US Patent 5,508,042: Scope, Claims, and US Landscape for Oral Controlled-Release Oxycodone Regimens
What does US 5,508,042 claim in practical terms?
US Drug Patent 5,508,042 claims methods for “reducing the range in daily dosages required to control pain” in human patients using oral controlled-release (CR) oxycodone formulations defined by plasma concentration targets at specified times after dosing and under 12-hour dosing through steady state.
The claims are not directed to:
- A manufacturing process
- A device
- Abuse-deterrence mechanisms (e.g., physical/chemical)
- A specific patient subgroup
They are directed to a pharmacokinetic (exposure) profile achieved by an oral CR oxycodone dose range and dosing interval.
Claim 1 scope: tighter exposure band and lower dose range
Independent Claim 1 is limited to:
- Route: oral
- Dosage form: controlled release
- Active: oxycodone or a salt thereof
- Strength range: about 10 to about 40 mg
- Dosing schedule: repeated administration every 12 hours and evaluated at steady-state conditions
- Exposure window constraints:
- Mean maximum plasma concentration (Cmax): about 6 to about 60 ng/mL
- Mean Tmax associated with Cmax: about 2 to about 4.5 hours after administration
- Mean minimum plasma concentration (Cmin): about 3 to about 30 ng/mL
- Mean time for Cmin: about 10 to about 14 hours after repeated administration (as part of steady-state every-12-hours regimen)
Claim 1 therefore covers CR oxycodone products that reliably produce a narrower, lower exposure plateau (Cmax 6–60; Cmin 3–30) under a q12h regimen.
Claim 2 scope: broader “substantially all” coverage and higher exposure cap
Independent Claim 2 expands both:
- Formulation strength: about 10 mg to about 160 mg
- Exposure range: expresses limits as upper bounds (“up to”)
Limits include:
- Route: oral
- Dosage form: solid controlled release dosage formulation
- Active: oxycodone or a salt thereof
- Dosing schedule: every 12 hours; steady-state
- Exposure window constraints:
- Mean maximum plasma concentration (Cmax): up to about 240 ng/mL
- Mean Tmax: up to about 2 to about 4.5 hours
- Mean minimum plasma concentration (Cmin): up to about 120 ng/mL
- Mean time for Cmin: about 10 to about 14 hours after repeated administration through steady state
Claim 2 therefore covers CR oxycodone regimens expected to control pain “in substantially all” human patients by targeting higher allowable exposure ceilings, consistent with a potentially wider variability of patient response. It still requires:
- controlled release oral oxycodone
- q12h steady state
- exposure timing windows aligned with the claim
How the claims define infringement: exposure-driven boundaries
The claims are structured as method of reducing dosage range by administering a formulation that yields measurable mean PK parameters at defined times.
An accused product or regimen would need to meet, at minimum:
- Controlled-release oral oxycodone (or salt)
- Dosed every 12 hours
- Mean Cmax within (Claim 1) 6–60 ng/mL or within Claim 2 up to 240 ng/mL
- Mean Cmin within (Claim 1) 3–30 ng/mL or Claim 2 up to 120 ng/mL
- Mean timing consistent with 2–4.5 hours to Cmax and 10–14 hours to Cmin after repeated dosing
Because the claims use “mean maximum” and “mean minimum” with time windows, the evidentiary posture in enforcement would typically revolve around:
- A clinical PK study design (steady state, q12h)
- Sampling times around Cmax and the pre-dose trough window (10–14 hours post-dose)
- Mean concentration computations across the treated population
What is the likely claim construction focus (for freedom-to-operate)?
Given the claim language, key construction levers are typically these:
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“Controlled release”
Coverage turns on whether the formulation releases oxycodone to meet the defined PK behavior. The claims do not list a specific excipient system, tablet geometry, coating thickness, or dissolution profile.
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“Oral solid controlled release” (Claim 2) vs “oral controlled release dosage formulation” (Claim 1)
Claim 2 explicitly states “solid,” which narrows potential oral liquid or suspension formats. Claim 1 is broader on “dosage formulation,” but still requires “controlled release.”
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“About” ranges and “up to” ceilings
The claims are tolerant (“about”), but they still impose specific PK boundaries.
- Claim 1 uses bounded ranges (Cmax 6–60; Cmin 3–30).
- Claim 2 uses maxima (“up to about 240” and “up to about 120”).
-
Steady state and q12h timing
Both claims require every-12-hours administration through steady state. Single-dose exposure would not satisfy the “minimum from 10 to 14 hours after repeated administration every 12 hours through steady-state conditions” structure.
Where this patent sits in the oxycodone CR landscape (US)
US 5,508,042 is a method patent keyed to pharmacokinetic exposure management to reduce inter-patient variability in daily oxycodone dosing needs.
In the US oxycodone CR landscape, this positions the patent within the same strategic zone as other CR oxycodone patents that try to differentiate products by:
- PK profile shaping (Cmax/Cmin and timing)
- Consistency across patients (lower required titration range)
- Dosing interval compatibility (often q12h)
From a landscape perspective, this patent is most likely to intersect with:
- Later CR oxycodone formulations that claim improved PK uniformity or reduce dosing variability
- Generic/authorized generic versions that match the exposure profile targeted by the claim
- Labeling-driven differentiation where the manufacturer argues that the claimed exposure profile is not met by a different formulation
Key landscape risk drivers for licensing or generic entry
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Exposure overlap risk
If a competitor’s q12h CR oxycodone formulation produces mean steady-state PK values falling inside Claim 1’s bounded Cmax/Cmin windows, the overlap risk is high. If it stays outside those windows but still achieves broader pain control, Claim 2 remains a risk due to its “up to” caps.
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Study design and dosing demonstration risk
In method patents, litigation evidence typically uses clinical PK studies. If a formulation’s regulatory PK package was built around different sampling schedules, it may be harder to prove a “mean maximum/minimum at specified times” match. Conversely, well-aligned sampling increases enforceability.
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Salt form and dosing strength permutations
Both claims cover oxycodone salts. That means redesigning around a specific salt is not a clean exit unless the salt and formulation materially alter PK away from the claim-defined exposure windows.
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Dose strength alone is not sufficient
Claim 2 includes broad strength (10 to 160 mg). Strength selection does not immunize a regimen if the resulting mean Cmax/Cmin meets the claimed exposure caps.
Competitive mapping: what product strategies would likely avoid the claim
Avoidance generally requires one or more of the following (based on the claim mechanics):
- A different route (not oral CR)
- A different release profile that yields mean steady-state Cmax/Cmin outside the asserted windows
- A different dosing interval (not q12h steady state)
- A dosing regimen that does not establish the “mean minimum plasma concentration from about 10 to about 14 hours” timing as part of steady-state q12h dosing
Because the claims are exposure-driven, design-around typically focuses on altering:
- Rate of release (affecting Cmax and Tmax)
- Extent of release and late-phase input (affecting Cmin and trough)
Potential validity and enforceability pressure points (claim-structure based)
No specific statutory grounds are asserted here, but the claim structure itself creates standard attack surfaces that parties in this field routinely evaluate:
- Indefiniteness/enablement risk tied to PK targets: the claims define exposure targets, so a challenger may argue that “about” plus time windows do not align to a reproducible formulation definition.
- Method-of-treatment framing: the claims attempt to link exposure targets to “reducing the range in daily dosages required” and may invite scrutiny about whether the method limitation is functionally defined by PK alone or whether it requires a demonstrated reduction in dosing variability.
Practical infringement checklist (for counsel and BD teams)
A regimen likely implicates US 5,508,042 when all are met:
- Oral controlled-release oxycodone or salt
- q12h dosing through steady state
- Mean PK values at steady state:
- Claim 1: mean Cmax 6–60 ng/mL at mean 2–4.5 hours and mean Cmin 3–30 ng/mL at mean 10–14 hours
- Claim 2: mean Cmax up to 240 ng/mL at mean up to 2–4.5 hours and mean Cmin up to 120 ng/mL at mean 10–14 hours
- Objective measurement of mean concentrations consistent with the sampling time windows
Claim coverage summary table
| Element |
Claim 1 |
Claim 2 |
| Method purpose |
Reduce range of daily dosages to control pain |
Reduce range of daily dosages to control pain “in substantially all” patients |
| Route |
Oral |
Oral |
| Dosage form |
Controlled release dosage formulation |
Oral solid controlled release dosage formulation |
| API |
Oxycodone or salt |
Oxycodone or salt |
| Dose strength (claimed range) |
About 10–40 mg |
About 10–160 mg |
| Dosing interval |
Every 12 hours through steady state |
Every 12 hours through steady state |
| Mean Cmax |
About 6–60 ng/mL |
Up to about 240 ng/mL |
| Mean timing to Cmax |
About 2–4.5 hours |
Up to about 2–4.5 hours |
| Mean Cmin |
About 3–30 ng/mL |
Up to about 120 ng/mL |
| Mean timing to Cmin |
About 10–14 hours |
About 10–14 hours |
Key Takeaways
- US 5,508,042 is an exposure-targeted method patent: it claims reducing dosing variability in pain control by administering q12h oral controlled-release oxycodone that achieves defined mean Cmax/Cmin at specified post-dose times at steady state.
- Claim 1 is tighter (Cmax 6–60 ng/mL; Cmin 3–30 ng/mL; 10–40 mg strength range), making PK overlap the core infringement axis.
- Claim 2 is broader on strengths and higher on exposure ceilings (10–160 mg; Cmax up to 240 ng/mL; Cmin up to 120 ng/mL), increasing the range of potentially implicated regimens that still meet q12h steady-state mean exposure maxima.
- For freedom-to-operate, the decisive factor is not excipient design but whether the formulation’s clinical PK package under q12h steady-state sampling produces mean concentrations inside the claim-defined boundaries.
FAQs
1) Does US 5,508,042 cover specific oxycodone brand names?
No. The claims cover oxycodone (or salts) in oral controlled-release dosage formulations defined by PK targets and q12h steady-state timing.
2) What is the dosing interval required by the claims?
Both claims require every 12 hours with evaluation at steady-state conditions.
3) What PK parameters matter most for infringement?
Mean Cmax and mean Cmin, each with associated time windows: Cmax at 2–4.5 hours and Cmin at 10–14 hours after repeated dosing through steady state.
4) Can a formulation avoid the patent by changing oxycodone salt form?
Salt form alone does not avoid coverage because the claims include oxycodone or a salt thereof. Avoidance typically requires shifting mean steady-state exposure outside the claim bounds.
5) Is the patent limited to a manufacturing method or excipient composition?
No. The claims are tied to oral controlled-release oxycodone and resulting plasma concentration profiles, not a manufacturing process.
References
[1] United States Patent 5,508,042. (claims as provided by user).
