indication

Ephedrine commonly used as a stimulant, appetite suppressant, concentration aid, decongestant, and to treat hypotension associated with anaesthesia.

pharmacology

Ephedrine is similar in structure to the 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.

mechanism of action

Ephedrine is a sympathomimetic amine - that is, its principal mechanism of action relies on its direct and indirect actions on the adrenergic receptor system, which is part of the sympathetic nervous system. Ephedrine increases post-synaptic noradrenergic receptor activity by (weakly) directly activating post-synaptic α-receptors and β-receptors, but the bulk of its effect comes from the pre-synaptic neuron being unable to distinguish between real adrenaline or noradrenaline from ephedrine. The ephedrine, mixed with noradrenaline, is transported through the noradrenaline reuptake complex and packaged (along with real noradrenaline) into vesicles that reside at the terminal button of a nerve cell. Ephedrine's action as an agonist at most major noradrenaline receptors and its ability to increase the release of both dopamine and to a lesser extent, serotonin by the same mechanism is presumed to have a major role in its mechanism of action.

toxicity

Cardiovascular: tachycardia, cardiac arrhythmias, angina pectoris, vasoconstriction with hypertension

absorption

85%

half life

3-6 hours

route of elimination

mainly renal

drug interactions

Amitriptyline: The tricyclic antidepressant, amitriptyline, increases the sympathomimetic effect of ephedrine.

Amoxapine: The tricyclic antidepressant, amoxapine, increases the sympathomimetic effect of ephedrine.

Clomipramine: The tricyclic antidepressant, clomipramine, increases the sympathomimetic effect of ephedrine.

Desipramine: The tricyclic antidepressant, desipramine, increases the sympathomimetic effect of ephedrine.

Desvenlafaxine: Desvenlafaxine may increase the tachycardic and vasopressor effects of ephedrine. Consider alternate therapy or monitor for increased sympathomimetic effects, such as increased blood pressure, chest pain and headache.

Doxepin: The tricyclic antidepressant, doxepin, increases the sympathomimetic effect of ephedrine.

Guanethidine: Ephedrine may decrease the effect of guanethidine.

Imipramine: The tricyclic antidepressant, imipramine, increases the sympathomimetic effect of ephedrine.

Isocarboxazid: Increased arterial pressure

Linezolid: Possible increase of arterial pressure

Methyldopa: Increased arterial pressure

Midodrine: Increased arterial pressure

Moclobemide: Moclobemide increases the sympathomimetic effect of ephedrine.

Nortriptyline: The tricyclic antidepressant, nortriptyline, increases the sympathomimetic effect of ephedrine.

Phenelzine: Increased arterial pressure

Rasagiline: Increased arterial pressure

Reserpine: Increased arterial pressure

Tranylcypromine: The MAO inhibitor, Tranylcypromine, may increase the vasopressor effect of Ephedrine. Concomitant therapy should be avoided.

Venlafaxine: Venlafaxine may increase the tachycardic and vasopressor effects of ephedrine. Consider alternate therapy or monitor for increased sympathomimetic effects, such as increased blood pressure, chest pain and headache.