<prompt> All are true about warfarin, except.It inhibits the activation of vitamin K dependent clotting factorsIts half life is 36 hoursIt can cross placentaIts dose is increased in liver disease  <response>: Ans. D Its dose is increased in liver diseaseRef: Katzung 11e p595-596Warfarin is an oral anticoagulant that acts by inhibiting the g- carboxylation of glutamate residues in vitamin-K dependent clotting factors II, VII, IX and X.It has a long half life t12 36 hoursIt readily crosses the placenta. If given during pregnancy, it can result in Contradi syndrome in the fetus.Liver disease reduces the synthesis of clotting factors, thus increases the effect of warfarin. The dose of this drug therefore, needs to be reduced in liver disease. 