Details for Patent: 6,503,884

United States Patent 6,503,884: What Is Claimed, What the Scope Covers, and Where the Patent Landscape Likely Cuts

US Drug Patent 6,503,884 claims methods of treating and preventing migraine in a “non-epileptic human patient” using sulfamates of a defined structural Markush formula (I) and derivatives of those sulfamates that include prodrugs, salts/esters, and “anti-migraine active metabolites.” The claims are drafted as method-of-use claims with broad chemical genus coverage, then narrowed via dependent claims to specific named sulfamates, dosing windows, and stereochemical detail.

What do the independent claims cover? (Claims 1 and 13)

Both independent claims run in the same structural pattern:

• Claim 1: Treating migraine (therapeutic method).
• Claim 13: Reducing frequency of migrainous episodes (prophylactic/preventive method).

Each is limited to a “non-epileptic human patient” in need of migraine therapy.

Core active matter in both claims

1. Option (a): administer an effective amount of a sulfamate of formula (I).
2. Option (b): administer an effective amount of a derivative of that sulfamate where the derivative is one of several enumerated categories, including:
   • (i) an ester of the sulfamate of formula (I)
   • (ii) a salt of the ester
   • (iii) a compound that on administration provides, directly or indirectly, a compound of formula (I) (prodrug type language)
   • (iv) an anti-migraine active metabolite of formula (I) or a residue thereof

Structural gating (formula (I) and formula (II))

• Formula (I) contains the following variable features as described in your claim text:
  • X is oxygen
  • R1 is hydrogen or a lower alkyl
  • R2, R3, R4, R5 are independently hydrogen or a lower alkyl
  • R2 and R3 and/or R4 and R5 together form a methylenedioxy group of formula (II)
• Formula (II) is defined with:
  • R6 and R7 same or different
  • each is hydrogen, lower alkyl, or alkyl and joined to form a cyclopentyl or cyclohexyl ring

Functional implication of the drafting

• The independent claims do not require a specific route, formulation type, or mechanism.
• They cover any sulfamate within the genus defined by (I)/(II), plus a broad set of derivatives that deliver or metabolize back to formula (I).

Where do the dependent claims narrow scope? (Claims 2–12 and 14–24)

The dependent claims mainly tighten scope along five axes:

1. Restriction to methylenedioxy placement (Claim 2, 14, 9, 21)
2. Restriction on alkyl size (Claim 3, 15)
3. Restriction to specific named sulfamates (Claims 4–6, 16–18)
4. Carrier and dose window (Claims 7–8, 19–20)
5. Expanded derivative list in derivative-dependent claims (Claim 12, 24; plus later categories in Claims 25–32)

Methylenedioxy group placement and stereochemistry

• Claim 2 / 14: “R2 and R3 and R4 and R5 together are groups of formula (II).”
  • This pins the methylenedioxy group definition to a specific “together” relationship of the substituents.
• Claim 9 / 21: the two oxygen atoms of the formula (II) are attached on the same side of the six-membered ring depicted in formula (I).
  • This is an explicit stereochemical/positional limitation.

Alkyl size limits

• Claim 3 / 15:
  • R1 is alkyl of 1 to 4 carbons
  • lower alkyl in R2–R5 is 1 to 3 carbons
  • lower alkyl in R6–R7 is 1 to 3 carbons
• These constraints limit the genus to relatively small alkyl substituents.

Specific exemplified sulfamates

The independent genus is narrowed in dependent claims to specific compounds:

• Claim 4 / 16: sulfamate of formula (I) is one of:
  1. (tetrahydro-2H-pyran-2-yl)methane sulfamate
  2. 2,3:4,5-bis-O-(1-methylethyldiene)-β-D-fructopyranose sulfate
  3. 2,3:4,5-bis-O-(1-methylethyldiene)-β-D-fructopyranose methylsulfamate
• Claim 5 / 17: 2,3:4,5-bis-O-(1-methylethyldiene)β-D-fructopyranose sulfamate
• Claim 6 / 18: 2,3:4,5-bis-O-(1-methylethyldiene)-β-D-fructopyranose methylsulfamate

Formulation and dosing boundaries

• Claim 7 / 19: sulfamate is administered with a pharmaceutically acceptable carrier
• Claim 8 / 20: unit dosage amount is about 50 to 400 mg
  • This is a meaningful constraint only for products falling under those dependent claim limitations. Independent claim 1/13 themselves do not state the dose.

R1 constraint and derivative categories

• Claim 11 / 22: in formula (I), R1 is hydrogen
• Claim 12 / 24: derivative includes:
  • “an imidate”
  • “a sorbopyranose sulfamate”
  • “a fructopyranose cyclic sulfite or sulfate”
  • “a phenylethyl sulfamate”
  • “acetazolamide”
  • “methazolamide”

This is a wide derivative list. It effectively links the Markush genus to a set of known sulfamate-related drug scaffolds and functional groups.

What do the later derivative claims add? (Claims 25–32)

Claims 25–32 add derivative category detail (mostly duplicative of the independent claim’s derivative option (b), but expressed separately and tied to claim 1 vs claim 13).

For Claim 1 descendants (Claims 25–28):

• Claim 25: derivative is a pharmaceutically acceptable ester of formula (I)
• Claim 26: derivative is a pharmaceutically acceptable salt of an ester of formula (I)
• Claim 27: derivative is a compound that provides formula (I) directly or indirectly
• Claim 28: derivative is an anti-migraine active metabolite of formula (I) or residue

For Claim 13 descendants (Claims 29–32):

• Claim 29: pharmaceutically acceptable ester
• Claim 30: pharmaceutically acceptable salt of an ester
• Claim 31: compound that provides formula (I) directly or indirectly
• Claim 32: active metabolite or residue

Scope effect

• These do not materially expand the independent derivative option (b), but they strengthen enforceability by keeping the claim language aligned to multiple derivative formats a challenger might argue are outside the independent description.

Practical scope map: What would likely infringe vs what is outside the claim language

Likely within scope

A product or regimen fits the independent method claims if it meets all of the following:

• Patient population: non-epileptic human patient
• Indication: treating migraine (Claim 1) or reducing migraine episode frequency (Claim 13)
• Drug provided:
  • a sulfamate that fits formula (I), or
  • a derivative of that sulfamate that fits the enumerated categories (ester/salt/prodrug to formula (I)/active metabolite)

Key drafting levers that broaden risk

• The claims cover prodrugs and metabolites that “provide, directly or indirectly” the formula (I) compound.
• The genus limits are structural (oxygen atom, R1, lower alkyl sizes, methylenedioxy ring structure), but the list of allowed substitution ranges is still broad.
• The derivative dependent claim list explicitly name acetazolamide and methazolamide, both classic carbonic anhydrase inhibitors. The claim ties those to derivative coverage under “anti-migraine active metabolite” or derivative categories.

Likely outside scope

• Therapies for migraine in epileptic patients are not within the literal patient limitation.
• Compounds that are close analogs to formula (I) but do not satisfy:
  • methylenedioxy construction as defined by formula (II), or
  • the oxygen-containing “X is oxygen” requirement, or
  • the alkyl-size constraints (when argued under dependent claims), or
  • the “derivative provides formula (I)” requirement (for prodrug/metabolite coverage)
• Indication changes (e.g., cluster headache, non-migraine headache syndromes) avoid the method-of-use language.

Patent landscape implications (based on the claim architecture and derivative breadth)

How to read the patent’s enforcement strategy

The patent’s structure signals two enforcement targets:

1. Chemical-genus capture
   The independent claims are written to cover “sulfamates of formula (I)” plus derivatives. This supports enforcement against any candidate that fits the Markush genus and is used for migraine in non-epileptic humans.

2. Lifecycle capture via derivatives and metabolites
   Ester/salt/prodrug/metabolite language reduces design-around value. A competitor can change formulation or prodrug form, but the patent still catches derivatives that regenerate formula (I) in vivo.

Design-around pressure points

• The strongest practical “escape route” would be to avoid producing a compound that qualifies as formula (I) or an “anti-migraine active metabolite” of formula (I), while also staying away from the defined methylenedioxy structural constraints.
• Changing dose, carrier, or unit dosage may reduce exposure to dependent claims, but it does not avoid the independent claims if the compound and indication match.

Competitive risk concentration

Enforcement risk is greatest for:

• Direct formula (I) sulfamate products
• Prodrugs that convert to formula (I)
• Metabolite-driven formulations if the metabolite qualifies as an “anti-migraine active metabolite”
• Known sulfamate drugs explicitly listed as derivatives (notably acetazolamide and methazolamide), where claim interpretation could turn on whether they are treated as derivatives capable of providing/relating to formula (I) under the patent’s Markush and metabolite definitions.

Claim-by-claim reference table

Key Takeaways

• US 6,503,884 claims migraine treatment and migraine prophylaxis in non-epileptic human patients using sulfamates defined by formula (I) plus a broad set of derivatives (esters, salts, prodrug-like compounds that generate formula (I), and “anti-migraine active metabolites”).
• The claim scope is genus-based (Markush (I)/(II)) with structural restrictions on alkyl sizes and methylenedioxy construction, then narrowed in dependent claims to specific named sulfamates, stereochemistry, dose range, and carrier.
• Derivative coverage is enforceability-critical: the claims explicitly include prodrug regeneration of formula (I) and name derivatives that include acetazolamide and methazolamide, which creates higher competitive overlap for known sulfamate-associated drug classes when linked to formula (I) under claim interpretation.
• Design-around efforts should focus on avoiding formula (I) qualification, including avoidance of metabolites that could be argued to be “active metabolites” of formula (I), and avoiding the defined methylenedioxy/alkyl structural constraints rather than relying on dose or salt/ester form changes.

FAQs

1) Does the patent claim a specific mechanism of action?

No. The independent method claims are written around administration of formula (I) sulfamates or derivatives for migraine outcomes.

2) Can a company avoid infringement by switching from one salt form to another?

Switching salt forms may avoid dependent claim limitations, but the independent claims already include “salt of the ester” and broad “derivatives” language that can still capture prodrug/metabolite regeneration of formula (I).

3) Are acetazolamide and methazolamide inside the claim scope?

They appear in the dependent derivative list (Claims 12 and 24) as derivatives. Whether a competitor’s compound is captured depends on claim interpretation tying the derivative to the formula (I) sulfamate framework and the method-of-use context.

4) What is the practical impact of the “non-epileptic human patient” limitation?

It limits literal claim coverage to patients who are non-epileptic. It is a patient-population constraint embedded directly in the method claims.

5) Which claim limitations most reduce scope in enforcement?

The biggest narrowing limits are:

• selection among specific named sulfamates (Claims 4–6, 16–18),
• stereochemical positioning (Claims 9, 21),
• and dose window (Claims 8, 20).

References

[1] United States Patent 6,503,884. “Method of treating migraine using sulfamates.” (Claims as provided in the prompt.)