Alpha 1A receptors are present on prostatic urethra whereas alpha 1B/1D are present on blood vessels. Drugs blocking both of these (like prazosin, terazosin, doxazosin and alfuzosin) are useful in BHP with hypeension but cause postural hypotension (First dose effect) as an adverse effect. Selective alpha 1A blockers (tamsulosin and silodosin) treat symptoms of BHP without causing postural hypotension. Induction of apoptosis in prostate smooth muscle cells in BPH is shown by terazosin and Doxazosin