List of Excipients in Branded Drug RIFAPENTINE

Generic Drugs Containing RIFAPENTINE

Company	Ingredient	NDC	Excipient
Macleods Pharmaceuticals Limited	rifapentine	33342-599	CALCIUM STEARATE
Macleods Pharmaceuticals Limited	rifapentine	33342-599	EDETATE DISODIUM
Macleods Pharmaceuticals Limited	rifapentine	33342-599	FERRIC OXIDE RED
Macleods Pharmaceuticals Limited	rifapentine	33342-599	HYDROXYPROPYL CELLULOSE
Macleods Pharmaceuticals Limited	rifapentine	33342-599	LOW-SUBSTITUTED HYDROXYPROPYL CELLULOSE
Macleods Pharmaceuticals Limited	rifapentine	33342-599	MICROCRYSTALLINE CELLULOSE 101
Macleods Pharmaceuticals Limited	rifapentine	33342-599	MICROCRYSTALLINE CELLULOSE 102

What are the Most Frequently-Used Excipients in RIFAPENTINE?

# Of NDCs	Excipient
1	CALCIUM STEARATE
1	EDETATE DISODIUM
1	FERRIC OXIDE RED
1	HYDROXYPROPYL CELLULOSE
1	LOW-SUBSTITUTED HYDROXYPROPYL CELLULOSE
1	MICROCRYSTALLINE CELLULOSE 101
1	MICROCRYSTALLINE CELLULOSE 102

Rifapentine Excipient Strategy and Commercial Opportunities

Last updated: August 5, 2026

Rifapentine's main formulation problem is poor aqueous solubility, while its principal commercial advantage is its long half-life and suitability for shorter tuberculosis prevention regimens. The strongest excipient opportunities are improved dissolution, food-independent exposure, pediatric dispersible delivery, fixed-dose combinations, and differentiated manufacturing platforms. Rifapentine is a small molecule, so biosimilar competition is irrelevant; generic and authorized-generic competition are the principal market risks.

What excipient strategy best addresses rifapentine's formulation challenges?

Rifapentine is a lipophilic rifamycin with low water solubility. Its approved oral product, Priftin, is administered with food because food increases systemic exposure. An excipient platform that improves wetting, dissolution, and dose uniformity could support a more convenient product and reduce dependence on a high-calorie meal.

Formulation problem	Commercial consequence	Excipient strategy
Low aqueous solubility	Variable dissolution and exposure	Sodium lauryl sulfate, poloxamers, surfactant blends, wetting agents
Food-dependent absorption	Administration burden and adherence risk	Solid dispersion, lipid-based delivery, amorphous material, self-emulsifying system
High dose requirement	Tablet size and swallowability problems	Granulation, high-load spray drying, co-processed excipients
Pediatric dosing	Limited flexibility for weight-based regimens	Dispersible tablet, oral granules, powder for suspension
Rifamycin discoloration and chemical sensitivity	Stability and appearance risks	Moisture control, opaque packaging, antioxidant and container-closure screening
Combination-regimen use	Potential content uniformity and compatibility issues	Bilayer tablet, co-granulation, separate granules, protective coating

The current Priftin tablet contains common pharmaceutical excipients, including lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, starch, povidone, magnesium stearate, hypromellose, colloidal silicon dioxide, and sodium lauryl sulfate, according to the U.S. prescribing information. Sodium lauryl sulfate is particularly relevant because it supports wetting of a poorly soluble active ingredient. The formulation remains food-dependent, indicating that the existing excipient system does not eliminate the absorption effect of food [1].

Which excipient technologies are commercially attractive for rifapentine?

Amorphous solid dispersions

An amorphous solid dispersion using polymers such as hypromellose acetate succinate, copovidone, or hydroxypropyl methylcellulose can increase apparent solubility and dissolution rate. The commercial value would be highest if the formulation achieved:

• Higher exposure under fasting conditions;
• Lower variability between fed and fasted administration;
• Smaller tablets at the same rifapentine dose;
• Improved performance in pediatric dispersible products.

The principal technical barrier is physical stability. Rifapentine must remain sufficiently amorphous during shelf life, and the formulation must control recrystallization under tropical temperature and humidity conditions common in tuberculosis-endemic markets.

Nanocrystal and wetting-agent systems

Nanocrystals, surfactant-stabilized particles, and micronized drug systems can improve dissolution without requiring a large polymer load. These technologies may fit a generic tablet or capsule because they can be manufactured through wet milling, bead milling, or controlled precipitation.

The commercial limitation is process complexity. A nanocrystal product must demonstrate robust particle-size control, redispersibility, and bioequivalence. Manufacturing scale-up can also create a higher cost of goods than a conventional wet-granulated tablet.

Lipid-based formulations

Self-emulsifying drug-delivery systems and lipid solid dispersions could address the food effect by supplying a controlled lipid environment. These systems are more suitable for soft capsules, lipid-filled hard capsules, or lipid-loaded tablets than for standard high-volume public-sector tablets.

A lipid-based rifapentine product could have value in:

• Fasting administration;
• Pediatric oral liquids;
• Patients with poor nutritional status;
• Combination regimens that require consistent exposure.

The main risks are capsule stability, excipient compatibility, oxidation, and higher packaging requirements. Lipid systems also require careful evaluation because rifapentine is a potent enzyme inducer and altered absorption may change interaction profiles with coadministered drugs.

Co-processed excipients and high-load tablets

Rifapentine regimens use a substantial dose relative to many oral medicines. A co-processed excipient system combining microcrystalline cellulose, mannitol, crospovidone, and a dry binder could improve flow, compressibility, and tablet robustness.

This approach is commercially practical for generic manufacturers because it does not require a new delivery platform. It is most useful when the target is:

• A smaller tablet;
• Better hardness without delayed disintegration;
• Lower friability during distribution;
• Direct compression rather than solvent-intensive granulation.

What formulations are protected by rifapentine patents?

The foundational rifapentine intellectual property is historical rather than a major current barrier to entry. U.S. Patent No. 5,100,882, covering rifamycin derivatives, was issued in 1992 and had an expiration date in the 2010 period based on the standard patent term applicable to the filing era [2]. The core active-ingredient protection therefore does not block modern generic development.

The commercially relevant question is whether later patents cover specific dosage forms, manufacturing processes, solid-state forms, combinations, or regimen uses. For rifapentine, the most important potential patent categories are:

1. Solid dispersions and particle-engineered forms.
2. Pediatric dispersible tablets or oral granules.
3. Fixed-dose combinations with isoniazid.
4. Short-course latent tuberculosis infection regimens.
5. Manufacturing processes that improve yield, purity, or particle size.
6. Stabilized formulations with reduced food effect.

An excipient-only formulation patent is generally weaker than a patent covering a defined composition with measurable dissolution, stability, or pharmacokinetic advantages. A generic developer would focus on design-around options involving different polymers, granulation conditions, surfactants, or particle-engineering methods.

What is the FDA regulatory status of rifapentine?

Rifapentine is approved in the United States under the brand name Priftin for tuberculosis indications. Its key regulatory milestones are:

Milestone	Date
Initial FDA approval of Priftin	1998
FDA approval for once-weekly rifapentine plus isoniazid in latent TB treatment	2011
FDA approval of the 1-month daily rifapentine plus isoniazid regimen	2018
Expanded pediatric use for latent TB infection	2021

The Centers for Disease Control and Prevention and the National Tuberculosis Controllers Association recommend shorter rifapentine-based regimens, including 3HP and 1HP, when clinically appropriate. These regimens have increased the commercial relevance of rifapentine beyond its original role in active tuberculosis treatment [3,4].

FDA exclusivity and Orange Book status

Rifapentine's original regulatory exclusivity periods have expired. The drug is a small molecule and has no Purple Book biologic exclusivity or biosimilar pathway.

The main current regulatory issues are:

• Abbreviated New Drug Application approval;
• Demonstration of bioequivalence;
• Product-specific guidance, if issued;
• Labeling for latent TB and active TB indications;
• Manufacturing controls for a high-dose, poorly soluble tablet;
• Pediatric dosage-form requirements;
• Drug-interaction labeling.

The FDA Orange Book is the controlling source for current listed patents and exclusivity entries for Priftin. Historical composition-of-matter protection does not create a present barrier, but later formulation or method-of-use listings must be reviewed before a Paragraph IV strategy is selected [5].

When does rifapentine lose exclusivity?

Rifapentine's basic patent exclusivity has already expired. The principal commercial exclusivity is therefore generated by product differentiation, supply reliability, regulatory execution, and procurement access rather than by the original active-ingredient patent.

Exclusivity or barrier	Status
Original rifapentine compound patent	Expired
FDA chemical exclusivity	Expired
Biologic exclusivity	Not applicable
Pediatric exclusivity	Historical periods have expired
Method-of-use protection	Must be checked against current Orange Book listings
Formulation protection	Product-specific review required
WHO or procurement preference	Commercially relevant but not statutory exclusivity

Which companies are challenging rifapentine exclusivity?

The competitive threat is likely to come from generic manufacturers rather than biosimilar developers. Rifapentine is a conventional small molecule, and the generic opportunity is structurally attractive because:

• The compound patent is old;
• The product has a defined tablet dosage form;
• The clinical demand is supported by global TB programs;
• Shorter preventive regimens improve adherence and public-health value.

Potential competitors include established tuberculosis suppliers and generic manufacturers with experience in rifamycin products. The commercial identity of an actual Paragraph IV challenger should be confirmed through current FDA ANDA litigation records and Orange Book entries. A public market strategy should not assume that absence of a widely reported lawsuit means absence of generic development.

What patent litigation affects rifapentine?

Rifapentine does not have the high-profile patent litigation profile associated with major oncology, immunology, or diabetes products. The likely disputes would concern:

• Whether a formulation patent is valid and infringed;
• Whether a generic product achieves bioequivalence without infringing a formulation claim;
• Whether a method-of-use patent can be enforced against a label limited to noninfringing uses;
• Whether a fixed-dose combination claim covers a particular ratio or release profile;
• Whether a manufacturing process patent can be avoided through an alternative API route.

A Paragraph IV litigation strategy would be more credible against a narrow formulation patent than against expired compound protection. Settlement agreements, if any, should be reviewed for launch dates, authorized-generic provisions, supply obligations, and geographic scope. No settlement should be assumed without a public court filing, FDA listing, or company disclosure.

How strong is the rifapentine patent estate?

The legacy patent estate is weak as a blocking platform because the core compound protection has expired. A new formulation estate could be moderate if it includes:

• A clearly defined solid-state form;
• A reproducible particle-size distribution;
• A specific polymer-to-drug ratio;
• A demonstrated reduction in food effect;
• Superior stability under accelerated conditions;
• Bioequivalent or superior exposure;
• A commercially important pediatric or fixed-dose product.

A patent based only on a conventional tablet containing rifapentine and standard excipients would face substantial validity and obviousness risk. Stronger protection would require a technical effect supported by comparative dissolution, pharmacokinetic, stability, or clinical data.

What commercial opportunities exist for rifapentine excipients?

Pediatric dispersible products

Pediatric formulation is the most actionable opportunity. WHO and CDC-supported short-course regimens create demand for weight-adjusted administration. A dispersible tablet or granule product could improve dosing accuracy and reduce dependence on tablet splitting.

Preferred excipient characteristics include:

• Low toxicity at pediatric exposure levels;
• Acceptable taste and mouthfeel;
• Rapid dispersion in a small volume of water;
• Low hygroscopicity;
• Compatibility with rifapentine's color and odor;
• Stability without refrigeration.

Mannitol, microcrystalline cellulose, crospovidone, low-substituted hydroxypropyl cellulose, and suitable flavors or sweeteners may support this product class. Taste masking is a central development issue because rifamycins can be unpleasant orally.

Fixed-dose combinations

A rifapentine-isoniazid fixed-dose combination could reduce pill burden for 1HP and 3HP regimens. The formulation must address differences in dose, solubility, stability, and manufacturing behavior between the two actives.

Possible designs include:

• Bilayer tablets;
• Separate granules compressed into one tablet;
• Multiparticulate sachets;
• Dispersible combination tablets;
• Dual-chamber or sequential-release systems.

The commercial advantage is strongest in public-health procurement, where adherence, logistics, and regimen completion are valued. The development burden includes combination-product bioequivalence, content uniformity, stability, and clinical bridging.

Food-independent tablets

A formulation that reduces the fed-fast exposure difference could support direct-to-patient administration and simplify community-based preventive therapy. This is potentially valuable in low-resource settings where meal composition is inconsistent.

The product would need comparative pharmacokinetic data showing that the excipient system improves fasting exposure without producing excessive peak concentrations. A food-independent claim could support method-of-use and formulation patent filings if backed by robust data.

Global-health supply products

Rifapentine demand is linked to national TB programs, the Global Fund, UN procurement, and donor-supported purchasing. In these channels, the lowest unit price is important, but supply continuity and WHO prequalification can determine access.

An excipient supplier can capture value through:

• Qualified polymer or surfactant systems;
• Localized formulation manufacturing;
• Stable tropical packaging;
• Co-processed excipients that simplify production;
• Pediatric dosage-form technology;
• Technical transfer packages for regional manufacturers.

How does rifapentine compare with rifampin?

Attribute	Rifapentine	Rifampin
Drug class	Rifamycin	Rifamycin
Half-life	Longer	Shorter
Role in latent TB	Central to 3HP and 1HP regimens	Used in alternative regimens
Food effect	Clinically relevant	Clinically relevant
Formulation challenge	Poor solubility and high dose	Poor solubility and high dose
Generic competition	Expected	Extensive
Excipient opportunity	Pediatric, fixed-dose, food-independent delivery	High-volume conventional and combination products
Biosimilar risk	None	None

Rifapentine has greater differentiation in preventive TB because its longer half-life enables intermittent and shorter regimens. Rifampin has broader generic availability and a more established supply base. The commercial opportunity for rifapentine is therefore more dependent on regimen adoption and procurement policy.

What generic launch scenarios exist for rifapentine?

Scenario 1: Conventional tablet

A generic manufacturer launches a 150 mg film-coated tablet using a formulation comparable to Priftin. This is the lowest-risk technical pathway but offers limited differentiation and may face aggressive price competition.

Scenario 2: Pediatric dispersible product

A manufacturer launches weight-band dispersible tablets or oral granules. This creates a stronger procurement position and may receive preference in pediatric TB programs.

Scenario 3: Fixed-dose combination

A rifapentine-isoniazid product targets 1HP or 3HP. This has the highest public-health value but also the greatest development and regulatory complexity.

Scenario 4: Improved fasted formulation

A formulation reduces the requirement to administer rifapentine with food. This could support premium pricing, a formulation patent, and differentiated labeling, but it requires meaningful pharmacokinetic evidence.

What manufacturing and IP barriers affect rifapentine?

The largest manufacturing barriers are not basic tableting. They are:

• Consistent API particle-size control;
• Wetting and dispersion of a hydrophobic powder;
• Prevention of recrystallization in amorphous systems;
• Control of rifamycin-related impurities;
• Blend uniformity at a relatively high drug load;
• Packaging for heat and humidity;
• Scale-up of nanocrystal or spray-drying processes.

Process patents can be more commercially relevant than excipient patents if they cover a reproducible route to high-purity API or a stable particle-engineered intermediate. A generic manufacturer should avoid dependence on a single specialized excipient supplier because procurement interruptions can affect regulatory comparability and public-sector supply contracts.

Key Takeaways

• Rifapentine's original compound patent protection has expired, making generic entry legally feasible.
• The best excipient opportunities target dissolution, food-independent absorption, pediatric administration, and fixed-dose combinations.
• Priftin's current tablet uses standard excipients but retains a clinically relevant food-administration requirement.
• Pediatric dispersible tablets and rifapentine-isoniazid combinations offer the clearest commercial differentiation.
• Amorphous solid dispersions, nanocrystals, and lipid-based systems may support formulation patents, but each creates scale-up and stability risks.
• Rifapentine has no biosimilar exposure because it is a small-molecule drug.
• Procurement access, WHO-related qualification, supply reliability, and manufacturing cost may matter more than legacy patent protection.
• A defensible new patent should claim a defined formulation linked to measurable dissolution, stability, pharmacokinetic, or dosing advantages.

FAQs

Can lactose be used in rifapentine formulations?

Yes. Lactose monohydrate is used in the approved Priftin tablet. Its suitability in a new product depends on moisture behavior, compatibility, dose loading, and the targeted dosage form.

Is sodium lauryl sulfate useful for rifapentine?

Yes. Sodium lauryl sulfate can improve wetting and dissolution of hydrophobic rifapentine. The formulation must control surfactant level because excessive surfactant can affect tolerability, tablet performance, and bioequivalence.

Does rifapentine require a lipid excipient?

No. The approved product uses a conventional solid oral formulation. Lipid excipients are optional technologies intended to improve dissolution or reduce food dependence.

Is a rifapentine oral suspension commercially attractive?

Yes, particularly for pediatric and community-based treatment. The product would require taste masking, dose uniformity, sedimentation control, microbial protection, and stability after reconstitution.

Can a new rifapentine excipient formulation receive patent protection?

Yes, but a generic combination of rifapentine with routine excipients may be vulnerable to obviousness challenges. Stronger protection requires a defined composition and evidence of an unexpected technical result.

References

1. U.S. Food and Drug Administration. (2023). Priftin (rifapentine) prescribing information. FDA.

2. U.S. Patent and Trademark Office. (1992). U.S. Patent No. 5,100,882: Rifamycin derivatives. U.S. Department of Commerce.

3. Centers for Disease Control and Prevention, & National Tuberculosis Controllers Association. (2020). Guidelines for the treatment of latent tuberculosis infection: Recommendations from the National Tuberculosis Controllers Association and CDC, 2020. Morbidity and Mortality Weekly Report, 69(1), 1-11.

4. World Health Organization. (2022). WHO consolidated guidelines on tuberculosis: Module 5, management of tuberculosis in children and adolescents. World Health Organization.

5. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.