List of Excipients in Branded Drug CHLOROQUINE PHOSPHATE

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Generic Drugs Containing CHLOROQUINE PHOSPHATE

Company	Ingredient	NDC	Excipient
Amneal Pharmaceuticals of New York LLC	chloroquine phosphate	0115-2790	ANHYDROUS CITRIC ACID
Amneal Pharmaceuticals of New York LLC	chloroquine phosphate	0115-2790	HYDROGENATED COTTONSEED OIL
Amneal Pharmaceuticals of New York LLC	chloroquine phosphate	0115-2790	LACTOSE MONOHYDRATE

What are the Most Frequently-Used Excipients in CHLOROQUINE PHOSPHATE?

# Of NDCs	Excipient
3	ANHYDROUS CITRIC ACID
4	ANHYDROUS DIBASIC CALCIUM PHOSPHATE
5	CELLULOSE, MICROCRYSTALLINE

Chloroquine Phosphate Excipient Strategy and Commercial Opportunities

Last updated: September 24, 2026

Chloroquine phosphate is a mature, off-patent small-molecule drug with low formulation complexity and limited originator exclusivity. Commercial value is concentrated in differentiated oral products: pediatric dispersible tablets, taste-masked liquids, stable emergency-stock formulations, and low-cost products for malaria and selected autoimmune indications. The strongest opportunities are manufacturing efficiency, dosing accuracy, tolerability, and procurement access rather than new chemical patents.

What is the commercial status of chloroquine phosphate?

Chloroquine phosphate is an established 4-aminoquinoline antimalarial. It is also used in certain jurisdictions for extraintestinal amebiasis and autoimmune diseases, including rheumatoid arthritis and lupus, although hydroxychloroquine has displaced it in many chronic-use markets because of tolerability and safety considerations.

Attribute	Chloroquine phosphate
Active moiety	Chloroquine
Salt form	Chloroquine phosphate
Common tablet strengths	250 mg and 500 mg chloroquine phosphate
Equivalent chloroquine base	Approximately 150 mg and 300 mg, respectively
Primary FDA-labeled use	Treatment and suppression of malaria caused by susceptible parasites
Product type	Small-molecule generic
Biologic status	Not a biologic; biosimilar pathway does not apply
Originator product	Aralen
U.S. regulatory pathway	NDA and abbreviated new drug applications
Patent position	Core composition and conventional oral formulation patents are expired
Main commercial constraints	Parasite resistance, narrow therapeutic margin, cardiac and ocular toxicity, low price

The U.S. prescribing information identifies chloroquine phosphate tablets as an oral product and provides dosing based on both salt weight and chloroquine-base equivalence. This conversion is commercially important because labeling errors can produce material dosing differences (FDA, 2018).

What patents protect chloroquine phosphate?

The original chloroquine composition-of-matter and conventional oral-product patent rights have expired. Chloroquine phosphate is therefore a generic-market product rather than an active patent-protected product.

Patent estate and exclusivity

IP category	Commercial position
Chloroquine molecule	Historical patents expired
Chloroquine phosphate salt	Historical protection expired
Conventional tablets	No meaningful remaining core patent barrier
Standard excipients	Generally unpatentable or expired as applied to this product
Pediatric dispersible formulations	Potentially patentable only if the formulation provides a non-obvious technical advantage
Taste-masking systems	Potential formulation or process claims
Modified-release products	Potentially patentable, but clinical and regulatory value is uncertain
Manufacturing processes	Potential process protection if novel, reproducible, and commercially relevant
Method-of-use claims	Possible for new indications, but limited by known pharmacology and safety profile

A new product would need to rely on formulation, process, device, packaging, or use claims. A patent directed only to combining chloroquine phosphate with routine excipients would face substantial novelty and obviousness risk.

When does chloroquine phosphate lose exclusivity?

Chloroquine phosphate lost practical market exclusivity decades ago. The product is now exposed to generic competition in major regulated markets. Any residual protection is likely to relate to a particular formulation, process, combination, or jurisdiction rather than to chloroquine phosphate itself.

The FDA Orange Book remains the relevant source for U.S. listed patents and regulatory exclusivity. For an ordinary chloroquine phosphate tablet, the commercial strategy should assume no blocking patent estate and no meaningful new-drug exclusivity (FDA, 2024a).

Orange Book status

Chloroquine phosphate is not a biologic and does not require a Purple Book analysis. It is evaluated through the small-molecule generic framework. A generic sponsor normally relies on an ANDA referencing the relevant listed drug, with bioequivalence demonstrated through pharmacokinetic or other FDA-accepted methods.

Because the active ingredient is old and the product is generic, the principal regulatory work concerns:

• Pharmaceutical equivalence
• Bioequivalence
• Manufacturing controls
• Stability
• Impurity control
• Labeling
• Container closure
• Dose uniformity
• Pediatric acceptability where relevant

What excipients are used in chloroquine phosphate tablets?

Conventional chloroquine phosphate tablets generally use standard excipients for direct compression or wet granulation. Public product labels identify common pharmaceutical excipients such as starch, calcium phosphate, magnesium stearate, talc, and coating materials, although the exact composition varies by manufacturer and market (FDA, 2018).

Core excipient functions

Excipient class	Typical function	Commercial relevance
Diluent	Controls tablet mass and compressibility	Low cost; important for high-dose tablets
Binder	Provides granule strength	Useful where direct compression is inadequate
Disintegrant	Promotes tablet breakup	Important for rapid and reproducible dissolution
Lubricant	Prevents sticking and tooling defects	Excess use can slow dissolution
Glidant	Improves powder flow	Reduces weight variation
Film coat	Protects tablet and improves swallowability	Can reduce odor and handling dust
Opacifier or colorant	Product identification	Supports counterfeit control and differentiation
Sweetener	Improves pediatric acceptance	Critical for liquid and dispersible products
Flavor	Masks bitterness	Core requirement for oral pediatric products
Suspending agent	Maintains liquid dose uniformity	Required for multidose suspensions
Buffer	Controls pH	Supports stability and palatability
Preservative	Limits microbial growth	Relevant for aqueous multidose liquids
Chelator or antioxidant	Limits degradation pathways	Product-specific and stability-dependent

Chloroquine phosphate is highly bitter. Bitterness is the most commercially important excipient problem because it affects pediatric adherence, especially when tablets are crushed or dispersed for children.

What formulation patents could protect chloroquine phosphate?

The strongest formulation opportunities involve measurable performance improvements rather than routine excipient substitution.

Pediatric dispersible tablets

A dispersible tablet could combine:

• Low-dose strength options
• Rapid dispersion in a small volume of water
• Controlled bitterness
• Low friability
• Acceptable taste after dispersion
• Stable performance in high humidity
• Clear dose conversion between salt and base

Potential claim scope could cover the composition, manufacturing process, dissolution profile, taste-masking architecture, and packaging system. A patent position would be stronger if the formulation demonstrated an unexpected dissolution, stability, or palatability result.

Taste-masked oral liquid

An oral suspension could use:

• Ion-exchange resins
• Polymer coating
• Cyclodextrin complexation
• Lipid or multiparticulate encapsulation
• Sweetener and flavor systems
• Structured suspending agents
• pH control

Taste masking must be balanced against drug release. Strong complexation can reduce bioavailability or create dose non-uniformity. For a generic or 505(b)(2) product, the sponsor would need to show that the formulation delivers a reliable dose and meets applicable dissolution and stability requirements.

Modified-release formulations

Modified release is technically possible but commercially less attractive. Chloroquine is ordinarily dosed according to therapeutic indication and patient weight, and malaria treatment requires predictable exposure. A sustained-release product would require clinical justification, may complicate bioequivalence, and could increase the risk of delayed toxicity if dosing errors occur.

Fixed-dose combinations

Combination products with other antimalarials could address resistance, but chloroquine is no longer suitable for many regions where Plasmodium falciparum resistance is prevalent. Combination development would therefore depend on local susceptibility patterns and public-health guidance. The WHO recommends treatment choices based on parasite resistance and national malaria policy, not solely on formulation convenience (WHO, 2023).

Which excipient strategies offer the strongest commercial opportunities?

1. Pediatric dispersible tablets

This is the highest-value formulation segment. The product could target malaria-endemic markets, humanitarian procurement, government tenders, and hospital pharmacies.

Commercial specifications should include:

• 25 mg, 50 mg, or other age-appropriate strengths
• Dose flexibility through scored tablets
• Dispersion in water without extensive shaking
• Minimal sedimentation
• Rapid dissolution
• Taste masking
• Moisture-resistant packaging
• Clear instructions for caregivers

The product should display both chloroquine phosphate and chloroquine-base equivalents. Confusion between salt weight and base weight is a recognized labeling and medication-safety risk.

2. Ready-to-use oral suspension

A ready-to-use suspension would address children who cannot swallow tablets and adults requiring dose adjustment. The principal challenges are chemical stability, preservative compatibility, microbial control, sedimentation, and multidose dosing accuracy.

A commercially viable product should use a calibrated oral syringe rather than a household spoon. Unit-dose sachets or small bottles could reduce contamination and improve field distribution.

3. Stable emergency-stock product

Chloroquine phosphate is inexpensive and compact. A manufacturer could develop packaging optimized for:

• Long-term government stockpiling
• High-temperature and high-humidity climates
• Flood, conflict, and disaster-response settings
• Simplified warehouse handling
• Extended shelf-life claims supported by stability data

Alu-Alu blister packs, high-barrier bottles, desiccants, and tamper-evident closures may provide more value than novel tablet excipients.

4. Low-cost manufacturing platform

The product is compatible with conventional solid-dose manufacturing. Opportunities include:

• Direct-compression formulations
• High-throughput tableting
• Common excipient platforms across multiple strengths
• Reduced coating weight
• Fewer raw-material suppliers
• Continuous manufacturing
• Local production in malaria-endemic regions

The principal advantage is cost and supply reliability, not proprietary chemistry.

What FDA regulatory status applies to chloroquine phosphate?

The FDA regulates chloroquine phosphate as an established small-molecule drug. The regulatory route depends on the proposed product.

Product concept	Likely regulatory route
Conventional tablet equivalent to listed drug	ANDA
New dosage form with limited changes	ANDA or 505(b)(2), depending on reference and formulation
New indication	505(b)(2) or supplemental application
Novel pediatric formulation	ANDA if therapeutically equivalent; 505(b)(2) if reliance on additional clinical data is required
Fixed-dose combination	Combination-product pathway with clinical and pharmaceutical justification
Veterinary product	Separate animal-drug regulatory pathway

FDA labeling warns about retinopathy, cardiomyopathy, cardiac conduction effects, hypoglycemia, neuropsychiatric reactions, and serious skin reactions. These risks influence excipient selection because the formulation must not create uncontrolled exposure or dose dumping (FDA, 2018).

Hydroxychloroquine and chloroquine should not be treated as interchangeable products. Hydroxychloroquine sulfate has a separate regulatory and clinical history, and its dosing, safety labeling, and market positioning differ.

Are there Paragraph IV challenges involving chloroquine phosphate?

Paragraph IV litigation is unlikely to be commercially significant for the basic chloroquine phosphate product because the core drug and conventional tablet technology are long off-patent. A Paragraph IV filing would become relevant only if a listed patent covered a particular branded formulation, delivery system, or method of use.

The more likely generic-market risks are:

• Manufacturing-site deficiencies
• Supply interruptions
• Failure to demonstrate bioequivalence
• Dissolution variability
• Inadequate stability data
• Labeling errors involving base equivalence
• Contamination or impurity findings
• Procurement disqualification

For a new formulation, patent litigation would more likely involve formulation or process claims than the chloroquine molecule itself.

What generic entry risks exist?

Generic entry risk is already high because the market is mature and the active ingredient is widely known. A differentiated sponsor should expect price pressure in standard tablets.

Product segment	Generic pressure	Differentiation potential
Standard 250 mg tablet	Very high	Low
Standard 500 mg tablet	Very high	Low
Pediatric dispersible tablet	Moderate	High
Taste-masked suspension	Moderate	High
Long-term stability package	Moderate	Moderate
Modified-release product	Lower initially	Uncertain
Fixed-dose combination	Depends on combination	Moderate to high
Hospital or government contract supply	High	Moderate through reliability

A new product must generate value through procurement performance, pediatric usability, documented stability, or supply assurance. A premium based only on a different color, flavor, or routine excipient is unlikely to persist.

How strong is the patent estate for chloroquine phosphate?

The core patent estate is weak because it is expired. A new formulation estate could be moderate if it includes:

1. A defined taste-masking mechanism.
2. A reproducible dissolution profile.
3. Demonstrated stability under climatic-zone conditions.
4. A non-obvious excipient ratio.
5. A manufacturing process that improves yield or dose uniformity.
6. Packaging claims tied to measurable shelf-life performance.
7. Pediatric dosing or administration data supporting the product design.

Patent value would be limited if the claims cover broad categories such as “a chloroquine tablet containing a sweetener and disintegrant.” Narrower claims supported by comparative data would be more defensible.

What licensing deals and commercial partnerships are relevant?

No major active licensing structure is required for a conventional generic chloroquine phosphate tablet. Commercial partnerships are more likely to involve:

• Contract manufacturing
• Government procurement
• Nonprofit malaria programs
• Regional distributors
• Pediatric product developers
• Local pharmaceutical manufacturers
• Public-health stockpiling programs

Licensing value may arise if a company owns a validated pediatric taste-masking platform, a heat-stable liquid technology, or a proprietary fixed-dose combination. The licensor’s value would depend on regulatory acceptance, manufacturing scale, and procurement access.

What revenue exposure does chloroquine phosphate create?

Revenue exposure is generally modest for a diversified pharmaceutical company because standard chloroquine tablets are low-priced. Exposure can be material for a focused generic manufacturer supplying government tenders or a limited number of malaria-endemic markets.

The main revenue variables are:

• Tender awards
• Country-level resistance patterns
• WHO and national treatment guidelines
• Manufacturing uptime
• Product registration coverage
• Pediatric product differentiation
• Raw-material cost
• Public-health procurement cycles
• Competitor shortages

Chloroquine should not be positioned as a broad global malaria-growth product. Its commercial role is narrower and depends on susceptible parasites, local treatment policy, and reliable supply.

How does chloroquine phosphate compare with hydroxychloroquine?

Factor	Chloroquine phosphate	Hydroxychloroquine sulfate
Main historical use	Malaria	Autoimmune disease and malaria
Pediatric formulation opportunity	High	High
Current autoimmune commercial strength	Lower	Higher
Antimalarial resistance exposure	Significant	Also relevant by region
Standard generic competition	High	High
Safety positioning	Less favorable in many chronic-use settings	Generally preferred for chronic autoimmune use
Patent opportunity	Formulation-led	Formulation-led
Biosimilar risk	None	None

Hydroxychloroquine has the stronger chronic autoimmune market position. Chloroquine phosphate has a more targeted opportunity in malaria procurement, pediatric dosing, and emergency supply.

Key Takeaways

• Chloroquine phosphate is an old, off-patent small-molecule drug with no meaningful core exclusivity.
• Conventional tablets are commodity products with high generic and price pressure.
• The best excipient opportunity is a palatable pediatric dispersible tablet or oral suspension.
• Taste masking, dose accuracy, humidity stability, and packaging are more valuable than routine excipient changes.
• A formulation patent would need comparative data showing a non-obvious technical advantage.
• Chloroquine is not subject to biosimilar competition because it is not a biologic.
• Paragraph IV litigation is unlikely to affect the basic product unless a new formulation creates listed patent rights.
• Revenue potential depends on malaria-endemic procurement, local susceptibility, public-health policy, and supply reliability.
• Hydroxychloroquine is the stronger autoimmune comparator, while chloroquine phosphate retains targeted malaria and pediatric opportunities.

FAQs About Chloroquine Phosphate Formulation and Commercialization

Can chloroquine phosphate be developed as a pediatric chewable tablet?

Yes. A chewable or dispersible tablet could target pediatric malaria treatment, but taste masking, dose flexibility, stability, and dissolution would need to be validated. The formulation should state chloroquine-base equivalence clearly.

Is chloroquine phosphate suitable for a 505(b)(2) product?

It can be, particularly for a novel liquid, modified-release system, combination product, or new indication. A conventional therapeutically equivalent tablet would more commonly use the ANDA pathway.

Which excipient is best for masking chloroquine bitterness?

No single excipient is universally optimal. Ion-exchange resins, polymer coatings, complexation systems, flavors, sweeteners, and multiparticulate technologies can be evaluated. The best system must preserve dissolution and dose uniformity.

Can chloroquine phosphate support a new patent?

Yes, but only a novel and non-obvious formulation, process, packaging system, delivery device, or method of use is likely to provide meaningful patent value. Routine excipient substitution is weak subject matter.

Is a chloroquine phosphate oral suspension commercially attractive?

It can be attractive in pediatric and institutional markets where tablets are difficult to administer. The product must solve sedimentation, microbial preservation, chemical stability, taste, dosing accuracy, and field-storage problems.

References

1. Food and Drug Administration. (2018). Chloroquine phosphate tablets, USP: Prescribing information. U.S. Department of Health and Human Services.

2. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services. https://www.accessdata.fda.gov/scripts/cder/ob/

3. United States Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary. USP Convention.

4. World Health Organization. (2023). Guidelines for malaria. World Health Organization. https://www.who.int/publications/i/item/guidelines-for-malaria

5. World Health Organization. (2023). WHO model list of essential medicines: 23rd list. World Health Organization.