<prompt> Oral anticoagulant causes all except: March 2012Interference with synthesis of vitamin K dependent clotting factorsAnticoagulant effect both in vivo and in vitroHematuriaInternal haemorrhage2  <response>: Ans: B i.e. Anticaogulant effect both in vivo and in vitro Anticoagulant Warfarin and its congeners act as antiocagulants only in vivo, not in vitro. This is so because they act indirectly by interfering with the synthesis of vitamin K dependent clotting factors in liver. Bleeding is the most impoant problem with anticoagulants; ecchymosis, epistaxis, hematuria, bleeding in gastrointestinal tract. Intracranial or other internal haemorrhages may be fatal. 