This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pharmacology
[{'content': 'True about oral anticoagulant warfarin are all EXCEPT: \nSelect and explain. \nA. Acts in vivo, B. Acts both in vivo and in vitro, C. Interferes with synthesis of Vit K, D. Causes Hematuria', 'role': 'user'}, {'content': 'Answer: B \nExplanation: * Oral anticoagulant is warfarin. It is used only in vivo (body), not in vitro (lab).* Warfarin is not used to store blood.* It acts by inhibiting Vitamin K. Due to overdose, hematuria is the first manifestation noted.* Dose monitoring is done by INR.* Antidote of warfarin overdose: Vitamin KPT (Prothrombin Time)aPTT (activated Partial Thromboplastin Time)Assess activity of Extrinsic coagulation pathway Used when on warfarin treatmentWePT: Warfarin for extrinsic; PT value assessed.Assess activity of Extrinsic coagulation pathway.Used while on heparin treatment.HINT: Heparin for Intrinsic; aPTT value assessed.', 'role': 'assistant'}]