ALDOMET Drug Patent Profile

Which patents cover Aldomet, and when can generic versions of Aldomet launch?

Aldomet is a drug marketed by Merck and is included in three NDAs.

The generic ingredient in ALDOMET is methyldopa. There are two drug master file entries for this compound. Two suppliers are listed for this compound. Additional details are available on the methyldopa profile page.

DrugPatentWatch^® Litigation and Generic Entry Outlook for Aldomet

A generic version of ALDOMET was approved as methyldopa by RISING on April 18^th, 1985.

Summary for ALDOMET

US Patents:	0
Applicants:	1
NDAs:	3
Raw Ingredient (Bulk) Api Vendors:	84
Clinical Trials:	8
Patent Applications:	7,420
DailyMed Link:	ALDOMET at DailyMed

Recent Clinical Trials for ALDOMET

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

Sponsor	Phase
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)	Phase 2
Maastricht University Medical Center	Phase 4
University of British Columbia	N/A

See all ALDOMET clinical trials

US Patents and Regulatory Information for ALDOMET

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Merck	ALDOMET	methyldopate hydrochloride	INJECTABLE;INJECTION	013401-001	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Merck	ALDOMET	methyldopa	TABLET;ORAL	013400-001	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Merck	ALDOMET	methyldopa	SUSPENSION;ORAL	018389-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Merck	ALDOMET	methyldopa	TABLET;ORAL	013400-003	Approved Prior to Jan 1, 1982		DISCN	Yes	No
Merck	ALDOMET	methyldopa	TABLET;ORAL	013400-002	Approved Prior to Jan 1, 1982		DISCN	Yes	No

Expired US Patents for ALDOMET

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Merck	ALDOMET	methyldopa	SUSPENSION;ORAL	018389-001	Approved Prior to Jan 1, 1982	4,404,193

ALDOMET Market Dynamics, Financial Trajectory, Generic Competition, and Patent Status

Last updated: September 25, 2026

Aldomet is the former Merck brand for methyldopa, an oral antihypertensive used mainly for chronic hypertension and pregnancy-related hypertension. Its commercial trajectory is that of a mature, largely genericized medicine: branded sales have declined or disappeared in many markets, generic methyldopa remains available, and low pricing, limited prescribing, and manufacturing economics now drive the market. There is no reliable public disclosure of standalone Aldomet revenue.

What is Aldomet and how does methyldopa work?

Aldomet contains methyldopa, a centrally acting alpha-2 adrenergic agonist. The drug is converted to an active metabolite in the central nervous system, reducing sympathetic nervous system activity and lowering blood pressure.[1]

Methyldopa was historically important because it provided an effective oral treatment for hypertension before the widespread adoption of modern antihypertensive classes. Current prescribing is concentrated in pregnancy-related hypertension, where clinicians may use methyldopa because of its long history of maternal and fetal exposure.

What dosage forms and strengths does Aldomet have?

The historical U.S. Aldomet product was marketed as oral tablets in several strengths, including:

Dosage form	Historical strength
Tablet	125 mg
Tablet	250 mg
Tablet	500 mg

Generic methyldopa has been marketed in comparable tablet strengths. Availability varies by country, manufacturer, wholesaler, and supply conditions. The branded Aldomet product is not the primary commercial source in the U.S. market.

What are the main clinical limitations of methyldopa?

Methyldopa has several disadvantages compared with newer agents:

• Sedation and fatigue
• Dizziness and orthostatic symptoms
• Depression in some patients
• Dry mouth
• Reduced adherence because of frequent dosing or tolerability
• Risk of hepatotoxicity
• Risk of hemolytic anemia with prolonged exposure
• Reduced suitability for routine first-line hypertension treatment outside selected populations

These limitations have restricted the drug’s use as newer calcium-channel blockers, ACE inhibitors, angiotensin receptor blockers, thiazide diuretics, and beta blockers gained market share.[2]

When did Aldomet lose commercial exclusivity?

Aldomet lost meaningful commercial exclusivity decades ago. Methyldopa is a small-molecule medicine with legacy patents and no current market exclusivity that protects the original product from generic competition.

The commercial sequence was:

Period	Market development
1960s	Methyldopa entered the antihypertensive market under Merck’s Aldomet brand
1970s-1980s	Generic and alternative antihypertensive competition expanded
1990s	Modern antihypertensive classes displaced methyldopa in routine hypertension
2000s onward	Use became concentrated in pregnancy and selected specialist settings
Current market	Generic methyldopa dominates where the product remains available

No active composition-of-matter or formulation patent is understood to create a material barrier to generic methyldopa in the United States. The principal competitive issues are manufacturing economics, supply continuity, product availability, and clinical demand rather than patent protection.

What is the Orange Book status of Aldomet?

Aldomet has no commercially meaningful current Orange Book exclusivity position. The U.S. Food and Drug Administration’s Orange Book focuses on approved drug products and patent or exclusivity information relevant to generic approval.[3]

Aldomet’s original intellectual-property position is historical. Any legacy patents associated with methyldopa or its original formulation would have expired long ago relative to the product’s 1960s launch. The key regulatory question today is whether an individual manufacturer has an active approved abbreviated new drug application, not whether the original Aldomet brand retains patent protection.

Are there current Paragraph IV challenges to Aldomet?

No material current Paragraph IV litigation is associated with Aldomet’s original product. Paragraph IV litigation is generally relevant when a generic applicant challenges an unexpired listed patent. Methyldopa does not present that type of active patent environment.

Generic applicants for methyldopa historically faced ordinary FDA approval requirements, including pharmaceutical equivalence, bioequivalence, manufacturing compliance, and product quality. Patent litigation is not the main source of launch risk.

How large is the Aldomet and methyldopa market?

The global market for Aldomet specifically is small relative to major branded cardiovascular medicines. The market for generic methyldopa is larger than the brand market but remains a low-value segment.

Public market data generally do not separate:

1. Aldomet brand revenue;
2. generic methyldopa revenue;
3. methyldopa tablets sold through hospitals, retail pharmacies, and government procurement; and
4. methyldopa revenue by pregnancy-related use versus other hypertension indications.

As a result, a precise global market size or Aldomet revenue figure cannot be established from public company filings.

What drives demand for methyldopa?

Demand is influenced by four factors:

• Pregnancy-related hypertension protocols
• Availability and pricing of substitute antihypertensives
• National treatment guidelines
• Procurement decisions by hospitals and public-health systems

Methyldopa remains clinically relevant in some pregnancy settings, but it competes with labetalol and nifedipine. The National Institute for Health and Care Excellence identifies labetalol, nifedipine, and methyldopa as treatment options for hypertension in pregnancy, with treatment selection based on clinical circumstances and patient factors.[4]

The U.S. market is less favorable for methyldopa than markets where it is routinely embedded in pregnancy protocols. Prescribing varies by physician preference, obstetric practice, formulary policy, and national guidelines.

What is the financial trajectory of Aldomet?

Aldomet’s financial trajectory follows a four-stage pattern.

Stage 1: Branded growth

Aldomet benefited from an early market position in oral hypertension treatment. At that stage, Merck controlled the principal branded commercial opportunity and could support premium pricing.

Stage 2: Therapeutic substitution

The product lost share as physicians adopted newer antihypertensive classes with improved dosing convenience, broader indications, and different tolerability profiles. This reduced the addressable market for a legacy centrally acting agent.

Stage 3: Generic erosion

After generic entry, pricing pressure accelerated. The economic value shifted from brand promotion to manufacturing scale, distribution reliability, and formulary access.

Stage 4: Low-value mature market

The current market is characterized by:

• Low average selling prices
• Limited promotional spending
• Generic competition
• Small and uneven demand
• Potential supply vulnerability
• Limited incentive for new entrants unless manufacturing costs are low

Merck does not report Aldomet as a standalone revenue line in its current financial disclosures. The company reports results by broader business segments and product categories rather than providing a current Aldomet revenue series.[5]

Can Aldomet revenue be estimated from public filings?

No reliable standalone estimate can be derived from Merck’s public filings. The product is not identified as a material current revenue driver, and generic sales are distributed among multiple manufacturers and channels.

For investment analysis, Aldomet should be classified as:

Metric	Assessment
Branded revenue potential	Minimal
Generic revenue potential	Low
Gross-margin potential	Low to moderate, depending on supply position
Volume stability	Uneven
Pricing power	Very low
Promotional requirement	Low
Patent value	Negligible
Manufacturing value	More important than IP
Strategic value	Limited, except for portfolio completeness or supply contracts

Which companies compete with Aldomet?

The competitive landscape has two levels: direct methyldopa suppliers and substitute antihypertensive manufacturers.

Direct generic competition

Generic methyldopa may be supplied by different manufacturers over time depending on regulatory approvals and commercial availability. The relevant competitive variables are:

• FDA or local-market approval
• Tablet strength availability
• Contract manufacturing capacity
• Quality history
• Wholesale distribution
• Government and hospital tenders
• Ability to maintain low-volume production

A manufacturer can gain share without a superior product if competitors exit the market or experience manufacturing problems.

Therapeutic substitutes

Drug class	Examples	Competitive position against methyldopa
Beta blockers	Labetalol	Major pregnancy-related substitute
Calcium-channel blockers	Nifedipine	Major pregnancy-related substitute
ACE inhibitors	Lisinopril, enalapril	Strong in general hypertension, generally avoided in pregnancy
ARBs	Losartan, valsartan	Strong in general hypertension, generally avoided in pregnancy
Thiazide diuretics	Hydrochlorothiazide	Established general-hypertension alternative
Other beta blockers	Metoprolol	Used in selected hypertension settings

Methyldopa’s strongest remaining commercial niche is not general hypertension. It is selected use in pregnancy and in markets where low-cost, familiar therapy remains important.

What FDA regulatory status does methyldopa have?

Methyldopa is an established small-molecule prescription drug. Generic manufacturers generally use the abbreviated new drug application pathway rather than submitting full clinical efficacy programs, provided the reference-product and bioequivalence requirements are satisfied.[6]

The regulatory burden is therefore concentrated in:

• Bioequivalence
• Chemistry, manufacturing, and controls
• Stability testing
• Labeling
• Pharmacovigilance
• Facility compliance
• Consistent supply of active pharmaceutical ingredient and finished tablets

The original Aldomet label identifies warnings relating to hepatic dysfunction, hemolytic anemia, and other adverse effects. These risks remain relevant to product labeling and physician use.[1]

What manufacturing and intellectual-property barriers affect methyldopa?

Patent barriers are weak. Manufacturing barriers can be more important.

Manufacturing risks

Methyldopa is a low-margin product. A manufacturer may discontinue production if:

• Demand is too low to support a production line;
• raw-material costs rise;
• quality remediation becomes expensive;
• regulatory compliance costs exceed revenue;
• procurement contracts force prices below sustainable levels; or
• supply-chain disruptions affect the active ingredient.

Low-margin generic medicines can experience shortages even after patent expiry because several suppliers may leave the market simultaneously.

Intellectual-property position

The product’s relevant IP profile is limited:

IP category	Current commercial significance
Original compound patents	Expired
Original Aldomet formulation patents	Expired or commercially irrelevant
Method-of-use patents	No material current exclusivity identified
Manufacturing patents	Potentially relevant to a specific process, but not a barrier to ordinary generic production
Brand trademark	Limited value without active branded distribution
Data exclusivity	Expired

A new formulation, controlled-release product, combination product, or differentiated delivery system could create a separate IP position. The historical Aldomet tablet does not have that protection.

What generic entry risks exist for Aldomet?

Generic-entry risk is effectively fully realized. The relevant risk for current participants is not generic entry against the brand. It is generic supplier competition and market exit.

Generic launch scenarios

Continued low-volume supply

Several manufacturers maintain limited production. Prices remain low, and availability is adequate but uneven.

Supplier consolidation

One or two manufacturers become the principal sources. This may improve volume efficiency but increases shortage risk if a major supplier encounters quality or capacity problems.

Brand discontinuation with generic persistence

The Aldomet brand disappears or becomes commercially insignificant while generic methyldopa remains available.

Demand contraction

Use declines as clinicians favor labetalol, nifedipine, and other modern agents, reducing the economic incentive to maintain multiple suppliers.

Regional persistence

Methyldopa remains important in selected countries because of treatment guidelines, pregnancy protocols, public procurement, or affordability requirements. The product can remain clinically relevant in those markets even if it is commercially marginal in the United States.

What licensing deals and settlements affect Aldomet?

No major current licensing transaction or settlement is publicly associated with Aldomet that materially changes its commercial outlook. The product’s original commercial value was tied to Merck’s historical branded portfolio. Current generic methyldopa supply is more likely to involve ordinary manufacturing, distribution, or procurement agreements than high-value strategic licensing.

No major active patent settlement is known to create delayed generic entry. The absence of such settlements is consistent with the product’s expired-patent status.

How strong is the Aldomet patent estate compared with newer antihypertensive drugs?

Aldomet’s patent estate is weak compared with newer branded medicines.

Product category	Patent position	Commercial implication
Aldomet/methyldopa	Historical patents expired	Generic competition and low pricing
New branded antihypertensive	May include formulation, combination, or method patents	Potentially extended exclusivity
Long-acting formulations	May support new patent filings	Higher pricing if clinically differentiated
Combination products	May obtain separate approvals and patents	Can delay direct substitution
Generic methyldopa	No meaningful proprietary platform	Volume and supply execution determine value

Aldomet should not be evaluated as an IP-backed asset. Its residual value lies in brand recognition, clinical familiarity, approved manufacturing infrastructure, and access to distribution channels.

What geographic markets remain relevant for methyldopa?

Methyldopa’s market is geographically fragmented.

United States

The U.S. market is generic and comparatively limited. Use is concentrated in selected pregnancy-related and specialist settings. The original Aldomet brand has little apparent commercial importance.

Europe

European availability varies by country. National guidelines, hospital procurement, and reimbursement policies determine whether methyldopa remains routinely used.

Emerging markets

Methyldopa may retain greater relevance where:

• low acquisition cost is a priority;
• pregnancy-related hypertension protocols include methyldopa;
• newer alternatives are less consistently available; or
• physicians have long-standing experience with the product.

The product’s international commercial value depends more on local distribution and procurement than on global brand strategy.

Key Takeaways

• Aldomet is the legacy Merck brand for methyldopa.
• The product has lost meaningful exclusivity, and its original patents are no longer commercial barriers.
• Generic methyldopa, not branded Aldomet, represents the active market opportunity.
• Standalone Aldomet revenue is not publicly disclosed and is unlikely to be material to Merck’s current financial results.
• Demand is concentrated in pregnancy-related hypertension and selected low-cost treatment markets.
• Labetalol and nifedipine are major clinical substitutes in pregnancy.
• The principal commercial risks are low pricing, limited demand, manufacturing economics, and supplier exits.
• No material current Paragraph IV litigation, patent settlement, or licensing transaction changes the product’s outlook.
• Methyldopa has low patent value but can retain regional clinical value where treatment guidelines and procurement systems support its use.

FAQs

Is Aldomet still available in the United States?

The original Aldomet brand is not the principal U.S. source. Generic methyldopa availability depends on manufacturer, pharmacy inventory, and supply conditions.

Is methyldopa profitable for generic manufacturers?

Usually, methyldopa is a low-value product. Profitability depends on manufacturing efficiency, reliable supply, procurement contracts, and the number of active competitors.

Why is methyldopa still used during pregnancy?

Methyldopa has extensive historical use in pregnancy and remains included in some hypertension-in-pregnancy treatment guidelines. Clinical selection depends on patient circumstances and physician judgment.

Does Aldomet have active U.S. patents?

No material active patent estate is understood to protect the original Aldomet product from ordinary generic competition.

Could a new methyldopa formulation create commercial value?

Yes. A sustained-release formulation, combination product, or delivery system could support separate regulatory and patent strategies. The historical Aldomet tablet does not have comparable differentiation.

References

1. Merck & Co., Inc. (n.d.). Aldomet (methyldopa) tablets prescribing information. U.S. Food and Drug Administration labeling archive.

2. Brunton, L. L., Hilal-Dandan, R., & Knollmann, B. C. (Eds.). (2018). Goodman & Gilman’s the pharmacological basis of therapeutics (13th ed.). McGraw-Hill.

3. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugsatfda

4. National Institute for Health and Care Excellence. (2019, updated 2023). Hypertension in pregnancy: Diagnosis and management, NG133. https://www.nice.org.uk/guidance/ng133

5. Merck & Co., Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. U.S. Securities and Exchange Commission.

6. U.S. Food and Drug Administration. (2024). Generic drug facts. https://www.fda.gov/drugs/generic-drugs/generic-drug-facts