1997 Volume 11 Issue 2 Pages 81-85
The present study was undertaken to examine the clinical usefulness of the optical isomers of isoproterenol by their bronchodilating effect in children with asthmatic attack and their heart rate increasing effect in healthy volunteers. Thirty patients with asthmatic attack were randomly assigned to inhale l-isoproterenol or dl-isomer which contained the same dose of l-isoproterenol. The pulmonary functions were measured in both groups before and after inhalation. In the group inhaled l-isoproterenol, mean% of forced expired volume in one second (%FEV1.0) increased significantly from 37.5% to 54.3%. We observed also significant increase in mean %FEV1.0 from 37.5% to 60.8% in the group inhaled dl-isomer. There was no significant difference in improvement of mean %FEV1.0 between both groups.
Concerning heart rate increasing effects, we measured changes in heart rate by electrocardiogram in thirteen healthy volunteers before and after inhalations of l-isoproterenol or dl-isoproterenol or saline.
Although both l-isoproterenol and dl-isomer significantly increased heart rate compared to saline from 1 minute after begining of inhalation to 3 minutes after completion, there was no significant difference in their effects on heart rate.
These findings suggest that l-isoproterenol and dl-isomer contained dose of l-isomer have similar clinical benefit for continuous inhalation therapy, because both induced same degree of bronchodilatation and of stimulation of heart.
