生物活性/药理作用 | Dabigatran etexilate is an inactive pro-drug that is converted to dabigatran, the active form, by esterase-catalyzed hydrolysis in the plasma and liver. Dabigatran, the main active principle in plasma, is a rapid-acting competitive and reversible direct inhibitor of thrombin. Thrombin, a serine protease, is responsible for the conversion of fibrinogen to fibrin in the coagulation cascade. Inhibition of thrombin consequently prevents thrombus development. Dabigatran inhibits free thrombin, fibrin-bound thrombin and thrombin-induced platelet aggregation. Dabigatran directly inhibits thrombin in a concentration-dependent, reversible, specific, and competitive manner which results in a prolongation of aPTT (partial thromboplastin time), ECT (Ecarin clotting time), and TT (thrombin time). It may increase INR but this laboratory parameter is relatively insensitive to the activity of dabigatran. CYP450 enzymes are not involved in the metabolism of dabigatran thus is not expected to interact with drugs metabolized by CYP isoenzymes. Dabigatran is typically metabolised by esterases and microsomal carboxylesterases. Pharmacologically active acylglucoronides are formed via conjugation. Four positional isomers, 1-O, 2-O, 3-O, and 4-O, acylglucuronides exist, each accounting for less than 10% of total plasma dabagatran. |
