US Drug Patent 6,332,985: scope, claims, and patent-landscape map
US Patent 6,332,985 is directed to processes for removing “toxins” from a fluid using microporous ion exchangers whose framework is limited to zirconium metallates or titanium metallates with strict empirical-formula constraints. The claims include both general fluid-contact removal and specific “body-system” implementations (notably gastrointestinal contact and peritoneal dialysis with dialysate recirculation/bed or membrane coupling).
The core claim scope is defined by four elements:
1) The fluid category (bodily fluids or dialysate solutions; bodily examples include blood and gastrointestinal fluid).
2) The toxin target category (explicitly includes ammonium ions).
3) The ion exchanger (microporous zirconium metallate/titanium metallate with empirical formula ApMxZr1−xSinGeyOm (I) or ApMxTi1−xSinGeyOm (II)).
4) The operating framework for ion exchange (contacting “at ion exchange conditions” to remove toxins; for peritoneal dialysis, filling a cavity with dialysate to contact peritoneum, then exchanging toxins onto the ion exchanger and collecting purified dialysate).
What is the invention boundary in the claims? (Claim architecture)
Independent process claims
Claim 1 (broad platform claim):
- Process for removing toxins from a fluid selected from:
- bodily fluid, or
- dialysate solution
- Contact fluid containing toxins with a microporous ion exchanger at ion exchange conditions to remove toxins.
- Ion exchanger is limited to:
- zirconium metallate
- titanium metallate
- mixtures thereof
- Metallates have empirical formulas:
- (I) ApMxZr1−xSinGeyOm
- (II) ApMxTi1−xSinGeyOm
- Formula constraints include:
- A = exchangeable cation: potassium, sodium, calcium, magnesium, mixtures
- M = at least one framework metal selected from: hafnium (4+), tin (4+), niobium (5+), titanium (4+), cerium (4+), germanium (4+), praseodymium (4+), terbium (4+)
- with explicit carveout: in formula (II), M is not titanium
- p: ~1 to ~20
- x: 0 to <1
- n: 0 to ~12
- y: 0 to ~12
- m: ~3 to ~36
- and 1 ≤ n + y ≤ 12
Claim 14 (peritoneal-dialysis workflow claim):
- Process for removing toxins from a mammalian body by:
1) filling peritoneal cavity with a first dialysate solution so it contacts peritoneum for time sufficient to remove toxins from blood,
2) discharging first dialysate and contacting it with the same microporous ion exchanger at ion exchange conditions to adsorb toxins,
3) collecting purified dialysate solution.
- Ion exchanger is the same limited metallate family and formula constraints.
Dependent claims that operationalize use
Claims 2–3 narrow bodily-fluid use to:
- Claim 2: bodily fluid is blood or gastrointestinal fluid
- Claim 3: exchanger is orally ingested and contacted with gastrointestinal fluids to remove toxins
Claims 4–5 narrow dialysate use to:
- Claim 4: fluid is dialysate solution
- Claim 5: includes flowing dialysate through a bed containing the exchanger for sufficient time
Claims 6, 7–10, 11–13 narrow target and formula variants:
- Claim 6: toxin = ammonium ions
- Claims 7–9, 18–20: specify M selection cases (Sn 4+, Ti 4+, Nb 5+)
- Claims 10 and 21: specify n = 0
- Claims 11–13, 22–24: specify exchangeable cation swap to secondary cations A′ (alkali metals, alkaline earth metals, hydronium ions, mixtures), including Na/Ca or Na/Ca/H3O+ mixtures
Claims 15–17 expand the peritoneal workflow into equipment/recirculation:
- Claim 15: contacting step (b) via flowing through at least one bed
- Claim 16: contacting step (b) via semipermeable membrane dialysis into second dialysate, then bed exchange
- Claim 17: purified dialysate continuously recirculated to step (a), steps (a) to (c) continuous
What exactly do the claims cover? (Scope by element)
1) Fluids
- Bodily fluids: claim set explicitly includes “blood and gastrointestinal fluid” (claims 2–3).
- Dialysate solutions: claims 1, 4–5 and 14–17.
- Operationally, the claim does not require a specific dialysate composition; it requires that a dialysate solution is contacted with the claimed ion exchanger at “ion exchange conditions.”
2) “Toxins” target definition
The claim uses the broad term “toxins.” It becomes concrete in at least one explicit embodiment:
- ammonium ions (claim 6; also consistent with cation-exchange design constraints via A/A′).
The claim language does not restrict toxin identity beyond the explicit dependent claim. This matters because it allows argument that the “ion exchanger” removes any ionic or ion-exchangeable toxin species consistent with ion-exchange mechanisms, while ammonium is called out as a known target for at least one version.
3) Microporous ion exchanger identity and formula limits (the real gate)
The claims repeatedly return to the same exchanger family: microporous zirconium metallate / titanium metallate with empirical formulas (I) and (II). The formula restrictions are the limiting feature that narrows infringement and design-around.
Empirical formula constraints (summary)
- Framework type:
- Formula (I): Zr-based metallate with substituted framework: Zr1−xSinGeyOm
- Formula (II): Ti-based metallate with substituted framework: Ti1−xSinGeyOm
- Substitution variable:
- Si and Ge substitution totals:
- n and y each 0 to ~12
- and 1 ≤ n + y ≤ 12 (so at least one of Si or Ge is present)
- Other index:
- Exchangeable cation A:
- potassium, sodium, calcium, magnesium, or mixtures
- Framework metal M (at least one):
- hafnium 4+, tin 4+, niobium 5+, titanium 4+, cerium 4+, germanium 4+, praseodymium 4+, terbium 4+
- explicit exclusion: in formula (II), M is not titanium
Design implication: any competitive ion exchanger not matching both the metallate identity (zirconium or titanium metallate) and the empirical formula constraints is outside these claims, even if it is microporous and used for toxin removal.
4) Contacting conditions
The claims require contacting “at ion exchange conditions.” For infringement, the method must perform ion exchange (not just adsorption). In the peritoneal/dialysate claims, this includes routing:
- contacting dialysate with the exchanger to adsorb toxins,
- collecting purified dialysate,
- and in dependent forms, using beds and semipermeable membranes.
How broad are the method claims versus the “system” claims? (Practical scope)
Claim 1 is broad on use, narrow on exchanger chemistry
- Broad on: fluid is any bodily fluid or dialysate solution; toxin is not limited except the dependent ammonium claim.
- Narrow on: ion exchanger must be from the zirconium/titanium metallate microporous family with constrained empirical formula and M/A selection.
Claim 14 is broad on system steps, narrow on exchanger chemistry
- Broad on: it covers filling peritoneal cavity with dialysate, removing toxins from blood into dialysate, then exchanging toxins onto the ion exchanger and collecting purified dialysate.
- Narrow on: exchanger formula identity remains controlling.
Dependent claims add “routes” that increase enforceability
- Oral administration route (claim 3) extends use into GI toxin removal by ingestion of exchanger.
- Equipment-dependent claims (claims 15–16) extend enforceability into bed-flow and membrane-coupled dialysate configurations.
- Continuous recirculation (claim 17) narrows to systems that run continuously.
What are the claim “tripwires” and likely infringement triggers?
1) Empirical formula matching
- The metallate must fall inside ApMxZr1−xSinGeyOm or ApMxTi1−xSinGeyOm with:
- 0 ≤ x < 1
- 1 ≤ n + y ≤ 12
- n, y each up to ~12
- m between ~3 and ~36
- A is from K/Na/Ca/Mg
- M set matches allowed framework metals, with the explicit “M is not titanium in formula (II)” constraint.
2) Ion exchange mechanism
- The claim needs ion exchange conditions and removal/adsorption onto the exchanger.
3) Peritoneal cavity workflow (for claim 14)
- Must include steps (a) fill peritoneal cavity dialysate for contact with peritoneum for time to remove toxins from blood, (b) discharge and contact dialysate with ion exchanger, (c) collect purified dialysate.
4) Oral ingestion (claim 3)
- The exchanger must be orally ingested and contacted with gastrointestinal fluids.
5) Ammonium ions (claim 6)
- If a competitor targets ammonium with a closely matching exchanger, claim 6 becomes a direct hook.
Where does the landscape likely concentrate? (Competing claim themes)
Given the claims, the competitive landscape clusters around four categories:
1) Microporous metallate ion exchangers used for ammonium or uremic toxin removal
2) Ion exchanger formulations and cation exchange compositions within the constrained empirical ranges
3) Dialysis and hemoperfusion workflows using ion exchange beds, including:
- peritoneal dialysis with dialysate exchange cartridges,
- membrane-coupled dialysate routing
4) Oral GI adsorbent/ion exchanger products for systemic toxin control (claim 3 route)
US patent 6,332,985: claim-to-technology “mapping” table
| Claim element |
What the claim requires |
Practical infringement condition |
| Fluid |
Bodily fluid or dialysate solution |
Use with blood/GI fluid or with dialysate in dialysis context |
| Target |
“toxins”; explicitly “ammonium ions” in claim 6 |
Ion-exchangeable toxin removal; ammonium removal is a direct dependent claim |
| Exchanger family |
Microporous zirconium metallate and/or titanium metallate |
Candidate must be in that metallate family |
| Empirical formulas |
ApMxZr1−xSinGeyOm (I) and ApMxTi1−xSinGeyOm (II) |
Candidate must match the formula constraints and parameter bounds |
| Exchanger cations |
A = K/Na/Ca/Mg (or mixtures) |
Candidate must use exchangeable cation in that set |
| Framework metal M |
Allowed list with explicit restriction for formula (II) |
Candidate’s M must match the allowed framework metal set and the “not titanium in (II)” rule |
| Operating steps |
Contact at ion exchange conditions |
Method must be performed as ion exchange, not merely filtration |
| Peritoneal workflow (claim 14) |
Steps a to c |
Must implement peritoneal fill, discharge, exchanger contact, and purified dialysate collection |
| Beds/membranes (claims 15–16) |
Bed-flow and/or semipermeable membrane coupling |
Equipment configuration becomes part of claim scope |
What is the scope of “M” selection and parameter-dependent coverage? (Claims 7–10 and 18–21)
The claim set explicitly includes these framework-metal cases:
- M = tin (+4) (claims 7 and 18)
- M = titanium (4+) (claims 8 and 19)
- M = niobium (5+) (claims 9 and 20)
It also explicitly includes:
- n = 0 (claims 10 and 21), which limits Si/Ge content in a specific way consistent with the constraint 1 ≤ n + y ≤ 12 (so if n = 0 then y must satisfy 1 ≤ y ≤ 12).
Landscape effect: competing technology that uses the same general class of microporous metallate frameworks but with different parameter bounds or different framework-metal membership can remain outside these claims even if it removes ammonium or other toxins.
Key Takeaways
- US 6,332,985 covers ion-exchange-based toxin removal using microporous zirconium/titanium metallate exchangers with strict empirical-formula constraints that control infringement more than the clinical workflow.
- Claim 1 is the broad platform for bodily fluids and dialysate; Claim 14 narrows to peritoneal dialysis workflows with dialysate exchange through the same constrained exchanger family.
- Dependent claims extend coverage into oral GI administration (claim 3), ammonium ion targeting (claim 6), bed-flow and membrane coupling (claims 15–16), and continuous recirculation (claim 17).
- The enforceable “center of gravity” is the match to ApMxZr1−xSinGeyOm / ApMxTi1−xSinGeyOm with A limited to K/Na/Ca/Mg, M limited to the listed framework metals with a specific restriction for formula (II), and n + y bounded between 1 and 12.
FAQs
1) What single element most determines whether a competitor can infringe US 6,332,985?
The exchanger must match the claimed microporous zirconium/titanium metallate empirical formulas and parameter bounds in claims 1 and 14.
2) Does the patent require a specific toxin definition beyond “toxins”?
No, “toxins” is broad in the independent claims, but the patent explicitly includes ammonium ions in claim 6.
3) Is peritoneal dialysis mandatory for all claims?
No. Peritoneal dialysis is required for claim 14 and its dependent claims; claim 1 covers broader fluid categories.
4) Can the invention cover oral administration?
Yes. Claim 3 covers orally ingesting the microporous ion exchanger and contacting it with gastrointestinal fluids to remove toxins.
5) Does the claim cover only bed-based exchanger contact?
No. It covers bed-flow contact (claim 15) and also membrane-coupled dialysate routing (claim 16), with recirculation options in claim 17.
References (APA)
[1] US Patent 6,332,985. (n.d.). Process for removing toxins from a fluid using microporous ion exchangers.
