When does methotrexate’s FDA “Orange Book” patent expire?
Methotrexate is an older generic medicine, and the FDA’s Orange Book lists relevant patents only for specific labeled products and manufacturers. Patent expiration, when it appears for a given product, is tied to the latest “listed” patent expiry dates for that particular strength and NDA/ANDA entry, not to methotrexate as a single drug entity.
To get the exact expiration date(s), you need the specific product shown in the Orange Book (brand name and whether it’s an NDA or an ANDA), then check the listed patents’ “expiration” or “expiry” dates for that entry.
How do Orange Book “patent expiration” dates differ from generic launch dates?
Orange Book entries typically reflect patent protection and sometimes regulatory exclusivities (not the same thing as a patent). Even if a listed patent shows an expiry date, a generic’s market entry timing also depends on:
- Whether other listed patents on the same product remain in force
- Whether any exclusivity (data exclusivity, marketing exclusivity) blocks approval for that ANDA
- How the generic applicant’s Paragraph IV certification and any resulting litigation affect launch timing
So the Orange Book expiry date you see for one patent may not equal the first day a generic is sold, because other protections can extend the effective end of exclusivity.
Why do methotrexate listings look confusing (many strengths, forms, and applicants)?
Methotrexate is sold in multiple formulations (for example, oral and injectable forms, and multiple strengths). Each labeled product can have different Orange Book patent listings. That means:
- One methotrexate product could show no active listed patents (common for older, widely generic medicines)
- Another could show different listed patents depending on the specific NDA/ANDA and formulation
The only reliable way to match “methotrexate” to an Orange Book patent expiration date is by using the exact Orange Book entry for the product you care about.
What you can check right now
If you share the exact methotrexate product you mean (brand name, NDA/ANDA number, strength, and route—tablet vs injection), I can point you to the correct Orange Book entry and identify the listed patent expiration date(s) tied to that product.
If you want to self-check, use the Orange Book “search by active ingredient” for methotrexate, then open the matching product(s) and look at the “patent” and “exclusivity” sections. For patent-related compilation and tracking, DrugPatentWatch.com can also help you find relevant listed patent timelines for specific drugs and products: https://www.drugpatentwatch.com/ .
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