Norepinephrine challenges in panic patients.

Six subjects with agoraphobia with panic attacks were pretreated with placebo and restricted use of lorazepam for 4 or 5 days. Then l-norepinephrine was infused intravenously with stepwise increases to 4 to 16 micrograms/min. All subjects developed DSM-III symptoms of a panic attack. Subjective results including idiosyncratic symptoms closely resembled the spontaneous panic attacks of these subjects. Cardiac rhythm and rate changes contradicted subjective reports of racing heart and palpitations. Tachypneic and hypertensive reactivities were benign. Both anxiety symptoms and cardiovascular changes reversed rapidly and spontaneously upon discontinuation of the infusion. To validate the possibility that norepinephrine infusion may specifically and reliably simulate spontaneous panic attacks, the authors recommend further work, particularly blinded controlled studies.