HYDROCHLOROTHIAZIDE; RESERPINE - Generic Drug Details

What are the generic drug sources for hydrochlorothiazide; reserpine and what is the scope of patent protection?

Hydrochlorothiazide; reserpine is the generic ingredient in eleven branded drugs marketed by Whiteworth Town Plsn, Abc Holding, Sandoz, Ivax Sub Teva Pharms, Pharmeral, Roxane, Watson Labs, Merck, Barr, West Ward, and Novartis, and is included in twenty-three NDAs. Additional information is available in the individual branded drug profile pages.

Summary for HYDROCHLOROTHIAZIDE; RESERPINE

US Patents:	0
Tradenames:	11
Applicants:	11
NDAs:	23
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	2
DailyMed Link:	HYDROCHLOROTHIAZIDE; RESERPINE at DailyMed

Recent Clinical Trials for HYDROCHLOROTHIAZIDE; RESERPINE

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

Sponsor	Phase
West China Hospital	Phase 4
US Department of Veterans Affairs
VA Office of Research and Development

See all HYDROCHLOROTHIAZIDE; RESERPINE clinical trials

Anatomical Therapeutic Chemical (ATC) Classes for HYDROCHLOROTHIAZIDE; RESERPINE

C02AA	Rauwolfia alkaloids
C02A	ANTIADRENERGIC AGENTS, CENTRALLY ACTING
C02	ANTIHYPERTENSIVES
C	Cardiovascular system

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

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

US Patents and Regulatory Information for HYDROCHLOROTHIAZIDE; RESERPINE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Pharmeral	HYDROCHLOROTHIAZIDE W/ RESERPINE	hydrochlorothiazide; reserpine	TABLET;ORAL	085420-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Ivax Sub Teva Pharms	HYDROCHLOROTHIAZIDE W/ RESERPINE	hydrochlorothiazide; reserpine	TABLET;ORAL	083573-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Merck	HYDROPRES 25	hydrochlorothiazide; reserpine	TABLET;ORAL	011958-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Watson Labs	HYDROCHLOROTHIAZIDE W/ RESERPINE	hydrochlorothiazide; reserpine	TABLET;ORAL	086330-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Abc Holding	HYDRO-RESERP	hydrochlorothiazide; reserpine	TABLET;ORAL	084714-002	Jun 29, 1982		DISCN	No	No

Hydrochlorothiazide and Reserpine Market Dynamics, Patent Status, and Financial Trajectory

Last updated: September 7, 2026

Hydrochlorothiazide is a high-volume, low-price generic diuretic with durable demand in hypertension and edema. Reserpine is an older, low-volume antihypertensive with limited contemporary use. Both active ingredients have negligible standalone patent protection, no meaningful biosimilar exposure, and limited financial value as independent products. Commercial value is concentrated in hydrochlorothiazide-containing fixed-dose combinations, while reserpine is primarily a legacy generic and research compound.

What are hydrochlorothiazide and reserpine used for?

Hydrochlorothiazide is a thiazide diuretic used for hypertension, edema, nephrogenic diabetes insipidus, and selected calcium kidney-stone indications. It is marketed as a standalone tablet and in combinations with agents including losartan, valsartan, lisinopril, irbesartan, candesartan, telmisartan, and triamterene.

Reserpine is an older sympatholytic antihypertensive. It reduces catecholamine storage in peripheral sympathetic neurons and has also been used in some movement-disorder and research settings. Its clinical use declined because of adverse-effect concerns, including depression, sedation, nasal congestion, gastrointestinal effects, and drug interactions.

Attribute	Hydrochlorothiazide	Reserpine
Drug class	Thiazide diuretic	Rauwolfia alkaloid sympatholytic
Principal use	Hypertension and edema	Legacy hypertension treatment
Common dosage forms	Oral tablets; fixed-dose combinations	Oral tablets; legacy combinations
Current commercial position	High-volume generic	Niche or limited generic
Standalone patent value	Effectively expired	Effectively expired
Biosimilar risk	Not applicable	Not applicable
Main commercial driver	Combination-product volume	Limited availability and legacy use
Pricing profile	Low-cost generic	Low-cost, low-volume generic
Innovation activity	Combination reformulation and adherence products	Minimal

When did hydrochlorothiazide and reserpine lose exclusivity?

Both compounds lost meaningful small-molecule exclusivity decades ago. The commercial market is governed by abbreviated new drug applications, state substitution rules, wholesaler contracts, and manufacturing economics rather than originator patent rights.

Hydrochlorothiazide was introduced in the 1950s and became a foundational antihypertensive. Any original compound, formulation, or use patents are expired. Current products generally rely on generic approval pathways and, for combination products, separate approval histories for the active ingredients.

Reserpine was introduced in the 1950s and has no commercially relevant unexpired composition-of-matter protection. Its decline reflects clinical substitution and low demand rather than patent expiry alone.

Exclusivity category	Hydrochlorothiazide	Reserpine
Original compound patent	Expired	Expired
Original branded-product exclusivity	Expired	Expired
Current FDA orphan exclusivity	None identified	None identified
Current new chemical entity exclusivity	None	None
Patent term extension exposure	None of commercial significance	None of commercial significance
Remaining branded monopoly	None	None

The FDA Orange Book is the principal U.S. reference for listed patents and regulatory exclusivity. It does not create exclusivity for products whose relevant patent terms have expired, and it does not provide a commercial barrier for ordinary generic hydrochlorothiazide or reserpine tablets [1].

What patents protect hydrochlorothiazide and reserpine today?

No commercially important patent estate protects the basic hydrochlorothiazide or reserpine molecules. The practical patent position is therefore weak for standalone products.

Hydrochlorothiazide patent position

Potential historical protection covered the active ingredient, tablet formulations, combinations, and methods of treating hypertension. Those rights are no longer material barriers to generic entry. Modern patent activity involving hydrochlorothiazide is more likely to concern:

• Fixed-dose combinations with renin-angiotensin system inhibitors
• Extended-release or modified-release delivery
• Polypills and adherence-oriented combinations
• Specific crystalline forms or manufacturing processes
• Digital adherence or packaging systems

A patent on a combination product does not necessarily block standalone hydrochlorothiazide. Conversely, a combination patent may remain relevant to a specific product even when hydrochlorothiazide itself is unprotected.

Reserpine patent position

Reserpine has no meaningful current patent moat around the active ingredient. Any surviving rights would likely relate to a particular formulation, combination, manufacturing process, or new therapeutic use. Demand is too limited to support a substantial modern patent program in most markets.

Patent-strength assessment

Patent factor	Hydrochlorothiazide	Reserpine
Composition-of-matter protection	None of commercial relevance	None of commercial relevance
Formulation protection	Possible in selected combinations	Limited and commercially weak
Method-of-use protection	Historical and expired for core hypertension use	Historical and expired for core hypertension use
Manufacturing barriers	Low	Moderate relative to demand, but not patent-driven
Generic design-around difficulty	Low	Low
Overall patent strength	Very low for standalone drug	Very low

How many patents cover hydrochlorothiazide and reserpine?

The number of active U.S. patents depends on claim scope, product identifier, applicant, and the date of the search. A raw patent count can overstate commercial protection because many records relate to expired patents, abandoned applications, combination products, or unrelated uses.

For standalone hydrochlorothiazide and reserpine products, there is no meaningful active patent estate comparable to that of a recently approved branded drug. The relevant commercial question is whether a particular combination product has an unexpired listed patent, not whether the molecule appears in patent databases.

Patent risk is therefore product-specific:

1. Standalone hydrochlorothiazide tablet: low.
2. Standalone reserpine tablet: low.
3. Hydrochlorothiazide plus an angiotensin receptor blocker: dependent on the partner drug and formulation.
4. Legacy reserpine combinations: generally low, with market access more constrained by demand and supply than patents.

What is the FDA regulatory status of hydrochlorothiazide and reserpine?

Hydrochlorothiazide is an established FDA-recognized active ingredient with numerous approved generic and combination products. FDA-approved dosage strengths commonly include 12.5 mg, 25 mg, and 50 mg tablets, although marketed strengths and manufacturers vary.

Reserpine has a much narrower modern regulatory footprint. Historical FDA approvals and legacy products exist, but current commercial availability is limited. The FDA has recognized reserpine as an established drug substance, yet regulatory status must be assessed by product and manufacturer rather than inferred from historical use.

Regulatory issue	Hydrochlorothiazide	Reserpine
FDA generic pathway	ANDA widely used	ANDA or legacy approval, depending on product
FDA-approved standalone tablets	Broad availability	Limited availability
Fixed-dose combinations	Extensive	Historically available, now uncommon
New drug approvals	Rare, generally combination-related	Rare
Regulatory exclusivity	None material	None material
Current regulatory value	Established generic platform	Legacy active ingredient

FDA product databases and DailyMed labeling show hydrochlorothiazide across multiple standalone and combination products. Reserpine labeling is less consistently represented across current manufacturers and should be evaluated by specific National Drug Code and approval record [2,3].

What formulation patents protect hydrochlorothiazide products?

Hydrochlorothiazide formulation patents are more commercially relevant in combinations than in standalone tablets. The principal product categories are:

• Hydrochlorothiazide plus an angiotensin-converting enzyme inhibitor
• Hydrochlorothiazide plus an angiotensin receptor blocker
• Hydrochlorothiazide plus a potassium-sparing diuretic
• Hydrochlorothiazide plus a calcium-channel blocker
• Multi-drug cardiovascular polypills

For a generic applicant, the active ingredient is usually not the principal barrier. The applicant instead evaluates listed patents, formulation claims, dosage limitations, labeling restrictions, and potential Paragraph IV certification.

Reserpine formulation innovation is limited. The drug’s low prescribing volume does not support extensive investment in controlled-release tablets, transdermal systems, or modern combination products.

Which companies are challenging hydrochlorothiazide and reserpine patents?

No major contemporary Paragraph IV litigation campaign is associated with standalone hydrochlorothiazide or reserpine. Generic manufacturers have long marketed these products, and the relevant patents for combination products generally belong to the partner molecule or the branded combination sponsor.

Companies active in generic hydrochlorothiazide products have included large and mid-sized generic manufacturers such as Teva, Sandoz, Dr. Reddy’s Laboratories, Lupin, Zydus, Torrent, Aurobindo, and Mylan/Viatris, subject to product-specific approvals and market participation.

The competitive issue is not a current patent challenge to hydrochlorothiazide or reserpine. It is whether a manufacturer can profitably maintain approval, sourcing, quality compliance, and distribution for a low-margin product.

What patent litigation affects hydrochlorothiazide and reserpine?

Standalone hydrochlorothiazide and reserpine have little current litigation value. Historical litigation involving these molecules would generally concern:

• Combination-product patents
• Formulation claims
• Invalidity or noninfringement disputes
• ANDA certifications for branded combinations
• Manufacturing or supply matters

The litigation exposure for a generic hydrochlorothiazide tablet is substantially lower than for a branded combination containing a still-protected active ingredient. Reserpine has an even lower litigation profile because the market is too small to support significant enforcement activity.

Settlement agreements

There is no widely recognized, commercially material settlement landscape centered on standalone hydrochlorothiazide or reserpine. Settlements involving hydrochlorothiazide are more likely to arise in disputes over broader combination products. Such agreements may establish an authorized generic launch date, a license, or a market-entry concession, but they do not restore exclusivity to the hydrochlorothiazide molecule.

When does hydrochlorothiazide lose exclusivity in major markets?

Hydrochlorothiazide has already lost core exclusivity in the United States, Europe, and other major pharmaceutical markets. The same applies to reserpine.

Market	Hydrochlorothiazide	Reserpine
United States	Generic market established	Generic or legacy market
European Union	Generic market established	Limited national availability
Japan	Generic and combination use	Limited use
Emerging markets	Broad low-cost availability	Variable and often limited
China and India	Multiple local manufacturers	More limited than hydrochlorothiazide

Geographic differences concern regulatory registration, local manufacturing, reimbursement, and supply continuity. They do not reflect a meaningful remaining patent monopoly.

What generic entry risks exist?

Hydrochlorothiazide

Generic entry risk is already realized for standalone hydrochlorothiazide. Additional entrants can affect supplier share, but price erosion is constrained by the fact that prices are already low. The more relevant risk is supply disruption caused by:

• Few active pharmaceutical ingredient suppliers
• Manufacturing-site remediation
• Low-margin contract manufacturing
• Demand spikes for combination antihypertensives
• Hospital or wholesaler purchasing concentration

For branded hydrochlorothiazide combinations, generic entry can materially affect revenue when partner-drug patents expire or when authorized generics enter.

Reserpine

Reserpine has limited incremental generic-entry risk because the market is already small and largely generic. New entrants could reduce prices but may not materially change total market revenue. The larger risk is product withdrawal, shortage, or discontinuation if sales do not justify compliance and manufacturing costs.

What is the financial trajectory for hydrochlorothiazide?

Standalone hydrochlorothiazide revenue is difficult to isolate because it is sold through generic channels and bundled into combination products. Public companies generally do not report hydrochlorothiazide as a separate material revenue line.

The financial trajectory has four phases:

Phase	Financial effect
Originator period	High-margin branded revenue
Early generic entry	Rapid price erosion and volume redistribution
Mature generic period	High unit volume and low unit revenue
Combination-product period	Value migrates to branded or differentiated combinations

Hydrochlorothiazide remains financially relevant because of prescription volume, not pricing power. Its strategic value is higher when included in a protected or commercially strong combination, such as an angiotensin receptor blocker/hydrochlorothiazide product. The ingredient itself contributes low incremental revenue.

Prescription data from national drug-utilization sources consistently place hydrochlorothiazide among widely used antihypertensive ingredients, although exact volume varies by year, product definition, and whether combination prescriptions are counted separately [4]. Generic price data also show a mature low-cost market rather than an originator-style margin profile [5].

What is the financial trajectory for reserpine?

Reserpine has a declining or flat niche-market trajectory. It lacks the prescription volume, differentiation, and reimbursement leverage needed to support significant standalone revenue.

Its economic profile is shaped by:

• Limited physician use
• Availability of newer antihypertensives
• Adverse-effect concerns
• Low commercial investment
• Potential supply interruptions
• Minimal branded promotion

Public financial filings generally do not identify reserpine revenue separately. Any revenue is likely immaterial within diversified generic portfolios. The product may retain a small role in selected markets, institutional formularies, or specialized clinical use, but it is not a meaningful growth asset.

How does hydrochlorothiazide compare with reserpine commercially?

Hydrochlorothiazide is a durable generic platform. Reserpine is a legacy product with limited strategic value.

Commercial metric	Hydrochlorothiazide	Reserpine
Demand	Broad and recurring	Narrow
Prescriber base	Primary care, cardiology, nephrology	Limited and specialized
Combination relevance	High	Low
Price competition	Intense	Intense, with low volume
Revenue visibility	Moderate through product-family data	Poor
Supply-chain importance	Meaningful	Discontinuation risk
Licensing value	Possible for combination products	Minimal
M&A value	Portfolio add-on only	Negligible alone
Litigation value	Combination-dependent	Minimal

What manufacturing and intellectual-property barriers exist?

Manufacturing barriers are operational rather than patent-based.

Hydrochlorothiazide has established synthesis routes and broad supplier availability, but profitability can be affected by quality systems, API sourcing, environmental controls, and minimum efficient batch size. A manufacturer may exit despite continued clinical demand if prices are too low.

Reserpine presents a different problem. The synthesis and sourcing chain may be less attractive because volumes are small, demand is inconsistent, and the product has limited commercial upside. That can create practical barriers even without strong intellectual property.

Neither drug has a meaningful biologic manufacturing barrier. Biosimilar regulation does not apply because both are small-molecule active ingredients.

What are the likely generic launch scenarios?

Hydrochlorothiazide

The most likely scenario is continued stable generic supply with periodic manufacturer entry and exit. Standalone price competition will remain severe. Growth will come from:

• Fixed-dose cardiovascular combinations
• Generic substitution
• Emerging-market access
• Chronic disease prevalence
• Polypill and adherence programs

A new standalone entrant would face limited pricing power unless it offers a supply advantage, reliable quality, or access to a large distribution network.

Reserpine

The likely scenario is continued niche availability with limited manufacturer participation. Market expansion is unlikely without a new clinical indication, a modern delivery system, or a materially different safety and adherence profile. Such development would require new clinical evidence and could create a separate regulatory and patent strategy, but the commercial rationale is weak under current demand conditions.

Key Takeaways

• Hydrochlorothiazide is a mature, high-volume generic with no meaningful standalone patent protection.
• Most current commercial value lies in hydrochlorothiazide-containing combination products, not the single ingredient.
• Reserpine is an old, low-volume antihypertensive with limited modern clinical and financial relevance.
• Neither drug has meaningful biosimilar exposure or remaining core composition-of-matter exclusivity.
• Standalone Paragraph IV and patent-litigation risk is low for both compounds.
• Hydrochlorothiazide has durable volume but minimal pricing power.
• Reserpine faces product-continuity and manufacturer-exit risk rather than patent risk.
• Public companies generally do not disclose standalone revenue for either ingredient.
• Manufacturing economics, API supply, regulatory compliance, and distribution determine market participation.

FAQs

Is hydrochlorothiazide still profitable for generic manufacturers?

Only at portfolio scale. The ingredient has high demand but low unit pricing. Profitability depends on manufacturing efficiency, supply reliability, and inclusion in larger combination-product portfolios.

Is reserpine still FDA approved?

Reserpine has a long FDA regulatory history, but current availability depends on the specific product and manufacturer. Historical approval does not guarantee broad current commercial distribution.

Can a company obtain a new patent on hydrochlorothiazide?

A company could seek patents on a novel formulation, combination, manufacturing process, or therapeutic use. A new patent would not restore exclusivity to the established hydrochlorothiazide molecule.

Are hydrochlorothiazide and reserpine subject to biosimilar competition?

No. Both are small-molecule drugs and compete through generic drug pathways rather than biosimilar regulation.

Which drug has greater licensing value?

Hydrochlorothiazide has greater licensing value when included in a differentiated fixed-dose combination or adherence product. Reserpine has minimal licensing value as a standalone asset.

References

1. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: The Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

2. U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/

3. National Library of Medicine. (2024). DailyMed: Current medication information. https://dailymed.nlm.nih.gov/dailymed/

4. Centers for Medicare & Medicaid Services. (2024). Medicare Part D drug spending dashboard. https://www.cms.gov/research-statistics-data-and-systems/statistics-trends-and-reports/part-d-drug-spending

5. U.S. Food and Drug Administration. (2024). FDA Drug Shortages database. https://www.accessdata.fda.gov/scripts/drugshortages/