DILANTIN-125 Drug Patent Profile
When do Dilantin-125 patents expire, and when can generic versions of Dilantin-125 launch?
Dilantin-125 is a drug marketed by Viatris and is included in one NDA.
The generic ingredient in DILANTIN-125 is phenytoin. There is one drug master file entry for this compound. Twelve suppliers are listed for this compound. Additional details are available on the phenytoin profile page.
DrugPatentWatch® Litigation and Generic Entry Outlook for Dilantin-125
A generic version of DILANTIN-125 was approved as phenytoin by TARO on March 8th, 2004.
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Questions you can ask:
- What is the 5 year forecast for DILANTIN-125?
- What are the global sales for DILANTIN-125?
- What is Average Wholesale Price for DILANTIN-125?
Summary for DILANTIN-125
| US Patents: | 0 |
| Applicants: | 1 |
| NDAs: | 1 |
| Finished Product Suppliers / Packagers: | 2 |
| Raw Ingredient (Bulk) Api Vendors: | 124 |
| Clinical Trials: | 24 |
| Patent Applications: | 4,116 |
| Drug Prices: | Drug price information for DILANTIN-125 |
| What excipients (inactive ingredients) are in DILANTIN-125? | DILANTIN-125 excipients list |
| DailyMed Link: | DILANTIN-125 at DailyMed |
Recent Clinical Trials for DILANTIN-125
Identify potential brand extensions & 505(b)(2) entrants
| Sponsor | Phase |
|---|---|
| Pfizer | PHASE1 |
| Bristol-Myers Squibb | Phase 1 |
| UCB Pharma GmbH | Phase 4 |
Pharmacology for DILANTIN-125
US Patents and Regulatory Information for DILANTIN-125
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Exclusivity Expiration |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Viatris | DILANTIN-125 | phenytoin | SUSPENSION;ORAL | 008762-001 | Approved Prior to Jan 1, 1982 | AB | RX | Yes | Yes | ⤷ Start Trial | ⤷ Start Trial | ⤷ Start Trial | |||
| >Applicant | >Tradename | >Generic Name | >Dosage | >NDA | >Approval Date | >TE | >Type | >RLD | >RS | >Patent No. | >Patent Expiration | >Product | >Substance | >Delist Req. | >Exclusivity Expiration |
ecutive summary: DILANTIN-125 is a mature phenytoin sodium oral suspension with no meaningful remaining regulatory exclusivity and a largely commoditized generic market. Pfizer markets the branded product, but does not disclose DILANTIN-125 revenue separately. Commercial value is concentrated in brand-prescribing continuity, hospital and specialty-pharmacy demand, and the product’s role as a liquid dosage form for patients who cannot use capsules or tablets. Generic competition, low unit pricing, narrow therapeutic index concerns, and manufacturing complexity constrain growth.
DILANTIN-125 Market Dynamics, Patent Status, Generic Competition, and Financial Trajectory
What is DILANTIN-125 and how is it used?
DILANTIN-125 is a phenytoin sodium oral suspension containing 125 mg of phenytoin sodium per 5 mL. Pfizer markets the product under the Dilantin brand. It is an antiepileptic drug used primarily for tonic-clonic and psychomotor seizures and for seizure prevention in selected clinical settings (Pfizer, 2023).
The product is a liquid formulation rather than a capsule or tablet. That distinction supports continued demand among:
- Pediatric patients
- Patients with dysphagia
- Patients receiving enteral nutrition
- Patients who require flexible dose measurement
- Institutional and long-term-care patients
Phenytoin has nonlinear pharmacokinetics and a narrow therapeutic range. Small changes in dose, formulation, absorption, or adherence can produce clinically meaningful changes in serum concentrations. This limits complete substitution in some treatment settings, even though generic phenytoin products are widely available.
Key product data
| Attribute | DILANTIN-125 |
|---|---|
| Active ingredient | Phenytoin sodium |
| Dosage form | Oral suspension |
| Strength | 125 mg/5 mL |
| Reference product sponsor | Pfizer Inc. |
| Therapeutic class | Antiepileptic |
| FDA pathway | New Drug Application |
| Primary commercial issue | Mature brand facing generic substitution |
| Regulatory exclusivity | Expired |
| Biosimilar exposure | Not applicable |
| Product-specific revenue disclosure | Not provided by Pfizer |
What is the FDA regulatory status of DILANTIN-125?
DILANTIN-125 is an FDA-approved prescription drug. The product is listed as phenytoin sodium oral suspension and is associated with Pfizer’s Dilantin labeling (U.S. Food and Drug Administration, 2024a).
The FDA-approved product remains commercially relevant because liquid phenytoin is a distinct dosage form. The approval does not provide meaningful new-drug exclusivity today. The product’s commercial position depends on manufacturing continuity, distribution, prescribing habits, and reimbursement rather than regulatory protection.
The principal regulatory and clinical considerations are:
- Dose measurement accuracy.
- Interchangeability between branded and generic liquid products.
- Absorption differences caused by excipients and formulation characteristics.
- Therapeutic drug monitoring.
- Drug interactions involving hepatic enzyme induction.
When does DILANTIN-125 lose exclusivity?
DILANTIN-125 lost conventional small-molecule exclusivity many years ago. The product is a legacy antiepileptic, and its original patent and regulatory protection periods expired before the current generic market developed.
The relevant commercial conclusion is that DILANTIN-125 has no effective remaining period of market exclusivity comparable to a newly approved drug. Generic manufacturers can rely on the abbreviated new drug application pathway, subject to FDA requirements for pharmaceutical equivalence, bioequivalence, manufacturing quality, and labeling.
Exclusivity timeline
| Milestone | Commercial effect |
|---|---|
| Original Dilantin approval | Established the branded phenytoin market |
| Original patent term | Expired |
| Generic phenytoin approvals | Removed meaningful brand exclusivity |
| Current period | Mature, multi-source generic market |
| Remaining exclusivity | No material new-drug exclusivity |
What patents protect DILANTIN-125?
The original composition and product patents associated with phenytoin and legacy Dilantin products are expired. DILANTIN-125 does not have the type of active patent estate typically associated with a recently launched drug.
The commercial protection profile is therefore weak from a patent perspective:
- No meaningful composition-of-matter protection remains.
- No relevant formulation exclusivity has been reported as a current barrier to generic entry.
- No biosimilar framework applies because phenytoin is a conventional small molecule.
- Any manufacturing know-how is more important commercially than patent exclusion.
The FDA Orange Book remains the primary source for current patents and exclusivity associated with approved prescription products. A mature product with no listed unexpired patents generally has limited ability to delay ANDA approval or prevent generic launch (U.S. Food and Drug Administration, 2024b).
How strong is the DILANTIN-125 patent estate?
The patent estate is weak for market-exclusion purposes. Its residual value is primarily operational:
- Brand recognition
- Established prescribing history
- Manufacturing experience
- Distribution relationships
- Historical physician familiarity
Those factors may support a branded price premium in limited channels, but they do not prevent substitution.
Are there Paragraph IV challenges to DILANTIN-125?
Paragraph IV litigation is not a significant current driver for DILANTIN-125. Paragraph IV challenges are most valuable when a branded product has unexpired patents capable of delaying generic approval. DILANTIN-125 is a legacy product with expired core protection and established generic competition.
The market has therefore moved beyond the typical pre-generic litigation cycle. The principal competitive risks are:
- Additional generic approvals
- Price erosion
- Contract-manufacturer changes
- Product discontinuations
- Supply interruptions
- Formulation or labeling differences
No current litigation materially changes the product’s exclusivity profile based on publicly available FDA and company information.
What formulations are protected by DILANTIN-125?
The commercial distinction is the oral suspension formulation, not a current patent monopoly. DILANTIN-125 is differentiated from other phenytoin products by dosage form and concentration.
| Phenytoin product type | Typical commercial role |
|---|---|
| DILANTIN-125 suspension | Liquid dosing and patients unable to swallow solid dosage forms |
| Phenytoin sodium capsules | Broad adult maintenance use |
| Phenytoin chewable tablets | Patients requiring chewable dosing |
| Injectable phenytoin | Acute or inpatient use |
| Fosphenytoin injection | Parenteral alternative with different administration characteristics |
The liquid formulation creates practical switching considerations. Concentration errors, inaccurate measuring devices, and changes in excipients can affect dosing. These issues may preserve some brand demand even where generic substitution is legally permitted.
What generic entry risks exist for DILANTIN-125?
Generic entry is already established, so the relevant question is incremental generic pressure rather than first entry.
Generic market dynamics
Phenytoin sodium oral suspension is a low-growth, price-sensitive market. Generic manufacturers compete primarily on:
- Wholesale acquisition cost
- Medicaid and commercial-plan reimbursement
- Pharmacy contracting
- Supply reliability
- Bottle sizes and packaging
- Manufacturing continuity
The product is not an attractive target for premium-priced genericization. Demand is stable but limited, and manufacturing controls for a suspension can be more demanding than for a simple solid oral dosage form.
Generic launch scenarios
| Scenario | Expected effect on DILANTIN-125 |
|---|---|
| Stable generic supply | Gradual brand share erosion and price pressure |
| Generic shortage | Temporary recovery in branded demand and pricing |
| Brand manufacturing disruption | Rapid substitution and potential loss of prescriptions |
| Additional generic entrant | Further reimbursement and volume pressure |
| Clinical preference for continuity | Retention in selected patients and institutions |
DILANTIN-125 may retain a niche share because phenytoin dosing is clinically sensitive. That retention is defensive rather than growth-oriented.
What is the Orange Book status of DILANTIN-125?
DILANTIN-125 is an FDA reference-listed drug in the phenytoin sodium oral suspension category. Its Orange Book significance is historical and regulatory rather than exclusivity-based.
The product’s listing allows generic manufacturers to reference the branded product when seeking approval for pharmaceutically equivalent versions. An active reference listing does not itself create patent protection or prevent generic competition.
The relevant Orange Book analysis is:
- Reference product: Yes
- Small-molecule ANDA pathway: Yes
- Unexpired core patent protection: No material protection identified
- Pediatric exclusivity: Not a current commercial barrier
- New chemical entity exclusivity: Expired
What patent litigation affects DILANTIN-125?
No active patent dispute is a major market determinant for DILANTIN-125. The product’s commercial history predates the modern litigation-driven launch model used for high-value pharmaceuticals.
Current legal exposure is more likely to involve:
- Product liability
- Labeling adequacy
- Manufacturing quality
- Distribution agreements
- Contracting disputes
- Generic substitution and reimbursement
Those issues can affect cost and supply but do not create a credible route to renewed exclusivity.
Does DILANTIN-125 have biosimilar risk?
No. Biosimilar risk does not apply to DILANTIN-125 because phenytoin sodium is a chemically synthesized small molecule, not a biologic. Competition occurs through conventional generic-drug approvals under section 505(j) of the Federal Food, Drug, and Cosmetic Act.
The competitive threat is therefore generic erosion, not biosimilar interchangeability.
What is the financial trajectory for DILANTIN-125?
Pfizer does not report DILANTIN-125 revenue, gross margin, prescription volume, or market share as separate financial line items in its public annual reports. The product is grouped within broader pharmaceutical portfolios, making a product-specific revenue estimate unavailable from company disclosures (Pfizer Inc., 2024).
The likely financial trajectory is mature-to-declining:
- Unit demand is relatively stable because epilepsy treatment is chronic.
- Net price is pressured by generic competition.
- Brand share declines as formularies prefer lower-cost alternatives.
- Revenue depends on supply reliability and niche liquid-form demand.
- Manufacturing and compliance costs can become material relative to sales.
DILANTIN-125 is unlikely to be a material contributor to Pfizer’s consolidated revenue. Its economic value is more consistent with a legacy product that produces recurring cash flow than with a growth asset.
Revenue exposure
| Financial factor | Assessment |
|---|---|
| Prescription demand | Stable, low-growth |
| Brand pricing power | Limited |
| Generic substitution | High |
| Revenue transparency | Low; no separate disclosure |
| Margin outlook | Vulnerable to low volume and compliance costs |
| Growth potential | Minimal |
| Downside risk | Price erosion, discontinuation, supply disruption |
| Strategic value | Portfolio continuity and niche liquid formulation |
How does DILANTIN-125 compare with competing phenytoin products?
DILANTIN-125 has the strongest brand recognition among phenytoin products, but brand recognition does not translate into strong market power in a mature generic category.
| Factor | DILANTIN-125 | Generic phenytoin suspension | Phenytoin capsules | Fosphenytoin |
|---|---|---|---|---|
| Dosage form | Oral suspension | Oral suspension | Solid oral | Injectable prodrug |
| Primary use | Maintenance therapy | Maintenance therapy | Maintenance therapy | Acute or inpatient use |
| Price position | Brand premium | Lowest-cost option | Low-cost generic | Higher institutional cost |
| Patent position | Expired | None needed for entry | Expired | Separate product category |
| Switching risk | Formulation and dose concerns | Same clinical class | Swallowing limitations | Administration-specific |
| Growth profile | Flat or declining | Commodity | Mature | Hospital-dependent |
What manufacturing and IP barriers remain?
Manufacturing is more important than intellectual property. Oral suspensions require control of:
- Active-ingredient uniformity
- Particle-size distribution
- Sedimentation
- Redispersibility
- Viscosity
- Preservative performance
- Container and closure compatibility
- Dose-measuring accuracy
These requirements can discourage marginal suppliers, but they do not create durable exclusivity. A manufacturer with a stable supply chain and an FDA-compliant facility may have a commercial advantage over a lower-cost competitor with recurring quality or shortage problems.
Geographic protection is also limited. U.S. patents do not prevent generic competition in foreign markets, and Dilantin’s legacy patent protection has expired in the major pharmaceutical jurisdictions. Market access now depends on national marketing authorizations, manufacturing compliance, reimbursement, and distribution.
What licensing deals affect DILANTIN-125?
No current licensing transaction is a major publicly disclosed driver of DILANTIN-125 economics. The product’s commercial history is associated with Parke-Davis and Pfizer. Its present value is tied to Pfizer’s continued marketing and supply decisions rather than a recently announced partnering arrangement.
Key takeaways
- DILANTIN-125 is a mature phenytoin sodium oral suspension marketed by Pfizer.
- Core patent and regulatory exclusivity have expired.
- Generic competition is established and is the primary source of price pressure.
- Paragraph IV litigation and biosimilar competition are not material current risks.
- The liquid dosage form supports a durable niche among patients unable to use solid oral products.
- Pfizer does not disclose product-level DILANTIN-125 revenue.
- The financial trajectory is likely stable-to-declining, with limited growth potential.
- Manufacturing reliability and therapeutic continuity matter more than patent strength.
- The product’s value is defensive and cash-generative rather than strategic-growth oriented.
FAQs about DILANTIN-125 market outlook
Is DILANTIN-125 still available in the United States?
DILANTIN-125 remains an FDA-listed branded phenytoin sodium oral suspension. Availability can vary by wholesaler, pharmacy, and supply conditions.
Can pharmacies substitute generic phenytoin suspension for DILANTIN-125?
Substitution depends on state pharmacy law, payer requirements, prescription instructions, and product equivalence. Clinicians may monitor patients more closely when changing phenytoin products because of nonlinear pharmacokinetics.
Is DILANTIN-125 a high-value pharmaceutical asset?
No. It is a mature legacy product with limited pricing power, no meaningful remaining exclusivity, and no disclosed standalone growth profile.
What would improve DILANTIN-125 revenue?
Temporary generic shortages, improved distribution, continued institutional demand, and retention among patients requiring a liquid dosage form could support revenue. None represents a durable growth catalyst.
Is DILANTIN-125 exposed to new patent-based generic delays?
The product has no material current patent barrier comparable to those protecting recently launched branded drugs. Generic access is primarily governed by FDA approval and manufacturing requirements.
References
-
Pfizer Inc. (2024). 2023 annual report. Pfizer Investor Relations.
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Pfizer Inc. (2023). Dilantin-125: Phenytoin sodium oral suspension prescribing information. Pfizer Laboratories.
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U.S. Food and Drug Administration. (2024a). Drugs@FDA: FDA-approved drugs database. https://www.accessdata.fda.gov/scripts/cder/daf/
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U.S. Food and Drug Administration. (2024b). Approved drug products with therapeutic equivalence evaluations, Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
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U.S. Food and Drug Administration. (2024c). Generic drug facts. https://www.fda.gov/drugs/generic-drugs/generic-drug-facts
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