The Gastrointestinal Hormones, Secretin and Cholecystokinin-Pancreozymin

Abstract
At the end of my lecture for the Gastroenterology Research Group at the World Congress of Gastroenterology in Washington in May 1958 (1) I drew attention to the length of the period between the observation made by a physiologist that a hormone exists and its introduction as a therapeutic or diagnostic tool in medicine. For insulin it lasted 32 years, for heparin, 20 years. Secretin was discovered in 1902, cholecystokinin in 1928, and pancreozymin in 1943, yet they are not commercially available and consequently are not used to the extent that they deserve to be. The early history of the