List of Excipients in Branded Drug ENALAPRILAT

Generic Drugs Containing ENALAPRILAT

Company	Ingredient	NDC	Excipient
Hikma Pharmaceuticals USA Inc	enalaprilat	0143-9787	BENZYL ALCOHOL
Hikma Pharmaceuticals USA Inc	enalaprilat	0143-9787	SODIUM CHLORIDE
Hikma Pharmaceuticals USA Inc	enalaprilat	0143-9787	SODIUM HYDROXIDE
Hikma Pharmaceuticals USA Inc	enalaprilat	0143-9787	WATER
Dr Reddys Laboratories Inc	enalaprilat	43598-078	BENZYL ALCOHOL
Dr Reddys Laboratories Inc	enalaprilat	43598-078	SODIUM CHLORIDE

What are the Most Frequently-Used Excipients in ENALAPRILAT?

# Of NDCs	Excipient
3	BENZYL ALCOHOL
3	SODIUM CHLORIDE
3	SODIUM HYDROXIDE
3	WATER

Enalaprilat Excipient Strategy and Commercial Opportunities

Last updated: August 27, 2026

Enalaprilat is an injectable angiotensin-converting enzyme inhibitor with limited commercial scale because it is used mainly when oral enalapril or another oral antihypertensive cannot be administered. The principal opportunity is not a new chemical entity or broad patent position. It is a reliable, preservative-free, ready-to-administer injectable product with lower preparation burden, improved supply continuity, and packaging suited to hospital use.

The formulation is technically straightforward: an aqueous sterile solution of enalaprilat, typically adjusted for pH and isotonicity. Commercial differentiation can come from prefilled syringes, small-volume bags, pharmacy-ready presentations, optimized container closure systems, and dependable global supply.

What is enalaprilat and how is it used?

Enalaprilat is the active dicarboxylate metabolite of enalapril. Unlike enalapril, it is not suitable for routine oral administration because of poor gastrointestinal absorption. Enalaprilat is therefore administered intravenously.

Attribute	Enalaprilat
Drug class	ACE inhibitor
Active moiety	Enalaprilat
Primary route	Intravenous
Typical marketed strength	1.25 mg/mL injection
Main use	Treatment of hypertension when oral therapy is not practical
Main commercial setting	Hospitals and acute-care facilities
Oral substitute	Enalapril maleate
Biosimilar pathway	Not applicable
Primary competitive threat	Generic injectable ACE inhibitors and alternative IV antihypertensives

FDA labeling identifies enalaprilat injection for the treatment of hypertension in patients who cannot take oral therapy. The label also requires careful blood-pressure monitoring because excessive hypotension can occur, particularly in volume-depleted patients or those receiving diuretics [1].

What excipients are used in enalaprilat injection?

The core formulation uses a small excipient system. U.S. labeling for enalaprilat injection identifies sodium chloride and water for injection as inactive ingredients, with pH adjustment as needed [1,2].

Reference excipient profile

Formulation component	Function	Commercial significance
Water for injection	Solvent	Must meet injectable-water and sterility requirements
Sodium chloride	Tonicity adjustment	Supports intravenous tolerability
Sodium hydroxide or hydrochloric acid, if used	pH adjustment	Controls solubility and stability
Nitrogen headspace, if used	Oxygen reduction	May reduce oxidative stress during storage
Preservative	Microbial control	Generally less attractive for single-dose injectable use

The target product profile should favor a preservative-free, single-dose presentation. A preservative may reduce manufacturing complexity in multidose packaging, but it introduces toxicological, compatibility, and labeling considerations. It is not necessary when the product is supplied in a single-use vial, ampoule, or prefilled syringe.

How should an enalaprilat excipient strategy be designed?

The formulation strategy should focus on chemical stability, injection compatibility, and hospital workflow rather than on complex drug delivery.

pH control

Enalaprilat contains ionizable carboxyl groups and has limited formulation flexibility compared with a neutral, highly water-soluble drug. The formulation must maintain a pH that preserves solubility without increasing degradation or causing injection-site irritation.

A narrow pH specification is commercially useful because it supports:

• consistent assay and impurity control;
• reproducible appearance;
• reduced risk of precipitation after dilution;
• better compatibility with common infusion systems;
• simplified stability justification.

The sponsor should establish degradation profiles across pH, temperature, light exposure, and oxygen conditions. The critical question is whether pH adjustment creates a stability tradeoff between solubility and chemical degradation.

Tonicity

Sodium chloride is the simplest tonicity agent and is already consistent with the labeled product profile. Excessive chloride or high osmolality can affect peripheral administration and dilution compatibility. The commercial formulation should therefore target near-isotonic or clinically acceptable osmolality without adding unnecessary buffers or polyols.

A phosphate, citrate, or acetate buffer could improve pH control, but each introduces additional regulatory and compatibility work. Buffers may alter degradation pathways, interact with container materials, or complicate coadministration. A low-excipient formulation is preferable unless forced degradation and long-term stability data support a buffer system.

Antioxidant and chelator assessment

Routine inclusion of antioxidants or chelators should not be assumed. Such excipients can create new toxicology and compatibility issues, particularly in an injectable product with a simple established composition.

A development program should first determine whether oxygen, trace metals, light, or container interaction drives degradation. If oxidation is material, the preferred sequence is:

1. reduce oxygen exposure during filling;
2. evaluate nitrogen purging and low-oxygen headspace;
3. select a low-permeability container closure;
4. assess light-protective packaging;
5. add a chelator or antioxidant only if necessary.

This approach limits formulation complexity and reduces the risk of excipient-related regulatory questions.

Preservative strategy

A single-dose preservative-free formulation is generally the stronger commercial option. It supports use in critical-care settings where preservative exposure is undesirable and avoids the need to justify repeated-entry use.

A multidose product could reduce packaging cost, but its value is limited because enalaprilat is used intermittently and hospitals increasingly favor ready-to-administer single-dose formats. Multidose packaging would require robust antimicrobial effectiveness data and a clear handling protocol.

What formulations are protected by patents?

No commercially meaningful unexpired composition-of-matter protection should be expected for enalaprilat. The original ACE inhibitor patent estate dates from the 1980s and has expired. Any current intellectual-property value is more likely to arise from a specific formulation, container system, manufacturing process, or device presentation than from enalaprilat itself.

IP category	Likely status	Commercial implication
Enalaprilat active ingredient	Expired historical protection	No meaningful entry barrier
Basic aqueous injection	Likely difficult to protect broadly	Narrow patent scope and weak exclusion value
pH or excipient optimization	Potentially patentable if unexpected	Requires comparative stability or clinical evidence
Prefilled syringe presentation	Potentially protectable	More relevant to device and packaging claims
Ready-to-use infusion bag	Potentially protectable	May support hospital procurement differentiation
Manufacturing controls	Potentially protectable as know-how	More valuable as trade secrets than patents
Method of use	Historical indications largely expired	Low practical blocking value
Container closure system	Potentially patentable	Useful only if it solves adsorption, leachables, or stability problems

A formulation patent would need more than the use of sodium chloride and water for injection. Broad claims covering a conventional aqueous enalaprilat solution would face novelty and obviousness problems. Stronger claims would require measurable advantages, such as materially improved shelf life, reduced impurity formation, enhanced syringe stability, or resistance to precipitation after dilution.

What is the Orange Book status of enalaprilat?

The Orange Book analysis is narrower than for a major oral branded drug. Enalaprilat has no active new chemical entity exclusivity and no expected commercial value from historical enalaprilat patents. The relevant issues are whether an approved reference product remains listed, whether active patents are listed against that reference product, and whether an applicant must rely on an ANDA or another abbreviated pathway.

FDA’s Orange Book identifies approved drug products and, where applicable, listed patents and exclusivity. A product may remain commercially relevant even when the original brand is discontinued if an approved reference listing or authorized generic pathway supports abbreviated development [3].

Regulatory pathway

For a new U.S. generic injectable, the principal pathway would generally be an ANDA if a suitable reference product and product-specific requirements are available. The development package would focus on:

• pharmaceutical equivalence;
• strength and dosage form;
• sterility and particulate matter;
• extractables and leachables;
• container-closure integrity;
• stability;
• labeling;
• manufacturing controls;
• in-use or dilution compatibility where required.

Because enalaprilat is an injectable solution, the product may avoid some of the bioequivalence complexity associated with oral solid dosage forms. The regulatory burden shifts toward sterile manufacturing, elemental impurities, container compatibility, and assurance of dose uniformity.

When does enalaprilat lose exclusivity?

Enalaprilat’s original exclusivity expired decades ago. There is no realistic pathway to restore broad exclusivity through the active ingredient. Any new exclusivity would need to arise from a qualifying new formulation, device, pediatric investigation, or other statutory mechanism.

Exclusivity type	Current strategic relevance
Original chemical patent	Expired
New chemical entity exclusivity	Expired
Orphan-drug exclusivity	Not central to the established product
Pediatric exclusivity	No current basis assumed
Formulation patent	Possible but narrow
Device or packaging patent	Possible
Data exclusivity for a new formulation	Dependent on FDA qualification

A sponsor should not underwrite the project on the assumption that a new excipient combination will receive broad regulatory exclusivity. Commercial returns should instead depend on manufacturing efficiency, supply reliability, and differentiated packaging.

How strong is the patent estate for enalaprilat?

The patent estate is weak for a conventional injectable formulation and potentially moderate for a narrowly defined delivery or packaging innovation.

Patent-strength assessment

Claim area	Relative strength	Reason
Enalaprilat itself	Very low	Historical protection expired
Conventional saline injection	Very low	Routine formulation approach
Specific pH range	Low to moderate	Requires unexpected stability or performance data
Preservative-free presentation	Low	Often an obvious product choice
Prefilled syringe	Moderate	Stronger if supported by compatibility and usability data
Ready-to-use infusion bag	Moderate	Potential operational benefit
Low-oxygen manufacturing process	Moderate	Better suited to know-how unless unusual
Novel stabilizer system	Moderate	Depends on unexpected results
Pediatric or critical-care method of use	Low	Method claims may face prior-art and eligibility issues

The most defensible strategy is a layered protection model:

1. patent a genuinely differentiated formulation or container system;
2. maintain filling, sterilization, and oxygen-control parameters as trade secrets;
3. protect human-factors and device integration through design and device rights;
4. build commercial barriers through validated supply and hospital contracts.

What commercial opportunities exist for enalaprilat?

The opportunity is a niche injectable business rather than a high-volume chronic-care product.

Ready-to-use hospital presentations

Hospitals often prefer products that reduce bedside preparation. A prefilled syringe containing the labeled dose could reduce dilution errors and pharmacy handling. The presentation would need to address syringe-material compatibility, dose accuracy, stability, terminal sterilization or aseptic processing, and labeling space.

Potential formats include:

• single-dose prefilled syringe;
• low-volume ready-to-administer vial;
• pharmacy bulk package;
• small-volume infusion bag;
• unit-dose emergency-cart presentation.

The strongest initial opportunity is likely a preservative-free single-dose syringe or vial, not a complex controlled-release system.

Supply-chain differentiation

Enalaprilat is a low-volume hospital product. A supplier can compete through:

• dual-source API procurement;
• domestic or regional sterile filling;
• extended shelf life;
• low minimum order quantities;
• reliable backorder performance;
• compatibility data for commonly used infusion materials.

For a product with limited clinical differentiation, supply reliability can determine formulary retention.

Global and geographic opportunities

Demand may be more attractive in markets where:

• IV antihypertensive alternatives are expensive or inconsistently available;
• oral administration is frequently interrupted in hospitalized patients;
• local sterile injectable capacity is limited;
• hospitals rely on imported branded or generic products;
• regulatory approval can be obtained through a straightforward generic pathway.

Country-specific opportunities require review of local reference products, procurement rules, import controls, pharmacopoeial requirements, and price ceilings. A single global formulation may not be optimal because some jurisdictions favor ampoules, while others prefer vials or prefilled syringes.

How does enalaprilat compare with competing injectable antihypertensives?

Enalaprilat competes against drugs with broader emergency-care use and more flexible titration.

Product	Main advantage	Limitation versus enalaprilat
Enalaprilat	ACE inhibition; useful when oral therapy is not possible	Slow or less predictable titration for acute pressure control
Nicardipine	Titrated IV infusion and broad critical-care use	Requires infusion management
Clevidipine	Rapid titration and short duration	Higher acquisition cost and specialized lipid formulation
Labetalol	Bolus and infusion options	Beta-blockade limits use in some patients
Hydralazine	Low-cost injectable option	Less predictable response
Sodium nitroprusside	Potent, rapid effect	Monitoring and toxicity concerns
Furosemide	Useful when volume overload is present	Not a direct substitute for ACE inhibition

Enalaprilat is most commercially defensible where the clinical need is continued renin-angiotensin system blockade and oral dosing is temporarily unavailable. It is less competitive where rapid minute-to-minute blood-pressure titration is required.

What generic entry risks exist?

Generic entry risk is high because the active ingredient and conventional dosage form are old, the formulation is simple, and no meaningful active composition patent barrier is expected.

The principal development risks are operational:

• sterile manufacturing failure;
• particulate contamination;
• container-closure leakage;
• low-level degradation impurities;
• syringe or vial adsorption;
• inadequate stability after dilution;
• inconsistent API supply;
• small market size relative to validation and launch costs.

The commercial risk is demand volatility. Hospitals may use little product during normal periods but require uninterrupted availability during shortages or formulary changes. A company can lose money if it builds capacity for a market that does not support efficient batch sizes.

What patent litigation affects enalaprilat?

No major current patent litigation should be expected to define the enalaprilat market. The historical product estate is mature, and the likely disputes would concern manufacturing, ANDA certification, formulation claims, or supply contracts rather than basic molecule ownership.

A future applicant should still conduct:

• Orange Book patent review;
• FDA approval-history review;
• terminal-disclaimer analysis;
• freedom-to-operate review for syringe and bag systems;
• patent searches covering pH, stabilizers, and sterile filling;
• Paragraph IV assessment if an active listed patent exists.

A Paragraph IV challenge would be commercially relevant only if an active patent is listed against the applicable reference product. For a conventional enalaprilat injection, the more likely outcome is a patent-light abbreviated filing with competition centered on cost and supply.

What licensing deals could support an enalaprilat launch?

Licensing is more likely to involve manufacturing and distribution than molecule rights. Attractive structures include:

• API supply and quality agreements;
• contract sterile-filling arrangements;
• regional commercialization licenses;
• hospital-contracting partnerships;
• co-development of prefilled syringes;
• authorized-generic distribution agreements;
• licensing of container-closure or syringe technology.

An exclusive license is difficult to justify without a differentiated formulation or device. A nonexclusive supply and distribution agreement may better match the product’s limited patent value and hospital-focused demand.

Key Takeaways

• Enalaprilat is an old, injectable ACE inhibitor used mainly when oral therapy is not practical.
• The commercial formulation is a simple aqueous sterile solution, commonly using water for injection and sodium chloride.
• A preservative-free, single-dose product is the most practical target profile.
• The strongest opportunities are prefilled syringes, ready-to-use hospital presentations, and supply-reliable generic products.
• The original enalaprilat patent and exclusivity position are expired; broad molecule protection is unavailable.
• A conventional formulation patent would likely be weak unless supported by unexpected stability, compatibility, or usability results.
• Biosimilar competition is irrelevant because enalaprilat is a small-molecule drug.
• The main barriers are sterile manufacturing, market size, procurement economics, and supply continuity.
• Commercial returns should be based on operational differentiation rather than regulatory exclusivity.

FAQs

Is enalaprilat the same drug as enalapril?

No. Enalaprilat is the active metabolite of enalapril and is administered intravenously. Enalapril is an orally administered prodrug.

Can enalaprilat be formulated as an oral tablet?

A conventional oral tablet is commercially unattractive because enalaprilat has poor oral absorption. Oral enalapril maleate is the established alternative.

Is a preservative required in enalaprilat injection?

No. A single-dose preservative-free formulation can use aseptic processing and container-closure integrity controls instead of an antimicrobial preservative.

What is the best commercial dosage form for a new enalaprilat product?

A preservative-free prefilled syringe or ready-to-use single-dose vial is the strongest initial format because it reduces preparation steps and fits hospital administration workflows.

Does enalaprilat have biosimilar competition?

No. Enalaprilat is a chemically synthesized small molecule. Competition comes through generic injectable products, not biosimilars.

References

1. U.S. Food and Drug Administration. (n.d.). Enalaprilat injection prescribing information. FDA/DailyMed labeling.

2. National Library of Medicine. (n.d.). DailyMed: Enalaprilat injection. U.S. National Library of Medicine.

3. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.