List of Excipients in Branded Drug RIFAMPIN

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Generic Drugs Containing RIFAMPIN

Company	Ingredient	NDC	Excipient
Hikma Pharmaceuticals USA Inc	rifampin	0143-9230	SODIUM FORMALDEHYDE SULFOXYLATE
Hikma Pharmaceuticals USA Inc	rifampin	0143-9230	SODIUM HYDROXIDE
Eon Labs Inc	rifampin	0185-0801	CELLULOSE, MICROCRYSTALLINE
Eon Labs Inc	rifampin	0185-0801	D&C RED NO. 28

What are the Most Frequently-Used Excipients in RIFAMPIN?

# Of NDCs	Excipient
3	ALCOHOL
2	ALUMINUM OXIDE
10	AMMONIA
13	BUTYL ALCOHOL

Rifampin Excipient Strategy and Commercial Opportunities in Pharmaceutical Formulation

Last updated: August 5, 2026

Rifampin is an established small-molecule antibiotic with minimal remaining molecule-level exclusivity value. Commercial opportunity is concentrated in excipient-enabled improvements: pediatric delivery, fixed-dose combinations, oral bioavailability, stability, taste masking, simplified dosing, and supply-chain resilience. The main technical constraints are poor aqueous solubility, chemical instability, strong color, food effects, and extensive drug-drug interactions.

What is the commercial position of rifampin?

Rifampin, also called rifampicin, is a rifamycin antibiotic used primarily against tuberculosis and other susceptible bacterial infections. It is commonly administered with other antituberculosis drugs to limit resistance.

Attribute	Rifampin position
Active ingredient	Rifampin
CAS number	13292-46-1
Therapeutic class	Rifamycin antibacterial
Main indications	Tuberculosis, leprosy, selected staphylococcal infections, meningococcal prophylaxis
Common oral strengths	150 mg and 300 mg capsules
Common IV strength	600 mg
Major combinations	Rifampin with isoniazid, pyrazinamide, and ethambutol
Regulatory status	Generic small-molecule drug
Biosimilar exposure	None
Core commercial issue	Formulation quality, access, and combination-product execution
Primary markets	Tuberculosis programs, hospitals, public-health procurement, generic retail

Rifampin has a large global demand base because tuberculosis treatment remains a major public-health program. The World Health Organization recommends rifampicin-containing multidrug regimens for drug-susceptible tuberculosis [1]. Demand is concentrated in government tenders and donor-supported procurement rather than premium branded prescriptions.

When does rifampin lose exclusivity?

Rifampin’s original composition-of-matter exclusivity expired decades ago. The molecule is widely available from multiple generic manufacturers, and commercial value does not depend on an active compound patent.

The relevant protection categories are now:

• Formulation patents
• Fixed-dose combination patents
• Pediatric dosage-form patents
• Manufacturing-process patents
• Crystalline or amorphous solid-state claims
• Drug-delivery patents
• Method-of-use patents for particular infections or dosing regimens
• Regulatory exclusivity for a newly developed combination or pediatric product

A new rifampin product would generally need to establish value through improved performance, lower manufacturing cost, easier administration, or access to a procurement channel. A conventional 150 mg or 300 mg capsule with standard excipients is unlikely to create durable differentiation.

What patents protect rifampin products?

The relevant patent estate is fragmented across historical pharmaceutical companies, generic manufacturers, universities, and development organizations. Most foundational rifampin patents have expired. Current freedom-to-operate analysis should focus on later patents covering combinations, dosage forms, excipient systems, and manufacturing methods rather than rifampin itself.

The strongest potential patent positions would cover:

Patent category	Potential commercial value	Typical claim focus
Pediatric dispersible tablet	High	Rapid dispersion, taste masking, dose flexibility
Fixed-dose tuberculosis combination	High	Specific drug ratios, stability, manufacturing process
Amorphous solid dispersion	Medium to high	Polymer carrier, dissolution enhancement, stability
Nanocrystal or nanoparticle formulation	Medium	Particle-size range, stabilizer system, process
Modified-release formulation	Medium	Release profile, dosing frequency
Injectable formulation	Medium	Stabilization, reconstitution, storage conditions
Manufacturing process	Medium	Impurity control, yield, solvent system
Conventional capsule	Low	Basic fill composition and shell

A patent owner must show more than the use of a known excipient. Claims are more defensible when they tie the excipient system to a measurable result, such as improved dissolution after storage, reduced degradation, controlled rifampin polymorph conversion, or improved pediatric acceptability.

What formulation problems must excipients solve?

Poor aqueous solubility

Rifampin has limited water solubility. Dissolution performance can vary with particle size, solid form, pH, wetting, and manufacturing history. Excipients that improve wetting or maintain a favorable solid-state structure can increase the consistency of oral exposure.

Useful excipient classes include:

• Surfactants and wetting agents
• Hydrophilic polymers
• Cyclodextrins
• Sugar-based carriers
• Disintegrants
• Solubilizing co-solvents in liquid systems
• Lipid-based carriers
• pH modifiers

The development risk is that a solubility improvement in vitro may not produce a clinically meaningful increase in exposure. Rifampin has a narrow practical formulation window because excessive exposure may increase toxicity while insufficient exposure can undermine treatment.

Chemical and solid-state instability

Rifampin can degrade during storage and may undergo conversion between solid forms. Moisture, heat, oxygen, and formulation pH can affect stability. Excipients should be screened for reducing sugars, reactive aldehydes, residual peroxides, moisture content, and catalytic impurities.

Risk controls include:

• Low-moisture excipients
• Low-peroxide grades of surfactants
• Protective packaging
• Desiccants
• Oxygen-barrier blisters
• Film coatings
• Controlled granulation conditions
• Solid-state characterization by XRPD, DSC, and microscopy

Excipient selection should be linked to impurity monitoring, not only dissolution testing. Rifampin degradation products can affect product color and assay results and may complicate stability specifications.

Strong color

Rifampin is intensely red-orange. The color can migrate into excipients, packaging, suspension vehicles, and dissolution media. This creates challenges for:

• Visual uniformity
• Dose measurement
• Content-uniformity testing
• Pediatric acceptance
• Cleaning validation
• Manufacturing-line changeover
• Stability-indicating analytical methods

Color masking is usually less important than controlling dose visibility and patient acceptability. Opaque capsules, compatible film coatings, and packaging that limits staining may be more practical than attempting to chemically suppress the drug’s color.

Taste and pediatric acceptability

Rifampin is bitter and strongly colored. Liquid formulations and dispersible tablets therefore require a combined taste-masking strategy. A single sweetener is unlikely to provide adequate masking.

Potential approaches include:

• Ion-exchange resins
• Polymer coating
• Lipid coating
• Complexation
• Multiparticulate systems
• Flavors and sweeteners
• Rapidly dispersible tablets with coated drug particles

Taste masking must preserve dose release and avoid reducing rifampin absorption. The system should also tolerate administration with water or soft food, depending on the label instructions.

What excipients are used in rifampin products?

Commercial composition varies by manufacturer and jurisdiction. Common oral capsule systems may include lactose, starch, magnesium stearate, colloidal silicon dioxide, gelatin, titanium dioxide, and iron oxides. Exact compositions must be confirmed from the applicable product label and regulatory filing.

The commercial use of lactose and other reducing or reactive excipients requires compatibility testing. A formulation that performs acceptably at release may develop impurity or dissolution problems during long-term storage.

A practical screening matrix should assess:

Excipient function	Candidate classes	Main rifampin risk
Diluent	Lactose, microcrystalline cellulose, mannitol	Chemical compatibility, moisture
Binder	Povidone, hypromellose, starch	Granule hardness, dissolution delay
Disintegrant	Crospovidone, croscarmellose sodium, sodium starch glycolate	Swelling and release variability
Surfactant	Sodium lauryl sulfate, poloxamers	Peroxide and tolerability risk
Glidant	Colloidal silicon dioxide	Flow and blend segregation
Lubricant	Magnesium stearate, sodium stearyl fumarate	Hydrophobic dissolution effects
Taste masker	Polymers, resins, lipids	Delayed release or reduced exposure
Stabilizer	Buffers, antioxidants, chelators	pH and impurity interactions
Coating	Hypromellose, methacrylate polymers	Moisture protection and release
Liquid vehicle	Glycerol, sorbitol, suspending polymers	Sedimentation, microbial control

What formulation opportunities have the highest commercial value?

Pediatric dispersible rifampin

This is one of the strongest opportunities. Tuberculosis treatment requires reliable dosing across children with different body weights, but conventional capsules create dose-splitting and administration problems.

A commercially attractive product would provide:

• 25 mg, 50 mg, or flexible-dose units
• Rapid dispersion in a small volume of water
• Acceptable taste
• Low staining
• Long-term stability in high-temperature and high-humidity markets
• Compatibility with coadministration of other tuberculosis drugs

The product could target government procurement, pediatric tuberculosis programs, and humanitarian supply channels. The regulatory route would likely require a new drug application, abbreviated application strategy where applicable, or a locally relevant variation depending on the jurisdiction and product architecture.

Fixed-dose combination products

Rifampin is already used in combination with isoniazid, pyrazinamide, and ethambutol. The opportunity is not simply to combine the drugs, but to solve the technical problems created by combining chemically and physically different active ingredients.

Key development issues include:

• Unequal dose ratios
• Different dissolution requirements
• Cross-drug degradation
• Blend segregation
• Rifampin color interference
• Tablet size
• Stability under tropical conditions
• Bioequivalence to the individual reference products

A robust fixed-dose combination may reduce pill burden and improve treatment logistics. It can also create a more defensible patent position than a conventional rifampin capsule.

Oral liquid and ready-to-use suspensions

A ready-to-use suspension would address patients unable to swallow capsules. The main commercial barriers are rifampin’s taste, sedimentation, chemical stability, microbial control, and packaging.

A dry powder for reconstitution may be more practical than a ready-to-use liquid because it reduces water activity and improves shelf life. The product must still provide accurate dosing after reconstitution and remain physically stable throughout the labeled in-use period.

Amorphous dispersions and nanocrystals

These technologies may improve dissolution and reduce dose variability. They are most commercially relevant when they produce a measurable advantage in:

• Fed and fasted exposure
• Storage stability
• Dose uniformity
• Smaller dosage form
• Reduced variability between manufacturers

The main risk is physical aging or recrystallization. A formulation that depends on a metastable amorphous state requires strong solid-state controls and accelerated stability data.

Injectable rifampin

Intravenous rifampin is used when oral administration is not feasible. Excipient opportunities include improved reconstitution, reduced precipitation, lower infusion-related problems, and better storage stability.

The injectable product has stricter requirements for:

• Sterility
• Endotoxin control
• Particulate matter
• Reconstitution time
• pH
• Container compatibility
• Infusion-line compatibility

The market is smaller than the oral tuberculosis market, but hospital procurement can support premium pricing if supply reliability and administration performance improve.

What is the FDA regulatory status of rifampin?

Rifampin is an FDA-approved prescription drug available in oral and injectable forms. FDA labeling identifies rifampin products for tuberculosis and other specified infections, with dosing and warnings relating to hepatotoxicity, hypersensitivity, body-fluid discoloration, and drug interactions [2].

Rifampin is a potent inducer of CYP3A4 and other metabolic pathways. It can materially reduce exposure to numerous medicines, including hormonal contraceptives, anticoagulants, antiretrovirals, immunosuppressants, and some antineoplastic agents. A formulation program cannot treat excipient performance as separate from clinical pharmacology.

For a new dosage form, regulatory value will depend on:

• Demonstrated pharmaceutical equivalence or clinical benefit
• Dissolution and bioequivalence
• Impurity and degradation control
• Pediatric or geriatric usability
• Food-effect characterization
• Stability in intended climate zones
• Compatibility with combination therapy

What is the Orange Book status of rifampin?

The Orange Book lists approved rifampin products and reference-listed products by application holder and dosage form. The Orange Book does not create broad exclusivity for rifampin as a molecule. Any listed patents are product-specific and must be reviewed by application number and dosage form [3].

For a generic applicant, the principal legal risks are:

1. Listed formulation or method-of-use patents.
2. Paragraph IV certifications against any relevant listed patents.
3. Patent litigation following a paragraph IV notice.
4. Regulatory delays caused by bioequivalence or stability deficiencies.
5. Market disruption caused by procurement contracts rather than patents.

Because rifampin is an old generic drug, a paragraph IV strategy is more likely to concern a later formulation or combination product than the active ingredient itself.

Which companies are challenging rifampin exclusivity?

Rifampin does not have a meaningful single-company exclusivity structure comparable with a recently launched branded medicine. Competition comes from generic manufacturers and public-health suppliers across the United States, Europe, India, China, and other manufacturing centers.

The competitive landscape is shaped by:

• FDA-approved generic suppliers
• WHO-prequalified manufacturers
• National tuberculosis procurement programs
• Fixed-dose combination developers
• Contract manufacturers
• Government and donor tenders

The most important competitive advantage is often reliable supply, acceptable product quality, and tender eligibility rather than patent ownership.

How strong is the rifampin patent estate?

The rifampin molecule patent estate is weak because the active ingredient is old and widely genericized. A new product can still have a moderate or strong patent position if its claims cover a technically necessary formulation architecture.

Patent strength is highest when claims include:

• Defined excipient ranges
• Critical particle-size distributions
• Specific impurity thresholds
• Stability performance after accelerated storage
• Dissolution limits under multiple conditions
• Defined manufacturing steps
• Bioavailability or food-effect results
• Pediatric administration parameters

Patent strength is lower when claims rely on a broad list of conventional excipients without a demonstrated technical effect.

What generic launch risks exist for rifampin?

A conventional generic launch has low patent risk but meaningful execution risk.

Risk	Commercial effect
Rifampin instability	Recalls, shortened shelf life, failed stability batches
Poor dissolution	Bioequivalence failure or variable exposure
Excipient incompatibility	Impurity growth and rejected batches
Pediatric taste failure	Low adherence and weak procurement uptake
Color interference	Analytical and manufacturing complications
Drug interaction profile	Labeling constraints and limited clinical positioning
API shortages	Supply interruption and tender penalties
Combination-product failure	Delayed approval or loss of tuberculosis-program contracts
Manufacturing contamination	Cleaning and cross-contamination costs

Manufacturing-process patents may matter more than conventional formulation patents where a supplier has developed a lower-impurity or higher-yield rifampin process. A freedom-to-operate review should cover API synthesis, solid form, granulation, coating, and combination-tablet manufacture.

How does rifampin compare with other tuberculosis drugs?

Rifampin has greater formulation complexity than isoniazid because of its color, stability profile, and interaction burden. It also has greater commercial importance in fixed-dose combinations because rifampin is a central component of standard tuberculosis regimens.

Drug	Excipient challenge	Commercial differentiation
Rifampin	Solubility, stability, color, taste	Pediatric products, FDCs, improved stability
Isoniazid	High solubility, compatibility	Combination dosing and toxicity management
Pyrazinamide	Taste and dose size	Pediatric dispersible formulations
Ethambutol	Dose size, visual effects	Combination products and dose flexibility
Rifapentine	Cost and availability	Shorter regimens and public-health procurement

Rifapentine may compete with rifampin in selected shorter-course regimens, but rifampin retains a broad global supply and treatment role. A rifampin formulation company should compete on access, usability, and combination performance rather than assume that higher solubility alone will displace established products.

What licensing deals and partnerships are commercially relevant?

The most practical partnership structures involve:

• API manufacturers licensing impurity-control processes
• Generic companies licensing pediatric dosage forms
• Nonprofit organizations developing tuberculosis fixed-dose combinations
• Contract development and manufacturing organizations supplying WHO-prequalified products
• Public-health agencies supporting pediatric or low-resource formulations
• Universities licensing solid-dispersion or nanocrystal technologies

Revenue potential is strongest where a formulation secures procurement eligibility or creates a differentiated regulatory product. A private-label capsule has limited licensing value unless it includes a protected manufacturing process or supply advantage.

Key Takeaways

• Rifampin has no meaningful remaining composition-of-matter exclusivity value.
• Excipient strategy should focus on stability, dissolution, taste masking, pediatric dosing, and fixed-dose combinations.
• Pediatric dispersible tablets and dry powders for reconstitution offer the clearest commercial opportunities.
• Rifampin’s color, degradation profile, and drug interactions create development risks beyond ordinary generic formulation work.
• Conventional capsule products have limited patent and pricing power.
• Stronger patent positions require defined excipient systems, measurable stability benefits, or manufacturing-process claims.
• The main commercial buyers are tuberculosis programs, hospitals, generic distributors, and public-health procurement agencies.
• FDA and WHO regulatory execution, supply reliability, and combination-product performance are likely to matter more than molecule-level patent rights.

FAQs About Rifampin Excipient and Commercial Strategy

Can lactose be used as an excipient in rifampin capsules?

Lactose can be used in some rifampin formulations, but compatibility must be demonstrated through impurity, assay, and stability testing. The grade, moisture level, storage conditions, and manufacturing process can affect performance.

What is the best dosage form for pediatric rifampin?

A dispersible tablet or dry powder for reconstitution is generally more commercially useful than a conventional capsule. The product must combine flexible dosing, taste masking, rapid dispersion, and stability in hot and humid environments.

Can cyclodextrins improve rifampin solubility?

Cyclodextrins may improve apparent solubility, but commercial feasibility depends on dose, complexation efficiency, excipient burden, cost, and demonstrated improvement in exposure or dissolution.

Does rifampin have biosimilar competition?

No. Rifampin is a chemically synthesized small molecule, so competing products are generics rather than biosimilars.

What is the most defensible rifampin patent strategy?

The strongest strategy generally combines a defined excipient composition with a manufacturing process and measurable performance claims, such as improved stability, dissolution, pediatric acceptability, or bioavailability.

References

1. World Health Organization. (2022). WHO consolidated guidelines on tuberculosis: Module 4: Treatment - drug-susceptible tuberculosis treatment. World Health Organization.

2. U.S. Food and Drug Administration. (2023). Rifadin (rifampin) prescribing information. FDA.

3. U.S. Food and Drug Administration. (2025). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.

4. U.S. Pharmacopeial Convention. (2024). Rifampin monograph. United States Pharmacopeia and National Formulary.

5. World Health Organization. (2024). WHO prequalification of medicines database. World Health Organization.