R-(-)-Naftopidil is the active enantiomer of the drug naftopidil, an α1-adrenergic receptor antagonist (α1-blocker) that primarily treats lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) by relaxing the muscles around the bladder exit and prostate gland. It is known for its selectivity towards the α1D-adrenergic receptor subtype, which differs from other α1-blockers like tamsulosin and silodosin, potentially leading to a lower incidence of side effects such as ejaculatory disorders and intraoperative floppy iris syndrome.