α1- and α2B-adrenoceptor antagonist (Ki values are 3.3, 0.7, 1.1, 7.7, 1510 and 78.2 nM for α1A, α1B, α1D, α2B, α2A and α2C receptors respectively). Antihypertensive following oral or intravenous administration in vivo. Purity 99%. MW (observed): 423.9