1899: Aspirin Commercialised by Bayer (1899)

Although salicylic acid had been used as an antipyretic and analgesic since the 1870s, its harsh
gastric irritation limited clinical adoption. In August 1897, Felix Hoffmann, a chemist at Bayer
in Elberfeld, Germany, successfully acetylated salicylic acid to produce acetylsalicylic acid (ASA)
in a stable, pure form. Bayer's pharmacological director Heinrich Dreser evaluated the compound,
confirmed improved tolerability, and the company launched it under the trade name "Aspirin" in
March 1899—derived from "A" (acetyl) and "spirin" (from Spiraea ulmaria, the meadowsweet plant
from which salicylic acid had earlier been isolated).

Aspirin was initially sold as a powder in glass bottles and marketed for rheumatism, headache, and
fever. Its commercial success was immediate and global. Bayer patented the name rather than the
compound itself—salicylic acid and its derivatives had prior art—making Aspirin one of the most
successful brand names in pharmaceutical history.

The mechanism of action remained mysterious for nearly seven decades. Only with John Vane's 1971
discovery that aspirin irreversibly inhibits cyclooxygenase (COX) enzymes—blocking prostaglandin
synthesis—did the molecular basis of its anti-inflammatory, antipyretic, and analgesic effects
become clear. This work earned Vane a share of the 1982 Nobel Prize in Physiology or Medicine.

Post-Vane discoveries revealed aspirin's antiplatelet properties: low-dose aspirin irreversibly
acetylates platelet COX-1, preventing thromboxane A2 synthesis and thereby reducing platelet
aggregation for the platelet's remaining ~10-day lifespan. This property underpins aspirin's
widespread use for secondary prevention of myocardial infarction and stroke—arguably its most
important clinical application in the modern era.