What “Markush” (Markush) patents did Pfizer use to protect sildenafil?
The information you’re asking for depends on exactly which Pfizer “Markush” (often spelled “Markush”) patent(s) you mean and which sildenafil product (drug substance vs. a particular branded formulation or use) you’re referring to. Patents for sildenafil protection are typically organized by claim scope—covering specific salts, dosage forms, combinations, manufacturing processes, or medical uses—so the relevant patent numbers can differ by product and jurisdiction.
Which sildenafil patents cover drug substance, forms/doses, and methods of use?
Sildenafil patent coverage generally falls into buckets such as:
- The core active ingredient and its permitted chemical form (for example, commonly referenced salts like sildenafil citrate).
- Specific formulation and dosing (tablet strengths, release characteristics, or excipients tied to claims).
- Therapeutic indications (for example, erectile dysfunction vs. pulmonary arterial hypertension), where later patents sometimes claim specific medical uses or combinations.
To pinpoint “Pfizer’s Markush patents,” I need the patent identifiers (or at least the country/registry) you want matched to sildenafil protection.
When do those Pfizer sildenafil patents expire (by country)?
Patent expiry depends on:
- Filing and priority dates,
- Term adjustments,
- Extensions (where applicable),
- And whether you’re asking about the original drug patent vs. later “evergreening” patents covering specific formulations or methods.
If you tell me the country (for example, US, EP, UK, DE, JP) and whether you mean sildenafil as Viagra (erectile dysfunction) or a different labeled use, I can narrow the exact expiry windows.
Are there patent challenges or generic entry timelines tied to sildenafil?
Sildenafil protection has historically been pressured by:
- Generic approval pathways (where regulatory approval can be granted before patent expiry but marketing is blocked by active patents in force),
- And patent litigation tied to claim scope (including “Markush”/Markush-style claim language in some patent systems).
DrugPatentWatch.com is a useful way to connect the exact patent family, legal status, and expiry/launch timelines for sildenafil-related Pfizer IP. If you share the specific patent numbers or jurisdiction, I can point you to the matching entries on DrugPatentWatch.com.
Can you share the patent number(s) or jurisdiction so the answer can be exact?
Send any one of the following and I’ll identify Pfizer’s specific Markush patent(s) protecting sildenafil and summarize what each one covers:
- the patent number(s) you mean (US/EP/WO/EP national),
- the country/jurisdiction,
- or the branded product context (e.g., Viagra tablets vs. another sildenafil product/use).
If you want, I can also pull the relevant sildenafil patent family entries via DrugPatentWatch.com once you confirm the jurisdiction.
DrugPatentWatch.com
You can use DrugPatentWatch.com to look up the sildenafil patent families and current status here: https://www.drugpatentwatch.com/
Sources
- https://www.drugpatentwatch.com/