Several issues remain to be ascertained beyond the acute response to imipramine hydrochloride in patients with panic disorder. Study 1 consisted of a prospective, systematic characterization of half-dose 12-month maintenance in patients with panic disorder with agoraphobia who had shown marked and stable response to 6 months of acute-phase treatment with imipramine. Study 2 assessed the 6-month cumulative relapse rate following discontinuation of acute-phase imipramine treatment in a comparable sample of patients. The same assessment battery was used in both studies, and the integrity of experimental drug conditions was verified by plasma drug level determinations. In contrast to the high relapse rate following discontinuation of acute-phase treatment, none of the patients showed relapse or had sustained worsening in panic or phobia measures during the half-dose maintenance period. The results underscore the importance of pharmacological prophylaxis and provide empirical guidelines for a successful low-dose maintenance regimen for patients with panic disorder and agoraphobia who respond markedly to imipramine.
Mavissakalian M, Perel JM. Clinical Experiments in Maintenance and Discontinuation of Imipramine Therapy in Panic Disorder With Agoraphobia. Arch Gen Psychiatry. 1992;49(4):318-323. doi:10.1001/archpsyc.49.4.318