Details for Patent: RE37516

United States RE37516 (Modafinil Particle Size) Patent Landscape: Claim Scope, Filing History, and US Exclusivity/Enforcement Read-Through

RE37516 recites a narrow physical-attribute solution to modafinil oral delivery: a substantially homogeneous mixture (or unit dose) of modafinil solid particles having a tight particle-size distribution. The enforceable core is the combination of (i) modafinil as the drug substance, (ii) solid particle form (including salt variants), (iii) particle-size distribution defined by a “≥95% cumulative total <200 μm” threshold, and in dependent claims a median size band “about 2 μm to about 60 μm,” plus (iv) oral unit dose amount ranges (notably 100–200 mg per unit dose) and administration ranges (notably 50–700 mg/day).

Below is a scope map of the literal claim language, a practical “design-around” lens, and how this type of particle-size patent typically sits in a US Orange Book and litigation ecosystem for modafinil-related generics.

What does RE37516 claim cover for modafinil particle size distributions in the US?

Core independent claim (Claim 1 concept): a pharmaceutical composition containing modafinil particles in which at least about 95% of the cumulative total of the modafinil particles have a diameter < about 200 μm, in a “substantially homogeneous mixture.”

This is the central infringement hook. Any formulation (composition) or dosing regimen (method) that matches the particle-size distribution and uses modafinil as the solid particle drug substance will land in the claim’s scope.

How Claim 1 “95% <200 μm” is likely measured and why it matters

The claim is defined by a cumulative distribution threshold, not an average. For infringement analysis, the critical question becomes whether an accused product’s particle size analysis yields ≥95% by cumulative mass (or cumulative count, depending on the test method used) below 200 μm.

The claim’s structure supports a two-pronged reading:

• The distribution is “cumulative,” so the measurement is relative to the full particle population.
• The threshold is “about,” which increases flexibility for rounding and slight drift, but does not remove the need to clear the “near 95%” requirement.

What “substantially homogeneous mixture” adds

Claim 1 requires not just an overall distribution, but a “substantially homogeneous mixture” of modafinil particles. Practically, that requirement is aimed at excluding blends where coarse fractions segregate or where the formulation is not meaningfully uniform. It pushes accused products toward standard powder processing and premix practices rather than physical stratification.

Does RE37516 protect medians between 2 μm and 60 μm, or only the <200 μm threshold?

Dependent claims narrow the distribution further:

• Claim 2: “median diameter range between about 2 μm and about 60 μm.”

This is a secondary gating feature. If an accused product meets the 95% <200 μm threshold but has a median outside 2–60 μm, then:

• Claim 2 specifically may not read,
• but independent Claim 1 (and the independent unit dose particle size claim concept) can still be implicated if the ≥95% <200 μm condition holds.

Why the median band increases enforceability

By reciting a median band, the patent gives a second dimension for infringement leverage:

• Competitors can’t avoid by only shaving the coarse tail; they also must avoid shifting the central tendency outside the stated median window if they want to clear dependent claim coverage.

What dosing ranges are covered by RE37516 for oral unit doses and daily regimens?

RE37516 includes both composition and method claims with specific dose ranges.

Unit dose composition quantities

• Claim 3: composition comprises 50 mg to 700 mg of modafinil.
• Claim 7 (unit dose form): unit dose containing an amount effective to alter somnolent state; particles meet ≥95% <200 μm.
• Claim 9: unit dose is 100 mg to 200 mg.
• Claim 18/19/20: unit dose compositions including solid particles or particles converted in vivo, with the same distribution and 100–200 mg per unit dose in dependent language.

Daily dosing regimens

• Claim 6: administer 50 mg/day to 700 mg/day (method derived from Claim 4).
• Claim 12: administer 100 mg/day to 200 mg/day (narcolepsy-specific method derived from Claim 10).
• Claim 23: similar 100 mg/day to 200 mg/day for narcolepsy in method derived from Claim 21.

How this interacts with standard modafinil clinical dosing

The presence of 100–200 mg/day and 100–200 mg unit dose ranges aligns closely with common commercial regimens. That means RE37516’s dose language is not merely decorative; it is positioned to read on typical strengths and titration windows.

What therapeutic or disease indications does RE37516 cover in the US?

RE37516 uses “modafinil-responsive” framing and explicitly enumerates disease areas in method claims.

Method claims explicitly naming narcolepsy

• Claims 5, 11, 22: somnolent state is narcolepsy.

Expanded disease list (modafinil-responsive diseases/conditions)

• Claim 16 and Claim 25 cover:
  narcolepsy; Parkinson’s disease; urinary incontinence; Alzheimer’s disorder.

Alertness/sleep rhythm language

• Claims 15 and 24: “enhancing alertness or increasing regularity of sleep rhythms.”

Business implication

Indication recitations affect enforcement primarily through:

• method-of-use infringement theories (where direct administration is the act),
• and Orange Book listing practices where relevant claims might be tied to labeling.

For generic and challenger products, the key risk is not only particle size, but also whether the method claims are asserted against actual prescribing and administration.

Is modafinil salt form included in RE37516?

Yes.

• Claim 17: particles are in the form of a modafinil salt.
• Claims 26 and similar “method or composition” language: also allow salt forms.

This matters because many generic products will select crystalline forms or salt forms (or equivalents) that can change particle-size processing outcomes. RE37516’s salt inclusion reduces an easy route out through salt switching.

What is the “converted to solid particles after oral administration” scope in RE37516?

Claim 18 includes modafinil:

• present in an amount effective to alter somnolent state upon oral administration,
• modafinil is in solid particle form, or converted to solid particles after oral administration, and
• particle-size distribution such that ≥95% <200 μm.

This clause broadens the claim’s reach in scenarios where:

• the administered form is not originally solid particles as manufactured,
• but becomes solid particulate in vivo in a way that satisfies the claimed distribution.

In enforcement, this “converted” language can be a litigation lever for products arguing that their pre-dose form is different. It also increases the evidentiary and causation complexity, but it is still an explicit claim feature.

What formulations are protected by RE37516 beyond particle size?

The claim set ties particle-size distribution to multiple formulation contexts:

• general pharmaceutical composition (Claim 1),
• unit dose oral dosage form (Claims 7–9),
• unit dose composition variants with explicit “solid particles or converted after administration” (Claims 18–20),
• optional inclusion of additional modafinil particles (Claims 13–14).

Additional modafinil particles feature

• Claim 13: further comprising additional modafinil particles in excess of the effective amount.
• Claim 14: additional particles represent about 10–15% of the effective amount.

This is a narrower dependent concept. Its role is to capture certain multipart loading strategies where the administered unit contains extra particulate content beyond the “minimum effective” fraction.

Excipients and matrix components

RE37516, based on the claim text supplied, does not require specific excipient compositions. That generally makes the patent more robust against “same particle distribution in different tablet matrix” efforts, though excipients can still affect particle engineering and measured size distributions.

How does RE37516 compare with typical modafinil patent estates (particle engineering vs. polymorph/process)?

RE37516 is a particle-size distribution patent. It is closer to:

• engineering/control patents for powders,
• than to core small-molecule modafinil composition-of-matter.

Practical comparison to typical modafinil estates:

• Composition-of-matter patents usually cover modafinil itself or specific crystalline forms.
• Process patents cover manufacturing steps and conditions.
• RE37516 adds a measurable product attribute: particle size distribution tied to oral dosing.

This positions RE37516 as a “formulation-and-attribute” barrier. It tends to remain relevant even after substance-level patents expire, because generics must also match formulation parameters (or avoid them).

What generic entry risks exist for modafinil when RE37516 is in-force?

The risk cluster for a generic manufacturer is straightforward:

1. If the generic’s modafinil solid particle distribution satisfies ≥95% <200 μm, RE37516’s key feature is met.
2. If the generic uses unit dose strengths and daily regimens within 100–200 mg/day and 100–200 mg per dose, it increases method and unit dose dependent claim exposure.
3. If the generic aligns labeling or is used in a way that matches the method-of-use claims (narcolepsy and other enumerated indications), method claims become more assertable.

Design-around levers consistent with the claim language

The most direct levers are:

• adjust milling/sieving/classification so that <95% of the cumulative distribution is below 200 μm, or
• shift the median outside 2–60 μm (to avoid dependent claim 2/19 coverage),
• modify the unit dose amount outside 100–200 mg (to reduce dependent claim coverage), and
• avoid matching “effective amount” ranges in asserted method-of-use contexts (though “effective amount” language is often hard to carve out cleanly).

Because RE37516 is attribute-based, “same active ingredient, different particle engineering” is the most effective avoidance concept.

What Orange Book status would RE37516 likely map to for modafinil generics?

Based on RE37516’s claim type (formulation attribute + method-of-use), it is the kind of patent that can be listed in the FDA Orange Book if the NDA holder/assignee linked it to drug product and/or use.

However, Orange Book status depends on:

• the NDA/BLA listing history,
• the specific claims designated for listing,
• and the patent expiration/RE status.

Given only the claim text provided and no Orange Book table/listing data, the only accurate statement is claim-structure relevance: RE37516’s coverage is formulation and dosing driven, which is the typical basis for Orange Book listing tied to methods or drug product characteristics.

What does RE37516’s “RE” designation imply for validity and enforcement posture?

“RE” indicates a reissued patent. Reissue typically matters for:

• claim scope that may be broadened/narrowed relative to an original,
• correction of errors,
• and re-publication of the claims.

In enforcement, reissue patents often show up in:

• litigation where challengers argue improper reissue scope or inequitable conduct around original prosecution,
• or standard validity attacks under anticipation/obviousness.

Specific validity dates and prosecution history are not present in the information provided here, so the enforceability implications are limited to how reissue patents are commonly treated procedurally.

What litigation and settlement dynamics usually follow from particle-size formulation patents like RE37516?

Particle-size attribute claims tend to produce evidence-intensive disputes. Typical litigation dynamics:

• claim construction focuses on how particle size distributions are measured and reported,
• accused products are tested using defined sampling and size analysis methods,
• expert testimony targets whether the distribution clears the “≥95% <200 μm” line and how “median diameter range” is computed.

If the patent holder sues, the settlement often involves:

• delayed launch,
• design-around formulation changes,
• or licensing for a defined product configuration.

This litigation pattern is not a claim-level fact; it is a procedural reality for powder-attribute disputes.

Key Takeaways

• RE37516’s enforceable center is the particle-size distribution requirement: ≥95% cumulative modafinil particles <200 μm in substantially homogeneous compositions and in oral unit dose forms.
• Dependent claim coverage tightens the profile with a median diameter of ~2–60 μm and with common commercial-like dosing: 100–200 mg per unit dose and 100–200 mg/day in narcolepsy methods.
• The patent reaches methods of altering somnolent state and expressly lists narcolepsy, Parkinson’s disease, urinary incontinence, and Alzheimer’s disorder, plus general alertness/sleep rhythm language.
• Modafinil salt forms are included, and “converted to solid particles after oral administration” language broadens the pathway for non-solid pre-dose forms.
• The primary generic entry risk is whether an ANDA product (or authorized product) matches the particle size distribution thresholds and dosing patterns, not merely whether it contains modafinil.

FAQs

1) What size distribution would avoid RE37516’s “at least about 95% <200 μm” requirement?
A product must fail to meet the “≥95%” cumulative threshold below 200 μm, using the distribution measurement consistent with the asserted claim construction.

2) Does RE37516 require a specific tablet excipient or crystalline form of modafinil?
No excipient is required in the supplied claim text, and modafinil salt forms are explicitly included. The dominant requirement is the particle size distribution of modafinil solid particles.

3) Can a generic avoid method-of-use infringement by changing labeling indications?
Method-of-use claim exposure can still arise where the accused product is administered for the claimed indications. Label changes may reduce direct alignment but do not eliminate risk for active clinical use matching the claim language.

4) How does the “median 2 μm to 60 μm” limitation affect design-around strategies?
Even if a product meets the ≥95% <200 μm threshold, it may still be vulnerable under dependent claims if the median falls within 2–60 μm. Shifting median outside that band can reduce dependent coverage.

5) Does RE37516 cover unit doses with strengths other than 100–200 mg?
The 100–200 mg band appears in dependent claims. Independent claim coverage depends on the particle size distribution and administration framework, so non-100–200 mg strengths may still face exposure unless they also avoid the remaining elements of the independent claims.

References (APA)

No sources were provided in the prompt and no patent/publication databases or Orange Book records were included; therefore, no citations can be listed.