Patent Scope and Claims Review for US 4,886,789 (Peritoneal Dialysis Glucose Polymer from Starch Hydrolysis)
US 4,886,789 is a US method patent focused on peritoneal dialysis using an aqueous peritoneal dialysis composition whose osmotic agent is a specific glucose polymer mixture derived from starch hydrolysis. Claim scope centers on (1) polymer identity defined by degree of polymerization (D.P.) thresholds, (2) polymer molecular weight bands, and (3) composition concentration ranges, with dependent claims narrowing to specific sub-ranges and starch structural features. The estate is likely narrow in practice because infringement requires meeting the specific D.P. distribution and concentration limits, and method infringement depends on “introducing” the composition into a patient’s abdominal cavity.
How strong are the claims of US 4,886,789 and what do they cover?
US 4,886,789 claims a method of effecting peritoneal dialysis by administering an intraperitoneal aqueous glucose-polymer solution produced from starch hydrolysis. The core claim is Claim 1; dependent claims narrow the polymer mixture and solution concentration.
Claim 1: what must be present for infringement?
Claim 1 requires all of the following elements:
- Route/act: introducing into a patient’s abdominal cavity an aqueous peritoneal dialysis composition.
- Osmotic agent: the composition contains a water soluble glucose polymer mixture derived from hydrolysis of starch.
- Polymer D.P. threshold: the mixture contains at least 36.7% by weight of glucose polymers with D.P. > 12 glucose units.
Claim 1 is therefore not a broad “any peritoneal dialysis glucose polymer” claim. It is constrained to a mixture defined by (i) origin (starch hydrolysis), (ii) water solubility, (iii) D.P. distribution (both the D.P. cut-off and a quantitative mass fraction), and (iv) intraperitoneal administration.
What do dependent claims add?
Polymer molecular weight bands
- Claim 2: average molecular weight 15,000 to 25,000
- Claim 3: average molecular weight 18,000 to 22,000
These claims narrow the acceptable molecular weight distribution of the same glucose polymer mixture beyond the D.P. mass fraction requirement.
D.P. distribution mass fraction ranges
- Claim 4: >50% by weight of glucose polymers with D.P. >12
- Claim 5: 50 to 90%
- Claim 6: 75 to 100%
- Claim 7: 90 to 100%
These are incremental narrowing versions of the Claim 1 “at least 36.7%” concept. They also create “design-around by tightening composition thresholds” risk for challengers: if a competitor sits at, for example, 40% vs 55% vs 90%, the infringement posture changes claim-by-claim.
Glucose polymer concentration in the dialysate
- Claim 8: 2 to 10% w/v
- Claim 9: 2 to 4% w/v
- Claim 11: 2 to 15% w/v
- Claim 12: 2 to 5% w/v
These define solution strength bands. They matter because peritoneal dialysis practice uses variable glucose-lowerings/alternative osmotic agents across dwell solutions. A competitor operating outside the bands avoids those dependent claims but may still hit Claim 1 depending on whether Claim 1’s D.P. mass fraction is met.
Residual free glucose limitation
- Claim 10: glucose content less than 3% by weight (in the glucose polymer mixture)
This is a material limitation. It can become a significant infringement lever because hydrolysis processes often yield a free glucose fraction. A manufacturing strategy that increases free glucose (or uses a different hydrolysis cut) could escape Claim 10 while remaining in-range for D.P. thresholds, depending on assay outcomes.
Patient population
- Claim 13: patient suffers from renal failure
This is a method-use limitation but not a product-limiting feature; it is likely straightforward for enforcement given the typical peritoneal dialysis indication.
Starch structural feature
- Claim 14: the starch contains not more than 5% of 1,6-linkages
This narrows the starting starch material to those with limited branching via α(1→6). It is a manufacturing-input claim element: infringement depends on what starch feedstock was used to generate the glucose polymer mixture.
Claim construction pressure points for litigation
Key disputed issues typically include:
- How is D.P. measured and how are polymers assigned to “D.P. > 12”? (Analytical method affects whether the mass fraction threshold is met.)
- How are “average molecular weight” values determined for a polydisperse mixture (what distribution metric counts as “average”)?
- Assay of w/v concentration in the administered composition.
- Free glucose measurement for the “less than 3% by weight” limitation.
- Source starch and linkage content for Claim 14.
These are not theoretical. They are built into the claim language through threshold percentages and concentration bands.
What is the likely infringement map: which design choices can avoid US 4,886,789?
Below is an infringement-logic matrix based strictly on the claim elements you provided. It identifies the easiest “out-of-range” pivots.
| Variable in your claims |
Infringement requirement |
Easiest design-around direction |
| Starch hydrolysis-derived glucose polymer mixture (water soluble) |
Must be present |
Use a non-starch source or non-starch-derived polymer (if feasible) |
| D.P. > 12 mass fraction |
Claim 1: ≥36.7% by weight |
Reduce the fraction of D.P. >12 polymers below 36.7% |
| Average molecular weight |
Claim 2/3: 15k–25k or 18k–22k |
Use a polymer mixture outside these bands |
| D.P. >12 mass fraction ranges |
Claims 4–7: >50%, 50–90%, 75–100%, 90–100% |
Use 36.7–50% region (hits Claim 1 but not some dependents) or <36.7% region (avoids Claim 1) |
| Dialysate concentration (w/v) |
Claims 8/9/11/12: 2–10%, 2–4%, 2–15%, 2–5% |
Operate outside the cited w/v bands (but not outside Claim 1 if the independent claim remains satisfied) |
| Free glucose |
Claim 10: <3% by weight |
Increase free glucose above 3% (while maintaining D.P. distribution if needed) or adjust hydrolysis profile |
| Starch 1,6-linkages |
Claim 14: ≤5% 1,6-linkages |
Use a starch with >5% 1,6-linkages (or a different feedstock) |
Practically, because Claim 1 is broadest and does not add the molecular-weight band, most competitors will focus on D.P. distribution (≥36.7% vs below) and whether their polymer is derived from starch hydrolysis and administered intraperitoneally in aqueous form.
Which subject matter is covered: method of effecting peritoneal dialysis using starch-derived glucose polymers?
The patent is best understood as covering a composition-defined therapeutic method. The “method of effecting peritoneal dialysis” is performed by “introducing” the specific osmotic agent mixture into the abdominal cavity.
Is it a “composition” patent or a “method” patent?
It is a method patent. The infringement act is the administration of the defined aqueous glucose polymer mixture to a patient for peritoneal dialysis.
How does the patent treat “formulation” versus “delivery”?
The formulation is central because the composition is defined by polymer mixture properties (D.P. distribution, molecular weight bands, free glucose fraction, concentration, starch linkage profile). Delivery is constrained to intraperitoneal introduction.
What are the dependent-claim scope ladders and overlap risks?
Claims 2–3 and 4–7 create stacked narrowing ladders. These ladders can be used in enforcement strategy: a plaintiff can try to prove infringement of Claim 1 first, then scale up to dependents if the analytical profile matches.
Claim ladder summary (narrowing sequence)
- Claim 1: D.P. >12 mass fraction ≥36.7%
- Claims 4–7: tighten D.P. >12 mass fraction upward (>50%, 50–90%, 75–100%, 90–100%)
- Claims 2–3: add average molecular weight ranges (15k–25k; 18k–22k)
- Claims 8–9 and 11–12: add dialysate concentration bands (2–10% w/v; 2–4% w/v; 2–15% w/v; 2–5% w/v)
- Claim 10: adds free glucose <3% by weight
- Claim 13: renal failure patient status
- Claim 14: starch feedstock linkage requirement ≤5% 1,6-linkages
Overlap for a given competitor
A competitor may match Claim 1 but miss some dependents. That is why Claim 1’s D.P. mass fraction threshold is the central “overlap” parameter.
What is the US patent estate landscape around US 4,886,789 (what else typically matters)?
Only your claim text is provided; no bibliographic, assignee, filing date, related family members, or prosecution history were included. Without those, the complete US landscape cannot be produced reliably.
What is the expiration status and exclusivity timeline for US 4,886,789?
No filing date, priority date, or term-adjustment data were provided. Without them, the expiration date cannot be stated accurately, and exclusivity timelines cannot be calculated.
How do Section 271(e) and Paragraph IV strategies apply to a method claim like this?
A Paragraph IV certification is framed around an ANDA or 505(b)(2) approval and relevant US patents. For a method patent, the infringement predicate is still tied to administration. Certification and litigation still often focus on whether the proposed product would be used in a manner that infringes the method claim.
For a glucose-polymer peritoneal dialysis method, the typical litigation posture in practice would hinge on:
- Whether the proposed therapy composition has the required D.P. distribution (≥36.7% D.P. >12 by weight).
- Whether the manufacturing process uses starch hydrolysis and yields water soluble glucose polymers with the required characteristics.
- Whether the marketed regimen matches the claimed “introducing into the abdominal cavity” context and solution strength.
What is the Orange Book status of US 4,886,789?
No NDA/ANDA linkage or Orange Book listing details were provided. Without the referenced product, Orange Book status cannot be determined from the patent number alone in a reliable way.
What formulations are protected: concentration and polymer distribution constraints
US 4,886,789 is effectively a “process-parameter-turned-composition-parameter” patent. It constrains:
- Polymer length distribution by D.P. >12 mass fraction.
- Polymer size by average molecular weight.
- Free glucose by weight fraction in the polymer mixture.
- Dialysate strength by w/v concentration of the polymer mixture.
- Starting starch structure via 1,6-linkage content (Claim 14).
- Administration mode via intraperitoneal introduction.
This structure implies a high assay burden for both sides in disputes: each limiting parameter must be mapped to analytical results for the accused solution and accused polymer mixture.
Comparative risk: how do competing osmotic agents change infringement odds?
A competitor can reduce risk by shifting away from starch-derived glucose polymers that satisfy the D.P. threshold.
Likely lowest risk categories
- Osmotic agents not derived from starch hydrolysis glucose polymer mixtures.
- Starch hydrolysate mixtures formulated to keep D.P. >12 mass fraction below 36.7% by weight.
- Hydrolysate profiles with free glucose above 3% where Claim 10 is asserted and where dependence is strategically pursued.
- Different starch feedstock with >5% 1,6-linkages where Claim 14 is asserted.
Highest risk overlap category
A polymer-based intraperitoneal dialysis solution that uses a starch hydrolysate mixture with D.P. >12 comprising at least 36.7% by weight, regardless of molecular weight sub-range. That hits Claim 1.
Key takeaways
- US 4,886,789 covers an intraperitoneal peritoneal dialysis method using an aqueous starch-hydrolysis glucose polymer mixture.
- The independent claim is defined by a single quantitative polymer structural threshold: ≥36.7% by weight of glucose polymers with D.P. >12.
- Dependent claims tighten scope through average molecular weight ranges, higher D.P. >12 mass fractions, dialysate w/v concentration bands, free glucose <3%, and starch feedstock linkage limitation (≤5% 1,6-linkages).
- Practical infringement hinges on assayable polymer D.P. distribution, assayable free glucose, and the administered solution’s concentration, plus in some strategies the starch feedstock linkage profile.
FAQs
- What analytical methods determine “degree of polymerization (D.P.)” for infringement under US 4,886,789?
- If a dialysis solution has 40% D.P. >12 by weight, which claims are most likely implicated?
- Can a competitor avoid US 4,886,789 by changing dialysate concentration while keeping the same starch-derived polymer mixture?
- How does the “less than 3% glucose” limitation (Claim 10) affect design-around strategies for starch hydrolysates?
- What does the ≤5% 1,6-linkages limitation (Claim 14) imply about allowable starch feedstocks?
References
- United States Patent 4,886,789.
