4-Diisobutylamino-1,1-diphenyl-1-butanol maleate 99465-44-8 Afd 21 Afd-21 Benzenemethanol, alpha-(3-(bis-(2-methylpropyl)amino)propyl)-alpha-phenyl-, (Z)-2-butenedioate (1:1) (salt) NS-2 Class 1 antiarrhythmic agent