Executive summary: US Patent 4,816,456 claims a family of monoamine acridine derivatives (including 1,2,3,4-tetrahydro-5-aminoacridine, “THA”) for treating cholinergic deficit states of the central or peripheral nervous system in mammals, with coverage driven by (i) broad structural Markush ranges for ring substituents R1-R7, (ii) method-of-treatment with an implied pharmacokinetic target (“suitable blood level”), (iii) dose ranges (notably 40 mg to 1 g/day and 100–300 mg/day for THA), and (iv) parallel coverage for pharmaceutical compositions and standalone compounds. The estate is concentrated in medical use and composition-of-matter-like structural claims (independent compound claim plus composition and multiple method claims), creating a litigation posture that typically screens generics by Paragraph IV-style “same active, same use, same dose/formulation” and, for nonclinical entry, by design-around against the specific R-group constraints and blood-level requirement.

US Patent 4,816,456 claim scope and patent landscape for monoamine acridine derivatives (THA/1,2,3,4-tetrahydro-5-aminoacridine) for cholinergic deficit states

What does US 4,816,456 claim for treating cholinergic deficit states?

Core claim theme: Treat mammals with a monoamine acridine derivative via administration to achieve a blood level effective for a cholinergic deficit state (central or peripheral nervous system). The specification text you provided is claim-heavy and contains multiple independent/near-independent claim tracks that fall into four layers:

Method of treating cholinergic deficit states (claims 1, 13; plus disease-specific dependents 6–7 and 15–16).
Method maintaining blood levels within an explicit range (claim 12).
Dose ranges tied to daily administration (claims 8–9, 17–19, 18–19, and composition equivalents).
Composition/compound coverage (pharmaceutical composition claims 21–27, plus compound claims 28 and 36, and composition claim 30–35 and claim 37).

Primary independent claim: claim 1

Claim 1 is the broadest method scaffold:

Treat central nervous system or peripheral nervous system cholinergic deficit state in a mammal.
Administer a monoamine acridine derivative effective for treatment.
Administer for a time sufficient to achieve a suitable blood level.
Compound must fall within a Markush structural formula with substituent constraints at positions R1–R7, including:
- R1: hydrogen/hydroxy/methyl/methoxy/ethyl/ethoxy
- R1 and R2 optionally form a double bond; R3 and R4 optionally form a double bond; or certain hydrogen-only configurations
- R5: hydrogen/hydroxy/methoxy/ethoxy
- R6: hydrogen/hydroxy/methoxy/ethoxy
- R7: either no substituent or oxygen atom
- plus an alternative R7 group: C1–C20 alkyl radical or a specified group set (##STR22) with each R independently C1–C20 alkyl
- plus pharmaceutically acceptable salts.

Litigation implication: This is not a narrow “THA-only” claim. It is a structure-defined therapeutic method. In enforcement, the patentee does not need to prove “Alzheimer’s” if the claim covers other CNS/PNS cholinergic deficit states and the accused product fits the Markush structure.

Disease-specific dependents under method claims

Claim 6 narrows claim 1 to enumerated conditions including:

Alzheimer’s disease
Myasthenia gravis
Huntington’s chorea
tardive dyskinesia
dementia associated with Down’s syndrome
Parkinson’s disease

Claim 7 specifies Alzheimer’s disease as a dependent narrowing route.

Scope effect: Dependents reduce the field but are often where disputes focus because real products are indicated for a specific disease.

How broad is the chemical Markush structure in US 4,816,456?

Across method, composition, and compound tracks, the same structural logic appears with variations in the allowed definition of R7.

Key structure variables (as provided)

Positions/substituent rules that drive breadth:

R1 can be H, OH, Me, OMe, Et, OEt.
Unsaturation options: R1+R2 or R3+R4 can form a double bond, or certain positions all hydrogen.
R5/R6 limited to H, OH, OMe, OEt.
R7 changes in different claim contexts:
- In claim 1 (and the related method scaffolds), R7 is “without substituent or oxygen atom,” with additional allowance language referencing alkyl (C1–C20) or specified radicals.
- In claim 28/36 (compound), R7 is explicitly C1–C20 alkyl or selected radicals from a listed group set.

Markush breadth practical takeaway

The claim is broad enough that multiple acridine hydrogenation states and substitution patterns can fall within scope, provided they match the exact constraints on R5/R6 and the R1 set and the double-bond/hydrogen configurations described.

Design-around leverage typically targets:

violating R5/R6 set membership (e.g., adding halogens or different heteroatoms not allowed),
changing unsaturation patterns outside the allowed double-bond configurations,
changing R7 away from the permitted “no substituent/oxygen/allowed alkyl or allowed radicals” regimes.

Which specific compound embodiments are explicitly covered (THA/1,2,3,4-tetrahydro-5-aminoacridine)?

Two explicit anchors appear in the claim text you provided:

Claim 4: method where the monoamine acridine derivative is 1,2,3,4-tetrahydro-5-aminoacridine.
Claim 11: Alzheimer’s method with 100–300 mg/24h of 1,2,3,4-tetrahydro-5-aminoacridine plus inert carrier.
Claim 14 and 16 mirror disease narrowing for oral dosing routes.

Compound claims 28 and 36 are standalone structural coverage. Claim 28 appears to list a compound formula with variable R7 as alkyl or substituted group set. Claim 36 includes provisos that function as negative limitations.

Enforcement impact: THA is not only a dependent embodiment. The independent compound claims can cover THA if THA’s structure matches the R1–R7 constraints and the provisos.

What dosing and blood-level limitations exist in US 4,816,456?

Daily dose windows

Your provided claims specify multiple ranges:

Claim 8: 40 mg to 1 g per 24 hours.
Claim 9: 100 mg to 300 mg per 24 hours.
Claim 11: Alzheimer’s method at 100 mg to 300 mg per 24 hours.
Claim 17: 40 mg to 1 g per 24 hours under the alternative method scaffold (claim 13 track).
Claim 18: 100 mg to 300 mg per 24 hours.
Claim 19: 100 mg to 200 mg per 24 hours (narrower dependent).
Composition equivalents mirror these ranges (claims 26–27, 33–35).

Blood-level maintenance claim

Claim 12 defines maintaining a blood level of 5 μg to 70 μg of the monoamine acridine derivative.

Scope effect: If an accused product argues it does not maintain blood levels in that window, claim 12 may be harder for the patentee. However, claim 1 and claim 13 are broader because they require administration “for a time sufficient to achieve a suitable blood level” rather than a fixed numeric range.

What administration routes are claimed in US 4,816,456?

Claim 2: oral, intramuscular, subcutaneous, rectal, or topical.
Claim 3: oral.
Claim 13: oral administering (independent method track).
Composition claims 22–23: suitable for oral and multiple non-oral routes.

Practical enforcement: Route limitations matter for method claims. Composition-of-matter-like “unit dosage + carrier” claims are harder to circumvent by route changes if the claimed composition is still made/marketed.

What is the patent coverage for pharmaceutical compositions (and what provisos limit R7)?

Composition claim set 21–27

Claim 21: “pharmaceutical composition of matter” including a unit dosage amount of the monoamine acridine derivative plus inert carrier, with three provisos that restrict how R1–R7 can be combined:
1. If R1–R6 are each hydrogen, then R7 cannot be without a substituent.
2. If R1 and R2 form a double bond, R3 and R4 form a double bond, and R5 and R6 are hydrogen, then R7 cannot be without a substituent.
3. If R3 and R4 form a double bond and R7 is without a substituent, then R1 cannot be hydrogen.
Claim 22 and 23: administration suitability (multi-route; oral).
Claims 24–25: disease narrowing (Alzheimer’s included).
Claims 26–27: 40 mg–1 g and 100–300 mg per unit dosage.

Composition claim set 30–35

Claim 30 repeats the “composition of matter” concept with the same provisos.
Claims 31–32 narrow to diseases including Alzheimer’s.
Claims 33–35 set dose ranges (40 mg–1 g; 100–300 mg; 100–200 mg).

Composition claim 37

Claim 37 expands R7 to include oxygen atom or radical selected from a group set including alkyl-substituted radicals, again with the same style of provisos restricting combinations.

Scope effect: The provisos are the main internal claim-consistency constraints. They function as negative claim limitations that must be respected for infringement. The provisos can also help in litigation by providing more exact structure exclusions.

What does US 4,816,456 claim as “compounds” (not just methods/compositions)?

Two explicit compound claim anchors appear in your text:

Claim 28: A compound having a defined formula where R7 is C1–C20 alkyl or a listed radical set (##STR30), with R1–R6 and double-bond rules described.
Claim 36: A second compound claim with the defined formula and provisos mirroring those in composition claim 21.

Scope effect: Standalone compound claims broaden the enforceable perimeter because they can cover:

the active ingredient itself as made and sold,
regardless of whether the accused party markets a method-of-use label,
subject to the exact match of structural definition and provisos.

This matters when a potential competitor markets a derivative or prodrug with the same backbone. The compound claim can still reach if the derivative falls in the Markush definition.

How does the claim set align to likely infringement theories (AND/OR pathways)?

Given the layered claim architecture, there are three common infringement patterns:

Active-ingredient product coverage (compound claims 28/36 + composition claims 21/30/37 + method claims 1/13).
- If the competitor sells THA or another covered monoamine acridine derivative in a dosage unit, the composition and compound claims are the easiest entry points.
Indication/label and regimen coverage (method claims 6–7, 15–16; dose dependent 9/11/18/19).
- If the product is labeled for Alzheimer’s and dosing matches the claimed windows, method claims become highly actionable.
PK-window coverage (claim 12).
- If blood levels are empirically shown to fall in the specified 5–70 μg range for the accused regimen, claim 12 can be added as a numeric tightening lever.

What does this mean for a generic or biosimilar entry risk profile?

Biosimilar risk: Not applicable. This is a small molecule patent, not a biologic.

Generic risk (small-molecule) is tied to three vectors:

Same active: Does the ANDA/generic contain a monoamine acridine derivative within the Markush scope?
Same regimen: If method claims are asserted, does the label instruct use for cholinergic deficit states (including Alzheimer’s) and does dosing align with 40 mg–1 g/day or 100–300 mg/day dependencies?
Blood level window: If claim 12 is asserted, does the regimen maintain 5–70 μg blood levels?

Design-around probability: Structural Markush claims increase freedom for a challenger to attempt alternate substituents, but the R-group space is still constrained by:

R5/R6 limited set,
R7 allowed substituent regimes,
provisos blocking “all hydrogen” combinations and certain unsaturation combos.

How strong is US 4,816,456’s enforceability based on claim structure and limitation density?

Claim strength drivers:

Independent compound claims (28, 36) plus composition claims (21, 30, 37) reduce dependence on label and patient instructions.
Multiple method claim scaffolds cover both CNS/PNS cholinergic deficit states and Alzheimer’s specifically.
Dose ranges are present and likely map to clinical dosing schedules.

Claim vulnerability drivers:

The Markush definition is broad but not unlimited. The claim contains multiple conditional provisos that can be used to narrow infringement arguments.
Blood-level claim 12 is numeric and can be harder to prove if regimen differs.

Net assessment: The estate is structurally robust because it is not limited to “use only” claims. It combines compound coverage with composition and method coverage, increasing the probability that at least one claim reads on an accused product.

What patents or legal events could affect the landscape for US 4,816,456?

Your prompt requests a “patent landscape,” but no bibliographic data (patent title, applicants/assignee, filing/priority dates, continuations, related patents, or litigation docket numbers) was provided. Without that dataset, it is not possible to produce a complete, accurate map of:

family members in the US and other jurisdictions,
continuation status,
post-grant events affecting validity/enforceability,
related patents covering formulation variants, polymorphs, prodrugs, or additional dosing regimens,
FDA Orange Book listings or Paragraph IV filings tied to specific products.

Per the operating constraints, this analysis therefore limits itself to claim scope and the intra-patent landscape within the provided claims, not cross-patent or cross-regulatory assertions that would require verifiable external data.

Key Takeaways

US 4,816,456 covers monoamine acridine derivatives for CNS/PNS cholinergic deficit states using a broad Markush structural formula with constraints on R1–R7, including an explicit embodiment for 1,2,3,4-tetrahydro-5-aminoacridine (THA).
The patent combines method-of-treatment claims (including Alzheimer’s-specific dependents), dose ranges (notably 40 mg–1 g/day and 100–300 mg/day), a numeric blood-level maintenance claim (5–70 μg), and pharmaceutical composition claims with provisos that restrict R-group combinations.
Standalone compound claims (28, 36) and composition claims increase enforceability beyond label-based infringement.
For competitor entry, the practical risk assessment centers on whether the product’s active ingredient and formulation fall within the structural limits and, for method claims, whether the labeled/dosed regimen aligns with the claimed dosing and disease framework.

FAQs

Does US 4,816,456 require Alzheimer’s specifically to infringe method claims?
No. Alzheimer’s appears as a dependent narrowing route; independent method coverage extends to broader CNS/PNS cholinergic deficit states.
What is the tightest dosing limitation in the claim set you provided?
The narrowest daily window shown is 100 mg to 200 mg per 24 hours (dependent claim 19 and composition dependent claim 35).
How does claim 12’s blood-level window change infringement leverage?
It adds a numeric PK condition (5–70 μg) that can be contested via regimen and measured exposure, unlike the broader “suitable blood level” language in claims 1/13.
Can a competitor avoid infringement by changing administration route?
Route changes can help against route-specific method dependents, but composition claims are not limited to a single route and independent method claim language varies (claim 2 includes multi-route; claim 13 is oral).
Is the patent’s strongest target likely the active ingredient or the clinical use?
The patent is strongest where compound and composition claims read on the active ingredient and marketed dosage form, with method claims supporting enforcement when disease indication and dosing align.

References

United States Patent 4,816,456 (provided claim text).

Title:	Administration of monoamine acridines in cholinergic neuronal deficit states
Abstract:	A method for treating central nervous system or peripheral nervous system cholinergic deficit states such as Alzheimer's disease in a mammal, said method comprising administering to said mammal an amount of a monoamine acridine derivative effective in the treatment of a cholinergic deficit state and for a time sufficient to achieve a suitable blood level to treat said cholinergic deficit state. The preferred monoamine acridine derivative is 1,2,3,4-tetrahydro-5-aminoacridine. A unit dosage pharmaceutical composition of matter comprising an effective amount of said monoamine acridine derivative sufficient to treat said cholinergic deficit state and a pharmaceutically acceptable inert carrier therefor is also disclosed.
Inventor(s):	William K. Summers
Assignee:	Individual
Application Number:	US07/098,871
Patent Claim Types: see list of patent claims	Use; Composition; Delivery; Dosage form;
Patent landscape, scope, and claims:	Executive summary: US Patent 4,816,456 claims a family of monoamine acridine derivatives (including 1,2,3,4-tetrahydro-5-aminoacridine, “THA”) for treating cholinergic deficit states of the central or peripheral nervous system in mammals, with coverage driven by (i) broad structural Markush ranges for ring substituents R1-R7, (ii) method-of-treatment with an implied pharmacokinetic target (“suitable blood level”), (iii) dose ranges (notably 40 mg to 1 g/day and 100–300 mg/day for THA), and (iv) parallel coverage for pharmaceutical compositions and standalone compounds. The estate is concentrated in medical use and composition-of-matter-like structural claims (independent compound claim plus composition and multiple method claims), creating a litigation posture that typically screens generics by Paragraph IV-style “same active, same use, same dose/formulation” and, for nonclinical entry, by design-around against the specific R-group constraints and blood-level requirement. US Patent 4,816,456 claim scope and patent landscape for monoamine acridine derivatives (THA/1,2,3,4-tetrahydro-5-aminoacridine) for cholinergic deficit states What does US 4,816,456 claim for treating cholinergic deficit states? Core claim theme: Treat mammals with a monoamine acridine derivative via administration to achieve a blood level effective for a cholinergic deficit state (central or peripheral nervous system). The specification text you provided is claim-heavy and contains multiple independent/near-independent claim tracks that fall into four layers: Method of treating cholinergic deficit states (claims 1, 13; plus disease-specific dependents 6–7 and 15–16). Method maintaining blood levels within an explicit range (claim 12). Dose ranges tied to daily administration (claims 8–9, 17–19, 18–19, and composition equivalents). Composition/compound coverage (pharmaceutical composition claims 21–27, plus compound claims 28 and 36, and composition claim 30–35 and claim 37). Primary independent claim: claim 1 Claim 1 is the broadest method scaffold: Treat central nervous system or peripheral nervous system cholinergic deficit state in a mammal. Administer a monoamine acridine derivative effective for treatment. Administer for a time sufficient to achieve a suitable blood level. Compound must fall within a Markush structural formula with substituent constraints at positions R1–R7, including: R1: hydrogen/hydroxy/methyl/methoxy/ethyl/ethoxy R1 and R2 optionally form a double bond; R3 and R4 optionally form a double bond; or certain hydrogen-only configurations R5: hydrogen/hydroxy/methoxy/ethoxy R6: hydrogen/hydroxy/methoxy/ethoxy R7: either no substituent or oxygen atom plus an alternative R7 group: C1–C20 alkyl radical or a specified group set (##STR22) with each R independently C1–C20 alkyl plus pharmaceutically acceptable salts. Litigation implication: This is not a narrow “THA-only” claim. It is a structure-defined therapeutic method. In enforcement, the patentee does not need to prove “Alzheimer’s” if the claim covers other CNS/PNS cholinergic deficit states and the accused product fits the Markush structure. Disease-specific dependents under method claims Claim 6 narrows claim 1 to enumerated conditions including: Alzheimer’s disease Myasthenia gravis Huntington’s chorea tardive dyskinesia dementia associated with Down’s syndrome Parkinson’s disease Claim 7 specifies Alzheimer’s disease as a dependent narrowing route. Scope effect: Dependents reduce the field but are often where disputes focus because real products are indicated for a specific disease. How broad is the chemical Markush structure in US 4,816,456? Across method, composition, and compound tracks, the same structural logic appears with variations in the allowed definition of R7. Key structure variables (as provided) Positions/substituent rules that drive breadth: R1 can be H, OH, Me, OMe, Et, OEt. Unsaturation options: R1+R2 or R3+R4 can form a double bond, or certain positions all hydrogen. R5/R6 limited to H, OH, OMe, OEt. R7 changes in different claim contexts: In claim 1 (and the related method scaffolds), R7 is “without substituent or oxygen atom,” with additional allowance language referencing alkyl (C1–C20) or specified radicals. In claim 28/36 (compound), R7 is explicitly C1–C20 alkyl or selected radicals from a listed group set. Markush breadth practical takeaway The claim is broad enough that multiple acridine hydrogenation states and substitution patterns can fall within scope, provided they match the exact constraints on R5/R6 and the R1 set and the double-bond/hydrogen configurations described. Design-around leverage typically targets: violating R5/R6 set membership (e.g., adding halogens or different heteroatoms not allowed), changing unsaturation patterns outside the allowed double-bond configurations, changing R7 away from the permitted “no substituent/oxygen/allowed alkyl or allowed radicals” regimes. Which specific compound embodiments are explicitly covered (THA/1,2,3,4-tetrahydro-5-aminoacridine)? Two explicit anchors appear in the claim text you provided: Claim 4: method where the monoamine acridine derivative is 1,2,3,4-tetrahydro-5-aminoacridine. Claim 11: Alzheimer’s method with 100–300 mg/24h of 1,2,3,4-tetrahydro-5-aminoacridine plus inert carrier. Claim 14 and 16 mirror disease narrowing for oral dosing routes. Compound claims 28 and 36 are standalone structural coverage. Claim 28 appears to list a compound formula with variable R7 as alkyl or substituted group set. Claim 36 includes provisos that function as negative limitations. Enforcement impact: THA is not only a dependent embodiment. The independent compound claims can cover THA if THA’s structure matches the R1–R7 constraints and the provisos. What dosing and blood-level limitations exist in US 4,816,456? Daily dose windows Your provided claims specify multiple ranges: Claim 8: 40 mg to 1 g per 24 hours. Claim 9: 100 mg to 300 mg per 24 hours. Claim 11: Alzheimer’s method at 100 mg to 300 mg per 24 hours. Claim 17: 40 mg to 1 g per 24 hours under the alternative method scaffold (claim 13 track). Claim 18: 100 mg to 300 mg per 24 hours. Claim 19: 100 mg to 200 mg per 24 hours (narrower dependent). Composition equivalents mirror these ranges (claims 26–27, 33–35). Blood-level maintenance claim Claim 12 defines maintaining a blood level of 5 μg to 70 μg of the monoamine acridine derivative. Scope effect: If an accused product argues it does not maintain blood levels in that window, claim 12 may be harder for the patentee. However, claim 1 and claim 13 are broader because they require administration “for a time sufficient to achieve a suitable blood level” rather than a fixed numeric range. What administration routes are claimed in US 4,816,456? Claim 2: oral, intramuscular, subcutaneous, rectal, or topical. Claim 3: oral. Claim 13: oral administering (independent method track). Composition claims 22–23: suitable for oral and multiple non-oral routes. Practical enforcement: Route limitations matter for method claims. Composition-of-matter-like “unit dosage + carrier” claims are harder to circumvent by route changes if the claimed composition is still made/marketed. What is the patent coverage for pharmaceutical compositions (and what provisos limit R7)? Composition claim set 21–27 Claim 21: “pharmaceutical composition of matter” including a unit dosage amount of the monoamine acridine derivative plus inert carrier, with three provisos that restrict how R1–R7 can be combined: If R1–R6 are each hydrogen, then R7 cannot be without a substituent. If R1 and R2 form a double bond, R3 and R4 form a double bond, and R5 and R6 are hydrogen, then R7 cannot be without a substituent. If R3 and R4 form a double bond and R7 is without a substituent, then R1 cannot be hydrogen. Claim 22 and 23: administration suitability (multi-route; oral). Claims 24–25: disease narrowing (Alzheimer’s included). Claims 26–27: 40 mg–1 g and 100–300 mg per unit dosage. Composition claim set 30–35 Claim 30 repeats the “composition of matter” concept with the same provisos. Claims 31–32 narrow to diseases including Alzheimer’s. Claims 33–35 set dose ranges (40 mg–1 g; 100–300 mg; 100–200 mg). Composition claim 37 Claim 37 expands R7 to include oxygen atom or radical selected from a group set including alkyl-substituted radicals, again with the same style of provisos restricting combinations. Scope effect: The provisos are the main internal claim-consistency constraints. They function as negative claim limitations that must be respected for infringement. The provisos can also help in litigation by providing more exact structure exclusions. What does US 4,816,456 claim as “compounds” (not just methods/compositions)? Two explicit compound claim anchors appear in your text: Claim 28: A compound having a defined formula where R7 is C1–C20 alkyl or a listed radical set (##STR30), with R1–R6 and double-bond rules described. Claim 36: A second compound claim with the defined formula and provisos mirroring those in composition claim 21. Scope effect: Standalone compound claims broaden the enforceable perimeter because they can cover: the active ingredient itself as made and sold, regardless of whether the accused party markets a method-of-use label, subject to the exact match of structural definition and provisos. This matters when a potential competitor markets a derivative or prodrug with the same backbone. The compound claim can still reach if the derivative falls in the Markush definition. How does the claim set align to likely infringement theories (AND/OR pathways)? Given the layered claim architecture, there are three common infringement patterns: Active-ingredient product coverage (compound claims 28/36 + composition claims 21/30/37 + method claims 1/13). If the competitor sells THA or another covered monoamine acridine derivative in a dosage unit, the composition and compound claims are the easiest entry points. Indication/label and regimen coverage (method claims 6–7, 15–16; dose dependent 9/11/18/19). If the product is labeled for Alzheimer’s and dosing matches the claimed windows, method claims become highly actionable. PK-window coverage (claim 12). If blood levels are empirically shown to fall in the specified 5–70 μg range for the accused regimen, claim 12 can be added as a numeric tightening lever. What does this mean for a generic or biosimilar entry risk profile? Biosimilar risk: Not applicable. This is a small molecule patent, not a biologic. Generic risk (small-molecule) is tied to three vectors: Same active: Does the ANDA/generic contain a monoamine acridine derivative within the Markush scope? Same regimen: If method claims are asserted, does the label instruct use for cholinergic deficit states (including Alzheimer’s) and does dosing align with 40 mg–1 g/day or 100–300 mg/day dependencies? Blood level window: If claim 12 is asserted, does the regimen maintain 5–70 μg blood levels? Design-around probability: Structural Markush claims increase freedom for a challenger to attempt alternate substituents, but the R-group space is still constrained by: R5/R6 limited set, R7 allowed substituent regimes, provisos blocking “all hydrogen” combinations and certain unsaturation combos. How strong is US 4,816,456’s enforceability based on claim structure and limitation density? Claim strength drivers: Independent compound claims (28, 36) plus composition claims (21, 30, 37) reduce dependence on label and patient instructions. Multiple method claim scaffolds cover both CNS/PNS cholinergic deficit states and Alzheimer’s specifically. Dose ranges are present and likely map to clinical dosing schedules. Claim vulnerability drivers: The Markush definition is broad but not unlimited. The claim contains multiple conditional provisos that can be used to narrow infringement arguments. Blood-level claim 12 is numeric and can be harder to prove if regimen differs. Net assessment: The estate is structurally robust because it is not limited to “use only” claims. It combines compound coverage with composition and method coverage, increasing the probability that at least one claim reads on an accused product. What patents or legal events could affect the landscape for US 4,816,456? Your prompt requests a “patent landscape,” but no bibliographic data (patent title, applicants/assignee, filing/priority dates, continuations, related patents, or litigation docket numbers) was provided. Without that dataset, it is not possible to produce a complete, accurate map of: family members in the US and other jurisdictions, continuation status, post-grant events affecting validity/enforceability, related patents covering formulation variants, polymorphs, prodrugs, or additional dosing regimens, FDA Orange Book listings or Paragraph IV filings tied to specific products. Per the operating constraints, this analysis therefore limits itself to claim scope and the intra-patent landscape within the provided claims, not cross-patent or cross-regulatory assertions that would require verifiable external data. Key Takeaways US 4,816,456 covers monoamine acridine derivatives for CNS/PNS cholinergic deficit states using a broad Markush structural formula with constraints on R1–R7, including an explicit embodiment for 1,2,3,4-tetrahydro-5-aminoacridine (THA). The patent combines method-of-treatment claims (including Alzheimer’s-specific dependents), dose ranges (notably 40 mg–1 g/day and 100–300 mg/day), a numeric blood-level maintenance claim (5–70 μg), and pharmaceutical composition claims with provisos that restrict R-group combinations. Standalone compound claims (28, 36) and composition claims increase enforceability beyond label-based infringement. For competitor entry, the practical risk assessment centers on whether the product’s active ingredient and formulation fall within the structural limits and, for method claims, whether the labeled/dosed regimen aligns with the claimed dosing and disease framework. FAQs Does US 4,816,456 require Alzheimer’s specifically to infringe method claims? No. Alzheimer’s appears as a dependent narrowing route; independent method coverage extends to broader CNS/PNS cholinergic deficit states. What is the tightest dosing limitation in the claim set you provided? The narrowest daily window shown is 100 mg to 200 mg per 24 hours (dependent claim 19 and composition dependent claim 35). How does claim 12’s blood-level window change infringement leverage? It adds a numeric PK condition (5–70 μg) that can be contested via regimen and measured exposure, unlike the broader “suitable blood level” language in claims 1/13. Can a competitor avoid infringement by changing administration route? Route changes can help against route-specific method dependents, but composition claims are not limited to a single route and independent method claim language varies (claim 2 includes multi-route; claim 13 is oral). Is the patent’s strongest target likely the active ingredient or the clinical use? The patent is strongest where compound and composition claims read on the active ingredient and marketed dosage form, with method claims supporting enforcement when disease indication and dosing align. References United States Patent 4,816,456 (provided claim text). 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Details for Patent: 4,816,456

Summary for Patent: 4,816,456