List of Excipients in Branded Drug DIURIL

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Salix Pharmaceuticals Inc	DIURIL	chlorothiazide	65649-311	ALCOHOL
Salix Pharmaceuticals Inc	DIURIL	chlorothiazide	65649-311	BENZOIC ACID
Salix Pharmaceuticals Inc	DIURIL	chlorothiazide	65649-311	D&C YELLOW NO. 10

Last updated: August 12, 2026

ecutive summary: DIURIL is the branded form of chlorothiazide, a legacy thiazide diuretic with no meaningful new-molecule exclusivity. Commercial opportunity is concentrated in formulation execution rather than active-ingredient protection. The strongest opportunities are palatable oral liquids, low-volume pediatric dosing, ready-to-use hospital products, preservative-free presentations, excipient substitution, and supply-chain improvements. Any new product must compete against low-cost chlorothiazide tablets and oral suspensions, while addressing chlorothiazide’s limited aqueous solubility, dose-volume burden, taste, and suspension uniformity.

DIURIL Excipient Strategy and Commercial Opportunities for Chlorothiazide

What is DIURIL and which dosage forms use chlorothiazide?

DIURIL contains chlorothiazide, a thiazide diuretic used primarily for hypertension and edema. The product has historically been available as oral tablets, oral suspension, and an injectable chlorothiazide sodium presentation for intravenous use. Current marketed availability depends on the specific manufacturer, strength, and distribution channel.

Product category	Active ingredient	Typical commercial strength	Key formulation issue
Oral tablet	Chlorothiazide	250 mg and 500 mg	High drug load, swallowing burden, excipient compactability
Oral suspension	Chlorothiazide	Commonly 250 mg/5 mL	Taste, sedimentation, redispersibility, dose-volume burden
Intravenous product	Chlorothiazide sodium	Commonly 500 mg vial	Reconstitution, pH, osmolality, particulate control, stability
Generic equivalents	Chlorothiazide or chlorothiazide sodium	Product-dependent	Price competition and reliable supply

The commercial formulation objective is not to create a new pharmacologic product. It is to deliver the same active ingredient with better administration, stability, manufacturability, or institutional workflow.

What excipients are used in DIURIL formulations?

Public labeling identifies excipient categories, but the exact composition varies by dosage form and manufacturer. Tablet formulations typically use conventional solid-dose excipients such as diluents, binders, disintegrants, lubricants, and colorants. Oral suspensions use a vehicle, suspending system, sweetener, flavoring system, buffer, and antimicrobial preservation where applicable. Injectable products use parenteral-grade pH adjusters, tonicity agents, and bulking or stabilizing excipients appropriate for a sterile powder or reconstituted solution.

The commercial target should be the function of each excipient rather than simple substitution.

Formulation function	Conventional approach	Opportunity for differentiated strategy
Tablet diluent	Lactose, starch, or similar carbohydrate	Direct compression, reduced tablet size, lactose-free platform
Binder	Povidone, starch, cellulose derivative	Lower water sensitivity and shorter granulation cycle
Disintegrant	Starch or superdisintegrant	Faster breakup without compromising tablet strength
Lubricant	Magnesium stearate	Lower lubricant loading to improve dissolution
Suspension vehicle	Purified water with polyol or sugar system	Reduced sedimentation and improved redispersibility
Suspending agent	Cellulose polymer, xanthan gum, or similar polymer	Lower viscosity at equivalent suspension stability
Sweetener	Sucrose, sorbitol, or artificial sweetener	Better palatability with lower sugar load
Preservative	Parabens or alternative antimicrobial system	Preservative-free unit doses or improved preservative acceptability
Flavor	Fruit or masking flavor	Pediatric and geriatric acceptability
Buffer	Citrate, phosphate, or other buffer	pH control without precipitation or taste penalty
Injectable stabilizer	Product-specific parenteral excipient system	Faster reconstitution and reduced container interaction

A reformulator must confirm excipient compatibility with chlorothiazide, which has limited water solubility and can create formulation challenges in liquid and injectable systems.

What excipient strategy is best for DIURIL tablets?

The tablet opportunity is primarily operational. Chlorothiazide tablets are relatively high-dose products, so an excipient system must support adequate powder flow, content uniformity, tablet hardness, rapid disintegration, and acceptable tablet dimensions.

Direct-compression opportunity

A direct-compression formulation could reduce manufacturing steps and avoid wet-granulation exposure. The most relevant excipient design points are:

• A highly compressible filler with low segregation risk.
• A superdisintegrant that maintains performance at high drug loading.
• A glidant system that improves flow without increasing lubricant sensitivity.
• Low magnesium stearate concentration or an alternative lubricant strategy.
• Particle-size control for chlorothiazide and the principal filler.
• Robust tablet hardness after accelerated storage.

The product could be positioned around smaller tablets, improved breakability, or easier swallowing. A smaller tablet is commercially useful if the excipient system increases drug loading without impairing dissolution.

Lactose-free and low-sugar positioning

A lactose-free tablet could address patients with lactose intolerance and institutional buyers that prefer simplified excipient profiles. The opportunity is incremental rather than transformational because generic chlorothiazide tablets are already inexpensive.

A lactose-free platform should not be marketed solely on excipient exclusion. The commercial case is stronger when combined with one of the following:

• Reduced tablet size.
• Scored or bisected dosage form.
• Improved dose flexibility.
• Lower friability.
• Better packaging stability.
• Supply continuity for hospitals and long-term-care facilities.

Modified-release strategy

Modified release is technically possible but commercially difficult. Chlorothiazide is an established immediate-release diuretic, and a modified-release product would require evidence of clinical relevance, dosing advantage, and bioequivalence or a suitable clinical bridge. A release-controlled product could create formulation IP, but it would face development costs that are disproportionate to the likely market size unless linked to a defined adherence or nighttime-urination problem.

What excipient strategy is best for DIURIL oral suspension?

The oral suspension presents the clearest formulation opportunity. Chlorothiazide has a strong taste profile, limited solubility, and a dose that can require substantial liquid volume. A successful product must balance palatability, physical stability, dose accuracy, and ease of administration.

Suspension performance targets

A differentiated chlorothiazide suspension should demonstrate:

1. Rapid and complete redispersion after storage.
2. Minimal hard-cake formation.
3. Consistent delivered dose from the first through the last dose.
4. Acceptable viscosity for oral syringes and feeding tubes.
5. Low sedimentation during normal handling.
6. Reliable chemical stability through the labeled in-use period.
7. Taste masking without excessive sweetness or aftertaste.
8. Compatibility with common enteral-administration devices.

Excipient system

A practical suspension platform could use a structured vehicle based on a cellulose derivative, xanthan gum, or a polymer blend. The formulation should avoid excessive viscosity because caregivers and hospitals need to withdraw the product through oral syringes.

A useful design space includes:

• A wetting agent to disperse hydrophobic drug particles.
• A low-level flocculation or structured-vehicle system to prevent hard settling.
• A sweetener combination rather than a single high-load sweetener.
• Flavor masking tailored to pediatric use.
• Buffering that controls pH without creating an unpleasant acidic taste.
• Preservative protection where the product is supplied in a multidose bottle.
• A dosing syringe calibrated to the commercial concentration.

Pediatric opportunity

Chlorothiazide is used in pediatric and neonatal settings, although dosing is weight-based and frequently requires extemporaneous preparation or manipulation of available products. A ready-to-use, appropriately concentrated suspension could reduce dosing error and pharmacy compounding labor.

The strongest pediatric proposition would be:

• A low-volume concentration.
• An oral-syringe presentation.
• Clear instructions for shaking and dosing.
• Low sugar or sugar-free composition.
• Compatibility with nasogastric and gastrostomy tubes.
• A documented in-use stability period.
• A child-acceptable flavor system.

A higher concentration increases convenience but also increases the risk of inaccurate dosing if the suspension is not uniform. Dose-volume reduction must therefore be supported by robust sedimentation and redispersion data.

What commercial opportunities exist for DIURIL injectable products?

The injectable opportunity is hospital-oriented and depends more on supply reliability than on consumer differentiation. Intravenous chlorothiazide is used when oral administration is not feasible or when rapid diuretic therapy is required in institutional settings.

Potential product improvements include:

• Faster reconstitution.
• Lower reconstitution volume.
• Clearer instructions for dilution and administration.
• Reduced particulate risk.
• Improved vial labeling and barcode compatibility.
• Ready-to-use or pharmacy-prepared presentations.
• Fewer preparation steps for intensive-care and neonatal units.
• Improved availability during generic shortages.

A ready-to-use solution would be more convenient but could create substantial stability, container-closure, sterilization, and pH challenges. A sterile liquid also introduces higher manufacturing and regulatory burdens than a lyophilized or powder-for-reconstitution product.

The more practical pathway may be an optimized sterile powder with faster reconstitution and improved packaging. Commercial differentiation could come from vial size, reconstitution device, preservative-free design, and hospital procurement reliability.

What FDA regulatory pathway applies to a new DIURIL formulation?

A chlorothiazide product that relies on the established active ingredient could use an abbreviated pathway if it qualifies as a generic equivalent to a listed drug. The regulatory strategy depends on whether the product is an equivalent dosage form, a materially different formulation, or a new dosage form with new clinical claims.

Product concept	Likely regulatory issue
Conventional tablet equivalent	ANDA, bioequivalence, quality and CMC requirements
New tablet excipient system	ANDA if equivalence is maintained; formulation-specific CMC review
New oral suspension	Comparative performance, assay uniformity, particle-size and stability data
New concentration	Dose-equivalence and labeling implications
Preservative-free multidose suspension	Microbiological and in-use stability burden
New injectable presentation	Sterility, endotoxin, particulate, reconstitution, stability, container closure
Modified-release product	More complex bioequivalence and potentially clinical development
New pediatric formulation	Pediatric labeling and formulation data; pathway depends on product design

The FDA Orange Book remains the source for reference-listed-drug status, therapeutic-equivalence codes, patent listings, and exclusivity information. DailyMed provides the current labeling record for marketed products and their inactive ingredients.[1-3]

What patents protect DIURIL and how strong is the patent estate?

DIURIL is a legacy small-molecule product. The original composition, active-ingredient, and basic formulation rights are expected to be expired. The commercial market is therefore driven by generic competition, manufacturing economics, regulatory execution, and supply reliability rather than by an active foundational patent estate.

The remaining IP opportunity is formulation-specific. A company could seek protection for:

• A stable chlorothiazide suspension with defined particle-size distribution.
• A low-viscosity vehicle with specified redispersion performance.
• A taste-masking system.
• A concentrated pediatric formulation.
• A preservative-free multidose package with validated in-use stability.
• A reconstitutable injectable product with improved dissolution or storage characteristics.
• A device-plus-formulation combination.
• A manufacturing process that controls polymorph, particle size, or agglomeration.

These claims must be drafted around measurable technical features. A patent directed only to routine excipient substitution is vulnerable to obviousness challenges. Stronger claims would link the excipient system to unexpected stability, dissolution, dose uniformity, taste reduction, or manufacturing performance.

Patent and exclusivity profile

Protection category	DIURIL commercial relevance
Original chlorothiazide composition claims	Expired or commercially obsolete
Original brand exclusivity	No current practical barrier to generic entry
Orange Book-listed formulation patents	Product-specific review required; no assumption should be made from the brand name alone
Method-of-use patents	Limited value for a mature diuretic unless tied to a differentiated labeled use
New formulation patents	Potentially relevant for a reformulated product
Regulatory exclusivity	Generally not expected for a conventional chlorothiazide generic
Biosimilar protection	Not applicable because chlorothiazide is a small molecule

When does DIURIL lose exclusivity and what generic entry risks exist?

The original DIURIL exclusivity period has long expired. Generic chlorothiazide products compete in tablets and liquid presentations, and the principal entry risks are price erosion, substitution, manufacturing disruption, and state or institutional formulary preference.

Generic entry risk is highest for a conventional tablet with no meaningful delivery advantage. A new entrant would need either:

• Lower cost of goods.
• A reliable shortage-resilient supply position.
• A differentiated oral suspension.
• A hospital-focused injectable offering.
• A customer-specific packaging or distribution model.
• An excipient profile that solves a recognized patient or institutional problem.

A formulation patent can delay direct copying of a specific product, but it will not prevent competitors from selling conventional chlorothiazide dosage forms outside the patent scope.

Which companies compete with DIURIL and chlorothiazide products?

Competition occurs across brand, generic, contract manufacturing, and hospital-distribution channels. The relevant competitive set includes:

• The DIURIL brand holder and its authorized distributors.
• Generic manufacturers of chlorothiazide tablets.
• Manufacturers of chlorothiazide oral suspension.
• Sterile injectable suppliers.
• Compounding pharmacies and hospital pharmacies, particularly where commercial liquid availability is limited.
• Other thiazide and thiazide-like diuretics, including hydrochlorothiazide, chlorthalidone, and metolazone.

Chlorothiazide competes clinically with inexpensive alternatives. Hydrochlorothiazide has much broader generic availability and stronger prescriber familiarity. Chlorthalidone competes in hypertension because of its long duration of action. Chlorothiazide retains a niche where its established dosing, intravenous availability, or liquid presentation fits the clinical setting.

How does DIURIL compare with competing thiazide products?

Factor	Chlorothiazide/DIURIL	Hydrochlorothiazide	Chlorthalidone
Market maturity	Mature generic market	Very mature generic market	Mature generic market
Oral liquid opportunity	More relevant due to limited commercial options in some channels	Broader availability in some markets	Less commonly available as a liquid
IV opportunity	Commercially relevant in hospitals	Limited compared with oral use	Primarily oral
Formulation challenge	Solubility, taste, suspension uniformity	Similar liquid-development issues but larger market	Dose and release control
Price pressure	High	Very high	High
Differentiation path	Pediatric liquid, injectable workflow, supply reliability	Convenience and combination products	Long-acting clinical positioning
Patent leverage	Weak foundational estate	Weak foundational estate	Weak foundational estate

The commercial case for DIURIL is strongest where formulation and distribution solve a problem that a conventional tablet does not solve.

What licensing deals and partnerships could create value?

Licensing value is more likely to arise from formulation technology, manufacturing capacity, or distribution rights than from the chlorothiazide molecule. Relevant deal structures include:

• Licensing a taste-masking platform for a pediatric suspension.
• Contract development and manufacturing of a sterile injectable.
• Regional rights for an oral liquid presentation.
• Hospital-channel distribution partnerships.
• Co-development with a pediatric specialty company.
• Supply agreements with group purchasing organizations.
• Technology transfer for a low-cost direct-compression tablet platform.

A license should be priced against the incremental market created by the formulation. Because conventional chlorothiazide has low unit economics, royalty-bearing arrangements require either substantial volume, a differentiated dosage form, or a shortage-driven hospital opportunity.

What manufacturing and IP barriers affect DIURIL commercialization?

The primary barriers are technical and operational:

• Chlorothiazide particle-size variability.
• Poor wetting and agglomeration in liquid products.
• Taste masking at therapeutically relevant concentrations.
• Suspension sedimentation and hard-cake formation.
• High tablet drug loading.
• Sterile manufacturing capacity for injectable products.
• Reconstitution time and particulate control.
• In-use microbiological stability.
• Tube and syringe compatibility.
• Reliable API sourcing and impurity control.
• Demonstrating equivalence for a formulation that differs materially from the reference product.

The most defensible commercial position combines a formulation patent with manufacturing know-how. A patent covering a suspension composition may be designed around by changing the polymer or sweetener. A validated manufacturing process, tight particle-size specification, and reliable sterile or liquid supply chain are harder to replicate quickly.

What is the revenue exposure and market potential for a DIURIL reformulation?

A conventional tablet launch would face severe price pressure and limited revenue upside. An oral suspension can support higher pricing if it replaces pharmacy compounding, improves pediatric administration, or secures hospital and long-term-care contracts. Injectable products can command stronger institutional value when they reduce preparation time or address supply shortages.

Opportunity	Revenue potential	Margin potential	Main risk
Commodity tablet	Low	Low	Immediate generic price competition
Lactose-free tablet	Low to moderate	Moderate	Weak willingness to pay
Pediatric oral suspension	Moderate	Moderate to high	Taste and stability failure
Concentrated oral suspension	Moderate	High if clinically accepted	Dose-uniformity risk
Preservative-free liquid	Moderate	Moderate	Packaging and microbiology burden
Optimized injectable	Moderate to high	Moderate to high	Sterile manufacturing and procurement concentration
Ready-to-use injectable	High potential	High potential	Stability and regulatory complexity
Hospital shortage-resilient supply	Variable	Moderate	Demand volatility

Key Takeaways

• DIURIL is chlorothiazide, a mature small-molecule product with no meaningful foundational exclusivity.
• Excipient strategy, not active-ingredient patent protection, is the main route to differentiation.
• Oral suspension is the clearest opportunity because of taste, solubility, dose-volume, and redispersion challenges.
• Pediatric and enteral-administration products can create value by reducing compounding and dosing burdens.
• Injectable chlorothiazide offers a hospital opportunity centered on reconstitution, packaging, sterility, and supply reliability.
• A new excipient patent needs measurable performance advantages, not routine ingredient substitution.
• Conventional tablets have the highest generic-entry risk and the lowest likely pricing power.
• The strongest commercial model combines formulation IP, manufacturing know-how, and institutional distribution.

FAQs about DIURIL excipient strategy

Can chlorothiazide be formulated as a sugar-free oral suspension?

Yes. A sugar-free system could use polyols and high-intensity sweeteners, but the formulation must address viscosity, taste, preservative efficacy, osmolality, and gastrointestinal tolerability.

Is a chlorothiazide oral suspension suitable for feeding tubes?

It can be, but tube compatibility must be demonstrated. The product should be tested for dose recovery, clogging, adsorption, flushing requirements, and suspension uniformity after administration through relevant tube sizes.

Can a new DIURIL formulation obtain patent protection?

Yes, but protection would generally need to cover a novel composition, manufacturing process, delivery system, or demonstrably superior performance profile. Routine substitution of one conventional excipient for another is vulnerable to invalidity challenges.

Is chlorothiazide a biosimilar opportunity?

No. Chlorothiazide is a chemically synthesized small molecule. The relevant regulatory pathway is generally generic drug approval rather than biosimilar approval.

What is the best commercial dosage form for a new chlorothiazide product?

A differentiated oral suspension is the most accessible opportunity. An optimized injectable may offer greater institutional value, but it requires more complex sterile manufacturing, stability, and regulatory development.

References

1. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
2. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs database. FDA.
3. National Library of Medicine. (2024). DailyMed: Current medication information. U.S. National Library of Medicine.
4. U.S. Food and Drug Administration. (2016). Inactive ingredient database. FDA.
5. United States Pharmacopeia. (2024). United States Pharmacopeia and National Formulary. U.S. Pharmacopeial Convention.
6. U.S. Food and Drug Administration. (2013). Guidance for industry: Bioequivalence studies with pharmacokinetic endpoints for drugs submitted under an ANDA. FDA.