Drug interactions:Epinephrine must not be administered concomitantly with other
sympathomimetic drugs(such as isoproterenol) because of possible additive effects and increased toxicity. Combined effects may induce serious cardiac arrhythmias. They may be administered alternately when the preceding effect of other such drugs has subsided.
Epinephrine is readily destroyed by
alkaliesand
oxidizing agents(e.g., oxygen, chlorine, bromine, iodine, permanganates, chromates, nitrites, and salts of easily reducible metals, especially iron).
The effects of epinephrine may be potentiated by
tricyclic antidepressants, certain
antihistamines(e.g., diphenhydramine, tripelennamine, chlorpheniramine) and
sodium I-thyroxine.
In obstetrics, if vasopressor drugs are used either to correct hypotension or added to the local anesthetic solution, some
oxytocic drugsmay cause severe persistent hypertension; even rupture of a cerebral blood vessel may occur during the postpartum period.
All vasopressors should be used cautiously in patients taking
monoamine oxidase (MAO) inhibitors.
Cyclopropaneor
halogenated hydrocarbon anestheticssuch as halothane which sensitize the myocardium may induce cardiac arrhythmia. (See Contraindications.) When encountered, such arrhythmias may respond to administration of a beta-adrenergic blocking drug.
Diruretic agentsmay decrease vascular response to pressor drugs such as epinephrine.
Epinephrine may antagonize the neuron blockade produced by
guanethidineresulting in decreased antihypertensive effect and requiring increased dosage of the latter.
Use of epinephrine with excessive doses of
digitalis, mercurial diureticsor other drugs that sensitize the heart to arrhythmias is not recommended.
Rapidly acting vasodilators such as
nitritesor
alpha-blocking agentsmay counteract the marked pressor effects of epinephrine.
Propranololadministered concomitantly with epinephrine may block the beta-adrenergic effects of epinephrine, causing hypertension.