This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti Adrenergic System, Subject name: Pharmacology
Alfa blocker useful in BPH is? 
Select and explain. 
A. Phentolamine, B. Prazosin, C. Tolazoline, D. Phenoxybenzamine
B: Prazosin
Answer: B: Prazosin 
Explanation: ANSWER: (B) PrazosinREF: Goodman and Gillman s 11TH edition page 172, 173, 183a BLOCKERSClassDrugsPharmacologicalActionsApplicationsUntoward EffectsNon selective/ classical a blockersPhenoxvbenzaminePhentolamineTolazolineDecrease in PVR and blood pressure VenodilationTreatment of catecholamine excess (Pheochromocytoma)Postural hypotension Failure of ejaculationSelective cq blockersPrazosinTerazosinDoxazosinTrimazosinAlfuzosinTamsulosinDecrease in PVR and blood pressure Relax smooth muscles in neck of urinary bladder and in prostatePrimary hypertension. Increase urine flow in BPHPostural hypotensionPrazosin, the prototypic quinazoline a blocker, is a potent and selective a receptor antagonist. In treating benign prostatic hyperplasia (BPH), doses from 1 to 5 mg twice daily typically are used. The twice-daily dosing requirement for prazosin is a disadvantage compared with newer a] receptor antagonists.