Coumarins—Rat Poison for the President

This book chapter tells the fascinating story of coumarin, a substance that has evolved from a supposed pest to a life-saving drug. Originally, coumarin was discovered in North America in the 1920s after cows had died from rotten sweet clover. The cows died from internal bleeding, which suggested a problem with blood clotting. Researchers discovered that sweet clover contained a substance called dicoumarol, which was responsible for this coagulation disorder. This discovery led to the development of warfarin, a derivative of dicoumarol, which was originally used as rat poison. Later, scientists discovered that warfarin and similar compounds act as anticoagulants and can be used to prevent blood clots, heart attacks, and strokes. The use of warfarin in medicine began after a soldier had tried to poison himself with warfarin but was saved. This incident demonstrated the potential of warfarin as a safe and effective drug. Another breakthrough was the development of phenprocoumon, an improved form of warfarin, which became known under the trade name Marcumar®. This chapter highlights the importance of research and unexpected discoveries and shows how a poison became a life-saving drug. It is an excellent example of the development of pharmacy and the unpredictable paths of scientific research.