Interactions : אינטראקציות

4.5 Interaction with other medicinal products and other forms of interaction

Contraindicated combinations
+ Indirect sympathomimetic agents: (phenylpropanolamine, pseudoephedrine, phenylephrine, methylphenidate): risk of vasoconstriction and/or of acute episodes of hypertension.
+ Non-selective MAO inhibitors: The administration of ephedrine to patients who are undergoing or have undergone treatment with MAO inhibitors within the last 2 weeks is contraindicated as the combination may cause severe, possibly fatal, hypertension.

Combinations not recommended
+ Volatile halogen anaesthetics: Serious ventricular arrhythmias (increase in cardiac excitability). Nonetheless, the new volatile drugs, such as sevoflurane and desflurane, show less cardiac side effect allowing a possible co-administration of ephedrine.
+ Tricyclic antidepressants (e.g. imipramine): Paroxysmal hypertension with possibility of arrhythmias (inhibition of adrenaline or noradrenaline entry in sympathetic fibers).
+ Noradrenergic-serotoninergic antidepressants (milnacipran, venlafaxine): Paroxysmal hypertension with possibility of arrhythmias (inhibition of adrenaline or noradrenaline entry in sympathetic fibers).
+ Guanethidine and related products: Substantial increase in blood pressure (hyperreactivity linked to the reduction in sympathetic tone and/or to the inhibition of adrenaline or noradrenaline entry in sympathetic fibers). If the combination cannot be avoided, use with caution lower doses of sympathomimetic agents.
+ Sibutramine: Paroxysmal hypertension with possibility of arrhythmias (inhibition of adrenaline or noradrenaline entry in sympathetic fibers).
+ Selective MAO-A inhibitors (moclobemide, toloxatone): Risk of vasoconstriction and/or episodes of hypertension.
+ Linezolid: Risk of vasoconstriction and/or episodes of hypertension.
+ Ergot alkaloids: Risk of vasoconstriction and/or episodes of hypertension.
Combinations requiring precautions for use
+ Alpha- and beta-adrenergic blocking agents: Alpha blockers (e.g. phentolamine) reduce the vasopressor effect of ephedrine. Beta blockers may inhibit the cardiac and bronchodilator effects of ephedrine.
+ Reserpine and methyldopa reduce the vasopressor action of ephedrine.
+ Theophylline and derivatives (aminophylline). Concomitant administration of ephedrine and theophylline may result in insomnia, nervousness and gastrointestinal complaints.
+ Agents that alter urine pH: alkalization, e.g. from Acetazolamide or Sodium Bicarbonate, inhibits renal excretion of ephedrine.
+ Corticosteroid: Ephedrine has been shown to increase the clearance of dexamethasone.
+ Antiepileptics: increased plasma concentration of phenytoin and possibly of phenobarbitone and primidone.
+ Clonidine, atropine: augment the pressor effect of ephedrine.
+ Oxytocin and oxytocic drugs: serious postpartum hypertension has been described in patients who received both a vasopressor (i.e., methoxamine, phenylephrine, ephedrine) and an oxytocic (i.e., methylergonovine, ergonovine). Some of these patients experienced a stroke.
+ Cardiac glycosides: ephedrine with a cardiac glycoside, such as digitalis, may increase the possibility of arrhythmias.
+ Aminophylline or other xanthines, diuretic therapy: concomitant administration may result in hypokalaemia