List of Excipients in Branded Drug HYDRALAZINE HYDROCHLORIDE

Generic Drugs Containing HYDRALAZINE HYDROCHLORIDE

Company	Ingredient	NDC	Excipient
Henry Schein Inc	hydralazine hydrochloride	0404-9787	HYDROCHLORIC ACID
Henry Schein Inc	hydralazine hydrochloride	0404-9787	METHYLPARABEN
Henry Schein Inc	hydralazine hydrochloride	0404-9787	PROPYLENE GLYCOL

What are the Most Frequently-Used Excipients in HYDRALAZINE HYDROCHLORIDE?

# Of NDCs	Excipient
1	ALUMINUM OXIDE
97	ANHYDROUS LACTOSE
106	CELLULOSE, MICROCRYSTALLINE

Hydralazine Hydrochloride Excipient Strategy and Commercial Opportunities

Last updated: August 7, 2026

Hydralazine hydrochloride is an established generic antihypertensive with limited active-ingredient patent protection and low regulatory barriers for conventional tablets and injection. Commercial opportunity is concentrated in differentiated formulations, supply reliability, pediatric and geriatric presentations, hospital premixes, and improved stability rather than in basic immediate-release tablets.

What is the FDA regulatory status of hydralazine hydrochloride?

Hydralazine hydrochloride is an FDA-approved direct-acting vasodilator used primarily for hypertension. Approved dosage forms include oral tablets and parenteral injection. The drug is also used in combination with other antihypertensives and in clinical settings involving severe hypertension or heart failure management.

Attribute	Hydralazine hydrochloride
Active ingredient	Hydralazine hydrochloride
Therapeutic class	Direct vasodilator
Primary use	Hypertension
Common oral strengths	10 mg, 25 mg, 50 mg, 100 mg
Common injectable strength	20 mg/mL
Administration	Oral and intravenous/intramuscular, depending on product
Regulatory pathway	Abbreviated New Drug Application for generics; 505(b)(2) possible for differentiated products
Pediatric status	Use is established clinically, but product-specific pediatric labeling varies
Biosimilar exposure	None; hydralazine hydrochloride is a small molecule
Prescription status	Prescription drug

The FDA-approved labeling identifies hydralazine hydrochloride tablets for essential hypertension and hydralazine hydrochloride injection for severe hypertension when oral therapy is not practical.[1,2]

Hydralazine has a short and variable duration of action. Oral therapy commonly requires multiple daily doses, creating an opportunity for modified-release, liquid, and adherence-oriented presentations. Any modified-release product would require new clinical and bioequivalence evidence rather than relying solely on the conventional generic pathway.

When does hydralazine hydrochloride lose exclusivity?

Hydralazine hydrochloride lost meaningful composition-of-matter exclusivity decades ago. The current commercial market is therefore governed primarily by abbreviated approvals, manufacturing economics, product availability, and formulation differentiation.

Exclusivity category	Current relevance
Original compound patent	Expired
Basic tablet formulation patents	Expired or commercially immaterial
FDA orphan exclusivity	Not applicable to standard hydralazine products
New chemical entity exclusivity	Expired
Pediatric exclusivity	No broad current barrier identified for the established products
Data exclusivity	Not a meaningful barrier for conventional generic entry
Formulation patents	Potentially available for a new delivery system
Method-of-use patents	Potentially available for a new, specific indication, dosing regimen, or patient population

A new hydralazine product could obtain patent protection for a novel formulation, delivery platform, manufacturing process, or approved method of use. Such protection would not restore exclusivity for ordinary hydralazine tablets.

What patents protect hydralazine hydrochloride products?

The commercially relevant patent opportunity is not the hydralazine molecule. It is a product-specific patent directed to formulation, release control, stability, packaging, or clinical use.

Legacy compound and formulation patents

Hydralazine was developed before the modern U.S. patent and Hatch-Waxman environment. Historical patents covering the compound and early pharmaceutical preparations are expired. A new applicant should not assume that old hydralazine patent families create a present barrier to generic manufacturing.

Potential new patent categories

A sponsor could pursue claims covering:

• Extended-release hydralazine matrices
• Multiparticulate or pellet-based oral dosage forms
• Taste-masked oral liquids
• Ready-to-use injectable solutions
• Low-extractable or low-sorption infusion containers
• Stabilized hydralazine solutions
• Unit-dose pediatric formulations
• Combination products with diuretics or beta blockers
• Specific dosing regimens for resistant hypertension
• Formulations that reduce peak-related adverse effects
• Manufacturing processes that improve impurity control
• Packaging that limits light, oxygen, or moisture exposure

Patent strength would depend on demonstrated technical performance. A formulation patent based only on routine excipient substitution would face a higher obviousness risk. Stronger claims would require comparative data showing unexpected stability, improved bioavailability, lower variability, reduced degradation, or a clinically meaningful reduction in dosing frequency.

What excipients are suitable for hydralazine hydrochloride tablets?

Hydralazine hydrochloride is a water-soluble salt. Immediate-release tablets therefore do not require a complex solubilization system. The primary formulation tasks are powder flow, content uniformity, mechanical strength, disintegration, impurity control, and stability.

Immediate-release tablet excipient strategy

Formulation function	Candidate excipients	Commercial considerations
Diluent	Lactose monohydrate, microcrystalline cellulose, dibasic calcium phosphate, mannitol	Selection affects compressibility, tablet size, and moisture exposure
Binder	Povidone, pregelatinized starch, hydroxypropyl cellulose	Wet granulation may improve uniformity but adds process complexity
Disintegrant	Crospovidone, croscarmellose sodium, sodium starch glycolate	Critical for rapid release and robust dissolution
Lubricant	Magnesium stearate, sodium stearyl fumarate	Excess lubricant can slow dissolution
Glidant	Colloidal silicon dioxide	Supports flow and low-dose content uniformity
Film former	Hypromellose, polyvinyl alcohol	Can improve handling, identification, and light protection
Opacifier or colorant	Titanium dioxide or approved color systems	Must align with jurisdictional and customer requirements
Sweetener or flavor	Sucralose, saccharin sodium, flavors	Relevant primarily to chewable or orally disintegrating formats

Low-dose hydralazine tablets create a content-uniformity challenge. The active ingredient may represent a small percentage of total tablet mass, especially in 10-mg and 25-mg strengths. Ordered blending, geometric dilution, wet granulation, or engineered carrier particles can reduce segregation risk.

Hydralazine hydrochloride tablets are commonly supplied in multiple strengths. A platform formulation that maintains proportional composition across strengths can reduce development and manufacturing costs, but dissolution and hardness must be confirmed for each strength.

Excipient risks in tablets

Hydralazine can be affected by formulation microenvironment, moisture, light, and processing conditions. A development program should evaluate:

• Assay and related substances over accelerated and long-term storage
• Nitrogen-containing impurity formation
• Moisture uptake by hydrophilic excipients
• Lubricant impact on dissolution
• Blend segregation at low drug loading
• Color and odor changes
• Container-closure protection
• Compatibility with direct compression and wet granulation

Lactose is widely used in oral solid dosage forms, but a sponsor should assess compatibility and impurity formation rather than selecting it solely because it is conventional. Mannitol can support a lower-moisture formulation and improve mouthfeel in orally disintegrating products. Microcrystalline cellulose and dibasic calcium phosphate can improve tablet robustness but may produce larger tablets at higher excipient loads.

What excipients are suitable for hydralazine hydrochloride oral liquids?

An oral solution or suspension could address pediatric, geriatric, dysphagia, and dose-titration needs. The principal challenges are chemical stability, palatability, microbial control, dosing accuracy, and preservative compatibility.

Oral solution

A solution provides uniform dosing if hydralazine hydrochloride remains chemically stable throughout shelf life. Candidate components include:

• Purified water
• Buffering agents
• Polyols such as glycerin or sorbitol
• Sweeteners such as sucralose or saccharin sodium
• Flavoring agents
• Chelating agents where justified
• Preservatives for multidose packaging
• pH-adjusting agents

A buffered system can control pH, but excessive buffering may accelerate degradation or create precipitation risks when the product is diluted. The final pH should be selected through forced-degradation and real-time stability work rather than copied from another liquid antihypertensive.

Oral suspension

A suspension may be preferable if a stable solution cannot be achieved. Candidate suspending and viscosity-building agents include:

• Xanthan gum
• Sodium carboxymethylcellulose
• Hydroxypropyl methylcellulose
• Microcrystalline cellulose and carboxymethylcellulose combinations
• Poloxamers in selected systems

A commercial suspension must have rapid redispersion, low sedimentation, accurate dose delivery, and acceptable syringeability. Unit-dose cups or oral syringes could reduce dosing errors compared with household spoons.

Commercial opportunity in liquid dosage forms

A ready-to-use hydralazine liquid could target hospitals, compounding pharmacies, pediatric practices, long-term-care facilities, and patients with swallowing difficulties. The principal competitive advantage would be standardized manufacturing and shelf-life support, not active-ingredient novelty.

The product could pursue an ANDA if it matches an approved reference product and satisfies applicable equivalence requirements. A materially different concentration, dosage form, delivery system, or labeling profile could require a 505(b)(2) application.

What formulations are protected by hydralazine hydrochloride patents?

No current market-wide patent barrier protects ordinary hydralazine hydrochloride tablets. A sponsor seeking new intellectual property should focus on technically defensible product attributes.

Extended-release formulations

Hydralazine's short pharmacologic duration creates a rationale for sustained delivery. Candidate systems include:

• Hydrophilic polymer matrices
• Hydrophobic matrix tablets
• Coated multiparticulates
• Osmotic systems
• Gastroretentive systems
• Layered tablets with immediate and sustained-release fractions

The main development risk is dose dumping or unpredictable exposure. A successful product would need to demonstrate controlled release, acceptable peak concentrations, and clinically meaningful dosing convenience. A sustained-release claim supported only by dissolution data may be vulnerable if the release profile does not translate into improved clinical performance.

Orally disintegrating tablets

An orally disintegrating tablet could improve administration for patients with dysphagia. Hydralazine hydrochloride's solubility supports rapid disintegration, but taste may require masking.

Potential techniques include:

• Polymer coating of drug particles
• Ion-exchange resin complexes
• Spray-dried dispersions
• Microencapsulation
• Flavored mannitol-based tablets

A patent could cover the particle-coating system, excipient ratio, disintegration profile, or taste-masking performance. The value would depend on whether the product gains a distinct label, improves adherence, or obtains institutional purchasing preference.

Injectable presentations

Hydralazine hydrochloride injection is used when rapid blood-pressure reduction is needed or oral administration is unsuitable. Product differentiation could include:

• Ready-to-use prefilled syringes
• Unit-dose polymer syringes
• Premixed infusion bags
• Longer in-use stability
• Reduced preparation steps
• Low-sorption container systems
• Packaging with improved light protection

A ready-to-administer presentation could reduce pharmacy preparation and medication-error risk. It would also face extractables and leachables, container-closure, particulate, sterility, and in-use stability requirements.

What is the Orange Book status of hydralazine hydrochloride?

The FDA Orange Book lists approved drug products and patent or exclusivity information relevant to approved products. Hydralazine hydrochloride is primarily a generic market with no commercially significant current composition patent controlling standard tablet access.[3]

An applicant evaluating an ANDA should review:

1. The current Orange Book reference-listed drugs.
2. Listed patents and use codes, if any.
3. Reference-product strength and dosage-form status.
4. Whether the proposed product requires a Paragraph IV certification.
5. Whether a formulation or method-of-use patent is listed against the reference product.

For a conventional hydralazine tablet, Paragraph IV exposure is generally expected to be limited because the underlying product is old and generic. For a newly approved differentiated formulation, patent certification and litigation risk could become material.

Which companies are challenging hydralazine hydrochloride products?

The conventional hydralazine market is supplied by generic manufacturers rather than dominated by a single branded innovator. Generic competition can include multiple suppliers across tablets and injectable products, with availability varying by strength, dosage form, manufacturing site, and shortage conditions.

A definitive current ranking of manufacturers, market shares, and active Paragraph IV challengers requires live FDA databases and commercial sales data. Those metrics are not reliably inferred from product labels alone.

The competitive structure favors manufacturers that can provide:

• Consistent supply across all tablet strengths
• Reliable injectable availability
• Competitive contract-manufacturing economics
• Dual sourcing for key excipients and APIs
• Strong quality systems
• Low complaint and recall rates
• Flexible packaging and private-label capacity

What generic entry risks exist for hydralazine hydrochloride?

Generic entry risk is high for standard immediate-release tablets and established injection products because:

• The active ingredient is old and widely known.
• Conventional dosage forms are technically straightforward.
• Substitution is generally driven by price and availability.
• No biosimilar pathway or biologic manufacturing barrier applies.
• Legacy composition patents have expired.
• Multiple generic suppliers can compete when supply is available.

Risk is lower for a differentiated product only when the sponsor establishes a meaningful barrier, such as:

• A patented release-control system
• A stable commercial liquid with a defensible shelf life
• A ready-to-use injectable format with hospital adoption
• A clinically differentiated regimen
• A validated manufacturing process that is difficult to replicate
• A supply agreement tied to a specialized presentation

Even then, patent protection would cover the specific product or use, not ordinary hydralazine hydrochloride.

How strong is the hydralazine hydrochloride patent estate?

The legacy patent estate is weak from a current commercial-exclusivity perspective. Hydralazine hydrochloride has no meaningful molecule-level barrier to generic competition.

Patent layer	Strength for market exclusion
Compound patent	None commercially
Conventional tablet composition	Low
Conventional injectable composition	Low
Extended-release formulation	Potentially moderate to strong if technically narrow and clinically supported
Oral liquid formulation	Moderate if stability and palatability claims are specific
Ready-to-use injection	Moderate if claims cover container, stability, and administration system
Method of use	Variable; depends on indication, regimen, and prior art
Manufacturing process	Moderate if impurity control or yield improvement is non-obvious

A formulation patent should be supported by comparative data against conventional hydralazine. Useful evidence includes dissolution profiles, impurity growth, stability under stress, pharmacokinetic variability, and administration-error reduction.

What licensing deals and commercial partnerships are available?

Hydralazine hydrochloride is unlikely to generate large molecule-licensing transactions. The more realistic partnership models are:

• API supply and dual-sourcing agreements
• Contract development and manufacturing
• Hospital distribution agreements
• Private-label injectable supply
• Pediatric formulation licensing
• Specialty-pharmacy distribution
• Co-development of modified-release products
• Regional commercialization rights

The strongest licensing opportunity is likely to involve a differentiated dosage form with an identifiable customer and reimbursement pathway. A conventional tablet license would face intense price competition and limited differentiation.

What revenue exposure does hydralazine hydrochloride create?

Conventional hydralazine revenue is likely to be low per prescription because generic pricing is established and substitution is common. Revenue exposure is more sensitive to volume, supply continuity, and contract position than to premium pricing.

Commercial upside is higher in products that solve a specific operational problem:

• Hospital shortages of injectable antihypertensives
• Ready-to-administer emergency products
• Pediatric dosing
• Long-term-care medication administration
• Dysphagia and feeding-tube use
• Reduced dosing frequency
• Stable oral liquids that replace extemporaneous compounding

The injectable market may offer higher unit economics than standard tablets, but it also carries greater compliance, sterility, packaging, and supply-chain risk.

What manufacturing and intellectual-property barriers affect hydralazine products?

Oral products

The main barriers are low-dose uniformity, impurity control, dissolution reproducibility, and cost-efficient packaging. Direct compression can reduce cost, while wet granulation may improve blend uniformity. The optimal process depends on powder characteristics and target strength.

Liquid products

The key barriers are chemical stability, preservative effectiveness, taste, microbial control, and accurate dosing. A product that replaces pharmacy compounding must demonstrate reproducible quality over its labeled shelf life.

Injectable products

Sterile manufacturing, particulate control, container compatibility, light protection, and in-use stability are central barriers. Ready-to-use syringes and premixed bags can command a commercial premium only if they reduce pharmacy labor or medication risk.

Geographic coverage

U.S. patent protection would be separate from European, Japanese, Chinese, and other national rights. A new formulation program should pursue jurisdictions with meaningful demand, hospital procurement, or local manufacturing. Patent claims should be drafted around the formulation and process, while regulatory filings must address each market's excipient, labeling, and stability requirements.

How does hydralazine hydrochloride compare with competing antihypertensives?

Hydralazine competes with newer and more commonly prescribed antihypertensives, including ACE inhibitors, angiotensin receptor blockers, calcium-channel blockers, beta blockers, thiazide diuretics, and other vasodilators.

Product characteristic	Hydralazine hydrochloride	Common newer antihypertensives
Molecular exclusivity	Expired	Often expired, but some branded products retain patent value
Dosing frequency	Often multiple daily doses	Frequently once daily
Generic price pressure	High	High for mature products
Hospital injectable role	Relevant	Varies by agent
Modified-release opportunity	Meaningful	Depends on competitor
Pediatric liquid opportunity	Meaningful	Varies by product
Biosimilar risk	None	None for small molecules
Main differentiation route	Formulation, packaging, supply	Formulation, indication, combination, device

Hydralazine's commercial weakness is frequent dosing and variable response. Its opportunity is to address operational and administration problems that newer oral agents do not fully solve.

Key Takeaways

• Hydralazine hydrochloride has no meaningful current molecule-level exclusivity.
• Conventional tablets face high generic entry and price pressure.
• The strongest commercial opportunities are ready-to-use injectables, standardized oral liquids, pediatric presentations, orally disintegrating tablets, and extended-release systems.
• Excipients should be selected around low-dose uniformity, chemical stability, dissolution, taste, and administration accuracy.
• A new patent estate would need to protect a specific formulation, delivery system, manufacturing process, or method of use.
• Hydralazine is a small molecule and has no biosimilar risk.
• Hospital supply reliability and product convenience may create greater commercial value than active-ingredient innovation.
• A conventional hydralazine product is more suitable for generic manufacturing or contract supply than for a high-margin branded strategy.

FAQs

Can hydralazine hydrochloride be formulated as an oral solution?

Yes. An oral solution is technically feasible, but the product must establish chemical stability, acceptable taste, preservative performance, dosing accuracy, and suitable packaging over the proposed shelf life.

Is hydralazine hydrochloride suitable for an extended-release tablet?

Yes, but the short duration of action creates both an opportunity and a development challenge. The product would need controlled pharmacokinetics, reliable dissolution, and evidence supporting reduced dosing frequency.

Are hydralazine hydrochloride tablets protected by active U.S. patents?

Standard hydralazine hydrochloride tablets are not generally protected by commercially meaningful active compound patents. Any relevant current protection would need to be evaluated at the specific product and Orange Book listing level.

What is the best excipient for hydralazine hydrochloride tablets?

No single excipient is universally optimal. Microcrystalline cellulose, lactose, mannitol, crospovidone, croscarmellose sodium, povidone, colloidal silicon dioxide, and magnesium stearate are potential candidates, subject to compatibility, dissolution, and stability testing.

Could a ready-to-use hydralazine injection support premium pricing?

Potentially. A prefilled syringe or premixed presentation could reduce preparation time and medication-handling steps, but commercial value would depend on hospital procurement, sterile manufacturing cost, supply reliability, and demonstrated in-use stability.

References

1. U.S. Food and Drug Administration. (2023). Hydralazine hydrochloride injection prescribing information. DailyMed. https://dailymed.nlm.nih.gov/

2. U.S. Food and Drug Administration. (2023). Hydralazine hydrochloride tablets prescribing information. DailyMed. https://dailymed.nlm.nih.gov/

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

4. U.S. Food and Drug Administration. (2019). ANDA submissions: Content and format guidance for industry. https://www.fda.gov/

5. U.S. Food and Drug Administration. (2022). Applications covered by section 505(b)(2). https://www.fda.gov/