Serotonin function in panic disorder: Intravenous administration of meta-chlorophenylpiperazine

A placebo-controlled study of the direct serotonin receptor agonist meta-chlorophenylpiperazine (MCPP), intravenously infused over 90 s in a 0.06 mg/kg dose, was conducted in 10 patients with panic disorder and 9 normal control subjects. Cortisol, MCPP serum levels, and behavioral responses were measured over a 180-min period. MCPP induced equivalent cortisol release and behavioral responses in both groups. Differences between intravenous and oral administration of MCPP are discussed, and the present findings are related to the serotonergic hypothesis of panic disorder.