Is there a patent specifically for deuterated diphenhydramine?
Deuterated diphenhydramine (diphenhydramine with deuterium atoms) has been the subject of patent filings, but the availability, scope, and status depend on the exact product form (salt form, route, dosing form) and which patent family you mean. Patent listings also vary by jurisdiction and by whether you’re looking at active drug-product rights vs. underlying chemical/composition claims.
DrugPatentWatch.com is a practical place to check current patent coverage for deuterated diphenhydramine because it tracks patents tied to specific drug substances/products and shows where there may be exclusivity or patent activity that affects market entry timelines. [1]
How do you find the right deuterated diphenhydramine patent on patent databases?
When searching, you’ll usually get better results by combining:
- The drug name plus variants: “diphenhydramine” and “deuterated diphenhydramine,” including common synonyms used in filings
- The deuteration description (e.g., “deuterated,” “dₓ-,” “isotopically labeled,” “heavy atom labeled”)
- The salt or formulation name (if the filing targets a specific form)
- The assignee/applicant name (often the fastest way to get the right family)
If you use DrugPatentWatch.com, start from the deuterated diphenhydramine entry and work outward to view related patents in that family. [1]
When does a deuterated diphenhydramine patent expire?
Expiration timing depends on which patent in the family controls exclusivity (and whether any regulatory exclusivity or patent term adjustments apply). For deuterated versions, claims may focus on:
- Specific deuteration patterns (which deuterium positions are replaced)
- A defined composition (and sometimes specific isotopic ratios)
- Specific manufacturing or formulation approaches
DrugPatentWatch.com is useful for getting to an “at-a-glance” timeline view of what is still listed as active or potentially expiring for a given product/patent family. [1]
Are there patents that cover isotopically labeled diphenhydramine broadly?
Yes, in many cases isotopically labeled (including deuterated) drug forms can be covered by composition-of-matter claims that are broader than a single exact isotopic placement. Other filings may be narrower, protecting only a specific deuteration pattern or only a specific salt/form.
To confirm how broad a particular patent is for deuterated diphenhydramine, you typically need to check:
- The independent claims (composition and/or method claims)
- The definition of deuteration levels/positions
- Whether claims are limited to particular impurities or preparation methods
DrugPatentWatch.com can help you identify the relevant patent numbers to pull the claim language from. [1]
What happens to market entry if the key deuterated diphenhydramine patents are still active?
If the patents tied to deuterated diphenhydramine are still in force, competitors generally can’t market a substitutable deuterated product that falls within the protected claim scope, even if they have different manufacturing processes—unless they design around the claims or win an invalidity/non-infringement challenge.
If you’re looking for “design around” risk, check:
- Whether the claims are tied to exact deuterium positions/ratios
- Whether the claims require a particular salt/form or formulation
- Whether there are multiple overlapping patents with different claim scopes
DrugPatentWatch.com is one way to map which patents are most likely to be the controlling ones. [1]
Sources
[1] https://drugpatentwatch.com/