This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anticoagulants and Coagulants, Subject name: Pharmacology
All are true bout Oral anticoagulants EXCEPT: 
Select and explain. 
A. Acts in vivo, B. Acts both in vivo and in vitro, C. Interferes with synthesis of Vit K, D. Causes Hematuria
B: Acts both in vivo and in vitro
Answer: B: Acts both in vivo and in vitro 
Explanation: Ans. (b) Acts both in vivo and in vitro* 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 treatment* WePT: Warfarin for extrinsic; PT value assessed.* Assess activity of Extrinsic coagulation pathway.* Used while on heparin treatment.* HINT: Heparin for Intrinsic; aPTT value assessed.