List of Excipients in Branded Drug GRISEOFULVIIN (MICROSIZE)

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Generic Drugs Containing GRISEOFULVIIN (MICROSIZE)

Company	Ingredient	NDC	Excipient
Rebel Distributors Corp	griseofulvin (microsize)	42254-306	ALCOHOL
Rebel Distributors Corp	griseofulvin (microsize)	42254-306	DOCUSATE SODIUM
Rebel Distributors Corp	griseofulvin (microsize)	42254-306	FD&C RED NO. 40

What are the Most Frequently-Used Excipients in GRISEOFULVIIN (MICROSIZE)?

# Of NDCs	Excipient
1	ALCOHOL
1	DOCUSATE SODIUM
1	FD&C RED NO. 40

Griseofulvin Microsize Excipient Strategy and Commercial Opportunities

Last updated: September 6, 2026

Griseofulvin microsize is an old, low-cost antifungal with limited patent protection and persistent formulation problems. Its commercial opportunity is not in core molecule exclusivity. It is in improving dissolution, dose consistency, pediatric acceptability, adherence, and supply reliability.

The strongest opportunities are an improved oral suspension, a rapidly dispersible tablet, and a lipid-enabled or amorphous formulation supported through an abbreviated new drug application or, where clinical differentiation is needed, a 505(b)(2) pathway. The main technical constraint is griseofulvin’s very low aqueous solubility and dose-dependent absorption variability, particularly when administered without dietary fat.[1,2]

What is griseofulvin microsize and how does it differ from ultramicrosize griseofulvin?

Griseofulvin microsize is a crystalline, poorly water-soluble drug substance used orally for dermatophyte infections. The microsize designation describes reduced particle size intended to improve dissolution and absorption compared with conventional griseofulvin.

Ultramicrosize griseofulvin uses a smaller particle distribution and is marketed in products such as Gris-PEG. It generally achieves exposure at lower milligram doses than microsize products. The two forms should not be treated as automatically interchangeable because dose conversion depends on the formulation, product labeling, and clinical use.

Attribute	Griseofulvin microsize	Griseofulvin ultramicrosize
Primary commercial use	Oral treatment of dermatophyte infections	Oral treatment of dermatophyte infections
Solubility	Very low in water	Very low in water, with smaller particles
Dose efficiency	Lower than ultramicrosize products	Higher milligram-to-milligram exposure
Main formulation issue	Dissolution and food-dependent absorption	Dissolution, dose uniformity, and product differentiation
Typical regulatory route for a new generic	ANDA, subject to reference-product requirements	ANDA, subject to the applicable reference product
Main commercial gap	Pediatric liquid, palatability, consistent exposure	Lower-dose convenience and improved tolerability

FDA labeling instructs patients to take griseofulvin products with a fatty meal to improve absorption. That instruction creates a direct formulation opportunity: reducing dependence on meal composition without changing the active ingredient.[1,2]

What excipients are suitable for griseofulvin microsize formulations?

The most relevant excipient classes are wetting agents, surfactants, lipid vehicles, polymeric precipitation inhibitors, suspension stabilizers, binders, and taste-masking materials.

Tablet excipient strategy

A conventional immediate-release tablet can use:

• A wetting agent such as sodium lauryl sulfate or a nonionic surfactant.
• A hydrophilic diluent such as lactose, mannitol, or microcrystalline cellulose.
• A superdisintegrant such as crospovidone, croscarmellose sodium, or sodium starch glycolate.
• A binder such as povidone or hypromellose.
• A glidant such as colloidal silicon dioxide.
• A lubricant such as magnesium stearate.

The objective is rapid tablet breakup and high surface wetting. Increasing tablet hardness without controlling disintegration can worsen dissolution. A formulation should therefore optimize disintegration time, particle deagglomeration, dissolution under biorelevant media, and content uniformity rather than rely on drug loading alone.

Lipid-enabled formulation strategy

A lipid-based formulation can use medium-chain triglycerides, mono- and diglycerides, fatty acids, phospholipids, or self-emulsifying excipient systems. The design objective is to maintain griseofulvin in a solubilized or finely dispersed state after administration.

This approach has commercial relevance because conventional griseofulvin absorption is enhanced by fat. A successful lipid system could reduce the dependence on a high-fat meal, but it would require careful control of:

• Drug precipitation after dilution in gastrointestinal fluid.
• Oxidative stability of lipid excipients.
• Capsule compatibility.
• Food-effect performance.
• Long-term physical stability.
• Dose uniformity at commercial scale.

Lipid systems are more likely to support a differentiated 505(b)(2) product than a straightforward ANDA unless the formulation remains pharmaceutically equivalent to the reference product.

Amorphous solid dispersion strategy

Polyvinylpyrrolidone, copovidone, hypromellose, and hypromellose acetate succinate can be evaluated as precipitation-inhibiting polymers. Spray drying, hot-melt processing, or solvent-based dispersion may increase apparent solubility.

The key risk is recrystallization. A formulation that produces high initial dissolution but loses performance during stability testing has limited commercial value. Development should include solid-state characterization by powder X-ray diffraction, differential scanning calorimetry, microscopy, and stress testing under humidity and temperature exposure.

Oral suspension strategy

A microsize griseofulvin suspension has the clearest unmet need for pediatric and dysphagia populations. A practical suspension system may include:

• A suspending polymer such as xanthan gum, sodium carboxymethylcellulose, or microcrystalline cellulose with carboxymethylcellulose sodium.
• A wetting agent to prevent floating and clumping.
• A sweetener such as sucralose or sucrose, subject to target-market requirements.
• A flavor system capable of masking griseofulvin’s bitter taste.
• A buffer to control pH.
• A preservative system where required.
• A density and viscosity profile that supports redispersion after storage.

The commercial target should be a suspension that remains homogeneous after moderate settling, redistributes with limited shaking, and delivers accurate doses through an oral syringe. A 125 mg/5 mL or 250 mg/5 mL presentation could support pediatric dosing, but the final concentration must be aligned with clinical dosing, palatability, and dose-measurement accuracy.

What formulations are protected by griseofulvin patents?

Legacy griseofulvin products were developed under an older patent environment. The principal commercial barrier is no longer an active compound patent. The remaining intellectual-property opportunity is formulation-specific.

Potentially protectable subject matter includes:

1. A defined particle-size distribution for microsize griseofulvin.
2. A solid dispersion with a specified polymer-to-drug ratio.
3. A self-emulsifying or lipid-based delivery system.
4. A stable aqueous suspension with defined viscosity and redispersibility.
5. A taste-masked pediatric formulation.
6. A tablet with a defined dissolution profile.
7. A method for reducing food-effect variability.
8. A manufacturing process that controls agglomeration and particle-size distribution.

Patent claims must be drafted around measurable technical features. Broad claims covering "griseofulvin with an excipient" are likely to face enablement, written-description, obviousness, and prior-art challenges. Stronger claims would link composition to a quantified performance result, such as dissolution, precipitation resistance, food-effect reduction, or stability.

When does griseofulvin microsize lose exclusivity?

Griseofulvin microsize has already lost the commercial exclusivity associated with its original branded products in the United States. FDA-listed products are legacy prescription medicines, and the market is supplied through generic and authorized-generic channels rather than a protected innovative-product cycle.[3]

Exclusivity category	Current commercial position
Original molecule patent	Expired
Original product exclusivity	Expired
Pediatric exclusivity	No current exclusivity relevant to the legacy molecule
New chemical entity exclusivity	Expired
Formulation patent opportunity	Available only for genuinely novel formulation subject matter
ANDA market entry	Generally available subject to reference-product and regulatory requirements
505(b)(2) opportunity	Possible where the product has a meaningful formulation or clinical-use difference

The absence of core exclusivity does not eliminate regulatory barriers. An applicant must still establish pharmaceutical quality, bioequivalence where applicable, stability, microbiological control for liquids, and compliance with current FDA manufacturing requirements.

What is the Orange Book status of griseofulvin microsize?

The FDA Orange Book remains the controlling source for current reference-listed-drug, patent, and exclusivity information. Griseofulvin products are legacy prescription products, and no active exclusivity period is expected to prevent ordinary generic development. The relevant diligence question is product-specific: whether a proposed microsize tablet or suspension has an active reference-listed product and whether FDA requires a conventional ANDA, a suitability petition, or another pathway.[3]

For an applicant, the regulatory sequence should include:

1. Identify the exact reference product and dosage form.
2. Confirm the active ingredient designation as microsize rather than ultramicrosize.
3. Review the relevant product-specific guidance, if available.
4. Determine whether the formulation is qualitatively and quantitatively comparable.
5. Evaluate dissolution and pharmacokinetic requirements.
6. Check current FDA Drug Shortages and discontinued-product information.
7. Review Orange Book patent and exclusivity listings at filing and before launch.

A formulation with a materially different excipient system, route, release profile, or clinical performance may require a 505(b)(2) application rather than a conventional ANDA.

How strong is the patent estate for griseofulvin microsize?

The patent estate is weak for the active ingredient and potentially moderate for a well-supported new formulation.

Patent category	Relative strength	Commercial assessment
Core griseofulvin composition	Low	Historic protection has expired
Conventional immediate-release tablet	Low	Numerous excipient combinations are predictable
Particle-size control	Low to moderate	Stronger if linked to defined performance and manufacturing control
Pediatric suspension	Moderate	Opportunity exists for taste, stability, and dose-delivery claims
Lipid or self-emulsifying system	Moderate	Patentability depends on composition and unexpected performance
Amorphous dispersion	Moderate	Main risk is extensive prior art across poorly soluble drugs
Manufacturing process	Moderate	Valuable if it produces consistent particle size or prevents agglomeration
Method of reducing food effect	Moderate to strong if demonstrated	Requires credible clinical or pharmacokinetic evidence

Patent value will depend less on the number of claims than on whether the formulation produces a defensible benefit that competitors cannot reproduce with routine substitution.

Which companies are challenging griseofulvin microsize exclusivity?

The product category is generic and fragmented. Competition has historically included manufacturers of griseofulvin tablets, microsize tablets, oral suspensions, and ultramicrosize products. The relevant competitive set includes legacy branded products, authorized generics, contract manufacturers, and generic prescription suppliers.

No active, high-value Paragraph IV campaign is central to the current griseofulvin microsize market. The drug’s commercial profile does not resemble a current blockbuster facing multiple first-wave Paragraph IV challengers. Any new applicant should focus on supply continuity, dosage-form availability, and formulation differentiation rather than litigation timing.

What patent litigation and settlement agreements affect griseofulvin microsize?

No major current U.S. patent litigation or settlement structure is known to define market entry for legacy griseofulvin microsize products. The absence of litigation reduces legal delay risk but also limits the value of a conventional Paragraph IV strategy.

A new formulation could create litigation exposure if it relies on patents covering:

• Specific surfactant systems.
• Solid dispersions.
• Particle engineering.
• Oral suspension compositions.
• Taste-masking technologies.
• Drug-device combinations.

Any settlement involving a new formulation would need to be assessed against the product’s expected low annual market value. Litigation economics are unfavorable when the addressable market is small and several non-infringing formulations are available.

What are the best commercial opportunities for griseofulvin microsize?

Pediatric oral suspension

This is the strongest opportunity. It addresses swallowing difficulty, pediatric adherence, and dosing flexibility. A differentiated product should prioritize palatability, low sedimentation, rapid redispersion, oral-syringe compatibility, and a commercially acceptable shelf life.

Supply-constrained generic

Griseofulvin is an older product with limited commercial incentive for some manufacturers. A reliable supplier can capture institutional and pharmacy demand if it maintains consistent availability, adequate shelf life, and competitive pricing.

Rapidly dispersible tablet

A tablet that disperses quickly in the mouth or gastrointestinal fluid could support patients who have difficulty swallowing conventional tablets. The product must avoid unacceptable taste and preserve dose uniformity.

Food-effect-reduced formulation

A product that produces more consistent exposure across fed and fasted conditions could command a premium, but this opportunity requires pharmacokinetic evidence. It is better suited to a 505(b)(2) strategy than to a simple generic substitution.

Combination adherence packaging

Packaging with dosing instructions, food guidance, and treatment-duration support could improve adherence for patients treating tinea capitis or other infections requiring prolonged therapy. Packaging alone is unlikely to create substantial exclusivity, but it can support institutional contracting and patient retention.

How does griseofulvin compare with competing antifungals?

Griseofulvin competes with terbinafine, itraconazole, fluconazole, and other systemic antifungals. Its main commercial disadvantage is administration complexity and food-dependent absorption. Its advantages include long clinical familiarity, established pediatric use in selected indications, and generic pricing.

Product class	Formulation challenge	Commercial position
Griseofulvin microsize	Poor dissolution and food-dependent absorption	Low-cost legacy therapy
Terbinafine	Tablet and granule formulation, liver-safety monitoring	Strong competitor in dermatophyte infections
Itraconazole	Complex absorption and drug-interaction profile	Specialist and indication-dependent use
Fluconazole	Broad generic availability and dose flexibility	Often selected for convenience
Topical antifungals	Limited penetration for some infections	Compete where infection severity permits

A griseofulvin product must therefore compete on adherence and usability, not only price.

What manufacturing and intellectual-property barriers exist?

The main manufacturing barriers are process control and analytical reproducibility. Micronized griseofulvin can agglomerate, segregate, and wet poorly. Critical controls include:

• Particle-size distribution.
• Bulk density and flow.
• Specific surface area.
• Moisture content.
• Blend uniformity.
• Granule porosity.
• Dissolution across pH conditions.
• Suspension sedimentation and redispersibility.
• Solid-state stability.

A supplier with reliable micronization, containment, and analytical methods can create a practical barrier even without strong patent protection. For a liquid product, preservative effectiveness, microbial limits, container-closure compatibility, and shipping stability add cost and complexity.

What is the likely revenue exposure and generic launch scenario?

Griseofulvin microsize is unlikely to support blockbuster revenue. The most credible launch scenario is a focused generic or differentiated niche product with modest unit volume and limited pricing power.

Launch scenario	Expected economics	Main success factor
Conventional tablet ANDA	Low margin	Low manufacturing cost and supply reliability
Pediatric suspension	Moderate niche value	Taste, stability, and availability
Premium lipid formulation	Higher price potential	Demonstrated food-effect or exposure benefit
Hospital or institutional supply	Moderate volume	Reliable tender pricing and continuity
Branded 505(b)(2) product	Higher development cost	Clinical differentiation and reimbursement

The strongest investment case is a low-cost suspension or tablet using a robust excipient platform that can be manufactured with existing equipment. A high-complexity lipid or amorphous-dispersion product requires a larger development budget and may not recover its cost unless it obtains differentiated labeling, clinical evidence, or geographic exclusivity.

Key Takeaways

• Griseofulvin microsize has no meaningful remaining core-molecule exclusivity in the United States.
• The central technical problem is poor aqueous solubility and food-dependent absorption.
• Pediatric oral suspension is the clearest commercial opportunity.
• Surfactants, wetting agents, lipid excipients, polymers, and suspension stabilizers are the most relevant excipient classes.
• A conventional tablet has limited patent value unless it delivers a measurable dissolution or exposure advantage.
• A 505(b)(2) strategy is more suitable for a materially differentiated formulation than a routine ANDA.
• Current market value is driven by generic supply, dosage-form availability, and adherence rather than Paragraph IV timing.
• Formulation patents should focus on particle engineering, precipitation control, taste masking, redispersibility, or reduced food-effect variability.
• Manufacturing consistency may be more commercially important than broad patent coverage.

FAQs

Is griseofulvin microsize interchangeable with Gris-PEG?

No. Gris-PEG is associated with ultramicrosize griseofulvin, while microsize products use a different particle-size designation and may require different dosing. Product substitution must follow the applicable FDA labeling and pharmacist requirements.

Which excipient is most important for griseofulvin dissolution?

No single excipient is universally decisive. A combination of particle-size control, wetting, disintegration, and precipitation management usually has greater impact than increasing any one excipient concentration.

Can griseofulvin microsize be developed as an over-the-counter product?

A switch would require FDA review of safety, labeling, consumer comprehension, and appropriate self-diagnosis. The legacy prescription status and need for diagnosis of dermatophyte infections make an OTC strategy more complex than a conventional generic launch.

Does a griseofulvin suspension require special stability studies?

Yes. In addition to chemical stability, the sponsor must evaluate sedimentation, redispersibility, dose uniformity throughout container use, preservative performance where applicable, microbial quality, and container-closure compatibility.

Is a new griseofulvin excipient combination automatically patentable?

No. Routine substitution of known excipients is vulnerable to obviousness challenges. Patent strength improves when the composition has defined structural limits and produces an unexpected result, such as materially improved dissolution, reduced precipitation, better taste, or lower food-effect variability.

References

1. U.S. Food and Drug Administration. (n.d.). Gris-PEG (griseofulvin ultramicrosize) tablet prescribing information. DailyMed.

2. U.S. Food and Drug Administration. (n.d.). Griseofulvin microsize tablet and oral suspension labeling. DailyMed.

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

4. U.S. Food and Drug Administration. (2015). Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system. FDA Guidance for Industry.

5. United States Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary. USP.