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 anesthetics: 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.
- Corticosteroids: 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.