L-771688 (SNAP 6383) is a novel potent and selective α1A-adrenoceptor antagonist with a Ki value of 0.43±0.02 nM.L-771688 KE is used for the treatment of benign prostatic hyperplasia.

Terazosin:1.8±0.65 nM (Ki), GG818:0.026 ± 0.002 nM (Ki), L-771688:0.052 ± 0.008 n M (Ki)

Highly potent inhibition of specific [3H]L-771688 binding to cloned human α1A-Adrenoceptors is observed with subtype-selective compounds GG818 (Ki=0.026±0.002 nM) and L-771688 (Ki=0.052±0.008 nM), as well as subtype non-selective α1-adrenoceptor antagonists prazosin (Ki=0.088±0.032 nM) and terazosin (Ki=1.8±0.65 nM).
The relative amount of [3H]L-771688 (0.5 nM) binding in various rat tissue membranes is highest in the submaxillary gland (9.5 pmol/g tissue), followed by the brain (5.8 pmol/g tissue), vas deferens (4.3 pmol/g tissue), kidney (3.4 pmol/g tissue), heart (1.5 pmol/g tissue), urethra (1.1 pmol/g tissue), and prostate (0.88 pmol/g tissue). In contrast, low specific [3H]L-771688 binding is observed in rat urinary bladder (0.55 pmol/g tissue), liver (0.44 pmol/g tissue), aorta (0.11 pmol/g tissue), and spleen (0.11 pmol/g tissue)[1].