4-Hydroxycoumarins are a class of vitamin K antagonist (VKA) anticoagulant drug molecules. Chemically, they are derived from coumarin by adding a hydroxy group at the 4 position to obtain 4-hydroxycoumarin, then adding a large aromatic substituent at the 3-position. The large 3-position substituent is required for anticoagulant activity.
Warning label on a tube of "brown rat" poison laid on a dike of the Scheldt river in Steendorp, Belgium. The tube contains bromadiolone, a second-generation ("super-warfarin") anticoagulant. The label in Dutch states, in part: Contains an anticoagulant with prolonged activity. Antidote Vitamin K1.
Vitamin K antagonists (VKA) are a group of substances that reduce blood clotting by reducing the action of vitamin K. The term "vitamin K antagonist" is technically a misnomer, as the drugs do not directly antagonize the action of vitamin K in the pharmacological sense, but rather the recycling of vitamin K. Vitamin K antagonists (VKAs) have been the mainstay of anticoagulation therapy for more than 50 years.
Warning label on a tube of "brown rat" poison laid on a dike of the Scheldt river in Steendorp, Belgium. The tube contains bromadiolone, a second-generation (superwarfarin) anticoagulant. The label in Dutch states, in part: Contains an anticoagulant with prolonged activity. Antidote Vitamin K1.