Enhanced Sensitivity to Cholecystokinin Tetrapeptide in Panic Disorder

We studied the action of cholecystokinin tetrapeptide (CCK-4) in patients with panic disorder and normal controls. Subjects received, in random order, one injection of CCK-4 and one injection of placebo (saline) on two separate days in a double-blind crossover design. Two doses of CCK-4, 50 and 25 micrograms, were administered to two different samples of subjects. The panic rate with 50 micrograms of CCK-4 was 100% (12/12) for patients and 47% (7/15) for controls. The panic rate with 25 micrograms of CCK-4 was 91% (10/11) for patients and 17% (2/12) for controls. Nine percent of patients compared with 0% of controls panicked with placebo. These findings concur with previous reports of a panicogenic effect of CCK-4 and suggest that patients with panic disorder are more sensitive to the panicogenic effect of the peptide than are normal controls.