Compounds (I) (R = aryl, cycloalkyl or polyhaloalkyl, R1 = alkyl, alkoxy, polyfluoroalkoxy, hydroxy or trifluoromethanesulphonyloxy, each of R2 and R3 independently = H, halogen, alkoxy or polyfluoroalkoxy, n is 0, 1 or 2) and their N-oxides or pharmaceutically acceptable salts are endowed with enhanced selectivity for the α1 adrenergic receptor and a low activity in lowering blood pressure. This activity profile makes these compounds useful in the treatment of obstructive syndromes of the lower urinary tract, including benign prostatic hyperplasia (BPH), in lowering intraocular pressure, in the treatment of cardiac arrhythmia and erectile and sexual dysfunction, and in the treatment of lower urinary tract symptoms (LUTS) and neurogenic lower urinary tract dysfunction (NLUTD). Compounds (I) per se, pharmaceutical compositions containing compounds (I) and medical uses of compounds (I) are claimed.