Bopindolol malonate is the malonate preparation of Bopindolol, a β1-adrenoceptor antagonist. Bopindolol malonate slowly dissociates into the active metabolites 4-(3-tert-butylamino-2-hydroxypropoxy)-2-methyl indole (18-502) and 4-(3-tert-butylaminopropoxy)-2-carboxyl indole (20-785) which both demonstrate potent β1-adrenoceptor blocking activity. The relative potencies of these compounds was determined with a radioligand binding assay, demonstrating 18-502 to be more potent than Bopindolol which is more potent than 20-785. Both Bopindolol and its metabolite 18-502 demonstrate inhibition of H2O2-induced lipid peroxdiation (IC50 = 1.8 μM and 10 μM, respectively) and both demonstrate scavenging of the radical species 1,1-diphenyl-2-picrylhydrazyl.