<prompt> Which of the following alpha-blocker drug is used in the treatment of benign hypertrophy of prostate without producing significant hypotension?DexazosinPhentolamineTerazosinTamsolusin  <response>: Ans. d Tamsulosin. Ref. KD Tripathi 6thpg. 135DRUG USED FOR BHP Alpha-adrenergic blockers:- Terazosin,- Tamsulosin,- Doxazosin: A 5-a reductase inhibitor - finasteride- Finasteride prevents conversion of testosterone to dihydrotestosterone. Cyproterone acetate Anti-androgenic drug is used for medical castration.Terazosin It is reversible al-selective antagonist that is effective in hypertension; It has also been approved for use in men with urinary symptoms due to BPH. Terazosin has high bioavailability But is extensively metabolized in liver only a small unchanged fraction excreted in urine The half-life of terazosin is 9-12 hours.Doxazosin Is efficacious in the treatment of hypertension and BPH. It differs from prazosin and terazosin in having a longer half-life of about 22 hours. It has moderate bioavailability and is extensively metabolized, with very little parent drug excreted in urine or feces. Doxazosin has active metabolites, although contribution to the drugs effects is probably small.Tamsulosin It is an uroselective a1A1D antagonist with a structure quite different from that of most other al-receptor blockers.Q It has high bioavailability and a long half-life of 9-15 hours. It is metabolized extensively in the liver. Tamsulosin has higher affinity for alA and alD receptors than for the alB subtype. The drugs efficacy in BPH suggests that the alA subtype may be the most important subtype mediating prostate smooth muscle contraction. Furthermore, compared with other antagonists, tamsulosin has less effect on standing blood pressure in patients causes minimal vascular side effects. Dizziness and retrograde ejaculation are the only vital side-effects.Alfuzosin is an al-selective quinazoline derivative that has also been shown to be efficacious in BPH. It has bioavailability of 60, is extensively metabolized, and has elimination halflife of about 5 hours.Indoramin It is another al-selective antagonist that also has efficacy as an antihypertensive.Urapidil It is an al antagonist its primary effect that also has weak 2-agonist and 5-HTlA-agonist actions and weak antagonist action at al receptors. It is used in Europe as an antihypertensive agent and for benign prostatic hyperplasia. 