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
[{'content': 'Alfa blocker useful in BPH is? \nSelect and explain. \nA. Phentolamine, B. Prazosin, C. Tolazoline, D. Phenoxybenzamine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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.', 'role': 'assistant'}]