List of Excipients in Branded Drug AZITHROMYCIN DIHYDRATE

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Generic Drugs Containing AZITHROMYCIN DIHYDRATE

Company	Ingredient	NDC	Excipient
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	ANHYDROUS DIBASIC CALCIUM PHOSPHATE
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	CROSCARMELLOSE SODIUM
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	FD&C BLUE NO. 1
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	FD&C RED NO. 40
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	FD&C YELLOW NO. 6
Medsource Pharmaceuticals	azithromycin dihydrate	45865-131	LECITHIN, SOYBEAN

What are the Most Frequently-Used Excipients in AZITHROMYCIN DIHYDRATE?

# Of NDCs	Excipient
1	ALUMINUM OXIDE
55	ANHYDROUS DIBASIC CALCIUM PHOSPHATE
8	CALCIUM PHOSPHATE, DIBASIC, ANHYDROUS
1	CALCIUM PHOSPHATE, DIBASIC, DIHYDRATE
1	CI 15985
2	CI 16035

Azithromycin Dihydrate Excipient Strategy and Commercial Opportunities

Last updated: October 5, 2026

Azithromycin dihydrate is a mature macrolide antibiotic with limited opportunity in basic immediate-release tablets but meaningful commercial potential in pediatric suspensions, taste-masked products, dispersible dosage forms, sachets, multiparticulates, and differentiated delivery systems. The core formulation challenges are poor aqueous solubility, intense bitterness, powder flow, suspension stability, moisture control, and palatability.

The strongest excipient opportunities are not new active-ingredient exclusivity. They are platform technologies that improve reconstitution, taste, dose uniformity, storage stability, adherence, and manufacturing efficiency while avoiding infringement of surviving formulation and method-of-use rights.

What formulation challenges does azithromycin dihydrate create?

Azithromycin dihydrate is a weakly basic, poorly water-soluble macrolide. Its formulation profile creates different problems by dosage form.

Formulation issue	Commercial consequence	Relevant excipient strategy
Low aqueous solubility	Slow dissolution and variable performance	Wetting agents, surfactants, particle-size reduction, solid dispersions
Strong bitterness	Poor pediatric adherence	Ion-exchange resins, polymeric taste barriers, lipids, sweetener-acid systems
High dose relative to potency	Large tablet or powder volume	Granulation, high-density carriers, multiparticulates
Powder segregation	Dose nonuniformity in suspensions and sachets	Granule engineering, controlled particle-size distribution, glidants
Moisture sensitivity of the dry product	Reduced shelf stability and caking	Desiccants, moisture-barrier packaging, low-water-activity excipients
Reconstitution requirements	Errors in pediatric dosing	Premeasured sachets, calibrated bottles, rapid-dispersing granules
Gastrointestinal intolerance	Reduced persistence and adherence	Food-effect management, modified release, lower peak exposure approaches

Azithromycin dihydrate is commonly used in solid oral and powder-for-reconstitution products. The dihydrate form must be controlled during granulation, drying, milling, and storage because water activity can affect physical properties and product consistency.

What excipients are used in azithromycin tablets and capsules?

Immediate-release azithromycin tablets generally use a conventional direct-compression or wet-granulation architecture. Public labels for branded and generic products identify excipient classes that commonly include diluents, binders, disintegrants, lubricants, film-coating agents, and colorants. Exact compositions vary by manufacturer and strength.

Core excipient classes

Function	Common excipient examples	Role in azithromycin products
Diluent	Lactose, microcrystalline cellulose, dibasic calcium phosphate	Controls tablet size, density, and compressibility
Binder	Povidone, hypromellose, pregelatinized starch	Improves granule and tablet strength
Disintegrant	Croscarmellose sodium, crospovidone, sodium starch glycolate	Accelerates tablet breakup
Lubricant	Magnesium stearate, sodium stearyl fumarate	Reduces ejection force and tooling adhesion
Glidant	Colloidal silicon dioxide	Improves powder flow and die filling
Film former	Hypromellose, polyvinyl alcohol	Protects the tablet and improves swallowability
Plasticizer	Polyethylene glycol, triacetin	Improves coating flexibility
Opacifier	Titanium dioxide or alternative pigments	Controls appearance and light protection
Colorant	Iron oxides and approved lake colors	Supports product identification

A direct-compression formulation can lower manufacturing cost but may be less tolerant of azithromycin’s flow and compactability profile. Roller compaction or wet granulation can improve blend uniformity, although aqueous processing requires tighter control of drying and residual moisture.

Commercial opportunity in tablets

The basic tablet market is highly competitive and price-sensitive. Differentiation is more credible when a formulation offers one or more measurable advantages:

• Smaller tablet dimensions at the same dose.
• Faster disintegration without excessive friability.
• Lower pill burden through fixed-dose combinations.
• Improved dissolution under physiologically relevant pH conditions.
• Scored tablets or flexible strengths for pediatric and geriatric dosing.
• Better stability in hot and humid distribution environments.
• Reduced use of controversial or supply-constrained excipients.

A new tablet excipient combination is unlikely to support strong standalone exclusivity unless it produces a documented performance improvement and is claimed through a novel composition, process, or dissolution profile.

What excipients are used in azithromycin oral suspensions?

Pediatric powder-for-suspension products are the most important excipient-driven segment. The commercial product must remain physically stable before reconstitution, disperse rapidly after water is added, deliver a consistent dose throughout use, and suppress azithromycin’s bitterness.

Typical suspension systems contain:

• Suspending agents such as xanthan gum, sodium carboxymethylcellulose, microcrystalline cellulose with carboxymethylcellulose sodium, or similar polymers.
• Wetting agents to promote rapid hydration.
• Sugars or polyols such as sucrose, glucose, sorbitol, or mannitol.
• Buffers and acids to control pH and flavor.
• Preservatives where permitted and necessary.
• Antifoaming agents.
• Flavors and sweeteners.
• Bulking agents and density modifiers.

The excipient system must balance viscosity and pourability. Excessive viscosity can improve sedimentation control but impair reconstitution, dosing accuracy, and bottle emptying. Low viscosity can cause rapid settling and dose variability.

Which taste-masking technologies are most commercially attractive?

Taste masking is the clearest excipient opportunity in pediatric azithromycin.

Ion-exchange resin complexes

Azithromycin can be associated with ion-exchange materials to reduce immediate contact with taste receptors. The complex must release the drug adequately after administration. Commercial advantages include compatibility with dry granulation, suspension manufacture, and multiparticulate delivery.

Key development risks are incomplete drug release, resin impurity control, dose-loading limits, and altered pharmacokinetics.

Polymer coating

Drug particles or granules can be coated with ethylcellulose, methacrylate copolymers, hypromellose, or related polymers. Coating thickness and permeability determine whether the system functions as taste masking or modified release.

A coating designed only for oral taste suppression may have a more manageable regulatory profile than a system that materially changes systemic exposure. Claims must distinguish the two.

Lipid and wax barriers

Lipid-coated particles can reduce bitterness and improve mouthfeel. These systems may also protect the drug from moisture. Development issues include coating uniformity, dissolution variability, temperature sensitivity, and interaction with suspension vehicles.

Flavor-acid systems

Fruit flavors, sweeteners, citric acid, malic acid, and buffering agents can reduce perceived bitterness without physically coating the drug. This is inexpensive and easy to scale, but it may provide weaker masking for high-dose administration.

A dual strategy combining physical taste masking with flavor correction is more commercially robust than either approach alone.

What formulations are protected by azithromycin patents?

Azithromycin’s original active-ingredient and broad product patents are legacy rights. The compound was commercialized decades ago, and the original U.S. composition-of-matter patent is expired. FDA-approved azithromycin tablets, capsules, and oral suspensions are therefore primarily generic markets rather than active-ingredient exclusivity markets.

Formulation patent opportunities

Potentially protectable subject matter includes:

• Specific taste-masked particles.
• Resin-drug complexes with defined loading and release.
• Narrow excipient ratios that produce a distinctive dissolution profile.
• Stable dry suspensions with defined water activity.
• Multiparticulates with controlled coating parameters.
• Reconstituted suspensions with improved sedimentation and redispersibility.
• Solid dispersions or amorphous systems with enhanced dissolution.
• Manufacturing processes that produce a defined particle morphology.
• Packaging systems that maintain stability in high humidity.

A formulation patent is stronger when the claims include objective parameters such as particle-size distribution, coating weight gain, dissolution limits, viscosity range, sedimentation volume, reconstitution time, or assay uniformity.

Method-of-use patents are more limited because azithromycin has broad, established clinical uses. New-use claims may face written-description, obviousness, enablement, and clinical-evidence challenges. Pediatric adherence, improved tolerability, or reduced dosing frequency can support commercial differentiation, but the patent case requires clinical or pharmacokinetic evidence.

What is the FDA regulatory status of azithromycin?

Azithromycin is an FDA-approved prescription antibacterial marketed in tablets, capsules, oral suspension, and extended-release oral suspension forms. Zithromax was the principal reference brand, and multiple generic products have entered the market under abbreviated new drug applications.

The regulatory pathway depends on the product:

Product type	Likely FDA pathway	Main development burden
Conventional tablet	ANDA	Pharmaceutical equivalence and bioequivalence
Conventional capsule	ANDA	Bioequivalence and product quality
Powder for oral suspension	ANDA	In vitro performance, reconstitution, stability, and bioequivalence
Taste-masked suspension	ANDA if equivalent; 505(b)(2) if materially different	Clinical or pharmacokinetic bridging may be required
Modified-release product	505(b)(2) or ANDA depending on reference and formulation	Comparative pharmacokinetics and clinical justification
Novel pediatric delivery system	505(b)(2) or NDA	Safety, efficacy bridging, human factors, and product performance

FDA labeling identifies the active ingredient and inactive ingredients for approved products. DailyMed provides manufacturer-specific labels and should be used to confirm the current excipient declaration for each product presentation.[1,2]

When does azithromycin lose exclusivity?

Azithromycin lost its original U.S. small-molecule exclusivity years ago. The commercial market is now governed by generic competition, product-specific formulation rights, regulatory exclusivities, and supply economics rather than compound exclusivity.

Exclusivity category	Azithromycin position
Original composition-of-matter protection	Expired
Original branded product exclusivity	Expired
Standard generic entry	Established
Pediatric exclusivity	Historical and expired
Orphan exclusivity	Not the basis of the mainstream azithromycin market
Formulation exclusivity	Possible only for specific later products or technologies
Trade-secret protection	Potentially relevant to manufacturing and taste-masking processes

The extended-release oral suspension product, marketed as Zmax, created a differentiated formulation and dosing profile. Any surviving rights must be checked by product, patent family, jurisdiction, and expiration status in the current Orange Book and public patent records. Broad statements that all azithromycin-related patents have expired would be inaccurate because later formulation and manufacturing rights can have different terms.

What is the Orange Book status of azithromycin?

Azithromycin products have historically appeared in the FDA Orange Book under multiple dosage forms and strengths. The Orange Book identifies reference listed drugs, therapeutic-equivalence codes, patents submitted for listing, and periods of generic exclusivity where applicable.[3]

For a commercial launch, the relevant diligence questions are:

1. Is the target product an ANDA reference to a listed azithromycin product?
2. Does the reference product have listed patents?
3. Is a Paragraph IV certification required?
4. Are any 30-month stays or patent litigation proceedings active?
5. Is the proposed formulation sufficiently similar for an ANDA?
6. Does the product require a 505(b)(2) application because of altered release, delivery, or clinical performance?

Which companies are challenging azithromycin patents?

Azithromycin’s principal competitive pressure comes from established generic manufacturers rather than current challenges to the original compound patent. Companies that have historically marketed or submitted generic azithromycin products include large multinational and specialty generic manufacturers such as Teva, Sandoz, Viatris, Dr. Reddy’s Laboratories, Lupin, Cipla, and other FDA-approved applicants.

The competitive question is product-specific. A company developing a novel taste-masked suspension or modified-release product could face Paragraph IV challenges if it relies on later formulation patents. A conventional generic tablet generally faces a mature market with limited patent-driven barriers.

What generic launch risks exist for azithromycin?

Generic launch risk is concentrated in pricing, manufacturing, regulatory review, and supply reliability.

Key risks

• Multiple approved suppliers can cause rapid price erosion.
• Institutional buyers may favor the lowest-cost supplier.
• Pediatric suspension products require more complex manufacturing than tablets.
• Shortages of flavors, suspending polymers, or packaging components can disrupt supply.
• Poor reconstitution or sedimentation performance can lead to recalls and loss of contracts.
• Taste-masking technology can create unexpected bioequivalence issues.
• Foreign manufacturing dependence increases logistics and quality-system exposure.
• A 505(b)(2) product may require more clinical evidence than expected.

A differentiated pediatric suspension can preserve margin if it demonstrates better adherence, lower dosing error, longer in-use stability, or improved acceptability. Those benefits must be supported by comparative data and translated into payer, hospital, or caregiver value.

How strong is the azithromycin patent estate?

The legacy azithromycin patent estate is weak for broad compound protection and stronger only where narrow formulation or process claims remain enforceable.

Patent layer	Relative strength
Active ingredient	Low; legacy protection expired
Conventional tablet excipients	Low unless tied to unexpected performance
Standard suspension vehicle	Low to moderate
Taste-masked particles	Moderate to strong if technically specific
Modified release	Moderate, subject to prior-art review
Manufacturing process	Moderate when difficult to replicate and well documented
Packaging and moisture control	Moderate, usually narrow
New method of use	Variable and evidence-dependent

The strongest commercial moat is likely a combination of formulation know-how, validated manufacturing controls, regulatory approval, and customer acceptance rather than a single broad patent.

What licensing deals and commercial partnerships are relevant?

Azithromycin licensing opportunities are more likely to involve technologies than the active ingredient itself. Potential transaction structures include:

• Licensing a taste-masking platform for pediatric antibiotics.
• Acquiring a ready-to-file suspension formulation.
• Partnering with a contract development and manufacturing organization.
• Licensing resin-complex or coated-particle technology.
• Co-developing a sachet or unit-dose product for emerging markets.
• Supplying specialty excipients under a preferred or exclusive agreement.
• Licensing a manufacturing process that reduces granulation time or improves yield.

Royalty value depends on whether the technology improves a regulated product attribute that competitors cannot easily reproduce. A generic flavor system has low licensing value. A validated platform that improves taste, stability, and bioequivalence has materially higher value.

How does azithromycin compare with other oral antibiotics?

Azithromycin competes with amoxicillin, amoxicillin-clavulanate, clarithromycin, doxycycline, and other oral antibiotics. Its formulation advantage is the potential for short-course therapy and once-daily dosing. Its main excipient disadvantage is the strong bitterness and relatively high pediatric dose volume.

Product	Excipient opportunity	Main commercial constraint
Azithromycin suspension	High-value taste masking and redispersibility	Mature generic competition
Amoxicillin suspension	Flavor, powder flow, reconstitution	High-volume price competition
Amoxicillin-clavulanate	Moisture control and stability	More complex stability profile
Clarithromycin suspension	Taste masking and suspension stability	Smaller market and resistance concerns
Doxycycline tablets/capsules	Swallowability and GI tolerability	Age and safety limitations in some populations

What geographic markets offer the best opportunity?

High-income markets reward regulatory differentiation, convenience, and pediatric acceptability. Emerging markets offer greater volume potential but are more price-sensitive and may have variable storage conditions.

High-priority geographic strategies

• United States: ANDA competition, Orange Book diligence, pediatric taste masking, and institutional contracts.
• European Union: decentralized or national procedures, pediatric formulation positioning, and excipient compliance.
• Latin America: suspension affordability, climate stability, and unit-dose packaging.
• South Asia: high-volume generic production and low-cost excipient sourcing.
• Africa: heat-stable formulations, simplified reconstitution, and distribution resilience.
• Middle East and Southeast Asia: flavored pediatric products and humidity-resistant packaging.

A formulation intended for tropical markets should prioritize low water activity, moisture-barrier packaging, rapid reconstitution with variable water quality, and extended in-use stability.

Key Takeaways

• Azithromycin dihydrate is a mature active ingredient with limited opportunity in undifferentiated immediate-release tablets.
• Pediatric suspensions, taste-masked particles, dispersible products, and unit-dose presentations offer the strongest excipient-led opportunities.
• The principal formulation problems are bitterness, low solubility, suspension stability, powder flow, and moisture control.
• Original azithromycin compound exclusivity is expired; commercial protection must come from formulation patents, process know-how, regulatory differentiation, and supply execution.
• FDA Orange Book and DailyMed records should be reviewed product by product because later formulations may have separate patent and regulatory histories.
• The most valuable commercial platform is likely a taste-masked, rapidly reconstituting, storage-stable pediatric product with demonstrated dose uniformity and bioequivalence.
• Licensing value is highest for validated technologies that improve measurable product attributes and reduce regulatory or manufacturing risk.

FAQs About Azithromycin Dihydrate Excipients and Commercialization

Can azithromycin dihydrate be formulated as a ready-to-drink liquid?

Yes. A ready-to-drink liquid can be developed, but solubility, bitterness, chemical stability, preservative control, and dose uniformity make it more challenging than a dry powder for reconstitution.

Which excipient is best for masking azithromycin bitterness?

No single excipient is universally best. Ion-exchange resins, polymer coatings, lipid barriers, and flavor-acid systems each have different effects on release, manufacturability, and regulatory risk. A combined physical and sensory approach is often the most practical.

Is azithromycin dihydrate suitable for orally disintegrating tablets?

It can be considered for orally disintegrating tablets, but the high dose and intense bitterness create significant constraints. Taste-masked granules, porous carriers, and low-volume dosage forms are generally more suitable than simply compressing unmodified drug.

Can a new azithromycin excipient combination receive patent protection?

Yes, if the combination is novel, nonobvious, adequately disclosed, and linked to measurable technical effects. Routine substitution of one diluent, binder, or flavor for another is unlikely to provide strong patent protection.

What is the most defensible commercial claim for a new azithromycin pediatric product?

A claim based on improved palatability, faster and more complete reconstitution, better dose uniformity, or stability under challenging storage conditions is generally more commercially defensible than a broad claim covering conventional azithromycin suspension excipients.

References

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

2. National Library of Medicine. (2024). DailyMed: Azithromycin product labeling. https://dailymed.nlm.nih.gov/dailymed/

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

4. U.S. Food and Drug Administration. (1999). Zithromax azithromycin prescribing information. Pfizer Laboratories.

5. U.S. Food and Drug Administration. (2017). Guidance for industry: Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system. https://www.fda.gov/

6. United States Patent and Trademark Office. (1985). U.S. Patent No. 4,517,359: 9-Deoxo-9a-aza-9a-methyl-9a-homoerythromycin A. Washington, DC.