Imipramine in panic disorder. 1. Clinical response and pharmacological changes

Clinical and biochemical variables were monitored in 18 patients with panic disorder before and during treatment with imipramine over 16 weeks. Imipramine dosage was slowly increased from a starting dose of 10 mg daily, to prevent early treatment drop-outs. All patients were effectively treated for at least 6 weeks, and only two patients dropped out before the end of the study. There were substantial reductions in panic attack frequency, ratings of depression and avoidance behaviour, but only small reductions in ratings of state and general anxiety. Plasma levels of the noradrenaline metabolite 3-methoxy-4-hydroxyphenyl- ethylene glycol initially fell after starting imipramine, but returned to pre-treatment levels by week 8 of treatment. Plasma imipramine and/or desipramine concentrations were very variable and did not correlate with either psychological or biochemical changes during treatment.