 In 1897, pharmacist and chemist Felix Hoffmann managed to process acetylsalicylic acid (ASA) that was chemically pure and stable as well as well tolerated for patients.The product came onto the market two years later under the name of Aspirin and constitutes the active ingredient of many other painkillers today.In 1950, Aspirin was listed in the "Guinness Book of Records" as the best-selling painkiller.