CHLOROTHIAZIDE Drug Patent Profile

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When do Chlorothiazide patents expire, and what generic alternatives are available?

Chlorothiazide is a drug marketed by Abc Holding, Hikma, Lederle, Pharmobedient, Sandoz, Watson Labs, Am Regent, Fresenius Kabi Usa, Gland, Rk Pharma, Sagent Pharms Inc, and Sun Pharm. and is included in twenty-three NDAs.

The generic ingredient in CHLOROTHIAZIDE is chlorothiazide sodium. There are three drug master file entries for this compound. Five suppliers are listed for this compound. Additional details are available on the chlorothiazide sodium profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Chlorothiazide

A generic version of CHLOROTHIAZIDE was approved as chlorothiazide sodium by FRESENIUS KABI USA on October 16^th, 2009.

Summary for CHLOROTHIAZIDE

US Patents:	0
Applicants:	12
NDAs:	23
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	8
Patent Applications:	4,306
Drug Prices:	Drug price information for CHLOROTHIAZIDE
DailyMed Link:	CHLOROTHIAZIDE at DailyMed

See drug prices for CHLOROTHIAZIDE

Recent Clinical Trials for CHLOROTHIAZIDE

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
University of Virginia	Phase 4
Vanderbilt University	Phase 4
National Heart, Lung, and Blood Institute (NHLBI)	Phase 1

See all CHLOROTHIAZIDE clinical trials

Medical Subject Heading (MeSH) Categories for CHLOROTHIAZIDE

Antihypertensive Agents

Diuretics

Sodium Chloride Symporter Inhibitors

Anatomical Therapeutic Chemical (ATC) Classes for CHLOROTHIAZIDE

C03AA	Thiazides, plain
C03A	LOW-CEILING DIURETICS, THIAZIDES
C03	DIURETICS
C	Cardiovascular system

US Patents and Regulatory Information for CHLOROTHIAZIDE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Abc Holding	CHLOROTHIAZIDE	chlorothiazide	TABLET;ORAL	085569-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Gland	CHLOROTHIAZIDE SODIUM	chlorothiazide sodium	INJECTABLE;INJECTION	218630-001	Oct 3, 2024	AP	RX	No	No
Pharmobedient	CHLOROTHIAZIDE-RESERPINE	chlorothiazide; reserpine	TABLET;ORAL	087744-001	May 6, 1982		DISCN	No	No
Pharmobedient	CHLOROTHIAZIDE	chlorothiazide	TABLET;ORAL	084217-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Chlorothiazide Market Dynamics, Financial Trajectory, Patents, and Generic Competition

Last updated: September 2, 2026

Chlorothiazide is a mature thiazide diuretic with limited branded revenue, extensive generic competition, and no meaningful remaining composition-of-matter exclusivity. Its commercial value is concentrated in low-cost oral products and hospital injectable supply. Financial performance depends more on manufacturing continuity, contract pricing, wholesaler access, and shortage conditions than on patent protection or clinical differentiation.

What is the current FDA status of chlorothiazide?

Chlorothiazide is an FDA-approved thiazide diuretic used to treat hypertension and edema associated with congestive heart failure, renal disorders, and hepatic disease. It is marketed in oral tablets, oral suspension, and injectable form as chlorothiazide sodium [1].

Product characteristic	Chlorothiazide status
Active ingredient	Chlorothiazide
Drug class	Thiazide diuretic
Original U.S. approval	1950s
Common brand	Diuril
Oral strengths	250 mg and 500 mg tablets
Oral liquid	250 mg/5 mL suspension
Injectable product	Chlorothiazide sodium injection, commonly 500 mg
FDA pathway today	Abbreviated New Drug Application, or ANDA, for generic products
Prescription status	Prescription-only
Biosimilar pathway	Not applicable
Primary markets	United States and international generic markets

The product’s long history places it in the mature-generic segment. FDA labeling identifies chlorothiazide as an established therapy rather than a newly differentiated cardiovascular product [1]. It is used less frequently than hydrochlorothiazide in routine hypertension treatment, but it retains utility in edema management and inpatient care.

When did chlorothiazide lose exclusivity?

Chlorothiazide lost meaningful market exclusivity decades ago. The active ingredient was introduced in the 1950s, and any original composition or basic-use patents would have expired long before the modern 20-year patent term became the governing U.S. framework.

No commercially relevant patent exclusivity remains for the active molecule. Product sales are therefore exposed to standard generic competition, pharmacy substitution, hospital purchasing pressure, and reimbursement controls.

The commercial exclusivity timeline is materially different from that of a modern small-molecule drug:

Milestone	Commercial effect
1950s launch	Original branded product entered the diuretic market
1960s-1980s	Broad clinical adoption and expansion of generic manufacturing
1990s onward	Mature generic pricing and multiple suppliers
Current market	Low-cost generic market with limited brand premium
Future outlook	Continued price pressure, interrupted by supply constraints or shortages

The absence of patent protection does not eliminate commercial barriers. Manufacturers still must maintain FDA approval, comply with current good manufacturing practices, qualify suppliers, and demonstrate bioequivalence for oral products. Sterile injectable manufacturing has higher technical and regulatory barriers than tablet production.

What patents protect chlorothiazide?

No active U.S. patent estate is expected to protect the core chlorothiazide molecule or its basic therapeutic use. Historical patents associated with chlorothiazide’s discovery and early commercialization are expired.

Are formulation patents still important?

Formulation patent risk is limited. Chlorothiazide tablets and suspensions are conventional dosage forms, and the injectable product is a long-established sodium formulation. Any later patents covering particular excipients, packaging, manufacturing processes, or delivery systems would need to be evaluated individually, but they would not recreate broad exclusivity over chlorothiazide itself.

A manufacturer could seek protection for a narrow formulation or process, but such a patent would face several commercial constraints:

• The underlying active ingredient is off patent.
• Generic manufacturers can potentially design around narrow claims.
• A formulation patent would not necessarily block all tablets, suspensions, or injections.
• Patent-term remaining would be limited for any late-filed application.
• The low unit price reduces the economic incentive for extensive patent litigation.

Are method-of-use patents relevant?

Method-of-use patents are unlikely to create material market exclusivity for the conventional indications of hypertension and edema. These uses are long established and heavily described in the medical literature and FDA labeling [1]. A later patent would require a novel, non-obvious, and legally defensible use, such as a narrowly defined patient population or dosing protocol. No such use is generally recognized as a major commercial barrier for chlorothiazide.

What is the Orange Book status of chlorothiazide?

Chlorothiazide products may appear in FDA drug databases through brand and generic records, but the relevant commercial question is whether any listed patent or regulatory exclusivity blocks ANDA approval. For this mature drug, generic approval history and long-standing market availability indicate that no effective market-wide Orange Book barrier remains.

The Orange Book is most relevant to:

• Identifying reference-listed drugs.
• Reviewing listed patents for branded products.
• Assessing paragraph IV certification exposure.
• Confirming therapeutic equivalence ratings.
• Tracking discontinued or active product records.

Because chlorothiazide has been available generically for many years, a new ANDA applicant would generally face a standard generic approval process rather than a contested launch against a live compound patent. FDA’s Orange Book framework distinguishes therapeutic equivalence from patent protection; an “AB” rating supports pharmacy substitution where state law and payer policy permit it [2].

Which companies manufacture or market chlorothiazide?

The market includes brand, generic, and hospital-oriented suppliers. Manufacturing participation can change as companies discontinue low-volume products, transfer applications, or outsource production.

Supplier category	Typical commercial role
Brand manufacturer	Maintains the Diuril brand where marketed
Generic tablet manufacturer	Supplies 250 mg and 500 mg tablets
Generic liquid manufacturer	Supplies oral suspension for patients unable to use tablets
Sterile injectable manufacturer	Supplies chlorothiazide sodium injection to hospitals
Contract manufacturer	Produces finished dosage forms for marketing authorization holders
Wholesaler or repackager	Distributes products under repackaged labels

The brand Diuril product has limited ability to sustain a premium against generic tablets. Brand economics may remain stronger in institutional purchasing or in dosage forms with fewer suppliers, particularly injectable chlorothiazide sodium.

Public FDA records, including Drugs@FDA and DailyMed, are the appropriate sources for identifying active labelers, application holders, package sizes, and current prescribing information [1, 3]. Supplier participation should not be treated as permanent because mature generic manufacturers frequently rationalize low-margin products.

How does chlorothiazide compare with hydrochlorothiazide and chlorthalidone?

Chlorothiazide competes primarily with hydrochlorothiazide, chlorthalidone, indapamide, and loop diuretics. Its clinical and commercial position is weaker in routine hypertension but remains relevant in selected edema and inpatient applications.

Drug	Competitive position	Commercial profile
Chlorothiazide	Established thiazide for hypertension and edema; available orally and by injection	Mature generic; injectable supply can support higher value
Hydrochlorothiazide	Widely used in hypertension combinations	Larger generic volume and broader primary-care use
Chlorthalidone	Longer-acting thiazide-like diuretic	Strong clinical profile in hypertension; generic pricing
Indapamide	Thiazide-like agent used for hypertension	Smaller but differentiated prescription segment
Furosemide	Loop diuretic for stronger fluid removal	Broader use in acute and chronic volume overload
Metolazone	Often used with loop diuretics in resistant edema	Niche generic demand

Hydrochlorothiazide has greater routine hypertension penetration and appears frequently in fixed-dose combinations. Chlorthalidone has benefited from clinical interest in longer duration of action and blood-pressure control. Chlorothiazide’s differentiator is not patent protection; it is dosage-form availability, including injectable administration in hospital settings.

What is the financial trajectory for chlorothiazide?

No reliable standalone revenue series is generally disclosed by branded manufacturers or generic suppliers. Chlorothiazide is typically bundled within broader cardiovascular, hospital, or generic portfolios. Its financial trajectory must therefore be assessed through market structure rather than reported product revenue.

Historical trajectory

The product likely generated its highest economic value during the early branded period, when chlorothiazide was a relatively novel antihypertensive and diuretic. Revenue then shifted through three stages:

1. Branded innovation phase: High pricing relative to manufacturing cost and limited competition.
2. Generic expansion phase: Rapid price erosion as multiple manufacturers entered.
3. Mature supply phase: Low unit prices, stable clinical demand, and value concentrated in efficient production and reliable distribution.

Current revenue drivers

The principal revenue drivers are:

• Prescription volume for oral tablets.
• Institutional demand for oral suspension.
• Hospital demand for injectable chlorothiazide sodium.
• Number of approved suppliers.
• Availability of active pharmaceutical ingredient.
• Contracting with group purchasing organizations.
• Medicaid, Medicare, and commercial payer reimbursement.
• Supply shortages affecting competitor products.

Generic price erosion is usually most severe for standard tablets with several approved suppliers. Liquid and injectable products can maintain better pricing because manufacturing, packaging, sterility, and supply qualification are more complex.

Financial sensitivity

Variable	Effect on chlorothiazide economics
Additional tablet entrants	Lower average selling price
Supplier discontinuation	Potential volume transfer and temporary price increases
Injectable shortage	Higher near-term demand and stronger pricing
API cost inflation	Margin compression
Hospital contract loss	Material volume decline for injection
Brand substitution	Lower Diuril share
Reimbursement cuts	Lower net realized price
Manufacturing failure	High risk of lost institutional business

The product is unlikely to be a meaningful growth asset for a large pharmaceutical company. It can be a useful portfolio product for a generic manufacturer with established oral-solid and sterile-injectable infrastructure.

What generic entry risks exist for chlorothiazide?

Generic entry risk is structurally high because the core molecule is unprotected and the product has a long clinical history. The relevant risk is not a future first generic launch; it is continued price competition and supplier turnover.

Oral tablets

Tablet supply has the lowest technical barrier. Bioequivalence requirements are established, and multiple manufacturers can potentially compete. A new approved entrant would likely reduce pricing unless the market has experienced supplier exits.

Oral suspension

Suspension products require control of particle size, uniformity, sedimentation, redispersibility, preservative performance, and dosing accuracy. These requirements create more manufacturing complexity than tablets. The market remains generic, but fewer qualified suppliers can support better pricing than in the tablet segment.

Injectable chlorothiazide sodium

The injection has the highest operational barrier. Sterile manufacturing, container closure integrity, endotoxin control, aseptic processing, and hospital procurement requirements limit the number of credible suppliers. The product may have greater commercial resilience than tablets, even without patent protection.

What patent litigation and Paragraph IV challenges affect chlorothiazide?

No major active Paragraph IV litigation is generally associated with chlorothiazide’s core product. Paragraph IV litigation is most relevant when an ANDA applicant challenges an unexpired listed patent. Chlorothiazide’s long market history and generic availability make a new compound-patent challenge unlikely.

Potential disputes would more likely involve:

• Product-specific labeling claims.
• Narrow formulation patents.
• Manufacturing-process patents.
• Trade-secret allegations involving sterile production.
• FDA approval or manufacturing compliance.
• Contract disputes over supply and distribution.

The absence of major patent litigation reduces legal cost and launch uncertainty. It does not eliminate regulatory risk. FDA inspection findings, product recalls, warning letters, and drug-shortage investigations can affect commercial continuity without involving patent law [3, 4].

Are biosimilar risks relevant to chlorothiazide?

Biosimilar risk is not relevant. Chlorothiazide is a chemically synthesized small molecule, not a biological product regulated through the biosimilar pathway under the Public Health Service Act.

Its competitive risks come from:

• ANDA-approved generics.
• Therapeutic substitution by other diuretics.
• Hospital formulary decisions.
• Fixed-dose combination products.
• Clinical preference for chlorthalidone or hydrochlorothiazide.
• Supplier consolidation and manufacturing exits.

What licensing deals affect chlorothiazide?

Large strategic licensing deals are unlikely to be material. Chlorothiazide is a low-cost generic with no active compound patent moat. Commercial arrangements are more likely to involve:

• Contract manufacturing.
• Authorized generic distribution.
• Product acquisition transactions.
• Regional marketing rights.
• Wholesale supply agreements.
• Hospital group purchasing contracts.

The economic value of a licensing deal would depend on manufacturing access and distribution scale rather than on intellectual property. Sterile injectable rights could command greater strategic interest than ordinary tablet rights because hospitals prioritize continuity and may have fewer qualified suppliers.

What geographic markets are most important?

The United States is commercially relevant because of its large prescription market, established generic substitution rules, hospital procurement infrastructure, and FDA shortage monitoring. International markets vary by regulatory status, local generic competition, reimbursement, and availability of thiazide alternatives.

Geographic considerations include:

• U.S. FDA-approved tablets, suspension, and injection.
• European national authorization and pricing systems.
• Emerging markets where older diuretics remain widely used.
• Countries with limited sterile-injectable capacity.
• Markets where brand prescribing remains more common.
• Regions dependent on imported active pharmaceutical ingredient or finished product.

The strongest geographic barrier is usually regulatory and manufacturing compliance, not patent coverage.

How strong is the chlorothiazide patent estate?

The patent estate is weak from a blocking perspective and irrelevant to broad market exclusivity. The product has:

• No expected active composition-of-matter protection.
• No meaningful exclusivity for conventional hypertension or edema uses.
• Limited practical value from narrow formulation claims.
• High generic substitution exposure.
• Greater protection from manufacturing complexity in injection than from patents.

A commercial diligence review should focus on FDA approval status, supplier count, shortage history, manufacturing sites, recalls, and hospital contracts. Patent searching remains appropriate for specific labelers and dosage forms, but patent risk should not be the central valuation variable.

What generic launch scenarios are most likely?

Three scenarios dominate the mature chlorothiazide market.

Scenario	Likely outcome
Stable multi-supplier tablet market	Continued low pricing and limited revenue growth
Supplier exits or manufacturing disruption	Temporary price increases and volume reallocation
Injectable supply tightening	Higher hospital value and stronger margins for reliable suppliers

The most attractive opportunity is operational rather than intellectual-property driven: maintaining supply of a difficult-to-source dosage form while competitors experience production interruptions.

Key Takeaways

• Chlorothiazide is a mature generic thiazide diuretic with no meaningful remaining compound exclusivity.
• The main U.S. products are tablets, oral suspension, and chlorothiazide sodium injection.
• No major active Paragraph IV or patent litigation risk is generally associated with the core product.
• Oral tablets face heavy price competition and limited differentiation.
• Oral suspension and injectable products have higher manufacturing barriers and may offer stronger margins.
• Standalone product revenue is not generally disclosed by major manufacturers.
• Financial performance depends on supply reliability, manufacturing cost, institutional contracts, and generic supplier concentration.
• Biosimilar competition does not apply.
• Hydrochlorothiazide and chlorthalidone are the most important therapeutic and commercial competitors.
• The strongest investment thesis is a supply-constrained generic or sterile-injectable position, not a patent-backed growth strategy.

FAQs About Chlorothiazide Market and Exclusivity

Is chlorothiazide still sold under the Diuril brand?

Yes. Diuril is the established brand associated with chlorothiazide, although generic products account for much of the market and brand availability can vary by dosage form and supplier [1].

Does chlorothiazide have a 30-month Paragraph IV stay risk?

A 30-month stay generally requires litigation based on an unexpired Orange Book-listed patent. Because chlorothiazide is a long-established generic product, broad 30-month patent litigation risk is low.

Which chlorothiazide dosage form has the strongest commercial position?

Injectable chlorothiazide sodium generally has the strongest supply-based position because sterile manufacturing is more difficult and hospital sourcing is less interchangeable than tablet purchasing.

Can chlorothiazide prices increase despite the absence of patents?

Yes. Generic prices can rise when manufacturers exit, active pharmaceutical ingredient supply is disrupted, production capacity is constrained, or hospitals face shortages.

Is chlorothiazide included in fixed-dose combination products?

Chlorothiazide is less prominent in fixed-dose combinations than hydrochlorothiazide. Its commercial use is more closely associated with standalone oral therapy, edema treatment, and injectable hospital use.

References

1. U.S. Food and Drug Administration. (n.d.). Diuril (chlorothiazide sodium) prescribing information. DailyMed. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (2023). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book

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. (n.d.). Drug shortages. https://www.accessdata.fda.gov/scripts/drugshortages/