ABSTRACT
Heparin was discovered in 1916 by Jay McLean and William Henry Howell, but was not used in humans until 1935 (1,2). It was originally isolated from canine liver cells, hence its name (“hepar” is Greek for liver). Howell isolated a water-soluble polysaccharide anticoagulant, which was also termed “heparin,” although it was distinct from the previously isolated phosphatide preparations. The first human trials of heparin began in 1935 and, by 1937, it was clear that Connaught’s heparin was a safe, readily available, and effective anticoagulant (3).
