Very potent ligand for α1 sites (Ki for displacement of prazosin = 0.2 nM). Displays different binding properties for each α1 subtype (pKi values are 8.74, 9.44 and 9.57 for α1B, α1D and α1A adrenoceptors respectively). Also binds to 5-HT1A sites (Ki = 50 nM).