United States Patent 5,998,427: Scope of Claims, Claim Dependencies, and US Patent Landscape

US Patent 5,998,427 claims a chemical series defined by a steroidal framework plus a substituted anilide/carbamoyl substituent, with downstream coverage spanning: compound compositions, formulation, synthetic processes, and therapeutic use tied to 5α-testosterone reductase (5α-DHT pathway) and androgen-responsive disorders.

What is the core claim scope in US 5,998,427?

Claim 1 is the nucleus: “compound of formula (I)”

Claim 1 is a genus claim to “a compound of formula (I)” (including pharmaceutically acceptable solvates), with the scope driven by three main variable sets: (1) steroid-side unsaturation (carbons 1 and 2), (2) small C1/C4 substituents (R1, R2), and (3) a substituted aromatic group defined through R3 (variables R6, R7, R8) plus X.

Key structural toggles in Claim 1

Structural element	Defined by	Scope in Claim 1
Bond between carbons 1 and 2	“carbons 1 and 2 are joined by either a single or a double bond”	Saturated (single) or unsaturated (double) steroid variant
Small substituents	R1, R2	Each is hydrogen or methyl
Aromatic substituent definition	R3 = (B)…	R6 is trifluoromethyl, halogen-free or halogen-substituted phenyl, or branched C4-7 alkyl; R7 and R8 have a “hetero-substitution” rule where one of them is from {trifluoromethyl, halogen, phenyl (halogen-substituted), branched C4-7 alkyl} and the other is hydrogen or halogen
Halo/solubility handle	X	hydrogen or halogen
Included subject matter	pharmaceutically acceptable solvate	all covered compounds include solvates

Practical breadth: Claim 1 is broad on (i) the steroid unsaturation (single or double bond), (ii) R1 and R2 being hydrogen or methyl, and (iii) the aromatic substituent classes (CF3 / substituted phenyl / branched alkyl / halogens). It is narrower on the aromatic substitution pattern through the “either/or” constraints between R7 and R8.

Claim 6 is a second nucleus: formula (IB) with narrower R3 allowance

Claim 6 covers “a compound as claimed in claim 6 of formula (IB)” (as written, it is dependent on Claim 6 and introduces formula (IB)). It carries forward the C1–C2 bond choice and R1, but constrains R6 and R7/R8 pattern similarly and limits X to hydrogen or halogen.

Claim 6 summary

C1–C2: single or double
R1: H or methyl
R6: CF3 / optionally halogen-substituted phenyl / branched C4-7 alkyl
R7/R8: one is from {CF3, halogen, halogen-substituted phenyl, branched C4-7 alkyl} and the other is H or halogen
X: H or halogen

Claim 11 covers product-by-formulation

Claim 11 is “A pharmaceutical formulation comprising an effective amount of a compound as claimed in claim 1” plus a pharmaceutically acceptable carrier.

This claim is standard but strategically important: it reaches commercial products regardless of whether competitors litigate on compound identity, as long as they sell a covered compound-containing formulation.

How do the dependent claims narrow or expand the genus?

Claims 2–5 tighten the variable set

Claim	Dependency	Main narrowing point
2	Claim 1	X is hydrogen (removes halogen option)
3	Claim 1	R2 is hydrogen (removes methyl option at that position)
4	Claim 1	Restates/chooses R6 and the “either/or” substitution between R7 and R8 with explicit admissible sets
5	Claim 1	C1–C2 joined by double bond (removes single bond option)

These dependent claims preserve multiple “islands” within the genus: some claims lock stereochemistry/unsaturation and some lock R2 or X.

Claims 7–10 implement “if-then” narrowing logic for formula (IB)

Claim 7 introduces an “if” condition:

If (i) either R7 or R8 is branched C4-7 alkyl and (ii) X is hydrogen, then R6 is CF3 or optionally halogen-substituted phenyl.

Claims 8–10 then carve out additional sub-classes:

Claim 8: R6 is CF3 or branched C4-7 alkyl; one of R7/R8 is CF3/halogen/halogen-substituted phenyl and the other is hydrogen or halogen
Claim 9: more specific: (i) R6 is CF3 or branched C4-7 alkyl, (ii) one of R7/R8 is CF3 and the other is hydrogen, (iii) X is hydrogen
Claim 10: R6 and R8 are independently CF3 or t-butyl, while R7 and X are hydrogen

Impact: These nested conditions matter for design-around. Competitors can sometimes avoid Claim 1’s broadest reading by ensuring the aromatic substitution pattern violates the R7/R8 “either/or” constraint or violates specific dependent “if-then” combinations.

What is claimed beyond compounds: processes and therapeutic methods?

Claim 12–14: synthetic process coverage

Claim 12 covers “A process for preparing a compound as claimed in claim 1” with two major routes depending on whether C1–C2 is single-bonded or double-bonded.

Claim 12 route structure

Process (A) (for C1–C2 single bond):
- Hydrogenate a compound of formula (IVa).
Process (B) (for C1–C2 double bond):
- React compound of formula (V) with compound (IIa), where IIa is an amine of the form H2NR3.
- Then optionally perform further reactions:
- (i) interconversion to another compound of formula (I)
- (ii) remove protecting groups
- (iii) convert compound (I) or solvate into pharmaceutically acceptable solvate

Claim 13 adds an intermediate operational detail:

In process (B), treat compound (V) with a halogenating agent in presence of a base prior to reaction with (IIa).

Claim 14 adds one more conversion step:

In step (i), a compound with C1–C2 double bond and R2 = hydrogen is prepared by dehydrogenating a compound of formula (Ia).

Scope note: Process claims can be a strong enforcement lever even when end products are sold by a different entity, depending on jurisdictional rules and evidence of manufacturing.

Claims 15–17: therapeutic method coverage

Claim 15: “method of inhibiting 5α-testosterone reductase enzyme” by contacting the enzyme with an effective inhibitory amount of a compound of Claim 1.
Claim 16: “method of treating an androgen responsive or mediated disease in a mammal” by administering an effective amount of a Claim 1 compound.
Claim 17: specifies disease list:
- benign prostatic hyperplasia
- prostate cancer
- acne
- male pattern baldness
- hirsutism

Practical effect: The claims are broad at disease definition level (androgen responsive or mediated disease), then lock enumerated examples. This structure often supports infringement across multiple markets if the same compound is used.

What specific compounds are explicitly listed in Claim 19?

Claim 19 enumerates a set of named compounds that fall within the Claim 1 genus. These named members define enforcement anchors for specific substitution patterns.

Claim 19 list (verbatim substance)

17β-N-(2,5-bis(Trifluoromethyl))phenylcarbamoyl-4-aza-5α-androstan-3-one
17β-N-(2,5-bis(Trifluoromethyl))phenylcarbamoyl-4-methyl-4-aza-5α-androstan-3-one
17β-N-(2-t-Butyl-5-trifluoromethyl)phenylcarbamoyl-4-aza-5α-androst-1-en-3-one
17β-N-(2-t-Butyl-5-trifluoromethyl)phenylcarbamoyl-4-aza-5α-androstan-3-one
17β-N-(2-t-Butyl-5-trifluoromethyl)phenylcarbamoyl-4-methyl-4-aza-5α-androstan-3-one
17β-N-(2,5-Di-t-butyl)phenylcarbamoyl-4-aza-5α-androst-1-en-3-one
17β-N-(2,5-Di-t-butyl)phenylcarbamoyl-4-aza-5α-androstan-3-one
17β-N-(2,5-Di-t-butyl)phenylcarbamoyl-4-methyl-4-aza-5α-androstan-3-one
17β-N-(2,5-bis(Trifluoromethyl)phenylcarbamoyl-4-aza-7β-methyl-5α-androst-1-en-3-one
17β-N-(2-t-Butyl-5-trifluoromethyl)phenylcarbamoyl-4-aza-7β-methyl-5α-androst-1-en-3-one

Strategic read-through: Named members cluster around aromatic rings with 2,5-disubstitution patterns using CF3, t-butyl, or combinations, plus steroid variants (androstan vs androst-1-en; with/without 7β-methyl; with/without 4-methyl). These enumerations often help courts construe genus boundaries by anchor.

How does the claim architecture map to enforceable infringement theories?

1) Product infringement (compound and formulation)

If a competitor sells a compound falling within Claim 1’s formula (I) variable matrix, Claim 1 and its nested dependents (2–5, 6–10) become relevant.
If the competitor sells a formulation containing those compounds, Claim 11 targets the dosage form.

2) Manufacturing infringement (process claims)

If a competitor uses the specified route logic, particularly:
- hydrogenation of IVa for single-bond cases
- reaction of V with IIa for double-bond cases
- optional halogenation of V in base prior to IIa
- optional dehydrogenation step for certain interconversions then Claim 12–14 provide manufacturing-based theories.

3) Method infringement (use claims)

Clinical use of the compound to inhibit 5α-reductase or to treat androgen-mediated conditions is directly claimed (Claims 15–17).

US patent landscape: what else matters around 5,998,427?

This request asks for a “detailed analysis” of scope and the broader US landscape for US 5,998,427. The usable content provided here includes only the claims text, and no bibliographic data (assignee, filing date, priority, publication, related continuations/divisionals, listed family members, prosecution history) is supplied. Without those identifiers, any attempt to enumerate related patents, continuations, cited references, or Orange Book/expiration data would be speculative.

Accordingly, only claim-structured landscape observations can be made from the claim set alone:

A. The patent targets a mechanism and a chemical scaffold, not a single drug product

The method claims tie to 5α-testosterone reductase inhibition and androgen responsive diseases, indicating the estate expects clinical use across multiple indications rather than a single named drug. That structure is typical of androgen-reductase inhibitors with steroid-like cores.

B. The inclusion of both compound genus and multiple manufacturing steps increases coverage resilience

If a competitor modifies formulation, Claim 11 still covers.
If a competitor buys the active from a different supplier, manufacturing process claims can still create exposure if the steps match.
If a competitor changes the route but still uses a covered compound, compound/use claims can still apply.

C. Subclass-dependent islands support partial design-around strategies

The dependencies that lock:

X = hydrogen (Claim 2, 9)
C1–C2 = double bond (Claim 5)
specific substitution constraints (Claims 7–10) suggest the patent is structured to retain enforceability even if some members of the genus are engineered away.

Key Takeaways

Claim 1 is a broad genus for steroidal compounds of formula (I) with C1–C2 single or double bond, R1/R2 = H or methyl, and an aromatic substitution defined by CF3 / halogen / optionally halogen-substituted phenyl / branched C4-7 alkyl, plus X = H or halogen, covering pharmaceutically acceptable solvates.
Claims 2–5 and 6–10 create enforceable sub-class “islands,” including constraints on X, R2, C1–C2 unsaturation, and specific CF3/t-butyl substitution patterns.
Claims 12–14 add route-dependent manufacturing coverage (hydrogenation of IVa for single-bond variants; V + IIa chemistry for double-bond variants; optional halogenation in base; optional dehydrogenation to access specific unsaturated variants).
Claims 15–17 cover 5α-reductase inhibition and treatment of androgen-responsive diseases, with enumerated examples including BPH, prostate cancer, acne, male pattern baldness, and hirsutism.
Claim 19 enumerates specific substitution members (CF3 and t-butyl patterns on a 2,5-disubstituted phenylcarbamoyl motif) that anchor the genus for infringement and claim construction.

FAQs

1) Is the protection primarily chemical, process, or therapeutic?

It is all three: compound genus (Claim 1), formulation (Claim 11), synthetic processes (Claims 12–14), and therapeutic/use methods (Claims 15–17).

2) How can a competitor design around the compound claim?

The claim architecture shows likely design-around vectors via violating the genus constraints on X, R2, C1–C2 bond, and the R7/R8 “either/or” substitution rule or the specific dependent “if-then” conditions in Claims 7–10.

3) Does the patent cover both saturated and unsaturated steroid cores?

Yes. Claim 1 expressly allows C1–C2 single or double bond, and Claim 5 and Claim 12(A)/(B) correspond to those distinctions.

4) What indications are directly named?

Claim 17 lists benign prostatic hyperplasia, prostate cancer, acne, male pattern baldness, and hirsutism.

5) Do the named compounds in Claim 19 expand or narrow protection?

They anchor protection by identifying specific members within the genus, while Claim 1 still controls the overall scope through formula-defined variables.

References

[1] United States Patent No. 5,998,427. Claim set as provided in the prompt.

Details for Patent: 5,998,427

Summary for Patent: 5,998,427