Details for Patent: 5,908,850

Summary for Patent: 5,908,850

Title:	Method of treating attention deficit disorders with d-threo methylphenidate
Abstract:	Methods for treating Attention Deficit Disorder, Attention Deficit Hyperactivity Disorder, AIDS Dementia Complex and cognitive decline in HIV-AIDS while minimizing drug hypersensitivity, toxicity, side effects, euphoric effect, and drug abuse potential by administration of d-threo-methylphenidate or pharmaceutically acceptable salts thereof.
Inventor(s):	Andrew L. Zeitlin, Maghsoud M. Dariani, David I. Stirling
Assignee:	Celgene Corp
Application Number:	US08/827,230
Patent Claim Types: see list of patent claims	Use; Composition;

US Patent 5,908,850 Landscape: D-threo Methylphenidate Method-of-Use Claims, Scope, and US Exclusivity Exposure

US Patent 5,908,850 is directed to a US method-of-treatment for Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD) using D-threo methylphenidate (or a pharmaceutically acceptable salt) substantially free of L-threo methylphenidate, framed around improved therapeutic profile versus racemic threo methylphenidate. The claim set is narrow on (1) stereochemistry (D-threo with substantially no L-threo), (2) daily dosing, and (3) therapeutic objectives tied to side effects/euphoria/abuse liability.

Scope in one line: the core claim protects treating ADD/ADHD with D-threo methylphenidate (or salt) administered daily at therapeutic doses, with stereochemical purity constraints and outcome-driven “reduced euphoria/potential for abuse” framing relative to racemic threo methylphenidate.

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What does US Patent 5,908,850 claim for treating ADHD using D-threo methylphenidate?

Featured snippet answer: Claim 1 covers a method of treating ADD/ADHD by daily administration of therapeutically effective amounts of D-threo methylphenidate (or salt) substantially free of L-threo methylphenidate, aiming for enhanced activity and reduced euphoria/side effects and potential for drug abuse versus racemic threo methylphenidate.

Claim 1 element-by-element scope

Claim 1 reads as a composite requirement. A product or regimen must meet all of these claim elements to infringe as a method-of-use:

1. Patient population / indication

   • “a human exhibiting symptoms” of ADD or ADHD.

2. Therapeutic act

   • “administering… therapeutically effective amounts” of the active.

3. Active ingredient identity

   • D-threo methylphenidate or “pharmaceutically acceptable salt thereof.”

4. Stereochemical constraint

   • “substantially free of L-threo methylphenidate.”

5. Dosing schedule

   • “on a daily basis.”

6. Outcome characterization relative to comparator

   • enhanced therapeutic activity and/or reduced side effects/euphoric effect and/or reduced potential for drug abuse “as compared to racemic threo methylphenidate.”

How “substantially free of L-threo methylphenidate” functions in claim scope

The claim uses functional purity language rather than a bright numeric limit. That means:

• infringement analysis turns on whether the administered material is “substantially free” in practice.
• dependent claim 3 supplies a numeric anchor (see next section), making Claim 1’s “substantially free” likely interpreted through that narrower range when claim construction considers the specification and dependents.

How the “as compared to racemic threo methylphenidate” language affects coverage

This is a comparator framing embedded in the method claim. Practically, it narrows the narrative purpose of the method to a differential therapeutic profile versus racemate. It does not change the administered active (still D-threo with limited L-threo), but it affects how enforceability is argued:

• in litigation, it supports positioning D-threo as the driver of reduced euphoria/abuse liability relative to racemate.
• it can be used to challenge “paper infringement” where the dosing is close but the claimed differential effects are disputed.

Day-to-day dosing requirement

Claim 1’s “on a daily basis” is a schedule element. Regimens that are intermittent and not daily can avoid Claim 1 even if they use D-threo with high purity.

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What do dependent claims 2–4 add to narrow infringement risk?

Claim 2: dose range 5 mg to 50 mg per day

• Adds a numeric regimen constraint: “amount administered is 5 mg to 50 mg per day.”
• If a generic or alternative regimen uses D-threo outside this daily total, it is outside Claim 2 (and potentially outside the broader Claim 1 depending on how “therapeutically effective amounts” is construed relative to the dependent range).

Claim 3: purity threshold greater than 99% by weight

• “greater than 99% by weight” D-threo methylphenidate (or salt).
• This is a decisive narrowing feature because it converts “substantially free” into a quantifiable threshold for a subset of infringement scenarios.
• If a competing product’s D-threo content is not >99% by weight, it may not meet Claim 3 and could be argued not to satisfy “substantially free” in Claim 1 depending on claim construction and how the prosecution history/spec supports the term.

Claim 4: administered together with a pharmaceutically acceptable carrier

• Typically broad because almost all oral dosage forms include carriers/excipients.
• This claim is most relevant to formulation-adjacent work where challengers might argue purity-only dosing without a carrier, or in unusual delivery formats.

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Which formulations or salts of D-threo methylphenidate are covered by 5,908,850?

Featured snippet answer: Coverage is for D-threo methylphenidate (or pharmaceutically acceptable salt) given daily at therapeutically effective doses for ADD/ADHD, using a stereochemical profile substantially free of L-threo and, in narrower claim sets, >99% by weight D-threo.

Dosage forms implied by “together with a pharmaceutically acceptable carrier”

Claim 4 indicates the patent contemplates conventional pharmaceutical preparations:

• oral tablets/capsules
• oral solutions/suspensions
• likely transdermal or other carriers only if the carrier element is met and the administration is “daily basis” for ADD/ADHD symptoms.

Immediate-release vs extended-release

Your claim language does not specify release profile. Enforcement focus would likely be on:

• whether administration results in daily dosing of D-threo at therapeutically effective amounts within the recited range, and
• whether the administered stereochemical purity meets “substantially free” and/or >99% (claim 3).

Salt forms

The claim explicitly covers “pharmaceutically acceptable salt thereof,” meaning salt identity is not limiting in claim 1. Any salt that still contains D-threo methylphenidate as the active stereoisomer and maintains the required purity likely falls within scope.

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How strong is the patent estate for stereochemically pure D-threo methylphenidate methods in the US?

Featured snippet answer: US 5,908,850 is a method-of-use claim with strong chemical identity constraints (D-threo, minimal L-threo) and dosing constraints (daily; dependent numeric dose 5–50 mg/day and purity >99% by weight). Its enforceability depends on proving (a) stereochemical purity at the time of administration and (b) that the accused regimen is daily and targeted to ADD/ADHD.

Strength drivers

1. Clear stereochemical novelty
   • D-threo methylphenidate vs racemate is an unambiguous chemical distinction.
2. Purity-limited claim term
   • “substantially free” and “>99% by weight” give the owner litigation leverage by creating objective analytical tests for the active content.
3. Regimen elements
   • daily dosing and (in claim 2) daily dose range provide additional compliance hooks for both parties.

Strength limitations

1. Method-of-use enforcement requires conduct
   • the patentee must establish that the accused provider (or label-driven practice) administers the claimed regimen.
2. Comparator language adds an argument surface
   • “as compared to racemic threo methylphenidate” can be attacked on whether the alleged effects are necessary to infringement or are only a statement of intended results.
3. Potential for design-around via dosing or purity
   • shifting outside 5–50 mg/day (claim 2) and/or using a D-threo ingredient that is not >99% by weight (claim 3) can reduce dependent claim exposure.
   • changing schedule to non-daily regimens can reduce claim 1 exposure.

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What generic entry risks exist for D-threo methylphenidate methods versus racemic methylphenidate?

Featured snippet answer: Generic and competitor risk is highest where the product uses stereochemically purified D-threo methylphenidate (ideally >99% by weight), is used daily for ADHD/ADD at therapeutically effective amounts within 5–50 mg/day, and is promoted/practiced for the claimed method profile.

Key design-around levers

• Purity lever
  • Avoiding >99% by weight can reduce Claim 3 exposure; avoiding “substantially free” can reduce Claim 1 exposure if claim construction rejects loose purity interpretations.
• Dose lever
  • For products targeting different daily totals than 5–50 mg/day, Claim 2 risk drops, while Claim 1 remains only dependent on “therapeutically effective amounts.”
• Schedule lever
  • If a regimen is not “daily basis,” claim 1 exposure can be reduced.
• Non-covered indication/care pattern
  • If the use case is not for ADD/ADHD symptoms, method claim exposure decreases.

Practical litigation focus for generics

In parallel with Orange Book entry strategy, the litigation question becomes whether the label and actual prescribed use aligns with “daily” and the required stereochemical purity. That makes the stereochemical spec and manufacturing release testing central.

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What does the claim wording imply about FDA labeling and Orange Book strategy?

Featured snippet answer: Because the patent is a method-of-use claim, FDA labeling carve-ins and label alignment with “daily” dosing and ADD/ADHD treatment become central to any Orange Book-related enforcement, licensing, or Paragraph IV posture.

Label-driven risk

• If a generic or alternative marketer files a submission intending to list a use that tracks the claimed method, the patentee’s leverage increases.
• If a label is modified to avoid the claimed method parameters (daily schedule alignment, stereochemical purity assurances, or the specific dose range), the patentee’s enforcement pathways can narrow to the risk of off-label or practice-based claims.

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How do D-threo methylphenidate method claims compare with racemic threo methylphenidate patents?

Featured snippet answer: US 5,908,850 is differentiated by stereochemistry (D-threo substantially free of L-threo) and by claimed differential outcomes (reduced euphoria/side effects/abuse potential versus racemic threo methylphenidate). This distinction shifts the competitive boundary away from racemate-based methods.

Competitive implications

• Any competing method using racemic threo methylphenidate is outside the claim’s stereochemical constraints.
• The patent does not protect “methylphenidate treatment for ADHD” broadly; it protects a specific stereochemical administration pattern with daily dosing and claimed differential effect profile.

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What would a plausible US Paragraph IV challenge look like for this patent?

Featured snippet answer: A Paragraph IV would most likely argue non-infringement by showing the accused product is not administered daily in the claimed dose band, or the formulation is not “substantially free” of L-threo (or not >99% by weight), or the use is not for ADD/ADHD as claimed. Separate validity attacks could target obviousness-type grounds for D-threo selection.

Non-infringement routes most consistent with the claim text

• Stereochemistry proof
  • analytical testing showing L-threo presence above “substantially free” or failing the >99% by weight limitation.
• Dosing schedule evidence
  • prescribing regimen data showing non-daily use.
• Dose band mismatch
  • daily totals outside 5–50 mg/day for the dependent claim.

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Timeline: when does US patent 5,908,850 lose exclusivity?

No complete and accurate exclusivity timeline can be produced from the claim excerpts alone. A complete answer requires the patent’s filing date, issue date, and any term adjustments or terminal disclaimers, none of which are provided in the prompt.

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Key Takeaways

• US 5,908,850 protects a method of treating ADD/ADHD with daily administration of D-threo methylphenidate (or its salt) that is substantially free of L-threo.
• Dependent claims add enforceable narrowing: 5–50 mg/day (claim 2) and >99% by weight D-threo (claim 3).
• The patent’s competitive “hot zone” is stereochemically purified D-threo methylphenidate used daily for ADHD/ADD in dose ranges aligned with the dependent limitations.
• Generics face the highest non-infringement burden on stereochemical purity and label/practice alignment with the daily regimen.

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FAQs

1. Can an extended-release D-threo methylphenidate product infringe a “daily basis” method claim?
2. What test method would typically establish whether a D-threo batch is “substantially free” of L-threo?
3. If a competitor’s daily dose is outside 5–50 mg/day, does it still risk infringement of claim 1?
4. Does “as compared to racemic threo methylphenidate” create a separate infringement requirement or only a claim framing limitation?
5. How do label changes that avoid daily dosing language affect method-of-use enforcement for ADD/ADHD?

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References (APA)

1. US Patent 5,908,850. (Claims text as provided in prompt).

Drugs Protected by US Patent 5,908,850

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate

International Family Members for US Patent 5,908,850

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	306266
Austria	368458
Australia	2002318302
Australia	738521
Australia	738744
Australia	7834398