Treatment of bipolar depression with twice-weekly fluoxetine: management of antidepressant-induced mania

OBJECTIVE: To report a case of treatment of bipolar depression and management of antidepressant-induced mania with a low-dose fluoxetine regimen. CASE SUMMARY: A 59-year-old white woman was admitted involuntarily to a New York State psychiatric center with a diagnosis of bipolar (type I) disorder, mixed, with psychotic features. Initial treatment with lithium, olanzapine, and clonazepam produced a remission of manic and psychotic symptoms. However, the patient remained clinically depressed. Addition of oral fluoxetine 10 mg every morning to her medication regimen was followed 22 days later by the development of a manic state. Reduction of the fluoxetine dosage to 10 mg twice weekly was associated with the attainment of euthymia in 18 days. Thirteen days after the fluoxetine dosage reduction, the patient's fluoxetine blood concentration was 20 micrograms/L and the norfluoxetine concentration was reported as 53 micrograms/L. DISCUSSION: To our knowledge, this is the first published case that describes the association between a low-dose fluoxetine regimen and the evolution of a bipolar affective state from depression to euthymia via manic switching. The temporal synchrony of this switching with initial implementation of fluoxetine 10 mg every morning, followed by a dose reduction to 10 mg twice weekly, suggests that bipolar depressed patients are extremely sensitive to low doses of antidepressants and to incremental changes in these doses. However, it also suggests that they can respond clinically to such treatment. Furthermore, our laboratory data indicate that antidepressant blood concentrations may play a contributory role in maintaining the balance between euthymia and mania in these patients. CONCLUSIONS: Manic switching is always a concern when treating a bipolar depressed patient. Utilization of a low-dose antidepressant drug regimen may be a clinically prudent approach in such an individual.