These arrhythmias also can develop in patients with profound hypoxia or hypercarbia. Norepinephrine is relatively contraindicated in patients with preexisting hyperthyroidism or hypertension it could exacerbate their underlying condition. Norepinephrine interacts with halogenated hydrocarbon general anesthetics, such as cyclopropane or halothane, because the anesthetics increase cardiac irritability, which can lead to arrhythmias. Bretylium can potentiate the action of vasopressors such as norepinephrine on adrenergic receptors, possibly resulting in arrhythmias. Norepinephrine interacts with guanethidine because guanethidine can increase the pressor response of direct-acting vasopressors, possibly resulting in severe hypertension.
Norepinephrine can cause severe persistent hypertension if administered concurrently with oxytocin.
Atropine blocks the vagal reflex bradycardia caused by norepinephrine and increases its pressor effect. MAOIs, tricyclic antidepressants, ergot alkaloids, and vasopressin, ADH have all been shown to potentiate norepinephrine's pressor action. The concomitant use of norepinephrine with diuretics can cause decreased arterial responsiveness to vasopressor agents. Generalized CNS stimulation can result in adverse effects manifested as fear, anxiety, nervousness, insomnia, excitability, psychomotor agitation, impaired memory, headache, dizziness and disorientation. These reactions can occur with therapeutic doses of systemic norepinephrine.