[Structure-activity relationships of halogenated phenylethanolamine and phenoxypropanolamine]

12 compounds from the series of halogenated phenylethanolamines and phenoxypropanolamines were tested at the isolated rabbit jejunum, and the pD2-and pA2-values were determined. All the substances act beta-adrenolytically. Except for 3,4-dichloronoradrenaline, which stimulates the alpha-receptors, all the compounds still have pronounced beta-mimetic effects. The 2,5-dihalogenated phenylethanolamines and phenoxypropanolamines block the beta-receptors at lower concentrations than 2,4-dihalogen derivatives. The weakest beta-adrenolytic effects at the intestine were found with compounds halogenated at the 3,4-position.