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
Which of the following drug is used postop to reverse the effect of heparin used intraoperatively in cardiac surgery? 
Select and explain. 
A. Protamine sulfate, B. Vitamin K, C. Tranexamic acid, D. Factor VIII concentrate
A: Protamine sulfate
Answer: A: Protamine sulfate 
Explanation: Ans. is 'a' i.e., Protamine sulfate Protamine Sulfate* It is a strongly basic, low molecular weight protein obtained from the sperm of certain fish.* Given i.v.it neutralises heparin weight for weight, i.e. 1 mg is needed for every 100 U of heparin.* For the treatment of heparin induced bleeding, due consideration must be given to the amount of heparin that may have been degraded by the patient's body in the mean time.* However, it is needed infrequently because theaction of heparin disappears by itself in a fewhours, and whole blood transfusion is needed toreplenish the loss when bleeding occurs.* Protamine is more commonly used when heparin action needs to be terminated rapidly, e.g. after cardiac or vascular surgery.