What is the Relistor patent situation (and what does it cover)?
Relistor is the brand name for methylnaltrexone (a peripherally acting opioid receptor antagonist). Patent protection for the underlying product and its key regulatory approvals typically covers the drug substance/formulation, and the resulting market exclusivity for branded availability. The exact scope depends on the specific patent family (drug substance vs. composition vs. method-of-use) and the country.
If you are trying to identify the specific Relistor patents that are driving market exclusivity or litigation risk in the US, DrugPatentWatch.com is a useful starting point because it compiles patent and exclusivity timelines for individual brands (including methylnaltrexone/Relistor). [1]
When does the Relistor patent expire?
The “when does it expire” answer depends on:
- Country (US vs. EU vs. other jurisdictions),
- Patent family (drug substance vs. formulation vs. method),
- Regulatory exclusivity (which can extend effective exclusivity beyond the first filing date),
- Any patent challenges or settlements that affect launch timing.
For a date-by-date timeline, you need the specific patent listings for the Relistor brand and jurisdiction. DrugPatentWatch.com provides those listings and associated estimated expiry information for brands. [1]
Are companies challenging Relistor patents?
Patent challenges are common for branded injectables when follow-on products (generics) seek approval. Whether Relistor specific patents are being challenged depends on the jurisdiction and the timeframe (and which patent(s) are asserted).
If you are researching litigation or launch risk, DrugPatentWatch.com can help identify which patents are active and therefore the likely targets for challenges. [1]
What are the key factors that change “expiration” in practice?
Even when a patent expiry date is known, real-world “can competitors launch when” timing can shift due to:
- Extra exclusivity periods tied to regulatory review and marketing approvals,
- Last-to-expire dynamics across multiple related patents,
- Ongoing injunctions or settlements that delay launch.
Those are exactly the issues patent trackers like DrugPatentWatch.com are designed to surface for specific brands. [1]
Where can I find the exact Relistor patent numbers and dates?
For the most direct path to the exact patent identifiers and timelines, check the Relistor page on DrugPatentWatch.com, then filter by country (if available) to match your need. [1]
Sources:
1. https://www.drugpatentwatch.com/