List of Excipients in Branded Drug CARDIZEM CD

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Bausch Health US LLC	CARDIZEM CD	diltiazem hydrochloride	0187-0795	CELLULOSE, MICROCRYSTALLINE
Bausch Health US LLC	CARDIZEM CD	diltiazem hydrochloride	0187-0795	ETHYL ACRYLATE AND METHYL METHACRYLATE COPOLYMER
Bausch Health US LLC	CARDIZEM CD	diltiazem hydrochloride	0187-0795	FD&C BLUE NO. 1
Bausch Health US LLC	CARDIZEM CD	diltiazem hydrochloride	0187-0795	FERROSOFERRIC OXIDE

Cardizem CD Excipient Strategy and Commercial Opportunities in Extended-Release Diltiazem

Last updated: September 3, 2026

Cardizem CD is a once-daily, multiparticulate extended-release capsule containing diltiazem hydrochloride. Its commercial value is concentrated in release-control engineering, dose-strength scalability, capsule presentation, and manufacturing reproducibility rather than in active-ingredient exclusivity. The product’s legacy brand patents and regulatory exclusivity have expired, leaving generic diltiazem ER capsules as the main competitive benchmark.[1][2]

What is Cardizem CD and how does its formulation work?

Cardizem CD is an extended-release oral capsule for hypertension and chronic stable angina. The active ingredient is diltiazem hydrochloride, a benzothiazepine calcium-channel blocker. FDA labeling identifies strengths of 120 mg, 180 mg, 240 mg, 300 mg, and 360 mg administered once daily.[1]

The dosage form uses a multiparticulate system rather than a single monolithic tablet. The capsule contains coated drug-containing units designed to control diltiazem release across the gastrointestinal tract. This architecture can reduce the risk of abrupt dose dumping and supports once-daily administration.

Core formulation functions

Formulation function	Likely excipient or component category	Commercial purpose
Drug loading	Diltiazem hydrochloride on inert starter cores or in multiparticulates	Controls dose and unit uniformity
Pellet formation	Sucrose spheres, microcrystalline cellulose, povidone or related binders	Creates mechanically stable drug-loaded units
Primary release control	Ethylcellulose or another water-insoluble polymer	Slows fluid penetration and drug diffusion
Film flexibility	Plasticizer such as triethyl citrate or equivalent	Reduces cracking during coating and storage
Coating process control	Talc or anti-tacking material	Improves coating efficiency and pellet flow
Capsule shell	Gelatin, colorants, titanium dioxide or equivalent pigments	Provides identification and patient-friendly presentation
Manufacturing support	Purified water, solvents and processing aids	Enables coating and drying; typically removed or controlled

The precise current formulation must be confirmed against the applicable FDA-approved labeling and regulatory filing. Excipient composition can differ among Cardizem CD, authorized generics, and ANDA products.[1][3]

What excipients are most important in Cardizem CD?

The principal technical opportunity is the release-control film. For a multiparticulate diltiazem product, polymer selection, coating weight gain, pore formation, plasticization, and pellet size distribution determine the in vitro and in vivo release profile.

Ethylcellulose and other release-control polymers

Ethylcellulose is widely used in sustained-release multiparticulates because it forms a water-insoluble barrier. Drug release depends on film thickness, polymer viscosity grade, coating porosity, pellet surface area, and the presence of hydrophilic pore-forming materials.

Potential commercial strategies include:

• Low-viscosity versus high-viscosity polymer grades for coating-process optimization.
• Polymer blends that improve release consistency across pH conditions.
• Aqueous dispersion systems that reduce organic-solvent handling.
• Controlled porosity to manage early release and terminal release.
• Film systems that reduce sensitivity to food, alcohol, agitation, and gastrointestinal transit.

A formulation developer must avoid changing the release mechanism solely to reduce excipient cost. A lower-cost polymer may alter dissolution similarity, residual solvent control, mechanical integrity, or scale-up performance.

Binder and pellet-core systems

Multiparticulate products require consistent drug deposition on starter cores or reliable extrusion-spheronization. Binder selection affects:

• Diltiazem content uniformity.
• Pellet friability.
• Coating adhesion.
• Moisture uptake.
• Compression or encapsulation behavior.
• Batch-to-batch dissolution.

Povidone, hypromellose, microcrystalline cellulose, and sugar-based cores are established options, but their use changes the manufacturing process and may require a new formulation-development package.

Plasticizers and anti-tacking agents

Plasticizers improve film flexibility and reduce cracking during drying, handling, and storage. Triethyl citrate is a common choice for aqueous or solvent-based polymer films. Talc and similar materials reduce pellet agglomeration during coating.

Optimization targets include:

• Minimum effective plasticizer concentration.
• Stable coating performance after storage.
• Reduced tack during high-solids processing.
• Lower residual solvent risk.
• Consistent film permeability across commercial equipment.

These excipients are less likely to create standalone product differentiation than a novel release-control architecture, but they can support manufacturing patents and process know-how.

What excipient strategies can improve Cardizem CD performance?

The strongest development strategy is a design-of-experiments program focused on dissolution robustness rather than nominal excipient substitution.

Priority development variables

Variable	Key risk	Development objective
Polymer type and grade	Release drift	Establish a robust release window
Coating weight gain	Under- or over-release	Define a commercially scalable target
Pellet diameter	Variable surface area	Narrow particle-size distribution
Plasticizer level	Film cracking or tack	Optimize flexibility and processability
Pore former level	Excessive early release	Control initial drug liberation
Capsule fill weight	Dose variability	Maintain content uniformity across strengths
Moisture exposure	Polymer and pellet changes	Set packaging and stability controls
Agitation and alcohol conditions	Dose dumping	Demonstrate abuse and food robustness

A sponsor should compare dissolution in multiple media and hydrodynamic conditions. The target is not only similarity to the reference product but also control of clinically relevant variability. For modified-release products, FDA expects product-specific evidence addressing release behavior and bioequivalence.[4]

Dose-strength strategy

Cardizem CD has multiple strengths. A platform formulation is commercially attractive if one pellet design can be scaled across strengths through capsule fill-weight changes. That approach can reduce:

• Number of coating formulations.
• Stability programs.
• Manufacturing changeovers.
• Raw-material inventory.
• Analytical method burden.

Dose proportionality must be demonstrated rather than assumed. Higher-strength capsules may require different pellet loading, more units per capsule, or a different capsule size. Excessive fill density can change pellet packing and dissolution.

What regulatory pathway applies to Cardizem CD generics?

A generic Cardizem CD product would generally be pursued through an abbreviated new drug application under section 505(j) of the Federal Food, Drug, and Cosmetic Act. The applicant must demonstrate pharmaceutical equivalence and bioequivalence to the reference listed drug, including the modified-release performance required for the product.[2][4]

FDA regulatory considerations

The principal regulatory risks are:

1. Failure to match the reference dissolution profile.
2. Food-effect differences.
3. Inadequate control of alcohol-induced release.
4. Inconsistent pellet coating during commercial scale-up.
5. Capsule-shell or excipient differences affecting release.
6. Incomplete justification for formulation changes.
7. Manufacturing-site changes that alter coating performance.

The FDA Orange Book identifies approved reference products, dosage forms, strengths, therapeutic equivalence codes, and patent or exclusivity information where applicable.[2] Cardizem CD is a legacy product, and generic diltiazem hydrochloride extended-release capsules have been available for years. The commercial question is therefore product positioning and manufacturing economics, not first generic entry.

What patents protect Cardizem CD and when did exclusivity expire?

Cardizem CD’s original composition, formulation, and regulatory exclusivity are legacy rights. The product has been exposed to generic competition for many years, and current commercial analysis should focus on active patents listed for the specific reference product and strength in the latest Orange Book publication.[2]

Patent categories relevant to Cardizem CD

Patent category	Relevance today
Core diltiazem compound patents	Expired
Original sustained-release formulation patents	Generally expired or commercially exhausted
Capsule and pellet architecture	Potentially relevant only if a later patent remains active
Manufacturing-process patents	May affect specific generic processes
Method-of-use patents	Limited relevance where approved indications are established and label scope is narrow
New formulation patents	Could protect a redesigned product, not the legacy product itself

No active patent should be assumed from the historical Cardizem brand name alone. A product-specific Orange Book review is required before relying on a Paragraph IV strategy, litigation forecast, or launch date.[2]

Which companies are challenging Cardizem CD, and what is the litigation status?

The market has already moved beyond the original Cardizem CD patent challenge cycle. Multiple generic manufacturers have marketed diltiazem hydrochloride extended-release capsules in the United States, including products therapeutically equivalent to the reference product where FDA has assigned the applicable rating.[2][5]

For a new entrant, the relevant legal issues are more likely to involve:

• ANDA formulation patents.
• Manufacturing-process patents.
• Trade-secret disputes involving coating parameters.
• Product-specific bioequivalence disputes.
• Hatch-Waxman litigation over later-listed patents.
• Contractual disputes involving authorized-generic supply or licensing.

Historical Cardizem and diltiazem litigation has included antitrust and generic-entry disputes, but those matters do not automatically create current barriers to launching a new diltiazem ER product. Litigation screening should separate expired brand patents from active patents covering a specific generic applicant’s formulation or process.

What commercial opportunities exist in Cardizem CD excipients?

The best opportunities are in supply, formulation services, and differentiated delivery systems.

Excipient supplier opportunities

Excipient manufacturers can compete through:

• High-purity ethylcellulose and aqueous polymer dispersions.
• Narrow-viscosity-grade polymers.
• Low-peroxide and low-metal excipient grades.
• Custom plasticizer systems.
• Direct-compression or encapsulation-grade starter cores.
• Coating systems qualified for multiparticulate dosage forms.
• Technical support for scale-up and dissolution troubleshooting.

A supplier that provides only a commodity polymer faces price pressure. A supplier that supports formulation design, coating-process transfer, and regulatory documentation can capture higher-value business.

Contract development and manufacturing

CDMOs with fluid-bed coating, wurster processing, pelletization, and multiparticulate encapsulation capabilities can target:

• ANDA development.
• 505(b)(2) reformulations.
• Authorized-generic supply.
• Regional licensing.
• Reformulation of diltiazem into sprinkle capsules or alternative delivery systems.

The main barrier is process reproducibility. Multiparticulate coating is equipment-sensitive, and laboratory dissolution results may not predict commercial-scale performance unless spray rate, inlet conditions, atomization, bed temperature, and coating endpoint are controlled.

Reformulation opportunities

Potential products include:

• Lower-cost generic ER capsules.
• Alcohol-resistant diltiazem ER products.
• Sprinkle formulations for patients unable to swallow conventional capsules.
• Smaller capsules with equivalent dose delivery.
• Reduced-dye or simplified excipient versions.
• Packaging optimized for moisture protection.
• Combination products involving antihypertensive or antianginal therapies, subject to regulatory and clinical requirements.

A new formulation would need a clear regulatory and commercial advantage. A simple excipient substitution is unlikely to command durable pricing power without measurable improvements in stability, tolerability, adherence, or manufacturing cost.

How does Cardizem CD compare with competing diltiazem formulations?

Product category	Release profile	Primary opportunity	Main risk
Cardizem CD-type capsules	Once daily, multiparticulate	Generic substitution and platform manufacturing	Dissolution matching
Immediate-release diltiazem tablets	Multiple daily doses	Lower-cost conventional therapy	Lower convenience
Other diltiazem ER capsules	Once daily or extended dosing	Price and supply competition	Therapeutic-equivalence and product differentiation
Diltiazem ER tablets	Extended release, formulation-specific	Alternative manufacturing platform	Different bioequivalence requirements
Novel sprinkle or pediatric systems	Modified-release	Adherence and administration convenience	Additional development complexity

The relevant comparator is not only another diltiazem product. A once-daily generic must compete with amlodipine, beta blockers, other calcium-channel blockers, and fixed-dose antihypertensive combinations. Pricing depends on generic supply density and payer substitution, not on Cardizem CD’s historical brand positioning.

What generic launch risks exist for Cardizem CD?

Generic launch risk is moderate from a patent perspective but significant from a technical and commercial perspective.

Technical risks

• Failure to reproduce the reference release curve.
• Food-related bioequivalence failure.
• Pellet agglomeration during scale-up.
• Moisture-driven dissolution drift.
• Capsule-fill variability.
• Inadequate stability under high-temperature and high-humidity conditions.

Commercial risks

• Multiple established generic suppliers.
• Low reimbursement and rapid price erosion.
• Limited differentiation among equivalent products.
• Wholesaler and pharmacy channel concentration.
• Shortage exposure if a major manufacturer exits.
• Low revenue per strength despite a broad strength portfolio.

Revenue exposure for the reference brand is difficult to isolate because diltiazem sales can be reported within broader cardiovascular portfolios. Generic revenue should be modeled by strength, channel, market share, contract price, and supply reliability rather than by historical Cardizem CD brand sales.

What manufacturing and geographic IP barriers remain?

The original Cardizem CD product is broadly exposed to generic competition in the United States and other mature markets. Geographic barriers may still arise from:

• Different patent statuses by country.
• Local registration requirements for modified-release products.
• Country-specific reference-product rules.
• Import and manufacturing-site approvals.
• Local excipient monographs.
• Data exclusivity periods for later reformulations.
• Supply-chain qualification for critical polymers.

Manufacturing know-how can remain commercially important after patent expiration. Coating endpoint control, pellet handling, humidity management, and dissolution testing may be protected through confidential know-how even when no enforceable formulation patent remains.

How strong is the Cardizem CD patent estate?

The legacy patent estate is weak as a barrier to generic entry because the product has long faced generic competition. The stronger defensible assets are likely to be later-developed technologies, including:

• New multiparticulate coating systems.
• Alcohol-resistant release mechanisms.
• Sprinkle-capable capsules.
• Manufacturing processes that reduce variability.
• Novel excipient combinations.
• Packaging systems that extend stability.

Patent strength should be assessed claim by claim. Broad claims covering a known diltiazem ER capsule are vulnerable to prior-art and obviousness attacks. Narrow process or formulation claims may be enforceable but usually provide limited market control unless they are difficult to design around.

Key Takeaways

• Cardizem CD is a once-daily, multiparticulate diltiazem hydrochloride extended-release capsule.
• The critical excipients are release-control polymers, binders, plasticizers, anti-tacking agents, and capsule-shell materials.
• The main formulation objective is dissolution robustness across food, agitation, alcohol, storage, and manufacturing-scale conditions.
• A platform pellet design could support multiple strengths and lower manufacturing complexity.
• Original Cardizem CD exclusivity is expired, and generic competition is established.
• Current opportunities are concentrated in generic supply, excipient technology, CDMO services, and differentiated reformulations.
• Manufacturing know-how may remain more valuable than legacy composition patents.
• The strongest commercial concepts are alcohol-resistant, sprinkle, lower-cost, or more stable multiparticulate products.

FAQs

Can Cardizem CD be reformulated with different excipients?

Yes. A reformulation can use different excipients if it meets applicable pharmaceutical-equivalence, bioequivalence, stability, quality, and labeling requirements. Release-control changes require particular scrutiny because they can alter systemic exposure.

Which excipient is most important for diltiazem extended release?

The release-control polymer is generally the most important excipient category. Its grade, concentration, coating thickness, permeability, and interaction with pore formers have a direct effect on the dissolution profile.

Is Cardizem CD suitable for a 505(b)(2) application?

A 505(b)(2) pathway may be relevant for a materially differentiated product, such as a new sprinkle presentation or delivery system, if the proposed product relies partly on FDA findings for an approved diltiazem product. The regulatory strategy depends on the extent of formulation and clinical differentiation.

Does Cardizem CD have biosimilar risk?

No. Diltiazem is a small-molecule drug, not a biologic. Its competitive risk comes from ANDA-approved generics and other small-molecule cardiovascular therapies, not biosimilars.

Can an excipient supplier patent a new Cardizem CD formulation?

Potentially. Patentable subject matter could include a novel excipient combination, release-control architecture, manufacturing process, or stability-enhancing system. The claims must provide novelty and non-obviousness over existing diltiazem and multiparticulate prior art.

References

1. U.S. Food and Drug Administration. (n.d.). Cardizem CD (diltiazem hydrochloride) extended-release capsules: Prescribing information.
2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
3. National Library of Medicine. (n.d.). DailyMed: Cardizem CD diltiazem hydrochloride extended-release capsule.
4. U.S. Food and Drug Administration. (1997). Guidance for industry: Extended release solid oral dosage forms: Development, evaluation, and application of in vitro/in vivo correlations.
5. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drug products.