United States Patent 5,037,845: Scope, Claims, and US Patent Landscape

US Patent 5,037,845 has an unusually clean claim structure that concentrates protection on a single structural genus (Formula I), its physiologically acceptable salts/solvates, and two therapeutic use lanes: (1) pain from dilatation of the cranial vasculature in a pharmaceutical composition, and (2) migraine treatment via a method of use, including oral administration and human dosing ranges.

Because the independent claim is a compound claim defined by Formula (I), the patent’s commercial value depends almost entirely on (a) how broadly Formula (I) is drawn by the substituent definitions in the missing image content, and (b) whether downstream products land within that structural envelope and are sold as salts/solvates that are included.

What does claim scope actually protect?

1) Is claim 1 a product-by-structure barrier or a narrower sub-genus?

Claim 1 is a compound of Formula (I) plus physiologically acceptable salts and solvates. The scope is therefore:

Product-by-structure: any compound falling within Formula (I) is captured.
Salt and solvate coverage: the claim explicitly includes physiologically acceptable salts and solvates of the Formula (I) compound.

Practical implication for freedom-to-operate and invalidity risk:

If Formula (I) is broad (multiple substituent options), claim 1 can reach many analogs.
If Formula (I) is narrow (few allowed substitutions), the scope contracts to a smaller set of exact chemotypes.

2) Do the salt claims broaden or narrow the genus?

Claims 2-4 are dependent on claim 1 and carve out the salt forms included. This does two things:

They confirm that certain pharmaceutically acceptable acid-addition salts are within the scope.
They also let you argue that any compound made and marketed as one of the enumerated salts is directly covered, even if the un-salted base is not sold.

Claim 3 enumerates:

hydrochloride, hydrobromide, sulphate, nitrate, phosphate, formate, mesylate, citrate, benzoate, fumarate, maleate, succinate.

Claim 4 narrows to:

1:1 succinate (a specific stoichiometry).

This matters because many commercial products are sold as specific salts with defined hydration/stoichiometry; claim 4 gives a direct handle for succinate salts with a defined ratio.

3) What does the composition claim lock down?

Claim 5 is a pharmaceutical composition with:

active ingredient: Formula (I) compound or a physiologically acceptable salt/solvate, plus
one or more pharmaceutically acceptable carriers/excipients, for use in
treatment or prevention of pain resulting from dilatation of the cranial vasculature.

Key point: this is an intended-use composition claim. If a competitor sells the same active ingredient in a different indication, that claim element can be a litigation pressure point.

Claim 6-9 impose additional constraints:

Claim 6: formulated for oral administration to humans.
Claim 7-9: unit dosage ranges:
- 0.1 mg to 100 mg (claim 7)
- 0.5 mg to 50 mg (claim 8)
- 2 mg to 40 mg (claim 9)

In practice, dependent dosage claims can become decisive if a competitor’s label and dosage fall outside the numeric ranges (or if dosage is outside the required “unit dosage form” mapping). These ranges create a numeric fence around formulation/labeling strategies.

4) What do the method claims cover?

Claims 10-12 cover treatment of a human susceptible to or suffering from migraine:

Claim 10: administer Formula (I) compound (or salt/solvate).
Claim 11: administer the pharmaceutical composition of claim 5.
Claim 12: administer by the oral route the composition of claim 6.

Method-claim practical implications:

If a product uses the right active ingredient but is delivered via a non-oral route, claim 12 can be avoided, while claim 10 may still be asserted (depending on what the competitor actually does in practice).
If a product is used for a different headache indication that is not “migraine” in the claim wording, claim 10-12 become harder to map.

Claim-by-claim scope map (US 5,037,845)

Claim	Claim type	Core protected subject matter	Key limitations that narrow coverage
1	Compound	Formula (I) + physiologically acceptable salts + solvates	Entire scope hinges on substituent definitions inside Formula (I) (image content not provided)
2	Compound (dependent)	Acid addition salts from organic/inorganic acids	Must be an acid addition salt
3	Compound (dependent)	Enumerated acid addition salts	Salt must be one of listed forms
4	Compound (dependent)	1:1 succinate salt	Stoichiometry requirement
5	Composition (dependent on claim 1)	Pharmaceutical composition with carriers; intended for pain from cranial vasculature dilatation	Intended use element
6	Composition	Oral to humans	Route restriction
7	Composition dosage	Unit dosage 0.1 mg to 100 mg	Unit dosage numeric range
8	Composition dosage	Unit dosage 0.5 mg to 50 mg	Unit dosage numeric range
9	Composition dosage	Unit dosage 2 mg to 40 mg	Unit dosage numeric range
10	Method	Treat migraine by administering compound/salt/solvate	Must be used for migraine in humans
11	Method	Treat migraine by administering composition of claim 5	Requires use of the composition as defined
12	Method	Treat migraine by oral administration of composition claim 6	Route restriction (oral) + composition elements

What “Formula (I)” implies for the landscape

The claims you provided define the scope through Formula (I), but the literal substituent pattern is not text-visible in your excerpt (it is shown as an image reference “##STR18##”). As a result, the only enforceable boundary we can state from the claim language itself is structural genus inclusion, not the explicit chemistry.

Operationally, for landscape work, Formula (I)-based patents typically form these zones in later filings:

Direct replacements: competitors attempt to launch compounds that stay outside Formula (I) by altering one or two allowed substituent options.
Salt/solvate workarounds: competitors choose salt forms not enumerated, or avoid the specific stoichiometry (e.g., not 1:1 succinate).
Formulation/dosing carve-outs: competitors shift unit dosage outside 2-40 mg and/or 0.5-50 mg bands, and/or change routes away from oral.
Use carve-outs: competitors position drugs for non-migraine indications, or use different clinical endpoints than “pain resulting from dilatation of the cranial vasculature.”

Those are the strategic levers that follow logically from the claim text you provided.

How strong is enforcement likely to be across product categories?

A. If a generic copies the same compound and salt

Claim 1 and claims 2-4 put strong pressure on ANDA-style launch if the generic’s active falls inside Formula (I) and uses an included salt/solvate.
The strongest assertion path is typically:
- product claim (claim 1) for the active,
- plus composition claim (claim 5-6) if product is oral and sold for the same therapeutic purpose,
- plus method claims (claim 10-12) depending on statutory enforceability and the way marketing and label instructions map to the claim.

B. If the generic uses an excluded salt

If the competitor uses a salt form not included in claim 3’s enumeration, claim 3 can be avoided.
But claim 1 still covers “physiologically acceptable salts and solvates” broadly, so salt enumeration in claim 3 does not fully eliminate coverage for other acceptable salts unless litigation construes claim 1 as limited by the dependent recitations (courts generally treat dependent claims as narrower, not as a limiting set on the independent claim unless the independent claim itself is limited).

So the enforceability hinge is whether the competitor’s salt is still a “physiologically acceptable salt” of the Formula (I) compound.

C. If the competitor changes route or dosage

Oral route is required for claim 6 and for method claim 12.
Numeric unit dosage ranges in claims 7-9 provide specific fences.
If a competitor’s marketed unit doses fall outside those ranges, the composition claims 7-9 can become harder to assert, but claim 5 and claim 6 may still be asserted if the product is oral and the intended use matches.

D. If the competitor targets migraine but changes clinical framing

The method claims use the word “migraine.”
For mapping, the product’s approved indication and prescribing information are usually decisive.

US patent landscape: how 5,037,845 typically fits

Given only the claim language excerpt, the most defensible landscape mapping is by claim-component strategy rather than by listing specific family members (which would require bibliographic and text data not provided here).

Landscape nodes created by the claim set

Landscape node	Why it exists	Typical competitor response
Formula I active-ingredient families	Protect core chemical matter under claim 1	Design around substituent limits; seek narrower novelty
Salt/solvate follow-on filings	Capture commercial salt selection under claims 2-4	Use different salt systems or non-covered stoichiometries
Formulation and unit-dose follow-ons	Lock into oral + dosage bands via claims 6-9	Adjust tablet strengths or dosage form to avoid numeric bands
Use-positioning	Restrict to “pain resulting from dilatation of the cranial vasculature” and “migraine”	Different indication language or route-specific positioning

Litigation and post-grant attack vectors implied by the claim text

Because the claims are broad by Formula (I) and include many salt forms, typical invalidity/unenforceability themes that arise in this claim architecture include:

Insufficient description or enablement for the full breadth of Formula (I) substitutions (depends on spec disclosure).
Lack of written description for claimed breadth over all substituent permutations.
Claim indefiniteness if Formula (I) boundaries depend on unclear substituent definitions.
Anticipation/obviousness: earlier filings in the same chemotype class may already disclose Formula (I) compounds or close analogs with the same salt and use.

These vectors cannot be ranked without the specification and the earlier-art record, but the claim architecture points to where disputes usually focus.

What to monitor in portfolio decisions (R&D and investment)

1) Product mapping checklist against the claim set

For any candidate active ingredient you consider as a substitute or entrant:

Does the candidate fall within Formula (I) boundaries?
Is it marketed as (or effectively as) a physiologically acceptable salt/solvate of that Formula (I) compound?
Is the salt one of the listed acids, including 1:1 succinate?
Is the formulation oral to humans?
Do unit dose strengths match 0.1-100 mg, 0.5-50 mg, or 2-40 mg bands?
Is the marketed therapeutic purpose aligned with:
- “pain resulting from dilatation of the cranial vasculature” (composition claim 5), and
- “migraine” (method claims 10-12)?

2) Claim leverage for licensing and design-arounds

If a design-around can move the compound outside Formula (I), it breaks the claim 1 barrier.
If only dosage and route can be changed, claim 1 can still bite unless the active is also outside Formula (I).
If only salt can change, claim 1 still has broad “physiologically acceptable salts and solvates,” reducing the chance of a full workaround.

Key Takeaways

US 5,037,845 is dominated by Formula (I) compound protection plus physiologically acceptable salts/solvates (claim 1), with explicit coverage for a list of acid-addition salts and 1:1 succinate (claims 2-4).
The enforceable therapeutic scope includes (i) pain from cranial vasculature dilatation in a composition (claim 5) and (ii) migraine treatment in methods (claims 10-12), including oral administration (claims 6 and 12).
The patent adds commercially actionable constraints via oral formulation and unit dosage ranges (claims 7-9), creating potential numeric carve-outs for tablet strengths.
The main freedom-to-operate hinges on whether a product’s active ingredient is inside Formula (I); salt, route, and dosage adjustments reduce exposure mainly to dependent claims but do not eliminate claim 1 risk if the active still falls within Formula (I).

FAQs

1) Does claim 5 require that the drug actually treats cranial vasculature dilatation pain in use?

Yes. Claim 5 is a composition claim “for use in the treatment or prevention of pain resulting from dilatation of the cranial vasculature,” so infringement turns on use mapping to that therapeutic purpose.

2) Is oral administration a requirement for all claims?

No. Oral administration is required for claim 6 and for method claim 12. Compound claim 1 and method claim 10 are not limited to oral route on their face.

3) Do claims 7-9 cover specific tablet strengths only?

They cover compositions “formulated in unit dosage form” within the recited ranges. If marketed unit strengths are outside those bands, those dependent claims become harder to map.

4) Is “1:1 succinate” automatically covered even if the marketed salt is another succinate form?

Claim 4 specifically requires a 1:1 succinate. If the product uses a different succinate stoichiometry, claim 4 may not apply, but claim 1 can still apply if the product is within Formula (I) and uses a physiologically acceptable salt.

5) What is the single most important element to clear for generic or competitor entry?

Whether the candidate active ingredient falls within Formula (I) under claim 1. If it does, later workarounds on salt form, dosage band, or oral route typically do not eliminate exposure.

References

[1] United States Patent 5,037,845 (claims as provided in user excerpt).

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
United Kingdom	8419575	Aug 01, 1984

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	386196	⤷ Start Trial
Austria	A226685	⤷ Start Trial
Australia	4568985	⤷ Start Trial
Australia	573878	⤷ Start Trial
Belgium	903006	⤷ Start Trial
Canada	1241004	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,037,845

Summary for Patent: 5,037,845