US Patent 8,664,239 Landscape: Tacrolimus “Substantially Zero-Order” Evening Dosing for Kidney Transplant Rejection Suppression
US Patent 8,664,239 is directed to a clinical method for suppressing kidney rejection in a kidney transplant recipient using an orally administered, once-daily evening, extended-release tacrolimus composition. The core claim scope is defined by a specific in vitro dissolution release pattern (USP II paddle, defined medium and conditions) that targets substantially zero-order release behavior over a 15-hour window, paired with dose timing and patient method limitations.
What does claim 1 actually claim (the enforceable core)?
Claim 1 recites a method with three stacked limitation blocks:
1) Clinical method purpose and patient context
- “Suppressing kidney rejection in a kidney transplant patient”
2) Dosing regimen
- “Orally administering once daily in the evening”
- Extended-release pharmaceutical composition comprising tacrolimus
3) Dissolution-defined extended-release profile (the main claim differentiator)
Claim 1 requires that the extended-release composition, in a specified USP II Paddle dissolution test, has:
- (i) “substantially zero order release profile”
- (ii) at least 8% of tacrolimus released at 4 hours
- (iii) at least 15% released at 8 hours
- (iv) less than 62% released within 15 hours
Dissolution test conditions embedded in claim 1
- Apparatus: USP II Paddle
- Rotation speed: 50 ppm
- Medium: 900 mL aqueous dissolution medium
- pH: 4.5
- Additive: 0.005% hydroxypropylcellulose
This structure means infringement analysis is likely to center on whether an accused product/clinical regimen meets the exact dissolution release thresholds under the exact in vitro test parameters, while also being dosed once daily in the evening as an extended-release tacrolimus composition.
What are the dependent claims adding (scope narrowing vs. fallback positions)?
Claim 2: tighter early and mid time-point release caps
Claim 2 adds upper-bound constraints measured in the same dissolution format:
- At most 20% released within 4 hours
- At most 40% released within 10 hours
This is a narrowing refinement over claim 1’s minimum release requirements by adding ceiling limits to control burstiness and mid-interval release.
Claim 3: minimum duration of treatment
- Once-daily dosing for “at least 7 days”
This affects method infringement where evidence includes adherence and duration.
Claims 4-6: explicit dose ranges
- Claim 4: 0.1 to 15 mg tacrolimus
- Claim 5: 0.5 to 5 mg tacrolimus
- Claim 6: 1 mg tacrolimus
These introduce multiple “dose-position” fallback claim sets. A product outside one range could still be captured by claim 1 or other ranges, depending on dosing amount.
Claim 7: fed-state limitation
- Orally administered without simultaneous food intake
This is a common avoidance and risk point for formulation developers and label design.
Claim 8: patient subtype
- “De novo kidney transplant patient”
This narrows to first transplant status versus maintenance patients.
Claims 9-12: vehicle and specific excipient selection
Claim 9 requires tacrolimus in a hydrophilic or water-miscible vehicle. Claim 10 lists a long menu of suitable vehicles; claim 11 and 12 narrow selection:
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Claim 10: vehicle selected from many listed materials including:
- polymers (e.g., hydroxypropyl cellulose, methylcellulose)
- PEG and poloxamers
- cyclodextrins
- pectin
- alginate, carragenate, xanthan gum
- and mixtures
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Claim 11: vehicle comprises poloxamer
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Claim 12: vehicle comprises a mixture of polyethylene glycol and poloxamer
These vehicle limitations matter because they can:
- Narrow enforceable scope to formulations built on those excipient systems; and
- Provide a structured entry point if competitor products use different release technologies but still meet dissolution thresholds.
What is the practical claim “shape” for infringement (who is most at risk)?
The claim is a method claim with an unusually strong in vitro dissolution gating. That pushes risk toward products whose release behavior under the claimed USP II/pH 4.5/HP(HPC)-containing medium matches both:
- minimum release floors at 4h and 8h, and
- an overall ceiling (less than 62% by 15h),
plus claim 2’s ceilings if asserted.
In addition, the method requires evening once-daily administration and (depending on asserted claims) potentially:
- no simultaneous food, and/or
- de novo patient population, and/or
- minimum 7-day dosing duration.
Finally, if the accused formulation is tied to excipient platform choices, claim 9-12 add further narrowing.
What does this say about formulation design targets (how the patent likely works technically)?
The dissolution thresholds imply a controlled release profile that aims to:
- Avoid under-release early (must reach ≥8% by 4h and ≥15% by 8h).
- Avoid excessive release late (must stay <62% by 15h).
- Be consistent with “substantially zero order” release over the interval.
Because the test uses pH 4.5 with 0.005% hydroxypropylcellulose, the formulation is likely engineered to use diffusion/erosion mechanisms and matrix behavior consistent with pH-relevant swelling and controlled permeability. The claim language does not require a specific matrix type, but it does restrict the release outcome and vehicle category for dependent claims.
What competitor product profiles are closest to the claim scope?
Without record-level prosecution data for 8,664,239 or the underlying patent family members, the safest statement is that the patent most directly covers:
- Extended-release tacrolimus administered once daily in the evening
- Formulations that show the claimed dissolution release thresholds under the exact conditions.
Where risk concentrates:
- If a competitor’s extended-release tacrolimus matches the USP II at 50 ppm dissolution outcome thresholds.
- If dosing is specifically evening and labeling or clinical practice supports that regimen for suppression of kidney rejection.
- If the regimen is used in de novo kidney transplant settings (claim 8) or without food (claim 7) when those dependent claims are asserted.
Where is the “hard wall” in the claim: dissolution or timing?
Timing and patient language are present, but the numerical dissolution release profile is the main hard wall.
- If dissolution thresholds do not match, the method likely fails the literal requirements even if the regimen uses evening once-daily tacrolimus.
- If dissolution matches but dosing is not “in the evening” or not once daily, then it may fall outside claim 1 even if dissolution is identical.
- If dissolution matches and timing matches, dependent claims add additional walls via dose amount, fed-state, de novo status, vehicle composition.
What does the dependent set imply for design-around?
A design-around strategy under these claims would typically try to miss one of these claim “axes”:
1) Dissolution profile
- Fail one of the minima (8% at 4h or 15% at 8h) or exceed late release (<62% by 15h).
- Or, if claim 2 is asserted, fail the ceilings (20% by 4h or 40% by 10h).
2) Regimen
- Use a different dosing time than “in the evening,” or a different dosing cadence than once daily.
- Use a regimen with food co-administration (to potentially avoid “without simultaneous food intake”).
3) Population
- Avoid de novo use if designing for maintenance patients.
4) Vehicle composition
- Avoid the specific vehicle limitations in claims 9-12 if relevant.
Patent landscape: what this patent likely blocks (and what it does not)
Blocks
This patent blocks method use of extended-release tacrolimus where the product/formulation meets the required dissolution outcome and where clinicians administer it under:
- once daily evening dosing,
- tacrolimus exposure for suppressing rejection,
- and potentially de novo and no food conditions for dependent coverage.
Does not, by itself, control
The claim is not drafted as a broad chemical entity or general tacrolimus release concept. It is framed as a specific release-behavior-defined extended-release method under defined dissolution test conditions.
So, it does not automatically block:
- tacrolimus formulations that use different release behavior (even if also extended-release),
- different dosing time paradigms,
- or non-extended-release regimens,
unless they meet the literal limitations.
Key risk map (what to test for in an accused product or protocol)
| Claim axis |
Literal requirement |
What to measure / verify |
| Release profile |
“Substantially zero order” plus numeric thresholds |
USP II Paddle at pH 4.5 with 0.005% hydroxypropylcellulose; rotation speed 50 ppm; 900 mL medium |
| Early release |
≥8% released at 4h |
Dissolution sample time point compliance |
| Mid release |
≥15% released at 8h |
Dissolution sample time point compliance |
| Late release |
<62% released within 15h |
15h total release cap |
| Dosing time |
once daily in the evening |
Labeling and administration record |
| Dosing form |
extended-release composition comprising tacrolimus |
Product characterization / regulatory classification |
| Food |
no simultaneous food intake (dep. claim 7) |
Clinical protocol and instructions |
| Patient type |
de novo kidney transplant (dep. claim 8) |
Indication and study/population |
| Duration |
at least 7 days (dep. claim 3) |
Trial regimen length / real-world adherence |
| Dose amount |
0.1-15 mg / 0.5-5 mg / 1 mg (dep. claims 4-6) |
Prescribed dose |
| Vehicle |
hydrophilic/water-miscible; plus vehicle list (dep. 9-12) |
Formulation composition |
Business implications for R&D and investment
- The patent’s novelty is functionally anchored to a dissolution-defined release envelope. That means R&D teams can assess infringement risk by running the same USP II dissolution protocol and comparing the release curve against the claim thresholds.
- Investor due diligence should treat this as a method-use + dissolution envelope patent rather than a broad tacrolimus platform patent. Monetization strength correlates with whether branded and generic extended-release tacrolimus offerings are engineered to match these specific in vitro release characteristics and are used in the covered timing/population context.
Key Takeaways
- US Patent 8,664,239 claims a method to suppress kidney rejection using once-daily evening oral extended-release tacrolimus.
- The main novelty and likely infringement determinant is the USP II dissolution release envelope at pH 4.5 with 0.005% hydroxypropylcellulose: ≥8% at 4h, ≥15% at 8h, and <62% by 15h, consistent with substantially zero order release.
- Dependent claims add enforceable narrowing via additional dissolution ceilings, duration (≥7 days), dose ranges (0.1-15 mg; 0.5-5 mg; 1 mg), no simultaneous food intake, de novo transplant population, and hydrophilic/water-miscible vehicles including poloxamer and PEG + poloxamer combinations.
- The landscape impact is strongest against competitors whose extended-release tacrolimus products and clinical protocols align with both the release profile and evening once-daily regimen, with additional risk points for fed-state and de novo use.
FAQs
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Is the core scope about tacrolimus chemistry or release performance?
Release performance dominates. Claim 1 is driven by numeric dissolution thresholds under fixed test conditions.
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Does “substantially zero order” alone define infringement?
No. “Substantially zero order release profile” is coupled with specific release amounts at 4h, 8h, and the cap within 15h.
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Can a product avoid the patent by changing only the time of dosing?
Potentially. Claim 1 requires once daily in the evening; other dosing times can defeat that element even if dissolution matches.
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What dependent claims create the tightest constraints?
Claim 2 adds additional release ceilings (≤20% at 4h, ≤40% at 10h). Claims 7-8 and 3-6 add practical regimen constraints (no food, de novo population, treatment duration, dose).
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Are vehicle excipient limitations mandatory across all claims?
No. Vehicle requirements are in dependent claims (9-12). Claim 1 itself is not vehicle-limited.
References
[1] United States Patent 8,664,239 (claim text provided in user prompt).
