Ephedrine

Ephedrine is similar in structure to the ( semi-synthetic ) derivatives amphetamine and methamphetamine. Chemically, it is an alkaloid derived from various plants in the genus // Ephedra // (family Ephedraceae ). It works mainly by increasing the activity of noradrenaline on adrenergic receptors. It is most usually marketed in the //hydrochloride// and //sulfate// forms. In traditional Chinese medicines, the herb //má huáng// (麻黄, // Ephedra sinica //) contains ephedrine and pseudoephedrine as its principal active constituents. The same is true of other herbal products containing extracts from some of the other //Ephedra// species.
 * Ephedrine** is a sympathomimetic amine commonly used as a stimulant, appetite suppressant , concentration aid, decongestant , and to treat hypotension associated with anaesthesia.

Ephedrine exhibits optical isomerism and has two chiral centres, giving rise to four stereoisomers. By convention the enantiomers with opposite stereochemistry around the chiral centres (1R,2S and 1S,2R) are designated ephedrine, while pseudoephedrine has same stereochemistry around the chiral carbons (1R,2R and 1S,2S). Ephedrine is a substituted amphetamine and a structural methamphetamine analogue. It differs from methamphetamine only by the presence of a hydroxyl (OH). Amphetamines, however, are more potent and have additional biological effects. The isomer which is marketed is (–)-(1R,2S)-ephedrine. Ephedrine hydrochloride has a melting point of 187−188 °C.



Ephedrine is a sympathomimetic amine. The principal mechanism of its action relies on its indirect stimulation of the [|adrenergic receptor] system, which is part of the [|sympathetic nervous system] (//SNS//), by increasing the activity of [|noradrenaline] at the post-synaptic α- and β-receptors. [|[1]] The presence of direct interactions with α-receptors is unlikely, but still controversial. L-Ephedrine, and particularly its [|stereoisomer][|norpseudoephedrine] (which is also present in [|Catha edulis] ) has indirect [|sympathomimetic] effects and due to its ability to cross the [|blood brain barrier], it is a [|CNS] [|stimulant] similar to [|amphetamines] but less pronounced, as it releases [|noradrenaline] and [|dopamine] in the [|substantia nigra]. [|[10]] The presence of an //N//- [|methyl group] decreases binding affinities at α-receptors, compared with [|norephedrine]. On the other hand ephedrine binds better than [|//N//-methylephedrine], which has an additional methyl group at the N-atom. Also the [|steric] orientation of the [|hydroxyl] group is important for receptor binding and functional activity.