<s>[INST] context: The mainstay of treatment for LUTS due to BPH is a1-adrenergic receptor blockers.a-adrenergic receptors are the most common adrenergic receptors in the bladder, and a1 is the most common subtype in the lower urinary system, prostate, and urethra. The action of a1 blockers is to relax the smooth muscle in the bladder neck and prostate and to reduce outflow resistance. (Prazosin)This class of drugs has become progressively more selective to the a1 subtypes, and many now target the a1asubtype receptor specifically. (Tamsulosin, Alfuzosin)The most common side effects of these drugs are dizziness related to ohostasis, retrograde ejaculation, and rhinitis.The second category of pharmacologic therapy is the 5a-reductase inhibitors that target the glandular component of the prostate. These drugs block the conversion of testosterone to dihydrotestosterone in the prostate and subsequently reduce the prostate volume, thereby reducing outflow resistance. (Finasteride, Dutasteride)Sabiston 20e pg: 2108 [/INST] question: Tamsulosin belongs to | options: A: 5a-reductase inhibitors B: a1a receptor blockers C: a1a receptor agonist D: 5a-transferase inhibitors | answer: B </s>