Ephedrine

Source

It is the principal alkaloid of the species of Ephedra (Ephedraceae) and was first isolated from Ma Huang, one of the oldest known drugs. Identified as Ephedra vulgaris var Helvetica, Ma Huang consists of the entire plant or tops of various Ephedra species including E. sinica and E. equisetina from China, E. gerardiana, E. intermedia and E. major from India and Pakistan. The plants are small bushes with slender aerial stems and minute leaves giving the appearance of being effectively leafless. The plants typically contain 2% to 5% of alkaloids according to species; 30% to 90% of the total alkaloids is (–) ephedrine. Related structures include the diastereoisomeric (–) pseudoephedrine and the demethyl analogues (–) norephedrine and (+) norpseudoephedrine are also present. In E. intermedia, the proportion of pseudoephedrine exceeds that of ephedrine. The root also contains a number of macrocyclic alkaloids (ephedradine) and ferruloyl histamine which have hypotensive properties.

Uses

A sympathomimetic amine, the effects of ephedrine are similar to those of adrenaline. It is orally active and has a longer duration of action than adrenaline. Due to its bronchodilator effect, it is used in the relief of asthma and hay fever. Its vasoconstrictor action on mucous membranes makes it an effective nasal decongestant. Ephedrine is of considerable value as a circulatory stimulant in surgical shock, as a mydriatic and in Addison’s disease. Pseudoephedrine is also widely used in compounded cough and cold preparations and as a decongestant. In indigenous medicine in Asia, ephedras are used as anti-inflammatory drugs.