Isomers of erythro-5-(1-hydroxy-2-isopropylaminobutyl)-8-hydroxycarbostyril, a new bronchodilator

Abstract
The isomers of .epsilon.rythro-5-(1-hydroxy-2-isopropylaminobutyl)-8-hydroxycarbostyril (1), a new potent and .beta.2-selective bronchodilator, were synthesized by optical resolution of compound 1 and inversion of the erythro to the threo isomers. The isomers were tested for activities to inhibit histamine-induced bronchospasm and to increase the heart rate of anesthetized dogs. Racemic and (-)-erythro-1 showed potent and .beta.2-selective bronchodilator activities. Among the isomers, (-)-erythro-1 showed the highest activities and (+)-erythro-1 showed the lowest.