You can freely build on How Felix Hoffmann Invented Aspirin
This patent expired in 1918. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
FARBENFABRIKEN OF ELBERFELD Co
Patent granted
1900
Expired
1918
Forward citations
6
What this patent covers
This patent describes the chemical process for creating acetylsalicylic acid. It involves reacting salicylic acid with acetic anhydride to produce a stable, usable form of the drug. By acetylating the salicylic acid, the inventor created a compound that was significantly less irritating to the stomach than the raw salicylic acid used previously for pain and inflammation.
What is now free to use
All 0 claims of US 644077 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover the natural source of salicylic acid found in willow bark.
Does not cover other non-acetylated derivatives of salicylic acid.
Does not cover the specific brand name Aspirin, which was a trademarked term.
Who is building on this today
Bayer AG continues to be the primary steward of the Aspirin brand. Countless pharmaceutical companies worldwide produce generic versions of the drug now that the original patent has long expired.
Products built on expired version of this technology
Bayer Aspirin
Generic acetylsalicylic acid tablets
Low-dose aspirin for cardiovascular health
How to cite this patent in your documentation
FARBENFABRIKEN OF ELBERFELD Co. US Patent 644077. Acetyl salicylic acid.. Granted 1900, expired 1918. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.