List of Excipients in Branded Drug CHEMET

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Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	FERRIC OXIDE RED
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	GELATIN
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	POVIDONE
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	SODIUM STARCH GLYCOLATE TYPE A POTATO
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	STARCH, CORN
Recordati Rare Diseases Inc	CHEMET	succimer	55292-201	SUCROSE

CHEMET Excipient Strategy and Commercial Opportunities for Succimer

Last updated: August 24, 2026

CHEMET is an oral succimer capsule used for lead poisoning and selected heavy-metal toxicities. Its commercial position is defined by an old, relatively simple capsule formulation, pediatric administration challenges, limited demand, and a narrow competitive field. The strongest excipient opportunities are not premium capsule reformulations. They are pediatric liquid or dispersible dosage forms, taste masking, dose flexibility, improved stability, and global supply optimization.

What is CHEMET and which excipients does the product contain?

CHEMET contains succimer, also called dimercaptosuccinic acid, at 100 mg per capsule. Succimer is an orally active chelating agent with sulfhydryl groups that bind lead and certain other heavy metals.

The U.S. product is an immediate-release hard gelatin capsule. FDA labeling identifies the following inactive ingredients:

Component	Likely formulation role
Gelatin	Hard capsule shell
Lactose monohydrate	Diluent and bulking agent
Microcrystalline cellulose	Filler and powder-structure aid
Magnesium stearate	Lubricant
Sodium lauryl sulfate	Wetting or powder-processing aid
Colloidal silicon dioxide	Glidant and flow-control agent
Titanium dioxide	Opacifier and colorant
FD&C Yellow No. 6	Capsule-shell colorant

The listed excipients are conventional and generally low-cost. They support a dry powder-fill process rather than a complex modified-release or solubilized formulation. The primary formulation constraints are capsule swallowing, dose adjustment, pediatric use, powder flow, content uniformity, and acceptable stability.

FDA, “CHEMET- succimer capsule” label.

What excipient strategy does CHEMET use?

CHEMET uses a conventional hard-capsule platform with a lactose-based powder blend. The strategy prioritizes manufacturability and established excipient safety over differentiated delivery.

Powder-flow and content-uniformity strategy

Succimer is administered in relatively high milligram quantities. A 100 mg capsule requires a blend with adequate flow, uniform distribution, and reproducible fill weight. Microcrystalline cellulose provides bulk and contributes to powder handling. Colloidal silicon dioxide improves flow, while magnesium stearate reduces adherence to processing equipment.

Sodium lauryl sulfate may improve wetting and powder dispersion. Its presence can support dissolution of a poorly wetting active ingredient, although the product is not positioned as a bioavailability-enhanced formulation.

Capsule-shell strategy

The gelatin shell provides a standard, low-cost delivery system. Titanium dioxide and FD&C Yellow No. 6 provide opacity and identification. Gelatin creates a potential barrier in markets that require vegetarian, halal, or bovine-source alternatives.

The shell also creates the main administration limitation. Young children may have difficulty swallowing a 100 mg capsule, even though succimer treatment is particularly relevant to pediatric lead exposure.

Excipient compatibility

Succimer contains thiol groups that can participate in oxidation and chemical interactions. The practical development focus is therefore on:

• Control of moisture and oxygen exposure.
• Avoidance of reactive impurities in excipients.
• Monitoring of degradation products.
• Packaging that limits humidity ingress.
• Compatibility of colorants, lubricants, and wetting agents with long-term stability.

A replacement formulation should not assume that a common excipient is interchangeable without extractables, leachables, impurity, and stability testing.

What formulations are protected by CHEMET patents?

No formulation patent is identified in the current FDA product labeling as the commercial basis for CHEMET exclusivity. CHEMET was approved in the United States in 1991 under NDA 019998, and the product is generally treated as an established, off-patent small-molecule medicine.

The commercial protection profile is therefore different from that of a recently approved branded drug:

Protection category	CHEMET position
Active ingredient	Old, established succimer molecule
U.S. composition-of-matter patent	No current commercial relevance identified
Branded capsule formulation	Conventional formulation; no current blocking patent identified
FDA new-drug exclusivity	Expired
Orphan-drug exclusivity	No current exclusivity period identified
Orange Book relevance	Product and patent-listing status must be checked against the current edition
Competitive barrier	Limited market size, toxicology requirements, supply reliability, and clinical familiarity

Any new excipient-based product would need to establish its own protection. Potential protectable subject matter could include:

• A stable liquid succimer composition.
• A taste-masked granule or powder.
• A dispersible tablet with defined dissolution properties.
• A preservative-free multidose formulation.
• A unit-dose pediatric sachet.
• A non-gelatin capsule.
• A formulation with improved resistance to oxidation.
• A process that controls impurity formation.
• A dosing system that enables weight-based administration.

A patent would need to claim technical performance, not simply the substitution of one routine excipient for another.

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

CHEMET’s core FDA exclusivity has already expired. The principal generic-entry route is an abbreviated new drug application, potentially supported by an ANDA with a Paragraph IV certification if an unexpired listed patent were identified.

For a conventional immediate-release capsule, the generic development burden is comparatively manageable. A competitor would typically need to demonstrate:

• Pharmaceutical equivalence.
• Bioequivalence.
• Equivalent strength and dosage form.
• Appropriate impurity controls.
• Stability through the proposed shelf life.
• Compliance with current manufacturing requirements.

The most important commercial barriers are not patent barriers. They are market economics and regulatory execution. Succimer is used for specific toxicology indications, and demand is materially smaller than for common cardiovascular, metabolic, or anti-infective products. A generic manufacturer must support pharmacovigilance, controlled distribution where applicable, inventory continuity, and emergency procurement.

What Paragraph IV challenges could affect CHEMET?

A Paragraph IV challenge would have the greatest impact if a later-listed formulation or method-of-use patent appeared in the Orange Book. Based on the conventional nature and age of the product, the central generic risk is more likely to arise from a standard ANDA pathway than from a contested patent launch.

The relevant litigation questions would include:

1. Whether any patent is listed for the specific succimer capsule.
2. Whether a listed patent claims the capsule composition or only a method of use.
3. Whether the patent covers the reference product or a separate formulation.
4. Whether the applicant can certify Paragraph III or Paragraph IV.
5. Whether a 30-month stay applies after a qualifying infringement action.

The absence of a meaningful patent barrier does not guarantee immediate generic launch. Product discontinuation, limited API sources, and commercial supply decisions can determine market timing.

FDA, Approved Drug Products with Therapeutic Equivalence Evaluations.

What pediatric excipient opportunities exist for CHEMET?

The highest-value opportunity is a pediatric formulation that avoids swallowing a hard capsule and permits more precise dose administration.

Taste-masked oral liquid

A liquid product could be supplied as:

• A ready-to-use suspension.
• A powder for reconstitution.
• A single-dose oral solution.
• A concentrated formulation administered with a calibrated syringe.

Succimer’s sulfur-containing structure may create taste and odor challenges. Taste masking could use polymeric coating, ion-exchange resins, lipid barriers, cyclodextrins, sweeteners, flavors, or multiparticulate encapsulation.

A liquid product would require careful control of:

• Chemical stability in water.
• Oxidation.
• Microbial growth.
• Preservative performance.
• Dose uniformity after shaking.
• Sedimentation and redispersibility.
• Container compatibility.
• In-use shelf life.

A dry powder for reconstitution may offer a better stability profile than a ready-to-use liquid. It can reduce water-driven degradation and lower preservative requirements.

Dispersible or orally disintegrating tablet

A dispersible tablet could improve administration while preserving a solid dosage-form supply chain. Excipients may include superdisintegrants, mannitol, microcrystalline cellulose, flavor systems, and taste-masking polymers.

The formulation must avoid excessive friability and ensure rapid dispersion in a small volume of water. A tablet dose may be easier for older children and adults but less flexible than a liquid for weight-based pediatric dosing.

Sprinkle capsule or granule

A sprinkle formulation could allow the capsule contents to be opened and mixed with a soft food or beverage. This approach may require:

• Coated granules.
• Reduced odor release.
• Controlled particle size.
• Reduced contact with the oral mucosa.
• Demonstrated dose recovery after mixing.
• Clear administration instructions.

The regulatory risk is lower than for a new chemical entity but higher than for an unchanged generic capsule because the administration method may alter in vivo performance and patient use.

How can excipient selection improve commercial differentiation?

Excipient changes can create commercial value when they solve a specific use problem. Routine replacement of lactose with another filler is unlikely to support a durable premium.

Product concept	Commercial benefit	Main technical risk
Powder for oral suspension	Better pediatric administration and stability	Reconstitution uniformity and oxidation
Taste-masked granules	Allows capsule opening or food mixing	Taste breakthrough and dose recovery
Orally disintegrating tablet	Convenient administration without water	High drug load and palatability
Preservative-free unit-dose liquid	Lower preservative exposure and dosing errors	Packaging cost and chemical stability
Non-gelatin capsule	Broader global and religious-market acceptance	Shell performance and supply qualification
Low-lactose or lactose-free capsule	Addresses excipient restrictions	No clear benefit for most patients
Oxygen-barrier packaging	Extends stability and reduces degradation	Packaging cost and manufacturing complexity

The strongest development case combines patient convenience with supply-chain value. A powder for reconstitution in unit-dose sachets could reduce moisture exposure, simplify transport, and address pediatric dosing.

What FDA regulatory pathway applies to a new CHEMET formulation?

A conventional generic capsule would generally proceed through an ANDA if it is pharmaceutically equivalent and therapeutically equivalent to the reference product. A materially different dosage form, such as a liquid or orally disintegrating tablet, may require a 505(b)(2) application.

The pathway depends on the formulation and claims:

Proposed product	Likely U.S. pathway
Equivalent 100 mg capsule	ANDA
Same active ingredient with different excipients but equivalent dosage form	ANDA, if equivalence criteria are met
Oral suspension	Potentially 505(b)(2)
Orally disintegrating tablet	Potentially 505(b)(2)
New dosing device or administration method	ANDA or 505(b)(2), depending on formulation differences
New indication	505(b)(2) or supplemental pathway, depending on evidence

A 505(b)(2) product may obtain method-of-use, formulation, or device-related exclusivity if it satisfies statutory requirements. Such exclusivity would not restore exclusivity to the old succimer molecule itself.

FDA, “Applications Covered by Section 505(b)(2).”

What manufacturing and intellectual-property barriers exist?

The API is the main technical input. A commercial developer needs a qualified succimer source with reliable control of:

• Identity and assay.
• Residual solvents.
• Elemental impurities.
• Oxidation-related impurities.
• Particle-size distribution.
• Bulk density.
• Water content.
• Microbial quality.

Succimer’s intended use in heavy-metal poisoning places a high burden on quality perception. Excipient and packaging changes must not introduce extractable metals or reactive impurities that could undermine product quality.

Potential manufacturing IP can arise from:

• Low-oxygen granulation.
• Controlled-humidity blending.
• Stabilized liquid systems.
• Coated multiparticulates.
• Specialized reconstitution packaging.
• Continuous manufacturing of a high-dose powder blend.

Process patents are more credible when they show improved impurity control, dissolution, stability, or dose uniformity.

Which companies could challenge or compete with CHEMET?

Competition can arise from three groups:

1. Generic pharmaceutical companies developing succimer capsules.
2. Specialty or rare-disease companies supplying toxicology products.
3. Formulation companies licensing pediatric delivery technology.

The addressable market is limited, which favors manufacturers with established generic operations, hospital and poison-center relationships, or public-sector procurement capabilities. A differentiated pediatric product may be more attractive to a specialty pharmaceutical company than an undifferentiated 100 mg capsule.

No current licensing or settlement agreement is established here as a material commercial constraint. Any transaction involving formulation rights, API supply, or regional distribution would need to be assessed against FDA labeling, Orange Book data, and the applicable national register.

How does CHEMET compare with competing heavy-metal chelators?

CHEMET occupies a niche between injectable chelation and other oral agents.

Product	Active ingredient	Typical administration position	Excipient opportunity
CHEMET	Succimer	Oral chelation for selected lead and heavy-metal exposures	Pediatric liquid, taste masking, dispersible formats
EDTA products	Calcium disodium edetate	Parenteral treatment in defined lead-poisoning settings	Less relevant to oral excipient innovation
Dimercaprol	British anti-Lewisite	Injectable chelation	Limited oral delivery opportunity
D-penicillamine	Penicillamine	Oral chelation for selected conditions	Broader chronic-use formulation considerations
DMPS products	2,3-dimercapto-1-propanesulfonic acid	Oral or parenteral use in some countries	Geographic and regulatory variability

CHEMET’s main differentiation is oral administration. Its main weakness is the capsule format for pediatric patients. A formulation that preserves oral delivery while improving palatability and dose flexibility could create the clearest commercial separation.

What revenue exposure and launch scenarios exist?

Revenue exposure is difficult to infer from public product-level data because succimer sales may be reported within broader specialty or rare-disease portfolios. The commercial opportunity should be modeled by treatment volume, not by broad population prevalence.

Scenario 1: Low-cost generic capsule

This strategy has the lowest development cost but also the weakest differentiation. Success depends on API cost, procurement access, and supply reliability. Price competition could be severe if multiple ANDA holders enter.

Scenario 2: Pediatric powder for reconstitution

This strategy requires more formulation development but may support premium pricing, hospital adoption, poison-center preference, and reduced administration errors. It has the strongest balance of technical differentiation and clinical utility.

Scenario 3: Taste-masked sprinkle product

This product could address young children who cannot swallow capsules while avoiding the stability challenges of a ready-to-use liquid. Demonstrating complete dose delivery after mixing would be essential.

Scenario 4: Global non-gelatin capsule

A vegetarian or regional-compliance capsule could support selected markets but is unlikely to justify a large premium without a distribution or procurement advantage.

How strong is the CHEMET patent estate?

The core patent estate is weak from a present-day exclusivity perspective because the active ingredient and conventional capsule technology are longstanding. Commercial strength instead depends on regulatory status, manufacturing reliability, brand recognition, and access to specialized toxicology channels.

A new formulation patent could be moderately strong if it protects a clinically useful dosage form and contains narrow, technically supported claims. Broad claims covering succimer with routine excipients would face greater validity and obviousness risk.

The most defensible claim categories are:

• Defined stability thresholds.
• Specific antioxidant or oxygen-control systems.
• Taste-masked multiparticulates with performance data.
• Reconstitution systems with validated dose uniformity.
• Pediatric dosing platforms.
• Packaging-formulation combinations that materially reduce degradation.

Key Takeaways

• CHEMET is a 100 mg succimer hard capsule with a conventional lactose, cellulose, lubricant, glidant, surfactant, gelatin, and colorant system.
• Core FDA exclusivity has expired, and the main generic pathway is likely an ANDA for an equivalent capsule.
• The capsule format creates a clear pediatric administration gap.
• The strongest excipient opportunity is a stable, taste-masked pediatric formulation, particularly a powder for reconstitution or sprinkle granule.
• A ready-to-use liquid offers convenience but carries greater oxidation, preservation, and in-use stability risk.
• Excipient substitution alone is unlikely to support meaningful patent protection or premium pricing.
• New formulation value must come from measurable improvements in stability, palatability, dose accuracy, or administration.
• The commercial market is specialized and volume-constrained. Supply reliability and toxicology-channel access may matter more than broad consumer demand.
• Any launch assessment should treat formulation IP, API qualification, FDA pathway, Orange Book status, and regional regulatory requirements as separate workstreams.

FAQs

Can CHEMET capsules be opened and mixed with food?

The capsule label should govern administration. A commercial sprinkle product would need validated dose recovery, palatability, stability, and compatibility data for the selected food or beverage.

Is lactose in CHEMET a major commercial liability?

Lactose may matter for patients with specific intolerance or excipient restrictions, but it is unlikely to be the principal market barrier. Pediatric swallowing and taste are more commercially relevant formulation issues.

Could a succimer oral liquid receive new market exclusivity?

A materially differentiated liquid may qualify for a 505(b)(2) pathway and potentially obtain limited exclusivity if statutory requirements are met. The exclusivity would attach to the qualifying product or clinical innovation, not to succimer generally.

Is a preservative-free CHEMET liquid commercially feasible?

It may be feasible as a unit-dose or powder-for-reconstitution product. A multidose ready-to-use liquid would require strong control of microbial risk, oxidation, in-use stability, and packaging performance.

What is the most attractive licensing asset around CHEMET?

A validated pediatric delivery platform with taste masking, dose flexibility, and improved succimer stability is more attractive than a routine capsule-excipient substitution. Such an asset could be licensed to a generic, specialty pharmaceutical, or toxicology-focused manufacturer.

References

1. U.S. Food and Drug Administration. (n.d.). CHEMET- succimer capsule prescribing information. DailyMed. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations. FDA Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

3. U.S. Food and Drug Administration. (n.d.). Applications covered by section 505(b)(2). https://www.fda.gov/

4. Agency for Toxic Substances and Disease Registry. (n.d.). Toxicological profile for lead. U.S. Department of Health and Human Services. https://www.atsdr.cdc.gov/

5. Centers for Disease Control and Prevention. (n.d.). Lead poisoning prevention and clinical management resources. https://www.cdc.gov/lead/