• panic disorder;
  • noradrenaline;
  • clonidine;
  • yohimbine

In order to evaluate possible abnormal noradrenergic neuronal functional regulation in patients with panic disorder, the behavioral, biochemical and cardiovascular effects of intravenous yohimbine (0.4 mg/kg) and clonidine (2 μg/kg) were determined in 15 healthy subjects and 38 patients with panic disorder. A subgroup of 24 panic disorder patients were observed to experience yohimbine-induced panic attacks and had larger yohimbine-induced increases in plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) than healthy subjects and other panic disorder patients. A blunted growth hormone response to clonidine and a significant clonidine-induced decrease in plasma MHPG was also observed in this subgroup of panic disorder patients. These data replicate and extend previous investigations, which are consistent with a large body of preclinical and human data relating increased noradrenergic neuronal function to human anxiety and fear states.