Details for Patent: 4,895,841

Scope and claim analysis of US Drug Patent 4,895,841 (cyclic amine acetylcholinesterase inhibitors) and the US patent landscape around it

US Patent 4,895,841 covers a defined chemical space of cyclic amine compounds (piperidine derivatives) and claims therapeutic compositions and methods for diseases caused by acetylcholinesterase activity, with explicit examples tied to senile dementia and Alzheimer-type senile dementia. The claim set is structurally broad on ring size and substituent classes, while narrowing on a specific phenylalkyl K substituent and an indanon aromatic substitution pattern that includes a methylenedioxy/ethylenedioxy option.

What exactly is claimed in US 4,895,841 and how broad is it?

Core claim (Claim 1) is a genus claim to “a cyclic amine compound having the formula” with parameters controlling:

• the cyclic amine scaffold (through r and a piperidine/alkyl variation),
• the indanon aromatic substitution pattern (through S and t),
• the benzyl/phenylalkyl N-substituent (through K),
• the phenylalkyl substituent length by the same K definition, and
• ring substituent at R22 controlled by R22 = hydrogen or methyl.

It also covers pharmacologically acceptable salts.

Claim 1 parameter map (read as claim construction levers)

Claim 1 recites a compound class defined by:

• r = 1 to 10, with a constraint on R22:
  • R22 is hydrogen or methyl
  • R22 radicals can be the same or different when r is from 2 to 10
• K is phenylalkyl or phenylalkyl having a substituent on the phenyl ring
• S is hydrogen or a substituent on the phenyl ring
• t = 1 to 4, with a proviso that:
  • (S)t can be a methylenedioxy group or an ethylenedioxy group joined to two adjacent carbon atoms of the phenyl ring
• q = 1 to 3
• plus pharmacologically acceptable salt(s)

Practical implication: Claim 1 is broad in the number of substitutable positions (t up to 4, q up to 3) and ring substitution multiplicity (r up to 10 with possible mixed R22 substitution). That breadth is then bounded by the requirement that the compound fits the particular structural formula and that the aromatic substitution conforms to the S/t/methylenedioxy/ethylenedioxy constraints, and the K moiety falls within phenylalkyl (optionally substituted phenylalkyl).

Which specific compounds are explicitly covered by dependent claims?

Claims 2-9 narrow Claim 1 using specific numerical parameters and named substituent examples. These dependents function as:

• fallback positions for infringement scope (if accused products land near the genus limits), and
• evidence of the inventor’s intended “core” embodiments.

Dependent claims focusing r, q, K, and S

• Claim 2: q = 2
• Claim 3: K is benzyl, m-nitrobenzyl, or m-fluorobenzyl
• Claim 4: q = 2 and K is benzyl
• Claim 5: S is lower alkyl C1-C6 or lower alkoxy C1-C6
• Claim 6: S is methoxy and t is 1 to 3
• Claim 7: r is 1 to 3

Explicitly enumerated compounds (Claim 8 and Claim 9)

• Claim 8: specifically recites
  1-benzyl-4-((5,6-dimethoxy-1-indanon)-2-yl)methylpiperidine (or pharmacologically acceptable salt)

• Claim 9: includes a defined set of named species, all built on the same general framework:

  1. 1-benzyl-4-((5-methoxy-1-indanon)-2-yl)methylpiperidine
  2. 1-benzyl-4-((5,6-diethoxy-1-indanon)-2-yl)methylpiperidine
  3. 1-benzyl-4-((5,6-methylenedioxy-1-indanon)-2-yl)methylpiperidine
  4. 1-(m-nitrobenzyl)-4-((5,6-dimethoxy-1-indanon)-2-yl)methylpiperidine
  5. 1-(m-fluorobenzyl)-4-((5,6-dimethoxy-1-indanon)-2-yl)methylpiperidine
  6. 1-benzyl-4-((5,6-dimethoxy-1-indanon)-2-yl)propylpiperidine
  7. 1-benzyl-4-((5-isopropoxy-6-methoxy-1-indanon)-2-yl)methylpiperidine

Practical implication: Claim 9 and Claim 8 convert some of the genus parameters into a tight list of “high-likelihood” infringing structures (benzyl with specific indanon oxygenation patterns and optional m-nitro/m-fluoro benzyl substituents, plus one propylpiperidine variant).

What is protected beyond the compound itself: compositions and methods?

The patent also covers therapeutic composition and use claims tied to the same “disease caused by acetylcholinesterase activity” theme.

Composition claim (Claim 10)

• Therapeutic composition comprising:
  • pharmacologically effective amount of the compound of Claim 1 (or salt)
  • pharmacologically acceptable carrier

Scope: broad on formulation excipients/carrier, as long as the active is within the Claim 1 compound definition (or salt).

Method-of-treatment claims (Claims 11-13)

• Claim 11: method for treating a disease caused by acetylcholinesterase activity by administering the compound (or salt) to a human patient
• Claim 12: disease is senile dementia
• Claim 13: disease is senile dementia of the Alzheimer type

Practical implication: These are use claims that can capture clinical use even if a product is framed as a therapeutic indication; they also matter for method-of-use carveouts in licensing and litigation because they are not limited by dose form.

How do the claim elements likely constrain infringement?

In US patent claim practice, genus claims still require the accused product to satisfy every structural limitation of Claim 1 as construed.

Key constraint clusters

1. Cyclic amine framework is not generic “any acetylcholinesterase inhibitor”; it is tied to the specific cyclic amine formula with parameters r, q, and R22.
2. K must be phenylalkyl (optionally substituted phenyl ring), which likely excludes aliphatic-only N-alkyl groups not matching phenylalkyl geometry/connection.
3. Indanon ring substitution is controlled by S and t, with special treatment for methylenedioxy/ethylenedioxy patterns joined to adjacent ring carbons.
4. Species fallbacks via Claim 8 and Claim 9 increase enforceability in practice for near-copy molecules.

How might validity arguments be framed for a genus like Claim 1?

Without the full specification, the patent landscape cannot be mapped to specific prior art dates or references. Still, the claim structure indicates typical validity pressure points:

• Broad parameterization (r 1-10, t 1-4, q 1-3) increases exposure to prior art that may disclose overlapping ranges.
• Genus with embedded “special-case” proviso (methylenedioxy/ethylenedioxy) can be attacked if prior art discloses those substitution patterns within the same scaffold.
• Narrowed named species (Claims 8-9) can survive if they are shown to be distinct from prior art embodiments even if the broader genus is challenged.

What does the patent landscape likely look like around US 4,895,841?

US 4,895,841’s scope indicates it belongs to the classic small-molecule AChE inhibitor space using benzylated cyclic amines. A typical surrounding landscape pattern in this art (for related compounds and related claims) is:

• Companion “process” patents (manufacturing routes) covering intermediates and salts.
• Additional “formulation” patents targeting oral or other delivery systems for the same actives.
• Derivative chemical patents around different N-substituents (changes to K), alternative ring substituents (changes to S), and alternative substitution placement patterns on the indanon phenyl ring (changes to t logic).
• Use patents that further specify disease subtypes, dosing regimens, or combination therapy.

However, no Orange Book entry, litigation docket, continuation family member, or specific co-pending patent numbers are provided in the prompt, so those landscape items cannot be stated with precision.

What commercial and litigation risk follows from this claim structure?

Risk drivers for would-be generics or entrants

• If a competitor product is a salt or close analogue that literally fits Claim 1, the compound claim is a direct barrier.
• If an entrant designs around Claim 1 by changing K (non-phenylalkyl N-substitution) or altering the indanon oxygenation scheme such that it no longer fits S/t provisos, the entrant may avoid compound coverage but could still face:
  • composition claim coverage if the active remains within Claim 1 definition, or
  • method-of-use coverage if the active is within Claim 1 and the intended indication matches acetylcholinesterase-caused disease use.

Why Claims 8-9 matter in enforcement

Courts often see higher infringement likelihood for enumerated embodiments because synthesis and characterization line up tightly. If a commercial candidate is one of the Claim 8/9 listed structures or a salt, the infringement path is simpler.

Claim-by-claim scope summary table

Key Takeaways

• US 4,895,841 is a genus-driven chemical patent (Claim 1) on cyclic amine compounds with parameterized constraints on r, q, R22, K, and S/t plus an explicit methylenedioxy/ethylenedioxy proviso tied to adjacent ring carbons.
• The patent’s enforcement posture is strengthened by named species in Claims 8 and 9 that define specific benzylated indanon- and piperidine-based actives, including methoxy/diethoxy/dimethoxy and methylenedioxy patterns and m-nitro/m-fluoro benzyl variants.
• It also covers therapeutic compositions (Claim 10) and method-of-use claims for diseases caused by acetylcholinesterase activity, with explicit ties to senile dementia and Alzheimer-type senile dementia (Claims 11-13).
• Practically, the highest infringement risk zones are products whose active ingredients are within Claim 1 and especially those matching the exact Claim 8/9 structures, including salts.

FAQs

1. Does US 4,895,841 cover pharmacologically acceptable salts, not just free bases?
   Yes, Claim 1 and dependent claims expressly include pharmacologically acceptable salts.

2. What structural change most easily avoids coverage under Claim 1?
   Changes that move the N-substituent outside phenylalkyl (the K limitation) or remove conformity with the S/t indanon substitution pattern, including the methylenedioxy/ethylenedioxy adjacent-carbon proviso.

3. Are the listed compounds in Claims 8 and 9 limited to the methylpiperidine form only?
   No. Claim 9 includes 1-benzyl-4-((5,6-dimethoxy-1-indanon)-2-yl)propylpiperidine, so a propylpiperidine variant is covered in the named set.

4. Is the method-of-use claim limited to Alzheimer’s disease only?
   No. Claim 11 covers “a disease caused by acetylcholinesterase activity,” with Claims 12 and 13 specifying senile dementia and Alzheimer type.

5. Does Claim 10 require a specific formulation or excipient?
   No. Claim 10 requires a pharmacologically acceptable carrier, without specifying a particular excipient system in the claim text.

References

1. United States Patent 4,895,841. “Cyclic amine compounds and their use as acetylcholinesterase inhibitors.” (Claim text as provided).