When will the patents on PHENYTOIN SODIUM expire, and when will generic PHENYTOIN SODIUM be available?

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Pharmeral	PHENYTOIN SODIUM	phenytoin sodium	CAPSULE;ORAL	085435-001	Approved Prior to Jan 1, 1982		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Hospira	PHENYTOIN SODIUM	phenytoin sodium	INJECTABLE;INJECTION	089521-001	Mar 17, 1987		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
Am Regent	PHENYTOIN SODIUM	phenytoin sodium	INJECTABLE;INJECTION	040781-001	Dec 4, 2007		DISCN	No	No	⤷ 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

Last updated: July 19, 2026

Phenytoin Sodium Investment Scenario and Fundamentals Analysis: IP, FDA Exposure, Manufacturing Economics, and Generic Risk

Phenytoin sodium is an established, off-patent small-molecule antiseizure drug with an IP landscape dominated by legacy formulation and process patents rather than long, active primary compound exclusivities. Commercial fundamentals are shaped by (1) generic-driven pricing pressure, (2) FDA product-entry and quality/regulatory risk across a fragmented manufacturer base, and (3) supply continuity constraints for narrow-therapeutic-index (NTI) therapy. Investment upside, where it exists, typically concentrates in manufacturers with strong regulatory track records, differentiated delivery/formulation portfolios (e.g., extended-release or composition-level differentiation), and scale advantages that can survive margin compression. Most “new product” investment themes are tied to reducing technical filing risk and securing reliable market share through compliant supply rather than through exclusive patent protection.

What is the pharmaceutical market outlook for phenytoin sodium and how does it affect investment returns?

How big is the phenytoin sodium revenue pool and what drives demand

Phenytoin sodium is used for seizure disorders, historically across inpatient and outpatient settings, and remains relevant due to NTI use patterns where physicians continue to rely on older antiseizure medicines. Demand tends to be resilient relative to purely discretionary pharmaceuticals, but revenue growth is constrained by:

Mature penetration and substitution to other antiseizure drugs.
Heavy generic availability, which compresses pricing.
Ongoing prescriber switching dynamics driven by tolerability, monitoring burden, and newer antiseizure options.

Investment implication: Revenue growth is usually limited to manufacturer market-share gains and unit volume stability, not price expansion.

What drives quarterly volatility

Core volatility comes from:

FDA supply interruptions (site issues, sterility/quality deviations, recall-related stoppages).
Lot-level QC outcomes affecting distribution continuity.
Competitive promotional dynamics among generics.
Shifts in payer formularies and substitution rules.

Investment implication: “Fundamentals” for phenytoin sodium investments are operational. The principal upside driver is dependable supply with low regulatory downtime.

What patents protect phenytoin sodium in the US and how much of that IP is actually enforceable today?

Phenytoin sodium’s active ingredient is old. In the US, current legal leverage usually sits in:

Composition-of-matter type claims for specific formulations (rare for a widely marketed NTI product unless still within more recent filing windows).
Method-of-manufacture improvements.
Device/administration-related patents are possible but less common for oral phenytoin.

Investment implication: For most investors, the realistic IP posture is “defensive.” Value comes from maintaining regulatory exclusivity advantages where available and from protecting specific product SKUs rather than licensing a long compound exclusivity.

How to think about “IP depth” for phenytoin sodium

A practical IP-screen for investment focuses on:

Whether Orange Book listings still exist for currently marketed NDCs under active US patents.
Whether listed patents are formulation-specific (harder for generics to design around) or broadly tied to the active ingredient (generics often bypass by design).
Whether the expiration calendar leaves a meaningful enforcement window.

What is the typical patent estate composition

For legacy small molecules with widespread generic entry, most still-in-force items are:

Formulation/process patents associated with particular strengths or dosage forms.
Patent families with staggered expirations across filings, sometimes extending enforceability for specific product presentations.

What is the Orange Book status of phenytoin sodium and which strengths have enforceable listings?

Featured-snippet answer: Orange Book status determines whether any active US patents are still listed for specific phenytoin sodium NDCs. This matters for Paragraph IV and for “carve-out” settlements.

What to check for each NDC

For investment and litigation planning, the critical Orange Book fields are:

Active listed patents tied to that NDC.
Expiration dates and patent type (composition, method, use).
Exclusivity codes (if any) that create regulatory barriers independent of patents.

How Orange Book status shapes generic entry

If a listed patent is active, generics must either carve around (fewer legal claims) or file a Paragraph IV with litigation risk.
If no active listed patents exist for a given NDC, generics can enter without Paragraph IV litigation.

Investment implication: The investment-grade question is not “is phenytoin sodium patented,” but “which NDCs are still shielded by listed claims.”

(No Orange Book listing content is provided in the prompt. Without product-NDC mapping, this article does not enumerate specific patents or expiration dates.)

When does phenytoin sodium lose exclusivity and what are the key expiration dates investors should model?

Because phenytoin sodium is widely generic, the main timing model usually centers on:

Patent expiration for any still-listed formulation/process patents on specific NDCs.
Any regulatory exclusivity attached to particular references (if still present for specific product presentations).

Investment implication: Investors should treat the exclusivity timeline as NDC-specific, not molecule-wide.

(No specific patent expiration dates were supplied in the prompt. Without them, enumerating a loss-of-exclusivity calendar would be incomplete.)

How strong is the patent estate for phenytoin sodium and what is the likelihood that generics can design around?

Typical design-around pathways for generics

For established NTI antiseizure drugs, generic challengers usually seek one or more of:

Formulation redesign while maintaining bioequivalence.
Manufacturing-process differentiation to avoid process-method claims.
Carve-out strategies limited to certain claim elements.

Why formulation/process patents matter economically

Even if a patent estate is short, it can:

Slow down entry.
Improve reimbursement negotiations.
Increase bargaining power in settlements (where multiple patents exist).

Investment implication: Evaluate patent strength as “time-to-entry protection,” not as “compound monopolization.”

What patent litigation affects phenytoin sodium and which companies have been active challengers?

Litigation pathways to monitor

Paragraph IV suits targeting Orange Book-listed patents tied to specific NDCs.
Settlement agreements that delay FDA approval dates.
Secondary litigation tied to supply continuity and regulatory compliance.

How litigation changes investment risk

Litigation risk affects:

Ability to sustain margins (delayed generic entry keeps price higher).
Cash costs (legal spend and contingency reserves).
Manufacturing planning (delayed entry can shift inventory strategy).

Investment implication: For legacy generics, a single NDC dispute can determine a year of incremental pricing, so investors map exposure by product line.

(No specific litigation docket or company list is provided in the prompt.)

What generic entry risks exist for phenytoin sodium and how could they impact pricing?

Market mechanism: generic overhang

With phenytoin sodium, margin pressure typically accelerates when:

Multiple ANDA approvals land around the same time.
A supply bottleneck relaxes, allowing wholesalers to normalize inventory.
Discounting increases due to tender mechanisms and contract competition.

Risk factors that make outcomes non-linear

Regulatory downtime at key sites can briefly tighten supply, raising realized prices.
Recalls or repeated QC failures can force temporary channel shortages.
Currency of pharmacists’ switching habits and payer step therapy policies.

Investment implication: Pricing models should incorporate supply-state scenarios, not just patent expiration.

How does phenytoin sodium compare with other antiseizure medicines in competitive intensity and investment attractiveness?

Competitive positioning

Phenytoin sodium’s competitive pressure comes from:

Newer antiseizure drugs with more convenient dosing and less monitoring.
Clinical preference shifts, especially where monitoring burden or tolerability drives conversion.

What it means for investors

The upside for phenytoin sodium is usually narrower than for differentiated specialty products.
The downside is also narrower in the sense that demand is less likely to collapse to zero given historical use and established workflows.

Investment implication: Returns track operational excellence and product continuity more than breakthrough science.

What formulations are protected by patents for phenytoin sodium and how do they map to commercialization?

Dosage form differentiation that can still matter

Investment-relevant differentiation includes:

Immediate-release vs extended-release composition claims (if any remain for specific NDCs).
Injection/formulation stability and excipient composition (where applicable).
Manufacturing control for NTI uniformity and dissolution profiles.

Investment implication: Even in a generic market, SKU-level protection can control share at the margins.

(No specific formulation-patent mappings are provided in the prompt.)

Are there biosimilar risks for phenytoin sodium?

No. Phenytoin sodium is a small-molecule chemical drug, not a biologic, so it does not face biosimilar pathways.

What manufacturing and regulatory barriers exist for phenytoin sodium that could protect margins?

Quality and NTI compliance

NTI drugs have heightened sensitivity to:

Content uniformity and dissolution consistency.
Stability and shelf-life controls.
Sterility and endotoxin controls for injectable presentations (where relevant).

Regulatory friction points

Manufacturers face recurring risks around:

Facility inspections and remediation time.
Batch failures tied to analytic method drift.
Documentation and validation gaps.

Investment implication: Barrier economics favor incumbents with robust QA systems and inspection readiness, even when patents expire.

Which FDA pathways apply to generic phenytoin sodium, and what is the timeline risk?

ANDAs and bioequivalence

Generic entries for phenytoin sodium typically proceed through ANDA pathways with bioequivalence to the reference listed drug.

Timing risk investors should model

FDA review duration variability.
Deficiencies that extend approval and push launch quarters.
Facility-related delays that limit launch readiness.

Investment implication: For market share modeling, assume schedule slippage for new entrants unless they have recent approvals.

(No drug-specific ANDA approval dates are provided in the prompt.)

Key investment scenario: how to underwrite phenytoin sodium exposure

Scenario A: “Operational alpha”

Thesis: secure predictable supply, minimize regulatory downtime, and outcompete by reliability.
Revenue driver: volume capture and tender wins.
Risk: generic overhang continues to compress pricing, so profitability depends on cost control.

Scenario B: “SKU-based protection”

Thesis: certain NDCs may still have enforceable listings or short-duration formulation/process patents.
Revenue driver: delayed generic entry at protected SKU level.
Risk: carve-outs and rapid design-around shorten the window.

Scenario C: “Regulatory bottleneck”

Thesis: quality events at key competitors create temporary shortages.
Revenue driver: price and volume benefit during constrained supply.
Risk: shortage durations are unpredictable; replenishment returns competition quickly.

Investment implication: Best-fit investors treat phenytoin sodium as a manufacturing and regulatory execution bet, with IP used for timing only.

Key Takeaways

Phenytoin sodium’s investment profile is dominated by generic-market mechanics, not by long compound exclusivity.
The highest-value diligence is NDC-specific: active Orange Book listings, patent life left by SKU, and any NDC-specific litigation risk.
Sustainable returns depend on operational excellence: QA systems, inspection resilience, and supply continuity.
Generic entry risk is real but often uneven, driven by regulatory readiness and site stability rather than only by patent calendars.
Biosimilar risk is not applicable; competitive intensity comes from ANDA generics and alternative antiseizure medicines.

FAQs

1) What determines whether an ANDA for phenytoin sodium triggers Paragraph IV litigation?
Orange Book-listed active patents tied to the specific NDC in question.

2) Can phenytoin sodium pricing rise even after patent expiry?
Yes, temporarily, if supply is constrained due to manufacturing or quality disruptions.

3) What differentiates profitable generic phenytoin sodium manufacturers?
Low regulatory downtime, consistent batch success, strong QA documentation, and cost-efficient scale.

4) Does phenytoin sodium face biosimilar competition?
No, it is not a biologic.

5) How should investors model time-to-market risk for new generic entrants?
Use FDA review and deficiency probabilities, site inspection timelines, and realistic launch readiness rather than best-case approval dates.

References

(No sources were provided in the prompt, and no Orange Book, FDA, or litigation records were cited. This section is intentionally left empty to comply with the instruction to avoid incomplete factual claims.)

US Patents:	0
Applicants:	11
NDAs:	15

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Summary for PHENYTOIN SODIUM