Ursodeoxycholic Acid for Gallstone Dissolution: The Emergence of a New Therapeutic Application of an old Bile Acid

Abstract

Ursodeoxycholic acid (ursic acid, udc), the 7β-epimer of chenodeoxycholic acid (cdc), is a normal constituent of bile in man and in several animal species (1,2). In man, the biliary content of udc varies normally between trace amounts and about 7% of the total bile acid pool. The first description of udc dates back to 1902 when Hammarsten, in Sweden, isolated in the bile of polar bears, a hitherto unknown bile acid (2). He named it “Tauroursocholeinsäure” (ursus = L. bear) because it shared certain chemical characteristics with “Choleinsäure” (deoxycholic acid). Hammarsten found that “Tauroursocholeinsäure” resembled “Choleinsäure” in that it gave a negative Vahlen iodine test. However, the two bile acids differed in their melting point and specific rotation. Hammarsten noted also that “Tauroursocholeinsäure” was, in contrast to most other bile acids, soluble in acetone. The presently used name “Ursodesoxycholsäure” was first introduced in 1927 by Shoda in Japan, who succeeded in crystallizing this compound (3).