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
Which of the following is an Alpha 1 blocker without any effect on blood pressure? 
Select and explain. 
A. Tamsulosin, B. Prazosin, C. Oxazocin, D. Terazocin
A: Tamsulosin
Answer: A: Tamsulosin 
Explanation: Tamsulosin a nonquinazoline, is a long acting selective alpha 1A adrenergic receptor antagonist. Tamsulosin and its metabolites are most specific for prostatic alpha 1A adrenergic receptor and less specific for vascular alpha 1A adrenergic receptor thereby having less effect on blood pressure. It is very effective for treating bladder outlet obstruction associated with BPH.