Page 139 - Pharmacognosy 2 PG303 (1)

Pharmacognosy-2 (PG303) Level 2 Clinical Pharmacy-Pharm D

EPHEDRA

It is the dried twigs of Ephedra sinica Stapf, E. equisetina Bunge (both are indigenous to
China), E. gerardiana Wall (indigenous to India) and E. nebrodensis Tineo (= E. scoparia
Lange, indigenous to India and Spain) Family: Gnetaceae.

The old stem is woody, 4-7 mm in diameter, procumbent, branching chiefly from the base
and covered with a brown cork with occasionally silvery patches. The young branches are green,
more slender, 1- 2 mm in diameter and 30 cm length. The leaves are reduced to sheaths 2- 5 mm
long, completely surrounding the stems and bearing minute opposite decussate reddish- brown
laminae, each terminating in sharp, recurved point. The internodes being rough and 3- 5 cm length.

Ephedra is collected in autumn, when the alkaloid content is very high (about 2%).

Constituents
Ephedrine and pseudoephedrine (which is readily convertible into ephedrine).

Mode of action
Ephedrine has a mixed action.
1- Releases stored norephedrine from nerve endings.
2- Directly stimulate α and β adrenergic receptors.

Through its action on α1 adrenergic receptors, ephedrine produces vasoconstriction in
mucous membranes, thus relieving to some degree congestion in the nasal passages.

Stimulation of β2 adrenergic receptors lead to relaxation of bronchial smooth muscles with
the increase of ciliary activity and liquification of mucus (mild expectorant action).

Uses
Antiasthmatic drug and in treatment of nasal congestion. It has been used in China since
very ancient times under the name Ma Huang.
Common side effects
headache, nausea, and vomiting. Higher dosages result in increased blood pressure and
cardiac rhythm disorders.

Contraindications
Patients suffering from heart conditions and hypertension.

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