Prazobind (SZL 49), a prazosin analog, is an irreversible α1-adrenoceptor antagonist. Prazobind competes for alpha 1-adrenoceptor binding sites with a similar potency (IC50 of 1 nM) in tissues enriched in both the alpha 1A (hippocampus) and alpha 1B (liver) subtypes. Prazobind partially inhibits the contractions of circular muscles, longitudinal muscles and smooth muscles of the spleen. Prazobind can be used for the study of blood pressure[1][2][3][4].