PT  - JOURNAL ARTICLE
AU  - Julius Axelrod
TI  - STUDIES ON SYMPATHOMIMETIC AMINES. I. THE BIOTRANSFORMATION AND PHYSIOLOGICAL DISPOSITION OF <em>l</em>-EPHEDRINE AND <em>l</em>-NOREPHEDRINE
DP  - 1953 Sep 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 62--73
VI  - 109
IP  - 1
4099  - http://jpet.aspetjournals.org/content/109/1/62.short
4100  - http://jpet.aspetjournals.org/content/109/1/62.full
SO  - J Pharmacol Exp Ther1953 Sep 01; 109
AB  - Methods for the estimation of ephedrine and its metabolic products, norephedrine, p-hydroxynorephedrine and p-hydroxyephedrine, in biological materials, are described. In the dog the main route of biotransformation of ephedrine involves demethylation to norephedrine. The rate of demethylation is rapid, indicating that the activity of ephedrine is mediated largely through norephedrine. Norephedrine is excreted in the urine mainly unchanged. A minor route of metabolism of ephedrine involves hydroxylation of the aromatic nucleus to form p-hydroxyephedrine and p-hydroxynorephedrine, which are excreted partly free and partly as conjugates. Both ephedrine and norephedrine are highly localized in various organ tissues. Demethylation to norephedrine is a major route of metabolism in the dog and guinea pig and a minor pathway in the rat. On the other hand, hydroxylation of the drug constitutes a minor pathway of metabolism in the dog and guinea pig but a major one in the rat.