This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Oral anticoagulant causes all except: March 2012 
Select and explain. 
A. Interference with synthesis of vitamin K dependent clotting factors, B. Anticoagulant effect both in vivo and in vitro, C. Hematuria, D. Internal haemorrhage2
B: Anticoagulant effect both in vivo and in vitro
Answer: B: Anticoagulant effect both in vivo and in vitro 
Explanation: 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.