Page 26 - phytochemistry II -pharmD general

Ephedrine has two chiral centres, giving rise to four stereoisomers.
The pair of enantiomers with the stereo chemistry (1R,2S) and (1S,2R) is
designated ephedrine, while the pair of enantiomers with the stereochemistry
(1R,2R) and (1S,2S) is called pseudoephedrine.

• The isomer which is marketed is (−)-(1R,2S)-ephedrine.
• it is the most active of the four isomers as a pressor amine.
• This isomer has the correct (R) configuration at the carbon atom bearing

the hydroxyl group, and the desired (S) configuration at the carbon bearing
the methyl group for optimal direct action at adrenergic receptors

Ephedrine is closely related to the animal hormone adrenaline (epinephrine) in its
chemical structure and pharmacological action (adrenergic)
Ephedrine has the advantage of being

- Effective if taken orally or by injection

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