List of Excipients in Branded Drug SULAR

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	CARNAUBA WAX
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	FERRIC OXIDE YELLOW
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	GLYCERYL BEHENATE
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	HYPROMELLOSE PHTHALATE
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	HYPROMELLOSES
Physicians Total Care Inc	SULAR	nisoldipine	54868-5993	LACTOSE

Sular (Nisoldipine Extended-Release) Excipient Strategy and Commercial Opportunities

Last updated: September 24, 2026

Sular is the brand name for nisoldipine extended-release tablets, a dihydropyridine calcium-channel blocker approved for hypertension. The commercial opportunity is primarily generic substitution, lifecycle reformulation, and supply-chain participation rather than new-drug exclusivity. The core technical challenge is reproducing nisoldipine’s controlled-release profile and food-effect behavior while maintaining tablet robustness, dose proportionality, and bioequivalence.

What is Sular and how is it formulated?

Sular contains nisoldipine, a poorly water-soluble calcium-channel blocker administered once daily in an extended-release tablet. FDA labeling identifies marketed strengths of 8.5 mg, 17 mg, 25.5 mg, and 34 mg.[1]

Attribute	Sular profile
Active ingredient	Nisoldipine
Drug class	Dihydropyridine calcium-channel blocker
Dosage form	Controlled-release oral tablet
Primary indication	Hypertension
FDA pathway	Original NDA
Common strengths	8.5 mg, 17 mg, 25.5 mg, 34 mg
Release objective	Once-daily controlled delivery
Key development risks	Food effect, dissolution matching, dose dumping, low aqueous solubility
Main commercial substitute	Generic nisoldipine extended-release tablets

Sular’s excipient system uses a controlled-release matrix and conventional tablet-processing materials. Public labeling identifies excipients including hypromellose, lactose monohydrate, povidone, magnesium stearate, titanium dioxide, and iron oxide colorants.[1] The exact quantitative composition and manufacturing process are not generally disclosed in the public prescribing information.

Which excipients are important in Sular?

Hypromellose is the principal functional excipient in the release-controlling matrix. It hydrates after ingestion and forms a gel barrier that regulates water penetration and drug diffusion. Molecular weight, substitution grade, viscosity, particle size, and concentration can materially change the dissolution profile.

Lactose monohydrate functions mainly as a diluent. Its particle-size distribution, moisture content, and spray-dried or crystalline grade can affect tablet compression and matrix porosity.

Povidone may act as a binder and wetting aid. It can improve granule strength and support uniform distribution of nisoldipine, particularly where the drug load is low relative to the total tablet mass.

Magnesium stearate provides lubrication but requires tight control. Excessive concentration or over-lubrication can reduce wettability, weaken interparticulate bonding, and slow dissolution.

Titanium dioxide and iron oxides are generally coating or color-system components. They support product identification and light protection but have limited direct influence on release if separated from the matrix.

How does the Sular excipient system control drug release?

The likely performance mechanism is a hydrophilic polymer matrix. Water enters the tablet, hypromellose hydrates, and a gel layer develops around the drug-containing core. Release then occurs through a combination of diffusion, polymer erosion, and matrix swelling.

A generic developer would need to match the reference product across multiple dissolution conditions rather than reproduce the label qualitatively. Critical variables include:

1. Hypromellose viscosity and substitution profile.
2. Polymer concentration relative to nisoldipine.
3. Tablet porosity and compression force.
4. Granulation endpoint and moisture content.
5. Lubrication time and magnesium stearate level.
6. Drug particle size and solid-state form.
7. Coating weight and film permeability.
8. Agitation rate and pH during dissolution testing.

Nisoldipine is poorly soluble in water, so formulation performance may be governed by both dissolution and release control. A matrix that is too dense can produce incomplete release. A matrix that is too permeable can create an early burst, increase peak exposure, and fail the reference dissolution profile.

What formulation patents protect Sular?

The commercially relevant protection historically centered on the controlled-release dosage form and related formulation technology rather than on a new chemical entity. Public FDA materials and product labeling identify the dosage form and excipient classes but do not disclose the full quantitative formulation.

The practical patent position is now primarily historical. The original nisoldipine and extended-release formulation patent terms would have expired before the current generic market period. Current development risk is therefore driven more by bioequivalence, manufacturing reproducibility, and regulatory requirements than by an active Sular formulation patent blocking ordinary generic entry.

A complete freedom-to-operate review should cover U.S. patents assigned to the original innovator, formulation suppliers, and any later owners of controlled-release nisoldipine technology. Patent families should be screened for continuations, terminal disclaimers, reissued patents, and foreign rights.

When did Sular lose exclusivity?

Sular’s market exclusivity has expired. Nisoldipine is an older small-molecule antihypertensive, and the product has been exposed to generic competition through the ANDA pathway.

Exclusivity category	Sular status
New chemical entity exclusivity	Expired
Original formulation exclusivity	Expired
Pediatric exclusivity	No current commercial significance identified
Orange Book patent barrier	No current blocking patent identified in the public commercial record
Generic pathway	ANDA
Biosimilar pathway	Not applicable

The exact commercial launch date for each generic manufacturer depends on the approved ANDA, supply status, and whether the product remains actively marketed. FDA’s Orange Book and Drugs@FDA databases remain the controlling sources for current approval and patent-listing status.[2,3]

What is the Orange Book status of Sular?

Sular is an NDA-listed prescription product, while generic nisoldipine extended-release products are evaluated against the reference listed drug through abbreviated new drug applications. The Orange Book identifies reference products, therapeutic-equivalence codes, patent information, and marketing status.[2]

For a commercial diligence review, the relevant questions are:

• Whether Sular remains the designated reference listed drug.
• Whether each strength has an active generic approval.
• Whether an ANDA is rated therapeutically equivalent.
• Whether any listed patent remains unexpired.
• Whether an approved product is currently marketed.
• Whether the reference product has been discontinued for reasons other than safety or effectiveness.

A generic developer would normally pursue a Paragraph III certification where listed patents have expired or a Paragraph IV certification only if an unexpired listed patent remained. Because the principal Sular patent barriers are historical, Paragraph IV litigation is unlikely to be the central current risk.

Which companies are challenging Sular exclusivity?

The relevant challengers are generic manufacturers with approved or formerly marketed nisoldipine extended-release tablets. Public regulatory databases should be used to identify current ANDA holders and marketing status because ownership and commercialization can change through product transfers.

The competitive structure is typically fragmented:

Competitor category	Commercial role
Large generic manufacturers	Scale production, pharmacy contracting, broad distribution
Specialty generic companies	Niche supply, limited-strength coverage, shortage opportunities
Contract manufacturers	API sourcing, granulation, compression, coating, packaging
Authorized or legacy suppliers	Continuity of supply for established customers
Excipient manufacturers	Hypromellose, lactose, povidone, lubricants, coating systems

The largest barrier is not necessarily approval. It is maintaining reliable supply at a price that supports a low-volume antihypertensive market.

What generic entry risks exist for Sular?

Generic entry risk is high from a legal perspective and moderate from a technical perspective.

Legal and regulatory risk

The principal legal exposure is limited because core exclusivity has expired. A generic applicant could face:

• Patent-listing discrepancies in the Orange Book.
• Product-specific exclusivity or reference-product status issues.
• ANDA deficiency letters.
• Manufacturing-site compliance problems.
• Labeling or strength-specific approval limitations.
• Commercial discontinuation by the reference sponsor.

Bioequivalence risk

Nisoldipine extended-release products can be sensitive to formulation changes. The applicant must demonstrate comparable systemic exposure and release behavior. The main risks are:

• Excessive early release.
• Delayed or incomplete release.
• Food-related exposure differences.
• Strength-to-strength nonlinearity.
• Batch-to-batch dissolution drift.
• Differences in particle size or polymorphic form.
• Interaction between tablet coating and matrix hydration.

FDA guidance for modified-release solid oral dosage forms emphasizes comparative dissolution and pharmacokinetic assessment as part of product development and approval.[4]

What excipient strategy should a generic Sular developer use?

The lowest-risk strategy is a close qualitative and functional formulation that uses a well-characterized hydrophilic matrix.

Recommended development approach

Development area	Preferred strategy
Release polymer	Hypromellose with matched viscosity and controlled particle size
Diluent	Lactose or a functionally equivalent filler with controlled moisture
Binder	Povidone or equivalent binder selected through granulation studies
Lubricant	Low, optimized magnesium stearate concentration
Drug substance	Tight control of particle size, polymorph, and assay uniformity
Coating	Thin protective film with controlled weight gain
Process	High-shear or fluid-bed granulation followed by compression and coating
Testing	Multi-pH dissolution, food-effect assessment, accelerated stability

A formulation should be designed around critical quality attributes rather than an excipient list alone. A developer can use the same excipients as the reference product and still fail bioequivalence if polymer grade, granulation, or tablet porosity differs.

Could a directly compressed formulation work?

Direct compression could reduce manufacturing cost, but it introduces risk where nisoldipine has poor flow, low dose loading, or inadequate content uniformity. It may be viable if the drug substance has suitable particle engineering and the excipient blend produces consistent compression and release.

Wet granulation offers greater control over blend uniformity and mechanical strength but adds water, drying, and scale-up variables. A dry-granulation process may reduce moisture exposure but can alter density and release kinetics.

What manufacturing and intellectual-property barriers remain?

The main manufacturing barriers are process-specific:

• Uniform dispersion of a low-dose active.
• Consistent hypromellose hydration.
• Compression-force control.
• Prevention of tablet capping and lamination.
• Reproducible coating weight.
• Control of nisoldipine degradation.
• API and excipient supply continuity.

The intellectual-property risk is concentrated in process know-how. Even where patents have expired, the reference product may have accumulated manufacturing knowledge around polymer grade, granule density, coating permeability, and dissolution specifications. Those parameters are difficult to infer from public labeling.

A company with a validated extended-release platform could reduce development time by adapting its matrix technology to nisoldipine. The platform must still demonstrate product-specific bioequivalence.

What commercial opportunities exist for Sular excipients?

The strongest opportunities are in supply and reformulation rather than in proprietary exclusivity.

Excipient supply opportunities

Hypromellose suppliers can compete on:

• Controlled-viscosity grades.
• Low-peroxide and low-moisture specifications.
• Reliable batch-to-batch hydration.
• Regulatory documentation.
• Regional supply security.

Lactose suppliers can compete through spray-dried grades that improve flow and compressibility. Povidone suppliers can target low-peroxide grades and consistent molecular-weight distribution. Coating suppliers can offer ready-to-use systems that reproduce color, film strength, and moisture protection.

CDMO opportunities

CDMOs with modified-release tablet capability can offer:

• Formulation screening.
• Dissolution method development.
• Pilot-scale granulation.
• Bioequivalence batch manufacture.
• Commercial tablet compression.
• Packaging and serialization.

Nisoldipine is suitable for a CDMO platform strategy because the dosage form is established and the regulatory pathway is familiar. Commercial volumes may be modest, so flexible multiproduct equipment is more valuable than a dedicated production line.

Reformulation opportunities

Potential lifecycle products include:

• Lower-cost generic extended-release tablets.
• Alternative tablet sizes.
• Improved swallowability.
• Dose-combination products with other antihypertensives.
• Packaging optimized for adherence.
• Regional products using locally available excipients.

A reformulation using a different release technology could qualify under a 505(b)(2) strategy in some circumstances, but it would face greater clinical and regulatory requirements than a conventional ANDA. The economic case would depend on differentiation, market access, and the ability to obtain meaningful pricing.

How does Sular compare with other calcium-channel blockers?

Sular competes with amlodipine, nifedipine extended-release, felodipine extended-release, and other antihypertensive therapies. Amlodipine has a stronger generic supply base and broader prescribing familiarity. Nifedipine extended-release has a larger installed base in many markets. Sular’s opportunity is therefore niche and supply-driven.

Product	Release format	Generic competition	Formulation complexity	Commercial position
Sular	Controlled-release tablet	High	Moderate to high	Niche
Amlodipine	Immediate-release tablet	Very high	Low	Broad
Nifedipine ER	Modified-release tablet	High	High	Broad in selected markets
Felodipine ER	Extended-release tablet	High	Moderate to high	Smaller niche

Sular may retain value where prescribers, formularies, or patients have an established preference for nisoldipine. It is less attractive as a large-scale branded investment.

What revenue exposure and launch scenarios exist?

Publicly available information does not establish a current, reliable standalone revenue figure for Sular. The product’s commercial value is better assessed through prescription volume, reimbursement status, generic count, supply continuity, and net price.

Launch scenario	Expected commercial result
Single generic entrant	Potential pricing power if supply is constrained
Multiple generic entrants	Rapid price erosion and limited margins
Limited-strength launch	Smaller opportunity with lower development cost
Full-strength portfolio	Better formulary coverage and manufacturing leverage
Supply disruption by incumbent	Temporary share gains for reliable suppliers
Reformulated product	Higher development cost but possible differentiation

A new entrant should prioritize all four strengths if the market supports the incremental manufacturing cost. A one- or two-strength launch may be justified where demand is concentrated or where the applicant is testing a constrained market.

Is there biosimilar risk for Sular?

No. Nisoldipine is a chemically synthesized small molecule, not a biologic. The relevant competitive pathway is generic substitution under an ANDA, not biosimilar interchangeability under the Public Health Service Act.

What litigation and settlement issues affect Sular?

No major current Sular patent litigation is central to the commercial assessment. Historical litigation, if any, would have focused on formulation patents, generic validity challenges, or Paragraph IV certifications. Because the principal exclusivity period has expired, settlement agreements are unlikely to provide a meaningful current barrier to entry.

A diligence review should still check PACER, FDA Orange Book patent listings, and ANDA litigation records for any later formulation patent or manufacturing dispute.[2,5]

Key Takeaways

• Sular is nisoldipine extended-release, an established small-molecule antihypertensive.
• The key formulation technology is a hydrophilic controlled-release matrix, with hypromellose as the principal release-controlling excipient.
• Generic entry is legally accessible because the original exclusivity and core patent barriers have expired.
• The main technical risks are dissolution matching, food effect, tablet porosity, drug uniformity, and release reproducibility.
• The strongest commercial opportunities are generic manufacture, excipient supply, CDMO services, and targeted reformulation.
• Biosimilar competition does not apply.
• Current revenue exposure is likely limited and should be evaluated through market volume, generic competition, reimbursement, and supply continuity rather than historical brand sales.

FAQs

What is the active ingredient in Sular?

Sular contains nisoldipine, a dihydropyridine calcium-channel blocker used to treat hypertension.

Which excipient controls release in Sular tablets?

Hypromellose is the principal release-controlling excipient identified in public product information. Its viscosity grade, concentration, and hydration behavior are critical to dissolution performance.

Can a company launch generic nisoldipine extended-release tablets?

Yes. Generic nisoldipine extended-release products can be developed through the ANDA pathway, subject to FDA approval, therapeutic-equivalence requirements, and current reference-product status.

Is nisoldipine a good candidate for a 505(b)(2) reformulation?

It may be suitable where a sponsor can demonstrate a meaningful dosage-form or delivery-system difference. The 505(b)(2) route would generally be more costly and clinically demanding than a conventional ANDA.

Which excipient suppliers are most relevant to a Sular generic?

The relevant suppliers are manufacturers of controlled-viscosity hypromellose, pharmaceutical lactose, povidone, magnesium stearate, and ready-to-use film-coating systems. Supplier selection should prioritize regulatory documentation and batch-to-batch release consistency.

References

1. DailyMed. (n.d.). Sular: Nisoldipine controlled-release tablets prescribing information. U.S. National Library of Medicine.
2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
3. U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
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. Courts. (n.d.). PACER case locator. https://pcl.uscourts.gov/