STERIC ASPECTS OF ADRENERGIC DRUGS. I. COMPARATIVE EFFECTS OF DL ISOMERS AND DESOXY DERIVATIVES

¹ College of Pharmacy, The Ohio State University, Columbus, Ohio

The action of D and L isomers of norephinephrine, epinephrine, cobefrin, metaraminol, phenylephrine, octopamine, synephrine, norephedrine, ephedrine and pseudoephedrine and their desoxy derivatives on the isolated rat vas deferens has been studied in the light of the Easson-Stedman hypothesis that dextro isomers act like desoxy derivatives. The dose-response curves and ED5O values of L(+)-norepinephrine and L(+)-epinephrine were indeed essentially the same as those of their desoxy derivatives, dopamine and epinine, respectively. In all other cases, dextro isomers produced much less contraction of the vas deferens than their desoxy derivatives. This indicates that in the normal vas deferens the hypothesis holds true for directly-acting L(+) isomers and their desoxy derivatives, but not for indirectly-acting compounds. In the latter case, dose-response curves appear to be related to the affinity of these compounds for catecholamine uptake sites. The importance of the relative configurations of the -hydroxyl and -methyl groups in relation to sympathomimetic effect is discussed.