Adequate treatment with imipramine in continuation treatment

Maintenance treatment studies done with tricyclic antidepressants have used the equivalent of 150 mg or less of imipramine in prophylactic clinical trials. In an ongoing 3-year maintenance trial, the authors are using imipramine in dosages greater than 150 mg/day for both acute and continuation treatment (4 to 6 months) of recurrent depression in order to test the efficacy of this dosage level. Fifty-seven depressed patients who received tricyclic drug treatment and interpersonal psychotherapy during the acute and continuation phases of the study tolerated this dosage level well (mean dose, 217 mg/day of imipramine), reported few adverse effects on a somatic symptom checklist, and demonstrated a high level of compliance as shown by plasma concentration/dosage (L/D) ratios. The authors found that the time course of the L/D ratio is associated with higher steady-state plasma concentrations than those observed with similar dosages in shorter-term tricyclic antidepressant treatment.