the development and bioequivalence burden is higher.

What commercial opportunities exist for Cardizem excipients?

Excipient suppliers can pursue several opportunities around diltiazem products.

Polymer systems for controlled release

Hypromellose, ethylcellulose, methacrylate copolymers, and related coating technologies can support extended-release products. Suppliers with validated grades, regulatory documentation, and global manufacturing capacity are better positioned than commodity suppliers.

Functional excipients for direct compression

Microcrystalline cellulose, co-processed excipients, lactose grades, crospovidone, and low-metal lubricants can improve tablet robustness and manufacturing throughput. The value proposition is lower rejection rates and more consistent dissolution rather than simple ingredient substitution.

Film-coating systems

Ready-to-use coating platforms can reduce development time and simplify color matching across strengths. Suppliers can differentiate through low-solvent or aqueous systems, faster processing, and improved moisture protection.

Patient-centric delivery

Potential products include:

• Sprinkle capsules
• Smaller tablets
• Swallowing-aid formulations
• Taste-masked liquid or multiparticulate products
• Unit-dose hospital presentations

Each approach must preserve diltiazem exposure and release behavior. A patient-centric product that changes pharmacokinetics may require a more demanding regulatory package.

What licensing deals and partnerships are relevant to Cardizem?

The original Cardizem commercial franchise involved brand owners, licensees, and later generic manufacturers. For current market entrants, the practical partnership opportunities are more likely to involve:

• Contract development and manufacturing organizations
• Sterile injectable manufacturers
• Controlled-release technology licensors
• Excipient suppliers with regulatory support
• Authorized-generic arrangements
• Regional commercialization partners

A licensing strategy based only on the diltiazem molecule has limited value because the active ingredient is off-patent. The strongest transaction targets are platform technologies, approved dossiers, manufacturing capacity, or differentiated delivery systems.

What litigation and settlement issues affect Cardizem?

Historic diltiazem litigation has included patent disputes involving extended-release formulations and generic entry. Current litigation exposure should be checked against federal court records, FDA Orange Book listings, and product-specific patent certifications.

For a new entrant, the most relevant legal risks are:

1. Infringement of surviving formulation or process claims.
2. ANDA litigation following a Paragraph IV certification.
3. Product-specific labeling or method-of-use claims.
4. Trade-secret or know-how disputes involving coating or release processes.
5. Antitrust scrutiny if supply, licensing, or settlement arrangements delay generic entry.

Settlement agreements can affect launch timing, but their terms are often confidential or only partially reflected in public filings. A generic company should not assume that historical Cardizem settlements control current entry rights for every diltiazem dosage form.

What is the FDA regulatory status of Cardizem and diltiazem?

Cardizem products are FDA-approved prescription medicines. Generic diltiazem products are approved through abbreviated pathways when they demonstrate pharmaceutical equivalence, bioequivalence, quality, and manufacturing compliance.[1-4]

Key regulatory distinctions include:

• Immediate-release and extended-release products are separate regulatory products.
• Strengths may require product-specific bioequivalence support.
• Extended-release formulations require dissolution testing under multiple conditions.
• Injectable products require sterile manufacturing and parenteral quality controls.
• Excipients must be suitable for the route, dose, and dosage form.
• Changes to release-controlling excipients may require regulatory filing and comparative dissolution or bioequivalence data.

The FDA Inactive Ingredient Database can support excipient selection, but prior use in another product does not automatically establish acceptability for a new route, dose, or population.[8]

What is the revenue exposure and competitive outlook for Cardizem?

The historic Cardizem brand franchise has been materially eroded by generic substitution. Revenue exposure is concentrated in:

• Generic diltiazem volume
• Hospital injectable supply
• Authorized-generic or branded-generic channels
• Specialty modified-release presentations
• Regional markets with lower generic penetration

Standard immediate-release tablets are unlikely to support strong margins without manufacturing scale. Extended-release products can retain better economics because the technical barrier is higher and substitution is product-specific. Injectable supply can also support attractive hospital contracts when competitors face capacity constraints, but sterile manufacturing carries higher fixed costs and quality risk.

The most attractive commercial position is a differentiated extended-release product supported by:

• Reliable once-daily performance
• Competitive cost per dose
• Multiple strengths
• Low food-effect variability
• Stable dissolution after scale-up
• Broad pharmacy and wholesaler access
• A defensible manufacturing process

Key Takeaways

• Cardizem is diltiazem hydrochloride, and its core molecule is off-patent.
• Current value lies in formulation, manufacturing, supply reliability, and patient-centric delivery.
• Immediate-release tablets offer volume but limited differentiation.
• Extended-release capsules and tablets provide stronger technical and commercial barriers.
• Multiparticulate capsules require coating expertise; matrix tablets require polymer and compression control.
• Injectable diltiazem offers hospital opportunities but requires validated sterile capacity.
• Orange Book and Paragraph IV analysis must be performed by dosage form and reference product.
• Excipient suppliers can create value through controlled-release polymers, direct-compression systems, film coatings, and patient-centric delivery platforms.
• The strongest licensing opportunities involve formulation technology, manufacturing capacity, or approved product rights rather than the diltiazem molecule itself.

FAQs

Can diltiazem extended-release capsules be reformulated with different excipients?

Yes. A generic manufacturer can use a different excipient system if the product meets FDA requirements for pharmaceutical equivalence, bioequivalence, quality, stability, and release performance.

Which excipient is most important in Cardizem CD-type products?

The release-controlling coating system is usually the most important formulation component. Polymer type, coating thickness, plasticizer level, and bead-size distribution collectively determine the dissolution profile.

Is Cardizem LA interchangeable with Cardizem CD?

Not automatically. Both are extended-release diltiazem products, but they use different dosage forms and release technologies. Substitution depends on FDA therapeutic-equivalence determinations and applicable product labeling.

Are diltiazem excipients subject to patent protection?

Some excipient combinations, coating systems, matrix technologies, and manufacturing processes may be patent-protected even though diltiazem itself is off-patent. Patent risk must be assessed claim by claim.

What is the lowest-risk commercial entry strategy for diltiazem?

A conventional immediate-release tablet is generally the lowest technical-risk entry. It is also the most exposed to price competition. A controlled-release product has greater development risk but offers stronger differentiation and potentially better margins.

References

1. U.S. Food and Drug Administration. (n.d.). Cardizem CD: Diltiazem hydrochloride extended-release capsules prescribing information. DailyMed.

2. U.S. Food and Drug Administration. (n.d.). Cardizem LA: Diltiazem hydrochloride extended-release tablets prescribing information. DailyMed.

3. U.S. Food and Drug Administration. (n.d.). Cardizem injection: Diltiazem hydrochloride injection prescribing information. DailyMed.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. FDA Orange Book.

5. U.S. Patent and Trademark Office. (n.d.). Patent Center. United States Department of Commerce.

6. U.S. Food and Drug Administration. (n.d.). Approved drug product and patent listing resources. FDA.

7. U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application submissions and patent certifications. FDA.

8. U.S. Food and Drug Administration. (n.d.). Inactive Ingredient Database. FDA.