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
All of the following statements about unfractionated heparin are true except:- 
Select and explain. 
A. It is a powerful anticoagulant only in vivo, B. Protamine sulfate is the antidote, C. It should not be given by intramuscular route, D. It acts by inhibiting factor IIa and Xa
A: It is a powerful anticoagulant only in vivo
Answer: A: It is a powerful anticoagulant only in vivo 
Explanation: Heparin Warfarin 1. Route of administration parenteral (IV, SC) Oral 2. Onset of action Rapid Delayed (1-3 days) 3. Activity In vitro and in vivo In vivo only 4. MOA Activates Antihrombin III | Activation of II, VII, IX, X 5 Monitoring by aPTT PT 6. Antagonist Protamine sulphate Vit. K1 (Phytonadione) 7. Placental barrier Does not cross placenta Fetal warfarin syndrome 8. Use To initiate therapy For maintenance