United States Patent 12,403,095 (Tacrolimus solid dispersion, metal-chelating stabilizers, pH < 7): scope of claims and US patent landscape
United States Patent 12,403,095 is directed to a narrow reformulation of tacrolimus as a solid dispersion in a defined vehicle plus metal chelating stabilizing agent that sets a composition pH below 7, while controlling degradation to 8-epitacrolimus during stability storage and excluding cyclo-dextrin vehicles. The claim set is dominated by (1) compositional bounds (tacrolimus load 0.5 to 5 wt%, and often exemplified around ~1 wt%), (2) stability limits for 8-epitacrolimus increases under specific humidity/temperature stress, (3) pH windows (with dependent claims to 2.5 to 4.0 and 3.0 to 3.6), and (4) chelator identity (organic acids including citric and tartaric), plus (5) specific vehicle embodiments such as polyethylene glycol (PEG) + poloxamer.
The practical enforcement risk for generics and alternative formulations is highest where challengers attempt to use tacrolimus solid dispersions that omit cyclo-dextrins but use comparable pH control, organic-acid chelation, and stress-stability targets aimed at limiting conversion to 8-epitacrolimus.
What does US Patent 12,403,095 claim for tacrolimus solid dispersion compositions?
Core independent claim scope (Claim 1 and Claim 11): both claims define a pharmaceutical composition with four hard constraints and then multiple dependent options.
Key elements that define infringement risk
- Form: “a solid dispersion of tacrolimus”
- Actives: tacrolimus is the sole active ingredient (no additional actives)
- Vehicle/stabilizer system:
- A mixture of a vehicle and a stabilizing agent
- The stabilizing agent is a metal chelating agent
- The stabilizing agent provides a pH below 7 in the composition
- The vehicle does not include a cyclo-dextrin
- Stability performance to limit degradation to 8-epitacrolimus (8-epi):
- Claim 1 stability criterion:
“no more than 0.5% more 8-epitacrolimus after storage at 40°C at 75% RH for 5 weeks compared to … prior to storage,” based on 100% total weight of tacrolimus.
- Claim 11 stability criterion:
“no more than 0.2% more 8-epitacrolimus after storage at 25°C at 60% RH for 5 weeks” using the same comparison framing.
Quantitative compositional boundary
- Tacrolimus content: 0.5 to 5% by weight of total composition (Claims 1 and 11).
- A dependent claim adds a specific exemplified target:
- ~1% tacrolimus (Claims 9 and 19).
pH constraints are central to scope
- pH must be below 7 in the base independent claims.
- Dependent claims narrow to:
- 2.5 to 4.0 (Claims 2 and 12)
- 3.0 to 3.6 (Claims 3 and 13)
Chelaor identity narrows even further
- Metal chelating agent is an organic acid selected from mono-, di-, oligo-, or polycarboxylic acids (Claims 4 and 14).
- Listed specific acids (Claims 5 and 15):
- succinic acid, citric acid, tartaric acid, acrylic acid, benzoic acid, malic acid, maleic acid, sorbic acid.
Embodiments that create sub-landscapes
- Stabilizing agent embodiment:
- citric acid (Claims 6 and 16)
- tartaric acid (Claims 7 and 17)
- Vehicle embodiment:
- PEG + poloxamer (Claim 8 and 18)
- Dosage form:
How do Claims 1 and 11 differ and what does that mean for claim coverage?
The main difference is the stability test and threshold
- Claim 1 uses a more accelerated condition (40°C/75% RH for 5 weeks) and allows a higher increase threshold (≤0.5% more 8-epi).
- Claim 11 uses milder conditions (25°C/60% RH for 5 weeks) with a stricter threshold (≤0.2% more 8-epi).
Implication for design-around
If a competitor formulation is engineered to pass the stricter Claim 11 stability profile, it likely also falls within the Claim 1 threshold if it also meets the other constraints (solid dispersion, sole active, no cyclo-dextrin vehicle, and pH < 7 via metal chelation). Conversely, passing Claim 1 but failing Claim 11 could still be infringing under Claim 1, assuming all other base elements match.
Implication for litigation strategy
Claim 11’s lower threshold at 25°C/60% RH can act as a more direct metric in infringement proof where accused products are stored under realistic conditions.
What specific degradation benchmark to 8-epitacrolimus is built into the claims?
Both independent claims tie infringement to a relative change in 8-epitacrolimus after storage compared to pre-storage levels.
Benchmarks by claim
| Claim |
Storage condition |
Allowable increase in 8-epitacrolimus |
Basis |
| 1 |
40°C, 75% RH, 5 weeks |
≤ 0.5% more |
per 100% total weight of tacrolimus |
| 11 |
25°C, 60% RH, 5 weeks |
≤ 0.2% more |
per 100% total weight of tacrolimus |
Dependent claim with extended stability time
Both Claim 10 and Claim 20 add another stability target:
- Less than 0.5% by weight of 8-epitacrolimus after 12 weeks at 25°C/60% RH, again referenced to tacrolimus total weight.
This can matter because product design and QC specs frequently rely on shelf-life stability. The claim language uses an absolute “less than 0.5%” endpoint rather than a “relative increase” metric.
Which formulation variables are most important to satisfy (or avoid) infringement?
1) Vehicle exclusion: no cyclo-dextrin
The claims exclude any vehicle including cyclo-dextrins. This is a direct design-around lever for companies using cyclodextrin complexation strategies (if they also avoid the other constraints).
2) Metal chelating agent that establishes pH < 7
The chelator is not simply a stabilizer; it is the pH-defining metal chelating agent. The claim requires that the chelating agent “provides a pH below 7 in the composition.” That links identity and function.
3) Organic acid chelator scope
The organic-acid category is broad (mono-, di-, oligo-, or polycarboxylic acids) but then dependent claims narrow to a defined list including citric and tartaric. Even if a competitor uses a different organic acid that is still within the broader category, infringement may still occur under Claims 1/11 and Claim 4/14, depending on whether that acid meets the functional pH criterion.
4) pH windows (2.5 to 4.0; 3.0 to 3.6)
Dependent claims tighten the pH. If a competitor formulates above 4.0 but still below 7, it may avoid dependent claim scope while still potentially falling under the independent claim if “pH below 7” is satisfied.
5) Tacrolimus loading
Independent claims cover 0.5 to 5 wt% tacrolimus in the composition. This is formulation-wide; it does not appear limited to a narrow dose strength unless the formulation is anchored in how tacrolimus is distributed by weight in the dosage form.
What formulations are explicitly included (PEG/poloxamer and citric/tartaric acid)?
Dependent claims provide anchor embodiments that can be used in both prosecution history and infringement construction.
Included stabilizers
- Citric acid (Claims 6 and 16)
- Tartaric acid (Claims 7 and 17)
Included vehicle
- PEG + poloxamer (Claims 8 and 18)
Included dosage form
These dependent claims are likely to map to actual development choices because they:
- align with common amorphous dispersion and surfactant vehicles for poorly soluble drugs,
- supply weak organic acid functionality that can chelate metals and control microenvironmental pH.
How does the claim architecture affect “partial overlap” infringement?
The claim language is mostly compositional and performance-based, with no product-process steps. That structure means:
- If the accused composition matches the independent claim elements, performance limits for 8-epi provide an additional infringement gate.
- Dependent claims add narrower ranges or identity lists and may become relevant for enforcement if the accused product misses those narrower conditions.
Practically, Claim 1 and Claim 11 set the “big fence,” while dependent claims carve out “smaller fences” around pH windows, specific organic acids, specific vehicles, and a tablet dosage form.
What is the likely US patent landscape around tacrolimus solid dispersions with chelating acids?
This patent is best treated as a formulation moat around:
- solid dispersion tacrolimus,
- metal-chelator driven microenvironmental pH control below 7,
- and targeted suppression of 8-epitacrolimus formation under humidity/temperature stress,
- without cyclodextrin in the vehicle.
Common adjacent US patent themes likely to cluster around it
Even without reproducing specific patent numbers, the technical motifs that typically co-exist in the US tacrolimus formulation space are:
- solid dispersion/amorphous dispersion methods and compositions (carrier selection, surfactants, polymer matrices),
- stability improvements for tacrolimus degradation products,
- pH microenvironment control and anti-oxidant or chelator systems,
- cyclodextrin inclusion/avoidance strategies,
- excipient sets for tablets/capsules.
For a claim like this, typical “adjacent” patent estates are those that overlap on:
- solid dispersion carriers,
- organic acids as stabilizers,
- chelating agents,
- and degradation-control metrics for 8-epitacrolimus.
What do these claims imply for paragraph IV and generic entry risk?
Infringement risk is highest for generics that:
- file an ANDA targeting a tacrolimus solid dispersion product,
- uses a vehicle with PEG and poloxamer (or an equivalent system that still matches the vehicle constraint),
- includes a metal-chelating organic acid and drives composition pH below 7,
- and passes stability specifications that mirror the 8-epitacrolimus thresholds in Claims 1/11.
Because the claims include functional performance limits, a generic that changes excipient chemistry may avoid infringement if it:
- keeps pH above the claim thresholds used for the performance profile (while still controlling stability via alternative mechanisms), and/or
- uses a different chelator type/function that does not satisfy the “metal chelating agent provides pH < 7” requirement, and/or
- uses a cyclodextrin-containing vehicle (if the generic’s platform permits that and it also avoids other independent claim elements).
A key litigation wedge
Even when excipients differ, the claim’s focus on 8-epitacrolimus formation under specific storage regimes gives plaintiffs a measured benchmark for infringement testing and expert evidence.
How strong is the patent estate implied by claim structure (scope breadth vs. proof burden)?
Breadth advantages
- Tacrolimus load spans 0.5 to 5% by weight.
- Metal chelator category includes broad organic acid classes.
- Exclusion is only one axis (no cyclodextrin in the vehicle).
- Vehicle is not fully limited unless dependent claim 8/18 is asserted.
Proof burden
- Infringement depends on demonstrating 8-epitacrolimus increase thresholds after defined storage conditions.
- That creates an evidentiary burden for claim construction and stability testing in litigation.
Net effect
The estate is likely to be enforceable against “close” reformulations because the core concept is specific but implementable across excipient variations, while the performance criteria increase the specificity of infringement proof.
What is the commercial and regulatory relevance for US tacrolimus product competition?
For US market strategy, the claims are relevant to any tacrolimus generic or authorized product that seeks to compete on:
- improved stability or controlled degradation profiles,
- solid-dispersion technology,
- and tablet dosage forms.
A company that plans shelf-life marketing claims or faces stability-driven batch recalls has an additional incentive to match the degradation-control profile. Doing so increases the probability of falling within the independent claim boundary.
Key claim-by-claim scope map (quick reference)
| Claim |
Subject |
What it adds to scope |
| 1 |
Independent |
Base composition: solid dispersion tacrolimus, sole active, vehicle no cyclodextrin, pH < 7 via metal-chelating stabilizer, 0.5 to 5 wt% tacrolimus, stability: ≤0.5% more 8-epi after 40°C/75% RH/5 weeks |
| 2 |
Dependent |
pH 2.5 to 4.0 |
| 3 |
Dependent |
pH 3.0 to 3.6 |
| 4 |
Dependent |
chelator is organic acid (mono/di/oligo/polycarboxylic) |
| 5 |
Dependent |
chelator list includes succinic/citric/tartaric/acrylic/benzoic/malic/maleic/sorbic |
| 6 |
Dependent |
stabilizing agent citric acid |
| 7 |
Dependent |
stabilizing agent tartaric acid |
| 8 |
Dependent |
vehicle PEG + poloxamer |
| 9 |
Dependent |
tacrolimus about 1 wt% |
| 10 |
Dependent |
8-epi <0.5 wt% after 12 weeks at 25°C/60% RH |
| 11 |
Independent |
Like claim 1 but stricter stability metric: ≤0.2% more 8-epi after 25°C/60% RH/5 weeks |
| 12 |
Dependent |
pH 2.5 to 4.0 |
| 13 |
Dependent |
pH 3.0 to 3.6 |
| 14 |
Dependent |
chelator category organic acid |
| 15 |
Dependent |
chelator list |
| 16 |
Dependent |
citric acid |
| 17 |
Dependent |
tartaric acid |
| 18 |
Dependent |
vehicle PEG + poloxamer |
| 19 |
Dependent |
tacrolimus about 1 wt% |
| 20 |
Dependent |
8-epi <0.5 wt% after 12 weeks at 25°C/60% RH |
| 21 |
Dependent |
form is tablet |
When does exclusivity end and how do expiration timelines affect enforcement risk?
No filing, priority, publication, or grant timeline information is provided in the prompt beyond the patent number. Without those dates, a definitive exclusivity and expiration schedule cannot be produced.
Key Takeaways
- US 12,403,095 targets tacrolimus solid dispersions with a metal-chelating organic-acid stabilizer that creates composition pH below 7, while preventing growth in 8-epitacrolimus under specified stability conditions.
- The independent claim set is split between two stability regimes: Claim 1 (40°C/75% RH/5 weeks; ≤0.5% increase) and Claim 11 (25°C/60% RH/5 weeks; ≤0.2% increase).
- The claims have a strong compositional anchor: 0.5 to 5 wt% tacrolimus, sole active, and no cyclo-dextrin in the vehicle.
- Dependent claims narrow to pH windows (2.5-4.0; 3.0-3.6), specific acids (including citric/tartaric), PEG + poloxamer vehicles, and a tablet dosage form.
- Competitive entry risk concentrates in generics that adopt the same stability objective and implement chelating organic acids that drive pH below 7 in a non-cyclodextrin vehicle.
FAQs
1) What stability test drives infringement for US 12,403,095?
Claims 1 and 11 require measured differences in 8-epitacrolimus after defined humidity/temperature storage (40°C/75% RH/5 weeks for Claim 1; 25°C/60% RH/5 weeks for Claim 11), using “no more than” thresholds compared to pre-storage.
2) Does US 12,403,095 cover tacrolimus compositions that include cyclodextrins?
No. The independent claims require that the vehicle does not include a cyclo-dextrin.
3) Are citric and tartaric acids mandatory to infringe?
No. They are covered by dependent claims, but the independent claims cover metal chelating stabilizers that establish pH < 7, including organic acids broadly within the dependent chelator category.
4) What dosage form is covered?
A dependent claim states the composition is in the form of a tablet.
5) How does changing pH affect claim coverage?
Keeping the composition pH above the dependent windows (2.5 to 4.0; 3.0 to 3.6) could avoid those dependent claims, but the independent claims still require pH below 7.
References (APA)
- United States Patent 12,403,095. (Tacrolimus solid dispersion with metal-chelating stabilizing agent and pH control; degradation to 8-epitacrolimus).
