A 5-(2-{[2-(2-ethoxyphenoxy)ethyl]amino}propyl)-2-methoxybenzenesulfonamide that has (R)-configuration. A specific alpha1 adrenoceptor antagonist used (generally as its hydrochloride salt, tamsulosin hydrochloride) in the treatment of prostatic hyperplasia, chronic prostatitis, urinary retention, and help with the passage of kidney stones.