(R)-Terazosin is an active R-enantiomer of Terazosin. (R)-Terazosin is a potent α1-adrenoceptor antagonist with Ki values of 6.51 nM, 1.01 nM and 1.97 nM for α1a, α1b and α1d-adrenoceptor, respectively[1].
[1]. Hancock AA, et al. Actions of terazosin and its enantiomers at subtypes of alpha 1- and alpha 2-adrenoceptors in vitro. J Recept Signal Transduct Res. 1995 Sep-Dec;15(7-8):863-85.