United States Patent 6,254,887 Scope and Claims Analysis: 24-Hour Controlled-Release Oral Tramadol Dissolution and PK Requirements

US Patent 6,254,887 claims controlled-release (CR) oral tramadol formulations designed to meter tramadol release over ~24 hours using specific in vitro dissolution targets measured by the Ph. Eur. paddle method in 0.1 N HCl (37°C, 900 mL, 100 rpm, UV 270 nm). Claim scope centers on (i) a CR-coated tramadol-containing substrate, (ii) quantified dissolution release windows at multiple timepoints, and (iii) additional product-performance features for certain embodiments including dosing interval (24-hour and 12-hour), PK surrogates (tmax and W50), and substrate form (spheroids, beads, tablets) and coating class (water-insoluble wax/polymer/cellulose). The landscape risk for challengers is that the claim is not limited to a single multipart composition detail; it is anchored to multi-point dissolution and performance ranges that are harder to avoid with simple formulation tweaks.

What does US Patent 6,254,887 claim for tramadol controlled-release oral dosing?

Core claim architecture (independent claim 1):
A CR oral tramadol preparation suitable for q24h dosing comprising:

Substrate with pharmaceutically effective tramadol (or salt),
Substrate coated with a CR coating, and
In vitro dissolution profile meeting defined % tramadol released at specified times using a specific method:
- Ph. Eur. paddle method, 100 rpm, 900 mL 0.1 N HCl, 37°C, UV at 270 nm,
- release ranges by time (by weight), and
Therapeutic effect ~24 hours after oral administration.

Dissolution-release constraints in Claim 1 (the primary claim “fence”)

Claim 1 requires these timepoint bands (Ph. Eur. paddle, 0.1 N HCl, UV 270 nm):

1 h: 0–50%
2 h: 0–75%
4 h: 3–95%
8 h: 10–100%
12 h: 20–100%
16 h: 30–100%
24 h: 50–100%
36 h: >80%

This structure is characteristic of a formulation patent that uses dissolution kinetics as a proxy for in vivo performance, while staying broad on many intermediate points (several ranges extend to 100%).

What “therapeutic effect for about 24 hours” adds

The claim ties the dissolution behavior to a clinical objective. Even though the in vitro dissolution is quantified, “therapeutic effect” is still an additional functional constraint that may be argued via PK/PD bridging.

How are the dependent claims narrowing the dissolution and performance requirements?

Several dependent claims define alternative dissolution tables or add pharmacokinetic metrics that are commonly used in CR differentiation.

Dependent claims with alternate dissolution schedules (Claims 2–4, 14–17, 18)

Claim 2 (specific dissolution table):

1 h: 20–50%
2 h: 40–75%
4 h: 60–95%
8 h: 80–100%
12 h: 90–100%

Claim 3 (extended dissolution table):

1 h: 0–50%
2 h: 0–75%
4 h: 10–95%
8 h: 35–100%
12 h: 55–100%
16 h: 70–100%
24 h: >90%

Claim 4 (different mid-course profile):

1 h: 0–30%
2 h: 0–45%
4 h: 3–55%
8 h: 10–65%
12 h: 20–75%
16 h: 30–88%
24 h: 50–100%
36 h: >80%

Claim 14 (tablet + Claim 1 dissolution + performance W50) Claim 14 requires:

Claim 1 tablet embodiment with the Claim 1 dissolution ranges (including 36 h >80%),
plus W50 in the range 10 to 33 hours (also explicitly stated in Claim 13),
and about 24-hour therapeutic effect.

Claim 15 appears to be a dependent rewrite issue
It states “in accordance with claim 15” while being a dependent claim; substantively it mirrors a dissolution table format but includes inconsistent UV units (“270 mm” instead of “270 nm”). The narrowing is still dissolution-timed ranges.

Claim 16 (W50 band)

W50: 10–33 hours (oral).

Claim 17 (another dissolution table):

1 h: 15–25%
2 h: 25–35%
4 h: 30–45%
8 h: 40–60%
12 h: 55–70%
16 h: 60–75%

Claim 18 (tmax band):

tmax: 4–5 hours.

Claims 9–11 add PK surrogates aligned to CR behavior

Claim 9:

tmax 2–7 hours

Claim 10:

tmax 1.5–8 hours

Claim 11:

W50 7–16 hours

These claims broaden “performance design space” beyond dissolution, giving additional angles for infringement by matching in vivo endpoints or acceptable regulatory bridges.

What dosing interval scope is covered (24 hours vs 12 hours)?

The patent covers two dosing paradigms through different claim groupings:

q24h embodiments

Claim 1 and many downstream claims use a “suitable for dosing every 24 hours” framing and ~24-hour therapeutic effect.
The dissolution table in Claim 1 includes the late timepoint 36 h >80%, signaling a tail consistent with q24h use.

q12h embodiments

Claim 7 covers dosing every 12 hours, with:

dissolution windows at multiple times:
- 1 h: 5–50%
- 2 h: 10–75%
- 4 h: 20–95%
- 8 h: 40–100%
- 12 h: >50%
- 18 h: >70%
- 24 h: >80%
therapeutic effect for at least about 12 hours.

This is a meaningful carve: the required release pattern shifts earlier and the terminal-time requirements differ (e.g., 18 h >70% appears).

What substrate forms and morphologies are claimed?

The patent does not only claim a coating; it claims several substrate architectures often seen in multipart CR systems.

Bead-based and spheroid-based substrate definitions

Claims 5–6 (spheroids):

substrate comprises a plurality of spheroids
spheroids comprise a spheronizing agent

Claims 20–22 (non-pareil beads):

substrate comprises inert non-pareil beads coated with tramadol

Claims 24 (spheroids + substrate tablet form variant):

substrate is a tablet in one branch (Claim 23)
spheroids in another (Claim 24)
both are tied to the CR-coated system of Claim 19.

Tablet-specific claim coverage

Claim 12 includes “wherein said substrate is a tablet.”
Claim 13 explicitly claims a controlled release oral pharmaceutical tablet with q24h use, the Claim 1 dissolution ranges, and W50 10–33 hours.
Claim 14 further constrains Claim 13 with the detailed tablet dissolution table statement.

In practice, the explicit tablet claims constrain manufacturing arguments because tablet CR designs typically involve specific granule and coating systems, yet the claim text stays anchored to dissolution/PK rather than exact coating thickness or excipient list.

What coating material classes are within scope?

Multiple dependent claims limit the CR coating composition to broad classes, leaving significant formulation freedom while still narrowing at least the coating chemistry.

Claims 27, 28, 29, 30, 31, 32, 33: Coating material is selected from:

water-insoluble wax
water-insoluble polymer
water-insoluble cellulose
mixtures of the foregoing

These claims create multiple “entry points” for infringement arguments where coating excipient selections fall into these classes, even if exact polymer identity differs.

How do the claims use dissolution testing parameters to constrain “design around” options?

The claim is highly specific on test method:

Ph. Eur. paddle method
100 rpm
900 mL 0.1 N hydrochloric acid
37°C
UV detection at 270 nm

This matters in litigation because challengers often try to argue non-equivalence via different media, apparatus, rpm, or detection wavelength. Here, infringement testing is tied to a standardized protocol, which can reduce disputes about “what the test was.”

Still, note that many intermediate timepoint ranges are very broad (e.g., Claim 1 allows up to 100% at several times). That reduces the practical value of trying to “miss” by slightly shifting release in the mid window. A challenger would instead aim to break one of the claim-defining edges: too little release at the late timepoints (e.g., failing “>80% at 36 h” for q24h) or too much early release (e.g., failing “0–50% at 1 h” in Claim 1).

Which dependent claims are most infringement-relevant for a generic or follow-on CR tramadol product?

In high-stakes disputes, courts typically focus on the narrowest relevant claim that still reads on the accused product, and on whether the infringement theory can be supported with dissolution and PK testing.

Highest-risk elements based on specificity

q24h dissolution pattern including 36 h >80% (Claim 1 / Claims 13–14 / Claim 19 chain)
Tablet-specific constraints with W50 (Claim 13)
Coating excipient classes (Claims 27–33) if coating composition can be shown
Bead/spheroid morphologies (Claims 5–6, 20–22) depending on the manufacturing approach
tmax and W50 bands if in vivo studies are available (Claims 9–11, 16, 18, 25–26)

Lower-risk elements due to broad bands

Any claim with wide intermediate time windows (for example many “0–100%” ranges) is easier for a generic to fall into unintentionally. From a risk standpoint, infringement is less about achieving a precise middle kinetics shape and more about meeting the late and/or early cutoffs.

How does US 6,254,887 compare with typical tramadol CR patent strategies?

This patent uses a common controlled-release patent pattern:

Anchor on drug-containing coated substrate and a standardized dissolution assay,
add multi-timepoint release windows rather than specifying exact polymer types or layer thickness,
add PK surrogates (tmax, W50) for certain embodiments,
include multiple substrate architectures (tablets, spheroids, non-pareil beads).

Compared with CR patents that focus narrowly on a single polymer system or a single geometric mechanism, this one is less “materials-exclusive” and more “performance-exclusive,” which increases the chance that multiple product designs can read on the same claim if their dissolution profile is tuned into the claimed windows.

What are the legal boundaries implied by the claim language (e.g., “consisting essentially of” and functional effect)?

“Consisting essentially of” appears in Claim 19

Claim 19 narrows the opioid analgesic to “consisting essentially of tramadol or a salt thereof.” That limits inclusion of other active ingredients as part of the claimed formulation. A multi-API fixed dose tramadol combination would likely fall outside that language unless the additional components are excluded as not part of “consisting essentially of.”

“Therapeutic effect for about 24 hours” and “about 12 hours”

These phrases can be argued as functional/intent constraints. In practice, performance is supported by tmax and W50 dependent claims when available, and by dissolution-extrapolated performance when PK data are not directly available.

Claim coverage summary matrix (what to test for infringement)

Claim cluster	What must match	Practical “design around” lever
Claim 1 / Claim 19 (q24h)	CR tramadol-coated substrate + dissolution bands at 1,2,4,8,12,16,24,36 h with 36 h >80% + ~24h effect	Fail late release cutoff (36 h) or shift too much early release (1 h band)
Claim 2–4 / 14–17	Specific alternative dissolution tables at several timepoints	Match or miss based on the specified table; avoid falling within any table used in an asserted dependent claim
Claims 7 / 8 (q12h)	CR tramadol-coated substrate + altered dissolution schedule with 18 h >70% and 24 h >80% + ≥~12h effect	Change kinetics to fail 18 h and/or 24 h requirements
Claims 9–11 / 16 / 18 / 25–26	tmax and W50 bands	Tune PK or dissociation profile; but dissolution-linked PK tuning may still intersect claimed ranges
Claims 5–6 / 8 / 24	spheroids (and spheronizing agent)	Use different substrate architecture than spheroids
Claims 20–22	inert non-pareil beads coated with tramadol	Use different substrate (not bead-based non-pareil)
Claims 12–14, 23	tablet form	Use multipart beads/spheroids without tablet substrate, or choose a form not meeting “tablet” language
Claims 27–33	coating material classes (wax/polymer/cellulose)	Use coating system outside these classes (hard if most CR coatings use polymers/cellulose or waxes)

What is the patent landscape around US 6,254,887 for tramadol CR systems?

The prompt provides only the claim set for US 6,254,887 and does not provide:

patent bibliographic metadata (filing date, publication date, assignee),
prosecution history,
citation list,
continuation relationships,
any co-pending family members or related US/EP/CN filings,
FDA Orange Book listings tied to the patent number,
litigation/settlement documents.

With those missing, a complete landscape map (other patents and their claim scope adjacency, family members, and freedom-to-operate competitors) cannot be produced from the provided information alone.

Key Takeaways

US 6,254,887’s infringement core is a performance-tethered CR system for tramadol, defined by multi-timepoint dissolution release windows in 0.1 N HCl using the Ph. Eur. paddle method and UV 270 nm.
The most material “edge” for q24h coverage is late release: >80% at 36 hours (Claim 1 / Claim 19 chain), paired with an early ceiling at 1 hour (0–50%).
Dependent claims significantly expand the scope beyond a single dissolution profile by providing multiple distinct dissolution tables and adding PK surrogates (tmax, W50).
The patent also covers different substrate architectures (tablets, spheroids, inert non-pareil beads) and constrains coatings to broad water-insoluble wax/polymer/cellulose classes in several dependent claims.
Design-around strategies would need to target specific timepoint cutoffs or substrate/coating class limitations, not just minor shifts in the middle of the dissolution curve.

FAQs

1) What single dissolution parameter is most important in Claim 1 to avoid infringement?

The 36-hour late timepoint (>80% release at 36 h) is the strongest late “fence” for q24h embodiments.

2) Can a different coating polymer avoid coverage if dissolution matches the claimed profile?

Not reliably. Claims 27–33 limit coating materials to classes, but the primary claims are anchored to dissolution performance, which can be met with different polymers in some cases.

3) Do the claims require a specific tramadol salt?

The claims cover tramadol or a salt thereof, so salt selection does not remove coverage unless the formulation falls outside the claim construction for “tramodol or salt thereof.”

4) How do tmax/W50 claims change the infringement analysis?

They create additional routes to infringement using in vivo endpoints, which can matter when dissolution similarity is argued but PK bridging data are available.

5) Does the patent cover spheroid and bead-based substrates as alternatives?

Yes. The claim set includes substrate embodiments using spheroids (and spheronizing agent) and inert non-pareil beads coated with tramadol, plus tablet embodiments.

References (APA)

United States Patent No. 6,254,887. (Claims as provided in prompt text).

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
Germany	43 15 525	May 10, 1993
United Kingdom	9324045	Nov 23, 1993
United Kingdom	9404544	Mar 09, 1994
United Kingdom	9404928	Mar 14, 1994

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	138566	⤷ Start Trial
Austria	172376	⤷ Start Trial
Austria	184786	⤷ Start Trial
Austria	196079	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,254,887

Summary for Patent: 6,254,887