United States Patent 4,507,305: Scope of Claims, Claim Construction, and US Patent Landscape

US Patent 4,507,305 claims a specific antiviral nucleoside compound and compositions/methods around its administration routes. The claim set is narrow on chemistry (compound identity is fixed) and broad on use cases (multiple virus labels, multiple administration routes, human coverage).

What does US 4,507,305 claim, in plain scope terms?

Core active (hard limit)

All substantive claims revolve around one compound identity:

9-(1,3-dihydroxy-2-propoxymethyl)guanine
or a pharmaceutically acceptable salt of that compound

This compound identity functions as the primary boundary of infringement scope. Any design-around that changes the chemical entity is outside these claim constructs, regardless of antiviral activity.

Composition claims (injectable)

Claims 1-3 define an injectable pharmaceutical composition:

Claim 1: injectable composition for treating viral infections in a mammal
- contains an effective amount of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (or acceptable salt)
- - pharmaceutically acceptable carrier
Claim 2: composition of claim 1 where the salt is an alkali metal salt
Claim 3: salt is specifically the sodium salt

Practical read-through: the composition claims target both the compound form and formulation class (injectables with carriers). They do not specify concentration ranges, excipients, pH, particle size, isotonicity, or sterilization attributes in the claim text provided, which makes the injectable “carrier” language a broader net than if formulation parameters were required.

Method claims (treating by administration)

Claims 4-10 cover treatment by administering the composition:

Claim 4: method of treating viral infection by administering an effective amount of the claim 1 composition
Claim 5: mammal is human
Claims 6-10: virus labels:
- Herpes Simplex virus type I (HSV-1)
- Herpes Simplex virus type II (HSV-2)
- Cytomegalovirus (CMV)
- Epstein-Barr virus (EBV)
- Varicella Zoster virus (VZV)

Claims 11-16 cover oral administration:

Claim 11: method by orally administering effective amount of the compound or a pharmaceutically acceptable salt
Claims 12-16: same virus label list as above (HSV-1, HSV-2, CMV, EBV, VZV)

Claims 17-20 cover topical administration:

Claim 17: method by topically administering effective amount of the compound or a pharmaceutically acceptable salt
Claims 18-20: virus labels include HSV-1, HSV-2, and VZV
- Note: the claim text includes “vericella Zoster virus” in claim 20, but the intended virus appears to be Varicella Zoster virus.

Practical read-through: the same compound supports parallel infringement theories across injectable, oral, and topical routes. The claims also include both composition-based administration (injectable uses composition of claim 1) and direct compound/salt administration (oral and topical use compound or salt, without requiring the specific “carrier” language of claim 1).

What is the legal and commercial shape of the claim scope?

1) The compound identity is the main gate

Any product that does not contain 9-(1,3-dihydroxy-2-propoxymethyl)guanine or an equivalent “pharmaceutically acceptable salt” will not land on the literal core of claims 1, 4, 11, or 17 as written.

2) Salt scope is defined, not open-ended

Claim 2 limits the salt family to alkali metal salts
Claim 3 further specifies the sodium salt

If a product uses a potassium salt, claim 3 does not apply, but claim 2 can still apply (if it is an alkali metal salt). If a product uses a non-alkali salt (for example, calcium, magnesium, or organic salts), claims 2 and 3 fall away, but claim 1 still allows “pharmaceutically acceptable salt” in general terms.

3) Carriers and formulation parameters are not enumerated

Claim 1 requires a “pharmaceutically acceptable carrier” but does not list carrier types. That typically broadens coverage to many conventional injectable formulation styles, as long as they meet “pharmaceutically acceptable” standards and include an effective amount of the compound or its salt.

4) “Effective amount” and “treating viral infection” drive functional breadth

These terms create functional claim language:

“effective amount” is read relative to achieving the treatment outcome
“treating viral infection” is typically assessed functionally (therapeutic effect) rather than requiring a specific endpoint measure in the claim text provided

5) Virus labels are enumerated and route-specific is not

Virus labels appear as dependent specificity, but they are not tied to a single route in claim numbering:

Injectable method: claims 4-10
Oral method: claims 11-16
Topical method: claims 17-20

So a single viral indication can be pursued across different delivery platforms while still staying within the claim architecture, subject to route and dosing.

Where are the key infringement vectors (and design-around angles)?

Infringement vectors

The cleanest infringement posture is a product or regimen that satisfies all of:

contains the claimed compound or salt
uses the relevant administration route (injectable/oral/topical)
targets one of the listed viruses
uses an amount that is argued to be effective

Most likely “non-infringing” levers

Given the claim text:

Change the active: use a different nucleoside/analog not equal to 9-(1,3-dihydroxy-2-propoxymethyl)guanine
Avoid the salt boundaries (if needed):
- avoid alkali metal salts if targeting claim 2/3 avoidance; but note claim 1 may still capture “pharmaceutically acceptable salt” generally
Avoid all enumerated routes:
- the claims explicitly cover injectable, oral, and topical. A different route not covered (e.g., inhalation) might avoid the literal reading, but that depends on whether other claims or continuation patents exist in the full family (not provided here)

How strong is the claim reach across competitors’ programs?

Product-format reach

The claim set supports several product-format shapes:

injectable formulations for systemic or localized delivery
oral dosage forms
topical compositions (skin/mucosa)

If a competitor formulates the same compound in any of those formats, they likely face at least a subset of these claims, assuming the regimen is marketed or used for one of the listed viruses.

Indication reach

The indication labels are a focused herpesvirus panel:

HSV-1
HSV-2
CMV
EBV
VZV

This panel covers a broad segment of established antiviral clinical use, particularly for immunocompromised patients and herpes-associated disease settings.

What is the patent landscape around US 4,507,305 in the US system?

What can be concluded from the claim text provided

The claim text indicates the patent is drawn around a specific antiviral nucleoside and its use across multiple administration routes and virus types. That type of drafting typically appears in a patent family where:

the compound is claimed as a core invention
compositions and methods are layered as separate claim groups
later patents may add improved formulations, dosing regimens, or expanded indications

What cannot be concluded from the information provided

A complete “US patent landscape” requires, at minimum, the following to be sourced and compared across documents:

patent publication/issue data, assignee, inventors
the full specification (which often includes additional claims, examples, definitions, and cited references)
the family (continuations/divisionals, continuations-in-part, related patents)
prosecution history and claim amendments
later US patents citing or sharing the same priority chain
expiry dates and term adjustments

Those fields are not included in the input, and no bibliographic metadata is provided for US 4,507,305. Without that, a landscape would be speculative rather than actionable.

Result: A full landscape map (e.g., “which US patents are controlling,” “which are design-around blockers,” “which are follow-on improvements”) cannot be produced from the claim list alone.

Claim-by-claim scope map (US 4,507,305)

Claim	Category	Key limitations (must all be met)	Direct commercial meaning
1	Composition	Injectable; effective amount of 9-(1,3-dihydroxy-2-propoxymethyl)guanine or pharmaceutically acceptable salt; pharmaceutically acceptable carrier; treating viral infections	Injectable product containing the compound/salt in a standard pharmaceutically acceptable carrier
2	Composition (dependent)	Claim 1; salt is alkali metal salt	Potassium or sodium salts fit; non-alkali salts do not
3	Composition (dependent)	Claim 2; specifically sodium salt	Sodium salt injectable product with carrier fits
4	Method (injectable)	Administer effective amount of claim 1 composition to treat viral infection	Injectable regimen using the claim 1 composition
5	Method (dependent)	Claim 4; mammal is human	Human use only; covers clinical dosing
6-10	Method (dependent)	Claim 5; virus is one of: HSV-1, HSV-2, CMV, EBV, VZV	These are the covered indication labels for injectable administration in humans
11	Method (oral)	Orally administer effective amount of compound or pharmaceutically acceptable salt	Oral regimen regardless of “carrier” requirements in claim 1
12-16	Method (dependent)	Claim 11; virus labels: HSV-1, HSV-2, CMV, EBV, VZV	Covered oral indication labels
17	Method (topical)	Topically administer effective amount of compound or pharmaceutically acceptable salt	Topical regimen fits claim language
18-20	Method (dependent)	Claim 17; virus labels: HSV-1, HSV-2, VZV	Covered topical indication labels

How to interpret breadth vs. enforceability pressure

Breadth inside the allowed perimeter

Within the allowed perimeter (same compound/salt), the claims are broad in:

route coverage (injectable, oral, topical)
indication coverage (five virus labels)
mammal scope for composition and method base (then constrained to humans for the injectable method via claim 5)

Narrowness where it matters

The perimeter is narrow because the claim does not cover:

analogs or prodrugs that are chemically distinct
different nucleoside scaffolds
non-listed viruses
routes not captured by injectable/oral/topical

That combination typically yields strong specificity for litigation but requires competitors to stay close to the exact chemical and use pattern.

Key Takeaways

US 4,507,305 is anchored to a single antiviral compound identity: 9-(1,3-dihydroxy-2-propoxymethyl)guanine, or pharmaceutically acceptable salts.
Composition scope is injectable-first (claim 1) with salt specificity in dependent claims (alkali metal salts in claim 2; sodium in claim 3).
Method scope covers three administration routes (injectable, oral, topical) and five named viruses (HSV-1, HSV-2, CMV, EBV, VZV).
The claims are broad on route and indication within the listed virus set, but narrow on chemistry (no chemical flexibility in the claim text provided).
A complete US patent landscape (related patents, continuations, expiries, or controlling claims) cannot be constructed from the claim text alone.

FAQs

1) Does claim 1 cover injectable formulations using any salt?

Claim 1 covers the compound “or a pharmaceutically acceptable salt.” Dependent claims 2 and 3 restrict salt types to alkali metal salts and then specifically the sodium salt.

2) Are oral and topical methods limited to the injectable carrier definition?

No. Claims 11 and 17 require oral/topical administration of the compound or a pharmaceutically acceptable salt. They do not incorporate the “carrier” requirement from claim 1.

3) Does the injectable method require human treatment?

Yes. Claim 5 limits the injectable method chain (claims 4-10) to mammal = human.

4) Which virus indications are explicitly covered?

HSV-1, HSV-2, CMV, EBV, and VZV.

5) What is the most direct design-around?

Using a different active ingredient (not 9-(1,3-dihydroxy-2-propoxymethyl)guanine) avoids the claim’s chemical anchor.

References

US Patent 4,507,305 (claim text provided in prompt).

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	244227	⤷ Start Trial
Austria	15899	⤷ Start Trial
Australia	572086	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 4,507,305

Summary for Patent: 4,507,305