Patent: 10,273,255

Summary for Patent: 10,273,255

Title:	High-purity large-scale preparation of stannsoporfin
Abstract:	Large scale (bulk) compositions comprising high-purity stannsoporfin are disclosed, as well as methods of synthesizing such compositions.
Inventor(s):	Drummond; George S. (New York, NY), Caroselli; Robert (East Brunswick, NJ), Cooke; Keith A. (Milton, CA), Levin; Daniel (Toronto, CA), Roe; David G. (Rockwood, CA), Boucher; Christopher P. (Newmarket, CA)
Assignee:	INFACARE PHARMACEUTICAL CORPORATION (Trevose, PA)
Application Number:	15/867,900
Patent Claims:	see list of patent claims

US Patent 10,273,255 (Claims 1–3): What does it actually protect, what are the critical claim-construction pressure points, and how does the US patent landscape look for tin(IV) mesoporphyrin manufacturing methods

US Patent 10,273,255 claims a specific US manufacturing sequence for producing tin(IV) mesoporphyrin compounds (and salts) starting from mesoporphyrin IX dihydrochloride (or salt), with the novelty concentrated in (i) how mesoporphyrin IX is made from hemin via a hydrogenation/purification scheme, and (ii) how the tin(II) oxide is converted with mesoporphyrin IX dihydrochloride by dropwise addition, followed by a defined “hot acid trituration → high pH (≥9) → re-acidification → hot acid trituration” purification cycle. Claim 3 narrows to palladium-on-carbon as the hydrogenation catalyst.

Critical upshot for freedom-to-operate: the claim is not a broad “any tin(IV) mesoporphyrin process.” It is a constrained process claim with multiple sequential and conditional features that can be designed around by changing (a) catalyst/pre-hydrogenation modality, (b) how vinyl-to-ethyl reduction is achieved, (c) whether mesoporphyrin IX formate is an intermediate, (d) tin(IV) generation route (tin(II) oxide source and addition mode), and/or (e) purification workup signature (acid/base/re-acid/base windows and the specific trituration steps).

Important limitation: the analysis below is restricted to the claims text you provided. It does not include a full claim chart against the full specification, because that requires the full application/issued-text beyond the claim excerpt.

---

What does US 10,273,255 claim 1 actually require for tin(IV) mesoporphyrin production in the US?

Claim 1 is a multi-feature process: every limitation must be met

Claim 1 is drafted as a method comprising steps (a) through (d). It requires, as pleaded in the claim, the following core elements:

1. Mesoporphyrin IX formation from hemin via pre-hydrogenated metallic catalyst

   • Prepare a solution/suspension of mesoporphyrin IX dihydrochloride (or salt) by:
     • Expose a metallic hydrogenation catalyst to hydrogen atmosphere to form a pre-hydrogenated catalyst.
     • Contact hemin with the pre-hydrogenated catalyst at combinations of temperature, hydrogen pressure, and time to:
       • remove iron from hemin
       • reduce vinyl groups of hemin to ethyl groups
       • form mesoporphyrin IX
     • Isolate mesoporphyrin IX as mesoporphyrin IX formate
     • Purify the isolated mesoporphyrin IX formate
     • Convert purified mesoporphyrin IX formate into mesoporphyrin IX dihydrochloride

2. Tin(II) oxide is prepared and combined with mesoporphyrin IX dihydrochloride

   • Prepare a solution/suspension of tin(II) oxide
   • Prepare a solution/suspension of mesoporphyrin IX dihydrochloride (or salt) in an organic solvent
   • Steps (a) and (b) can occur in any order or simultaneously

3. Dropwise addition to form tin(IV) mesoporphyrin

   • Contact tin(II) oxide suspension with mesoporphyrin IX dihydrochloride solution/suspension by dropwise addition of the mesoporphyrin component to the tin(II) oxide mixture to form the tin(IV) mesoporphyrin compound or salt.

4. Defined purification workup for tin(IV) product

   • Purify the tin(IV) mesoporphyrin IX compound via:
     • hot acid trituration
     • then treatment at high pH ≥ 9
     • then re-acidification
     • then subsequent hot acid trituration

Featured-snippet answer: US 10,273,255 claim 1 protects a particular integrated manufacturing flow that locks together hydrogenation-driven hemin de-metalation and vinyl-to-ethyl reduction with mesoporphyrin IX formate isolation, then tin(IV) formation by dropwise addition to tin(II) oxide, then a distinctive acid-base-acid hot trituration purification cycle.

---

Where are the strongest patent-value “hinges” in claim 1 for enforcement and licensing leverage?

1) “Pre-hydrogenated catalyst” before contacting hemin

A process can be easier to design around if the alleged infringer uses a catalyst that is never pre-exposed to hydrogen to “activate” it in the claimed way. Here, the claim is explicit that metallic hydrogenation catalyst is “exposed to a hydrogen atmosphere” to form a “pre-hydrogenated catalyst.”

• Enforcement leverage: if the accused process includes a catalyst activation stage under hydrogen prior to hemin contact, this feature is likely to be argued as literally satisfied or at least within a doctrine-of-equivalents theory.
• Design-around lever: omit pre-hydrogenation, or use a different activation concept that does not involve hydrogen pre-exposure.

2) The vinyl-to-ethyl reduction and iron removal are tied to hemin contact conditions

The claim demands contact conditions “under one or more combinations of temperature, hydrogen pressure, and time” to remove iron and reduce vinyl groups to ethyl groups.

• Enforcement leverage: this limits the claim to a hydrogenation pathway that accomplishes both transformations in the same step (hemin + pre-hydrogenated catalyst).
• Design-around lever: separate de-metallation and reduction steps, or use a non-hydrogenation route for vinyl reduction.

3) Isolation as mesoporphyrin IX formate is an intermediate “signature”

The claim states:

• form mesoporphyrin IX

• isolate mesoporphyrin IX as mesoporphyrin IX formate

• purify the isolated mesoporphyrin IX formate

• convert to mesoporphyrin IX dihydrochloride

• Enforcement leverage: intermediates can be analyzed through manufacturing records, solvent/formate presence, and unit operations. If the accused process never produces or isolates a formate intermediate (or does not purify it as such), the claim may not read on it.

• Design-around lever: use direct conversion to mesoporphyrin IX dihydrochloride without isolating a mesoporphyrin IX formate.

4) Tin(II) oxide plus dropwise addition direction matters

Claim 1 requires:

• preparing a suspension/solution of tin(II) oxide
• contacting it with mesoporphyrin IX dihydrochloride solution/suspension
• by dropwise addition of mesoporphyrin IX dihydrochloride/salt to tin(II) oxide.

This “addition direction + tin oxidation state + dropwise” combination can narrow infringement.

• Enforcement leverage: if a competitor performs the reaction in reverse addition order (adding tin to mesoporphyrin), or uses a different tin precursor (e.g., tin salts that are already soluble and reduce/oxidize under different conditions), the claim may not be met.
• Design-around lever: reverse the addition order, use a different tin(II) source, or carry out tin introduction as a pre-formed organometallic complex or alternative precursor.

5) The purification sequence is unusual and therefore potentially distinctive

“Hot acid trituration” then high pH ≥ 9 then re-acidification then subsequent hot acid trituration is a four-part workup signature.

• Enforcement leverage: purification instructions are often harder to replicate unknowingly; if manufacturing logs show this exact sequence or close functional equivalence, it strengthens an infringement theory.
• Design-around lever: change the order of pH excursions, change trituration approach (e.g., filtration-only vs trituration), avoid ≥9 pH treatment, or replace with alternative purification such as chromatography/recrystallization under different pH regime.

---

How do claims 2 and 3 narrow the protected process?

Claim 2: acid identity during independent preparation

Claim 2 states that solutions/suspensions of both tin(II) oxide and mesoporphyrin IX dihydrochloride can be independently prepared with formic acid or acetic acid.

• Scope effect: claim 2 narrows on solvent/additive identity for the preparation steps of tin oxide and mesoporphyrin solution/suspension.
• Enforcement impact: if an accused process uses another acid (mineral acids, propionic acid, oxalic acid, hydrochloric acid, etc.), claim 2 would not be literally satisfied.

Claim 3: palladium on carbon hydrogenation catalyst

Claim 3 limits the metallic hydrogenation catalyst to palladium on carbon.

• Scope effect: claim 3 is a dependent claim that likely sets the evidentiary target for the most common hydrogenation catalysts.
• Enforcement impact: if the accused process uses a different hydrogenation catalyst (Raney Ni, Pt/C, Rh/C, etc.), it may avoid claim 3 while still potentially touching claim 1 (depending on whether claim 1’s broader “metallic hydrogenation catalyst” is alleged).

---

What is the strongest infringement theory an applicant or patentee would use for US 10,273,255?

A. Literal infringement is plausible only if manufacturing mirrors the full integrated flow

Because claim 1 is tightly tethered to multiple specific unit operations and intermediates, the most credible infringement case typically requires showing that the accused infringer:

• starts from hemin and performs hydrogenation with pre-hydrogenated metallic catalyst,
• isolates mesoporphyrin IX as formate and purifies it,
• converts to dihydrochloride,
• introduces tin(IV) through tin(II) oxide with the specified dropwise addition direction, and
• uses the same acid-hot/base-high-pH/re-acid/hot-acid purification sequence.

B. If one element is missing, doctrine-of-equivalents becomes fact-heavy

Process patents with explicit intermediate isolation and workup sequences often face limits on equivalents due to prosecution history estoppel or subject-matter dedication, but that can’t be evaluated without the file history and specification text.

---

What are the most practical design-around pathways for manufacturers?

Below are the highest-leverage modifications consistent with how claim 1 is written.

1) Eliminate “mesoporphyrin IX formate” isolation

• Make mesoporphyrin IX via hemin reduction but convert directly to dihydrochloride without isolating mesoporphyrin IX as formate, or use a different salt intermediate.

2) Remove or alter the “pre-hydrogenated catalyst” step

• Use hydrogen in a way that does not constitute “exposing” the catalyst to a hydrogen atmosphere to form a pre-hydrogenated catalyst prior to contacting hemin.

3) Change tin precursor and/or addition mode

• Replace tin(II) oxide suspension with another tin(II) or tin(IV) precursor that does not require the same dropwise addition into tin(II) oxide.
• Add tin reagent to mesoporphyrin solution rather than dropwise adding mesoporphyrin solution to tin(II) oxide.

4) Change the purification cycle

• Avoid high pH ≥ 9 treatment, or change sequence/order so it is not the claimed hot acid trituration then high pH then re-acidification then subsequent hot acid trituration.

5) Use a different hydrogenation catalyst

• If trying to avoid claim 3 specifically: use a non-Pd/C catalyst.

---

What does the broader US tin(IV) mesoporphyrin patent landscape likely look like (and how to read it)?

Critical limitation of this analysis

A true “comprehensive” landscape requires the full patent family set, publication histories, and Orange Book or regulatory coupling where applicable. The only verified input here is US 10,273,255 claim text. Without the patent’s title, assignee, priority data, specification, and bibliographic record, a correct enumerated landscape cannot be produced.

How to conduct the landscape read using claim structure

Even without enumerating each cited patent, the claim itself indicates what competing process patents would target:

1. Core synthesis patents for mesoporphyrin IX from hemin

   • Hydrogenation catalyst systems
   • Pre-activation under hydrogen
   • Iron removal and vinyl-to-ethyl conversion conditions
   • Specific isolation intermediates (formate, other salt forms)
   • Conversion to dihydrochloride

2. Metal insertion patents

   • Tin oxidation state control (tin(II) oxide versus tin salts versus pre-chelated systems)
   • Order and rate of addition (dropwise direction)
   • Solvent/acid systems for tin and porphyrin compatibility

3. Purification/workup patents

   • Acid trituration steps
   • High pH regimes (≥9)
   • Re-acidification cycles
   • Recrystallization, filtration, and polymorph/purity specifications

For enforcement, patents that match or closely overlap any one of these “hinges” can be used to build multi-patent assertion strategies around a single manufacturing flow.

---

Key takeaways: what US 10,273,255 most likely means for market entry and litigation posture

• The claim is a tightly bounded process definition, not a genus claim for all tin(IV) mesoporphyrin manufacturing.
• The enforceable value is concentrated in five elements: pre-hydrogenated catalyst; hemin hydrogenation achieving both de-metalation and vinyl-to-ethyl reduction; isolation/purification of mesoporphyrin IX as formate; tin(II) oxide with mesoporphyrin dropwise addition; and the acid-high pH-re-acid-hot acid purification sequence.
• Downstream licensing leverage and litigation exposure depend on whether an accused process includes the same intermediate and workup signature, not just whether it produces tin(IV) mesoporphyrin.

---

FAQs

1) Does producing tin(IV) mesoporphyrin by a different tin precursor avoid US 10,273,255 claim 1?
If the process does not use tin(II) oxide suspension and the specified dropwise addition direction, claim 1’s tin-formation limitation is likely not met.

2) If a competitor still uses hemin hydrogenation, can they avoid infringement by skipping mesoporphyrin IX formate isolation?
Skipping isolation/purification of mesoporphyrin IX as mesoporphyrin IX formate is a direct pathway to avoid a key intermediate limitation.

3) Does using palladium on carbon automatically satisfy claim 3?
Only if the hydrogenation catalyst is Pd/C and the rest of claim 1’s method elements are also practiced.

4) Can a process using the same acids (formic or acetic) still avoid claim 2?
Yes, if the process changes other required limitations of claim 1, such as the tin(II) oxide/dropwise addition mode or the purification cycle.

5) How does purification workup affect infringement risk under this patent?
Because claim 1 specifies a multi-step workup (hot acid trituration, high pH ≥ 9, re-acidification, then subsequent hot acid trituration), deviations in that sequence or pH window can reduce infringement risk.

---

References (APA)

No references can be listed because no authoritative bibliographic or regulatory sources were provided in the prompt beyond the claim text.

Details for Patent 10,273,255

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Recordati Rare Diseases, Inc.	PANHEMATIN	hemin for injection	For Injection	101246	July 20, 1983		2038-01-11