Details for Patent: 6,407,128

Summary for Patent: 6,407,128

Title:	Method for increasing the bioavailability of metaxalone
Abstract:	A method of increasing the bioavailability of metaxalone by administration of an oral dosage form with food is provided, as well as an article of manufacture comprising an oral dosage form of metaxalone in a suitable container and associated with printed labeling which describes the increased bioavailability of the medication in the container when taken with food.
Inventor(s):	Michael Scaife, Jaymin Shah
Assignee:	King Pharmaceuticals Research and Development Inc
Application Number:	US09/998,206
Patent Claim Types: see list of patent claims	Use; Composition; Dosage form;

United States Patent 6,407,128: Claims, Claim Scope, and US Metaxalone Food-Effect Patent Landscape

US Patent 6,407,128 claims methods for increasing the oral bioavailability and absorption (Cmax and AUC(last)) of metaxalone when administered with food, including timing windows, dose ranges, and tablet/unit-dose limitations, plus patient-labeling and patient-informing steps. The claim set is directed to a relatively narrow therapeutic and administration-use concept: metaxalone dosing with food at specified dose levels and time relationships to food consumption, where the administration yields measurable pharmacokinetic increases versus dosing without food.

The patent’s enforceable scope in practice tracks the dosing label mechanics (dose amount, tablet form, administration timing relative to food, and the PK outcome requirement where claimed). This creates a clearance framework for generics and reformulators: the key infringement question is not “metaxalone has food effects,” but whether the accused regimen practices the claimed dose ranges and time windows and (for the higher-specificity claim group) produces the claimed Cmax and AUC(last) increases.

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What is US Patent 6,407,128 and what does it claim about metaxalone with food?

Direct answer: US 6,407,128 is an administration-method patent covering metaxalone dosing with food to increase oral bioavailability and absorption rate/extent, using defined dose ranges, defined administration timing relative to food, and tablet/unit-dose constraints, with additional claims tying infringement to PK readouts (Cmax and AUC(last)) and to patient labeling/informing.

Claim architecture: three overlapping claim groups

1. Broad “bioavailability with food” method group (claims 1–6, 9–14)

   • Claim 1: increases oral bioavailability of metaxalone in a patient receiving metaxalone therapy by administering metaxalone in a pharmaceutical composition with food.
   • Claims 2–3: constrain the therapeutically effective amount to 200–900 mg and 400–800 mg.
   • Claims 4–6: constrain the administration time relative to food:
     • 30 min prior to 2 hours after consuming food
     • substantially at the same time
     • immediately after consumption up to 1 hour after
   • Claims 7–8: constrain the composition to tablet and unit dosage form.

2. PK-outcome measuring group (claims 9–16, 17–20)

   • Claim 9: increases rate and extent of absorption measured by drug concentration over time in blood, by administering metaxalone with food.
   • Claims 10–14: add the same dose and timing constraints.
   • Claims 15–16: add tablet/unit-dose constraints.
   • Claim 17: constrains the composition more tightly and adds explicit PK outcome language:
     • administer a 400–800 mg metaxalone tablet with food
     • administration results in increased Cmax and AUC(last) vs administration without food.
   • Claims 18–20: add the same timing constraints to claim 17.

3. Patient communication / labeling group (claims 21–22)

   • Claim 21: method further comprises informing the patient that administration with food increases Cmax and AUC(last] vs administration without food.
   • Claim 22: metaxalone is from a container with printed labeling advising that administration with food increases Cmax and AUC(last) vs administration without food.

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How broad are the claims and what elements must be present for infringement?

Step-by-step infringement element checklist (by claim group)

Claims 1–8 (bioavailability increase with food; dose/timing/form optional depending on dependent claim)

An asserted method claim from this group requires:

• Metaxalone therapy for a patient.
• Administration of metaxalone in a pharmaceutical composition.
• Administration “with food.”
• Dependent limitations add:
  • Dose range (200–900 mg or 400–800 mg).
  • Administration timing relative to food (30 min prior to 2 hours after; or substantially same time; or immediately after up to 1 hour after).
  • Dosage form: tablet.
  • Unit dosage form.

Key breadth drivers:

• Claim 1 is not restricted to a tablet, a dose range, or a narrow time window. It only requires metaxalone administration with food as part of therapy.
• Dependent claims narrow further, which matters because they create “fallback” positions for enforcement and potentially for claim charting.

Claims 9–16 (absorption rate/extent measured by blood concentrations; dose/timing/form optional depending on dependent claim)

These claims retain the same core:

• Metaxalone administration with food
• Patient in need of therapeutic effect
• Absorption measured by blood concentration over time

Practical read:

• Even without an explicit Cmax/AUC requirement in claim 9, the language ties to pharmacokinetic measurement. In litigation, this often becomes an evidentiary question: does the accused use regimen produce the claimed “rate and extent” effect as assessed over time?

Claims 17–20 (400–800 mg tablet with food; explicit Cmax and AUC(last) increases)

This group has the tightest factual tether:

• 400–800 mg metaxalone tablet
• Administered with food
• Results in increased Cmax and increased AUC(last) versus dosing without food
• Timing windows: same time; within defined window(s)

This group is narrower because:

• It requires a specific dose band (400–800 mg).
• It requires explicit PK increases versus a comparator condition (without food).
• It requires tablet formulation in at least the claim 17 phrasing (“metaxalone tablet comprising 400 mg to 800 mg”).

Claims 21–22 (patient informing / printed labeling tied to Cmax and AUC(last) increases)

These claims hinge on communications infrastructure rather than solely on administration:

• Claim 21: the method includes informing the patient of the PK impact of food co-administration.
• Claim 22: metaxalone is provided in a container with printed labeling with the specified advisory.

In enforcement, claim 22 is often the easiest to connect to product labeling, packaging, and instructions for use. It also increases non-practice risk for manufacturers if they ship packaging that matches the claim language.

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What is the practical scope around “with food” and food-timing windows?

The claims define multiple timing regimes, creating multiple infringement “lanes”

The patent contains three timing constructs:

1. 30 minutes prior to 2 hours after consuming food (claims 4, 12, 18)
2. Substantially at the same time as consuming food (claims 5, 13, 19)
3. Immediately after consumption up to 1 hour after (claims 6, 14, 20)

Scope consequence: If an accused regimen falls within any one of these windows for relevant dependent claims, it can satisfy the timing element even if it misses the others. For claim 1 (and claim 9), timing is not limited, so any “with food” dosing could qualify depending on how “with food” is construed during litigation.

Dose scope in the dependent claims

• 200–900 mg (claims 2, 10)
• 400–800 mg (claims 3, 11, and directly in claim 17)

Scope consequence: If an accused product is 250 mg tablets and dosing is outside 400–800 mg, it can avoid direct overlap with claim 17 but still potentially face risk under broader claims 1 and 9 if those do not require the 400–800 mg band.

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How do the PK-based limitations (Cmax and AUC(last)) change claim strength and proof?

Claims 17, 21, and 22 explicitly require PK outcomes

• Claim 17: increased Cmax and AUC(last) vs without food.
• Claim 21: patient informing that administration with food increases those PK parameters.
• Claim 22: labeling advising that administration with food increases those PK parameters.

Proof model in disputes

• For claim 17, proof typically relies on pharmacokinetic study evidence comparing food vs fasted dosing and demonstrating the directionality of both Cmax and AUC(last) increases.
• For claim 21/22, proof can be more documentation-driven:
  • what the patient was told, or
  • what the packaging labeling states.

Scope consequence: Claims 21 and 22 potentially reduce the need for live PK disputes in some enforcement scenarios, but they are still tethered to the content matching “results in increase in Cmax and AUC(last) … compared to administration without food.”

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What formulations and dosage forms are covered?

Covered dosage forms

• Claim 7: pharmaceutical composition comprises a tablet
• Claim 8: tablet is in unit dosage form
• Claims 15–16: same limitations attached to the absorption group (tablet and unit dosage form)
• Claim 17: tablet comprising 400 mg to 800 mg metaxalone with food

What is not explicitly limited (from the provided claims text)

The claims text you provided does not restrict:

• specific excipients,
• immediate-release vs modified-release,
• manufacturing methods,
• salt form (metaxalone is typically administered as the active itself, but no salt constraint appears in the claim text you supplied).

Given the explicit “tablet” and “unit dosage form” limitations appear in dependent claims, enforcement breadth for oral non-tablet forms depends on whether a court construes the independent claims to include non-tablet compositions. Based on your claim text, claim 1 and claim 9 read on “a pharmaceutical composition,” which can include tablets but is not limited to tablets unless dependent claims are asserted.

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How does this patent compare with other potential metaxalone patent estate categories?

Based on claim content alone, US 6,407,128 sits in the administration-use and food-effect category, not core composition-of-matter or synthesis.

Typical adjacent estate categories for metaxalone (not derived from US 6,407,128 claim text) often include:

• polymorphs / solid forms,
• compositions and unit-dose combinations,
• dissolution/absorption rate enhancement,
• process patents,
• method-of-treatment patents for specific indications and dosing regimens,
• controlled-release approaches.

Scope implication: Even if a competitor has strong IP on a formulation, US 6,407,128 can still matter if the competitor’s dosing instructions and labeling implement the “with food” PK outcome and timing/dose constraints.

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What does the claim set imply for Paragraph IV generic or 505(b)(2) reformulation risk?

The “infringement trigger” for generics is the label and patient instructions

• If the approved generic label for metaxalone contains instructions that effectively implement dosing “with food” in a timing range and dose range that matches dependent limitations, risk rises.
• Claim 22 is particularly label-sensitive: it can target printed labeling content.

How to map product labeling to claims

For clearance, the critical mapping is:

1. Does the label recommend metaxalone administration with food?
2. Does it specify dose bands (200–900 mg, 400–800 mg) that overlap with the claimed ranges?
3. Does it specify a time relationship to meals (30 min prior to 2 hours after; substantially same time; or immediately after up to 1 hour)?
4. Does the label include PK statements about increased Cmax and AUC(last) when taken with food vs without food?
5. Does the packaging (container labeling) include those PK statements?

If all are yes for any asserted claim, infringement exposure increases. If only partially aligned, depending on which claims are asserted, exposure may still exist via independent claims that are less restrictive than claim 17.

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Does this patent create exposure for biosimilars or biologics?

Not from the provided claims. The claims are specific to metaxalone, a small-molecule oral drug. The patent’s scope is pharmacokinetic and administration-with-food, not biologics.

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What is the strongest portion of the claim set for enforcement?

Highest specificity and easiest claim charting

• Claim 17 is the tightest: it combines dose band (400–800 mg), tablet, food co-administration, and explicit PK outcomes (Cmax and AUC(last) increases).
• Claims 21–22 can be enforced through packaging and patient instructions, depending on claim construction and evidence.

Broadest risk

• Claim 1 and claim 9 are broad in the sense that they do not require the specific dose band or timing window. They still require “with food” administration during metaxalone therapy.

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Timelines: where would this patent likely sit in the metaxalone exclusivity lifecycle?

Your prompt provides the patent number and claims only. Without the publication/filing/issuance dates, maintenance/terminal disclaimer status, and any PTA details, a precise exclusivity timeline cannot be produced from the provided information.

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Key Takeaways

• US 6,407,128 claims metaxalone administration methods that increase oral bioavailability and absorption when dosed with food.
• The claim set includes dependent narrowings for dose (200–900 mg; 400–800 mg), administration timing relative to meals, and tablet/unit-dose form.
• Claims 17, 21, and 22 add explicit pharmacokinetic language requiring increased Cmax and AUC(last) versus dosing without food, with claims 21–22 adding patient communication/labeling requirements.
• Enforcement leverage typically comes from claim 17 (PK outcomes plus dose/tablet) and claim 22 (packaging labeling matching the PK advisory language).
• Generic/reformulation risk is driven primarily by label instructions and packaging text on food co-administration and meal timing, plus whether the regimen aligns with the claimed dose band and PK statements.

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FAQs

1) Does US 6,407,128 require a specific meal timing to infringe?
Not for the broadest independent method claims you provided (claim 1 and claim 9). Timing is added via dependent claims (claims 4–6, 12–14, 18–20).

2) Which claims are most sensitive to drug label language?
Claims 21 (informing the patient) and 22 (printed labeling advising PK increases with food vs without food).

3) If a generic label recommends taking metaxalone with food but does not mention Cmax/AUC(last), is it still at risk?
Yes for the broader bioavailability/absorption claims (claims 1, 2–8, 9–16) that do not require explicit Cmax/AUC(last) language, subject to how “with food” and other elements are proven.

4) What regimen changes can reduce overlap with claim 17?
Avoiding a regimen that uses a 400–800 mg metaxalone tablet with food as claimed, or dosing outside the claimed meal timing windows in dependent claims (claims 18–20), can reduce overlap with claim 17’s specific constraints.

5) Does the patent cover non-tablet metaxalone formulations?
The provided claims explicitly require “tablet” in dependent claims (7–8 and 15–16) and in claim 17. The independent claims use broader “pharmaceutical composition” language, so coverage for non-tablet forms depends on how those independents are asserted and construed.

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References

1. US Patent 6,407,128 (claims provided in prompt).

Drugs Protected by US Patent 6,407,128

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