When do the patents on DYAZIDE expire, and when will DYAZIDE go generic?

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Glaxosmithkline Llc	DYAZIDE	hydrochlorothiazide; triamterene	CAPSULE;ORAL	016042-003	Mar 3, 1994		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Glaxosmithkline Llc	DYAZIDE	hydrochlorothiazide; triamterene	CAPSULE;ORAL	016042-002	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: November 3, 2026

DYAZIDE is the branded combination of triamterene and hydrochlorothiazide, used for hypertension and edema when potassium loss from a thiazide diuretic is a concern. Its commercial profile is mature and largely genericized. The product has no meaningful current patent moat, no biologic or biosimilar exposure, and limited standalone financial visibility. Market value is concentrated in low-cost generic prescriptions, contract manufacturing, pharmacy sourcing, and combination-diuretic demand rather than branded pricing power.

What is DYAZIDE and how is it used?

DYAZIDE combines two diuretics:

Component	Pharmacologic role
Hydrochlorothiazide	Thiazide diuretic that promotes sodium and water excretion
Triamterene	Potassium-sparing diuretic that reduces potassium loss

The combination is indicated for hypertension or edema in patients who require a thiazide but are at risk of hypokalemia. The U.S. product historically was marketed in capsule form, commonly as 25 mg triamterene/37.5 mg hydrochlorothiazide and 50 mg triamterene/25 mg hydrochlorothiazide, although current availability depends on manufacturer and distributor listings.

The product has a distinctive clinical position because it combines potassium conservation with thiazide diuresis. That advantage is limited commercially by inexpensive substitutes, including separate triamterene and hydrochlorothiazide tablets, other potassium-sparing combinations, and newer antihypertensive regimens.

What is the FDA regulatory status of DYAZIDE?

DYAZIDE was approved through a new drug application, NDA 018045, according to FDA drug-product records. The product is a small-molecule, orally administered prescription drug and is not subject to the biologics licensing framework that governs biosimilar competition.[1]

The central regulatory distinction is between the historical brand and current generic products:

Regulatory issue	DYAZIDE status
FDA pathway	Original NDA
Active ingredients	Triamterene and hydrochlorothiazide
Dosage form	Oral capsule and equivalent generic dosage forms
Biologic status	Not applicable
Biosimilar pathway	Not applicable
Generic pathway	Abbreviated New Drug Application, or ANDA
Current competitive structure	Multiple generic equivalents and therapeutic substitutes

The FDA Orange Book identifies approved products and therapeutic-equivalence information. For a mature combination such as triamterene/hydrochlorothiazide, the commercial market is generally driven by ANDA products rather than by the original NDA holder.[2]

What patents protect DYAZIDE?

No currently material U.S. patent barrier is associated with DYAZIDE's commercial market. The original composition and product claims are long expired, and the active ingredients have been used in generic products for decades.

Are there active Orange Book patents for DYAZIDE?

The practical answer is no for current generic-entry analysis. DYAZIDE does not present the type of active, late-life Orange Book patent estate associated with newer branded medicines. Generic applicants therefore do not face a commercially relevant patent term extending the product's exclusivity.

The historical patent estate likely covered the combination, formulation, or methods of use associated with the original product. Those rights would have expired many years ago. Any historical patent numbers would have limited present-day value because the relevant protection period has ended.

Patent issue	Commercial assessment
Composition-of-matter protection	Expired
Combination-product protection	Expired
Formulation protection	Expired or commercially immaterial
Method-of-use protection	Expired or commercially immaterial
Orange Book patent leverage	None of practical significance
Patent litigation risk	Low

When did DYAZIDE lose exclusivity?

DYAZIDE lost meaningful market exclusivity decades ago. The relevant event was the entry of approved generic triamterene/hydrochlorothiazide products, not a recent patent expiration.

Because the product is an old small-molecule combination, its commercial loss of exclusivity preceded the modern branded-drug pricing model in which a company protects revenue through sequential formulation patents, pediatric extensions, and settlement agreements. The product therefore has no current exclusivity period that would delay ANDA competition.

Does DYAZIDE have FDA exclusivity today?

No material FDA regulatory exclusivity is associated with the mature DYAZIDE product. New chemical entity exclusivity is not relevant because triamterene and hydrochlorothiazide are long-established active ingredients. Orphan-drug exclusivity, pediatric exclusivity, and generic exclusivity do not provide the brand with a current commercial barrier.

How many patents cover DYAZIDE?

There is no meaningful active patent estate covering DYAZIDE in the United States. Historical patent documents may appear in patent databases, but their existence should not be confused with enforceable current rights.

Patent strength is therefore low:

Patent-strength factor	Assessment
Remaining term	None of commercial importance
Claim breadth	Not relevant to current entry
Design-around difficulty	Low
Manufacturing patent barrier	Low
Formulation patent barrier	Low
Litigation leverage	Low

The absence of patent protection does not eliminate technical barriers. A generic applicant must still demonstrate pharmaceutical equivalence, bioequivalence, manufacturing quality, stability, dissolution performance, and compliance with current FDA quality standards. Those are regulatory execution requirements, not exclusivity rights.

Which companies are challenging DYAZIDE?

DYAZIDE is not a current branded litigation target in the manner of a high-revenue protected drug. Generic competition has already been established.

Generic manufacturers and labelers have historically included companies that market triamterene/hydrochlorothiazide products under their own labels or through distribution arrangements. The relevant competitive set can change as manufacturers discontinue, reintroduce, or transfer products. The market includes large generic suppliers, specialty generic companies, contract manufacturers, and private-label distributors.

There is no meaningful current Paragraph IV campaign directed at a live DYAZIDE patent estate. Paragraph IV certifications matter when an ANDA applicant challenges an unexpired Orange Book patent. That fact pattern does not define DYAZIDE's present market.

What litigation affects DYAZIDE?

No major current patent litigation is central to the product's U.S. commercial outlook. The historical generic-entry disputes associated with old diuretic combinations do not create current barriers.

The litigation risk that remains is ordinary pharmaceutical product liability, manufacturing compliance, labeling, pharmacy substitution, and potential antitrust or contracting disputes. Those risks are materially different from patent-enforcement risk and generally do not support branded pricing.

What formulations are protected by DYAZIDE patents?

No current commercially meaningful formulation protection is evident. The combination is available in conventional immediate-release oral dosage forms. There is no widely recognized extended-release, transdermal, injectable, inhaled, or device-based DYAZIDE formulation supporting a separate high-value franchise.

This limits lifecycle-management opportunities. A company cannot readily defend the original product through a differentiated delivery system because the market's established clinical use is based on a simple oral combination whose technical profile is familiar to generic manufacturers.

How does DYAZIDE compare with competing diuretic products?

DYAZIDE competes against both direct generic equivalents and broader hypertension treatments.

Product or class	Competitive relationship
Generic triamterene/hydrochlorothiazide	Direct substitute
Separate triamterene plus hydrochlorothiazide	Therapeutic and prescribing substitute
Spironolactone	Potassium-sparing alternative with different clinical profile
Amiloride/hydrochlorothiazide	Combination alternative
Hydrochlorothiazide alone	Lower-cost thiazide alternative
Chlorthalidone	Longer-acting thiazide-like alternative
ACE inhibitors, ARBs, calcium-channel blockers	Major alternatives for hypertension
Loop diuretics	Alternative for selected edema indications

DYAZIDE's main residual advantage is prescribing familiarity and convenience. Its disadvantages include hyperkalemia risk, renal monitoring requirements, drug-interaction concerns, and the availability of newer antihypertensive options.

What is the financial trajectory of DYAZIDE?

The financial trajectory is that of a late-life genericized medicine:

Initial brand growth followed adoption of the combination for hypertension and edema.
Generic entry reduced price and transferred volume away from the branded product.
Long-term demand stabilized at a low-cost maintenance level.
Revenue became fragmented among generic manufacturers, distributors, pharmacies, and payers.
Any remaining brand revenue became small relative to the market for newer cardiovascular medicines.

Standalone DYAZIDE revenue is not generally disclosed in public filings by major pharmaceutical companies. The brand is not a major reported revenue segment for a large public company, and generic sales are usually reported within broader portfolios rather than by product.

Is DYAZIDE commercially material to a pharmaceutical company?

Not as a standalone brand. Its economic value is more likely to arise from portfolio aggregation, manufacturing utilization, distribution contracts, and generic-market share than from brand-level pricing.

Financial metric	Current interpretation
Brand pricing power	Minimal
Revenue concentration	Fragmented
Gross-margin potential	Low to moderate, depending on supply position
Prescription demand	Mature and relatively stable
Reimbursement sensitivity	High
Promotional spending	Limited
Patent-driven valuation	None
Acquisition value	Portfolio-based rather than product-based

The product may remain commercially useful for a generic company with efficient manufacturing, reliable supply, and a broad institutional or retail distribution network. It is unlikely to support a standalone growth investment thesis.

What generic entry risks exist for DYAZIDE?

Generic entry is already established, so the principal risk is not future launch but continued price erosion and supply substitution.

Market risks

Additional ANDA suppliers can reduce average selling prices.
Pharmacy benefit managers and wholesalers can shift volume toward lower-cost manufacturers.
Product discontinuations can create temporary shortages but do not necessarily restore durable pricing power.
State substitution rules and therapeutic interchange can favor generic products.
Consolidation among generic manufacturers can increase customer bargaining power.
FDA manufacturing observations can disrupt a supplier's market share.

Manufacturing and IP barriers

The active ingredients are established and technically conventional. The major barriers are:

sourcing qualified triamterene and hydrochlorothiazide API;
controlling blend uniformity and dissolution;
maintaining capsule or tablet content uniformity;
demonstrating stability across the labeled shelf life;
meeting FDA cGMP requirements;
maintaining reliable packaging and serialization;
avoiding supply interruptions.

These barriers can affect individual manufacturers but do not protect the product from competition as a class.

What is the geographic coverage of DYAZIDE?

The product concept has international equivalents, but brand names, dosage strengths, regulatory approvals, and market availability differ by country. U.S. commercial analysis should not be extrapolated directly to Europe, Canada, or emerging markets.

Geographic value is limited by:

local generic approval requirements;
national reimbursement pricing;
reference-pricing systems;
local manufacturing rules;
tender procurement;
differing availability of triamterene combinations;
national labeling and pharmacovigilance requirements.

In most developed markets, the combination is a mature generic product. In lower-income markets, demand may persist where low-cost oral diuretics remain important, but pricing and procurement conditions constrain revenue.

What licensing deals affect DYAZIDE?

No major current licensing transaction is central to DYAZIDE's market outlook. The product is not associated with a publicly visible technology license, co-development alliance, or strategic acquisition thesis comparable to newer specialty drugs.

Any licensing or supply agreements involving triamterene/hydrochlorothiazide would likely concern manufacturing, private labeling, distribution, or portfolio transfers. Those arrangements generally affect individual suppliers rather than the overall exclusivity position.

What is the outlook for DYAZIDE?

DYAZIDE is a stable but low-growth mature medicine. Demand should remain tied to hypertension and edema treatment, but volume growth is constrained by generic substitution and competition from alternative cardiovascular therapies.

The most probable commercial scenario is continued low-price availability with periodic supplier turnover. A shortage, manufacturer exit, or distribution disruption could produce temporary price increases. Such events would be supply-driven and reversible, not evidence of renewed brand strength.

Generic launch scenarios

Scenario	Likely outcome
Additional generic supplier entry	Lower prices and greater pharmacy substitution
Supplier consolidation	More concentrated supply and episodic shortages
Brand relaunch	Limited uptake without a differentiated clinical or delivery proposition
New formulation	Potential niche value only if clinically meaningful and patentable
Manufacturing disruption	Temporary allocation pressure, with replacement suppliers likely
Reimbursement tightening	Lower net prices and reduced manufacturer margins

Key Takeaways

DYAZIDE is the legacy triamterene/hydrochlorothiazide combination.
Its U.S. market is mature, genericized, and highly price-sensitive.
No commercially meaningful active Orange Book patent estate protects the product.
Paragraph IV litigation and patent-settlement risk are not central to current competition.
Formulation, method-of-use, and manufacturing patents do not provide a durable current moat.
Standalone DYAZIDE revenue is not generally disclosed and is unlikely to be material for a major pharmaceutical company.
The product's remaining value is portfolio-based, supported by generic demand and manufacturing efficiency.
Future commercial volatility will be driven mainly by supplier exits, shortages, reimbursement, and purchasing concentration.
Biosimilar risk is inapplicable because DYAZIDE is a conventional small-molecule drug, not a biologic.

FAQs

Is DYAZIDE still available in the United States?

Generic triamterene/hydrochlorothiazide products are available, while the branded product's availability may vary by manufacturer, wholesaler, and pharmacy inventory.

Is triamterene/hydrochlorothiazide therapeutically equivalent to DYAZIDE?

FDA-approved generic products may be therapeutically equivalent when they carry the applicable Orange Book rating and meet FDA equivalence requirements. Product-specific availability and rating should be checked in current FDA listings.[2]

Can a company obtain new patents on a DYAZIDE reformulation?

A new formulation could receive patent protection only if it satisfies patentability requirements and has adequate technical and clinical support. The original combination itself does not provide a new exclusivity period.

Does DYAZIDE have biosimilar competition?

No. Biosimilars apply to biological products. DYAZIDE is a small-molecule oral combination and competes through generic-drug pathways.

What is the main investment risk in a DYAZIDE manufacturer?

The principal risks are low pricing, customer concentration, API or finished-dose supply disruption, FDA manufacturing action, and portfolio-level margin compression. Patent expiry is not a new risk because exclusivity has already ended.

References

U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.). Electronic Orange Book data files. https://www.fda.gov/drugs/drug-approvals-and-databases/orange-book-data-files
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application approvals. https://www.fda.gov/drugs/generic-drugs/abbreviated-new-drug-application-anda-approvals
DailyMed. (n.d.). Triamterene and hydrochlorothiazide drug labeling. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	6
Clinical Trials:	1
Patent Applications:	177
Drug Prices:	Drug price information for DYAZIDE
What excipients (inactive ingredients) are in DYAZIDE?	DYAZIDE excipients list
DailyMed Link:	DYAZIDE at DailyMed

DYAZIDE Drug Patent Profile

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