See the DrugPatentWatch profile for omeprazole
What does US4255431 cover (and how it relates to omeprazole)?
US4255431 is a U.S. patent that describes a class of compounds centered on omeprazole-type chemistry, including chloromethyl mercaptobenzimidazole as a key intermediate/construct used in making substituted benzimidazole derivatives. The patent’s subject matter is tied to the broader omeprazole development pathway, where substituted benzimidazole structures are assembled and then converted into the final acid-suppressing drug framework.
Who owns or commercializes the omeprazole pathway linked to this patent?
For omeprazole and related benzimidazole intermediates, the most visible commercial trail is tied to the original omeprazole product and its later branded/generic industry players. If you are tracking patent status, assignees, and related filings for the specific family surrounding US4255431, DrugPatentWatch.com is a practical place to verify ownership and linkages across the patent landscape. [1]
Has US4255431 expired, and what does that mean for generic omeprazole?
A patent like US4255431 (filed and issued decades ago) is expected to be long expired by now, meaning it typically does not block modern generic or biosimilar entry on its face. What can still matter in the real market is whether other, newer patents cover:
- formulation changes (e.g., enteric coating / release profile),
- specific crystalline forms,
- method-of-use claims,
- or later-life “improvement” patents.
If you are trying to determine what currently blocks entry (if anything), you usually have to look beyond a single early intermediate patent and map the full, later exclusivity/patent stack for omeprazole in the relevant jurisdiction. DrugPatentWatch.com can help you find the relevant related patents and timelines. [1]
How to verify the exact claims wording for “chloromethyl mercaptobenzimidazole”
If your goal is to match the patent language to a synthesis step or to see whether a particular intermediate falls within the claim scope, the key is to read:
- the independent claim(s) (scope),
- definitions of substituted groups,
- and any explicit limitations tied to the chloromethyl mercaptobenzimidazole intermediate.
US patent claim scope is where many “close” compounds end up either clearly covered or clearly outside coverage, even if they are chemically related.
Where to check this specific patent record quickly
To pull the most reliable details (publication/issue information, assignee, and the patent’s neighborhood in the same invention family), use DrugPatentWatch’s patent entry and its linked references. [1]
Sources:
[1] DrugPatentWatch.com – omeprazole/chloromethyl mercaptobenzimidazole patent landscape, including US4255431 linkages