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Patent landscape, scope, and claims: |
United States Patent 4,843,086 claim scope and US patent landscape analysis
Core takeaway: US 4,843,086 is an expansive use-method patent built around a tetrahydro-benzthiazole scaffold with broad substituent-variable Markush ranges (R1–R4). It covers methods for lowering blood pressure, lowering heart rate, and treating Parkinsonism/Parkinson’s disease and schizophrenia, with additional dependent-position claims (notably NR3R4 at the 5- or 6-positions) and named examples for 2-amino-6-(n-propylamino / dimethylamino)-4,5,6,7-tetrahydrobenzthiazole. Because the claims are method-of-treatment, the infringement analysis centers on administering a covered tetrahydro-benzthiazole to a patient for the claimed indication (and on whether the product is a compound falling within the Markush structure).
What patents protect tetrahydro-benzthiazole compounds for blood pressure lowering, heart rate lowering, Parkinsonism, and schizophrenia? (US 4,843,086 scope)
US 4,843,086 claims are structured as medical-use methods for administering tetrahydro-benzthiazole compounds and their pharmaceutically acceptable acid addition salts. The patent does not claim a composition as such in the excerpted claim set you provided; it claims methods.
What exactly is being claimed?
Across the independent claims, the asserted subject matter is:
- Blood pressure lowering (claims 1, 3, 6, 9, 10)
- Heart rate lowering (claims 11, 13, 16, 19, 20)
- Treating Parkinsonism/Parkinson’s disease (claims 21, 23, 26, 29, 30)
- Treating schizophrenia (claims 31, 33, 36, 39, 40)
Each independent method claim requires administration of a “therapeutically effective” / “blood pressure lowering amount” / “heart rate lowering amount” of a tetrahydro-benzthiazole of the recited structural formula.
The core chemical scaffold
The repeated theme is a tetrahydro-benzthiazole with substituent variables:
- R1: hydrogen or alkyl / alkenyl / alkynyl / phenyl-alkyl (with optional halogen substitution on the phenyl ring)
- R2: hydrogen or alkyl (with narrower ranges in later versions)
- R3 and R4: hydrogen or broad classes, including the possibility that R3 and R4 plus the nitrogen atom between them form a cyclic amine:
- pyrrolidino
- piperidino
- hexamethyleneimino
- morpholino
Then dependent claims narrow to placement (commonly: NR3R4 in the 5- or 6-positions).
How broad are the structural ranges?
The claims are wide in three separate ways:
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Substituent breadth (Markush ranges):
The compounds covered are not limited to a single drug substance. The ranges cover many alkyl and unsaturated groups and multiple aromatic substitutions.
-
Halogen substitution allowed:
The phenyl nucleus may be substituted by 1 or 2 halogens in some claims, and by fluorine, chlorine or bromine in the others.
-
N-substitution modes and ring-form amines:
The nitrogen substitution is flexible:
- either R3 and R4 individually as alkyl/alkenyl/alkynyl-like groups; or
- R3 and R4 together with the intervening nitrogen forming one of several secondary/tertiary ring amine systems (piperidino class, morpholino class, etc.).
What do the named compounds add?
The named examples (claims 9, 10, 19, 20, 29, 30, 39, 40) add specific anchors:
- 2-Amino-6-n-propylamino-4,5,6,7-tetrahydro-benzthiazole
- 2-Amino-6-dimethylamino-4,5,6,7-tetrahydro-benzthiazole
These do not replace the broad Markush claims; they function as additional independent coverage and fallback positions.
How do claims 1–40 structure method-of-treatment coverage (blood pressure, heart rate, Parkinsonism, schizophrenia)?
Blood pressure lowering claims
Independent coverage
- Claim 1: tetrahydro-benzthiazole formula for lowering blood pressure
- Claim 3: narrower R1/R3/R4 examples but still Markush broad ranges
- Claim 6: simplified “compound of the formula” version (R variable) for blood pressure lowering
- Claims 9–10: named compounds (2-amino-6-n-propylamino; 2-amino-6-dimethylamino)
Dependent refinements
- Claim 2: NR3R4 at 5- or 6-positions
- Claim 4: NR3R4 at the 6-position
- Claim 5: specific additional conformation:
- R1 and R2 together with the nitrogen atom between them form amino or allylamino
- R3 and R4 together form one of several dialkyl/benzyl/allyl/pyrrolidino-type moieties
Heart rate lowering claims
Independent coverage
- Claim 11: tetrahydro-benzthiazole formula for lowering heart rate
- Claim 13: another Markush set
- Claim 16: simplified “compound formula” version
- Claims 19–20: named 2-amino-6-n-propylamino / 2-amino-6-dimethylamino tetrahydro-benzthiazoles
Dependent refinements
- Claim 12: NR3R4 at 5- or 6-positions
- Claim 14: NR3R4 at the 6-position
- Claim 15: specific amine construction options
Parkinsonism/Parkinson’s disease claims
Independent coverage
- Claim 21: broad Markush formula
- Claim 23: narrower Markush formula
- Claim 26: simplified R variable formula
- Claims 29–30: named examples for Parkinsonism/Parkinson’s disease
Dependent refinements
- Claim 22: NR3R4 at 5- or 6-positions
- Claim 24: NR3R4 at the 6-position
- Claim 25: specific R1/R2 amine assembly plus R3/R4 dialkyl/benzyl/allyl or pyrrolidino-type assembly
Schizophrenia claims
Independent coverage
- Claim 31: broad Markush formula
- Claim 33: narrower Markush formula
- Claim 36: simplified R variable formula
- Claims 39–40: named examples
Dependent refinements
- Claim 32: NR3R4 at 5- or 6-positions
- Claim 34: NR3R4 at the 6-position
- Claim 35: specific R1/R2 and R3/R4 assembly
Which substituent positions (5- vs 6-position) matter for infringement risk?
The dependent claims tie a key structural feature to positional specificity:
- NR3R4 at 5- or 6-positions: claims 2, 12, 22, 32
- NR3R4 at 6-position: claims 4, 14, 24, 34
Practical infringement implication for “close design-arounds”
If a competitor’s tetrahydro-benzthiazole differs only in whether the N-substituted group is installed at the 5-position versus 6-position, the independent Markush coverage may still capture the compound, but the dependent claims create:
- an additional ladder of narrower coverage for validity and enforcement, and
- more targeted claim-to-compound mapping for litigation and licensing.
How strong is the patent estate for US 4,843,086: what claims are likely to be broader vs narrower?
Broadest coverage (highest Markush breadth)
- Independent formula claims with:
- widest R1/R2/R3/R4 ranges and
- optional halogen substitution
- optional N-ring-forming (pyrrolidino/piperidino/hexamethyleneimino/morpholino)
These include:
- blood pressure: claims 1 and 6
- heart rate: claims 11 and 16
- Parkinsonism: claims 21 and 26
- schizophrenia: claims 31 and 36
Narrowest anchor coverage
- Named examples (claims 9, 10, 19, 20, 29, 30, 39, 40) provide compact claim-to-substance mapping.
- Dependent claims that specify:
- positional installation (5/6; especially 6)
- constrained assemblies of R1/R2 with nitrogen
- constrained R3/R4 combinations (dimethylamino, diethylamino, n-propylamino, allyl/benzyl/chloro-benzyl variants; pyrrolidino)
Those dependent claims are usually the most litigable if a product fits closely, because they reduce the designer-space ambiguity.
What are the regulatory and Orange Book implications for method claims like US 4,843,086?
Orange Book relevance (directionally)
The claims you provided are method-of-treatment claims tied to therapeutic uses. For typical small-molecule systems, Orange Book listing is generally driven by FDA-approved drug products and active ingredients, while method claims are frequently tied to approved labeling indications.
From a enforcement perspective:
- an accused product can face risk even if the active ingredient matches, but method-of-use infringement usually turns on labeling, instructions, and actual prescribing/administering practices.
FDA label design-around vector
A challenger often attempts to reduce method-of-use exposure by:
- removing the claimed indication from labeling, and/or
- avoiding recommended dosing instructions that align with “blood pressure lowering amount” / “heart rate lowering amount” / “therapeutically effective amount” for the relevant disease.
Because US 4,843,086 is not just one indication but four (blood pressure, heart rate, Parkinsonism, schizophrenia), label carve-outs can be harder if the sponsor wants multi-indication positioning.
What generic entry risks exist for US 4,843,086 if there is an approved tetrahydro-benzthiazole product?
Core risk driver
If an ANDA applicant uses the same active ingredient(s) that fall within the Markush-defined tetrahydro-benzthiazole formula and the product is prescribed for one of the claimed uses, method claims create exposure.
Key differentiators that change risk
- Indication alignment:
Blood pressure vs heart rate vs Parkinsonism vs schizophrenia uses are each separately claimed.
- Compound structural fit:
If a generic’s tetrahydro-benzthiazole has substituents outside the R1–R4 ranges, it can avoid falling within the formula claims.
- Salt form:
The claims cover pharmaceutically acceptable acid addition salts; avoidance typically requires using a salt form not recognized as “pharmaceutically acceptable” or not used in commerce, which is harder than changing the core scaffold.
“Same scaffold, different amine”: likely litigation theme
Because the nitrogen substituent is heavily integrated via R3/R4 and ring-amine options, competitors can reduce risk by changing:
- the N-substitution pattern,
- the ring type (avoid pyrrolidino/piperidino/hexamethyleneimino/morpholino construction when that is necessary to match the Markush definition),
- or the positional relationship targeted by dependent claims.
Patent litigation landscape: what claims are most likely to be asserted and how would courts map infringement?
Courts generally perform a two-step mapping:
- whether the accused product’s administered compound meets the claim structural definition (formula/Markush),
- whether the accused activity meets the claimed method purpose (blood pressure lowering, heart rate lowering, Parkinsonism, schizophrenia) and is “administering” within the method scope.
Most assertable claim groupings (by use-case)
- If the accused product is marketed for cardiovascular effects: likely claims 1–6 and 11–16 clusters.
- If marketed for neurologic/psychiatric: likely claims 21–26 and 31–36 clusters.
Most defendable narrow fallbacks for plaintiff
Named examples plus position-specific dependents often provide clean claim-to-compound mapping:
- 2-amino-6-n-propylamino-4,5,6,7-tetrahydrobenzthiazole
- 2-amino-6-dimethylamino-4,5,6,7-tetrahydrobenzthiazole
- NR3R4 at 5/6 and specifically 6-position dependents
How does US 4,843,086 compare with typical tetrahydro-benzthiazole competitor estates (claim coverage strategy)?
Within the excerpted claims, the strategy mirrors a classic “broad Markush + multiple indications” estate design:
- broad formula to capture many substitution variants,
- multiple independent methods on different indications,
- dependent claim narrowing to positional and substitution-specific subsets,
- and named exemplars to strengthen evidentiary and infringement mapping.
This creates a litigation posture where an accused product can be confronted on:
- at least one independent method claim if structural fit exists, and
- multiple dependent claim variations if positional/substitution elements align.
Timeline: when does US 4,843,086 lose exclusivity?
No filing/issue date, term adjustments, prosecution history, or maintenance status was provided with the claim text. Without those, an exclusivity timeline cannot be computed from the information in your prompt alone.
Key Takeaways
- US 4,843,086 is a multi-indication method-of-use patent covering blood pressure lowering, heart rate lowering, Parkinsonism/Parkinson’s disease, and schizophrenia.
- The structural coverage is broad: tetrahydro-benzthiazole compounds defined by R1–R4 Markush ranges, halogen-substituted phenyl variability, and optional ring-amine formation (pyrrolidino, piperidino, hexamethyleneimino, morpholino).
- Positional dependents are important for enforcement: NR3R4 at 5- or 6-positions and specifically 6-position.
- The patent includes named compound anchors (2-amino-6-n-propylamino- and 2-amino-6-dimethylamino-4,5,6,7-tetrahydro-benzthiazole), which strengthen infringement mapping.
- Risk for generics centers on two questions: (1) whether the generic’s compound falls within the Markush ranges and (2) whether the product is used/prescribed for the claimed indication.
FAQs
1) Does US 4,843,086 cover both compound forms and salts?
Yes. The claims expressly include pharmaceutically acceptable acid addition salts of the covered tetrahydro-benzthiazole compounds.
2) Can a product avoid infringement by changing only R3/R4 substituents?
Potentially. Because R3 and R4 define extensive classes and can alternatively form ring amines, changing N-substitution patterns or the ring-amine construction can move the product outside the claim’s structural definition.
3) Are Parkinsonism and schizophrenia covered by separate independent claims?
Yes. Parkinsonism/Parkinson’s disease is claimed in claims 21, 23, 26, 29, 30, while schizophrenia is claimed in claims 31, 33, 36, 39, 40.
4) Does the patent require cardiovascular endpoints only, or also psychiatric/neurologic outcomes?
It covers both. It includes blood pressure lowering and heart rate lowering plus methods for Parkinsonism/Parkinson’s disease and schizophrenia.
5) What positional limitation appears in multiple dependent claims?
Multiple dependent claims require the group –NR3R4 to be in the 5- or 6-positions (claims 2, 12, 22, 32) and separately in the 6-position (claims 4, 14, 24, 34).
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