Switching Patients From Daily Citalopram, Paroxetine, or Sertraline to Once-Weekly Fluoxetine in the Maintenance of Response for Depression

Background: Major depressive disorder is frequently a chronic, recurrent condition necessitating maintenance treatment. For some patients, compliance with daily pharmacotherapy is difficult over time. As an alternative approach, a once-weekly administered formulation of fluoxetine has recently been made available. This raises the important question of whether once-weekly enteric-coated fluoxetine, 90 mg, is effective for maintenance of response in patients whose depressive symptoms have responded to daily dosing with selective serotonin reuptake inhibitors (SSRIs) such as citalopram, paroxetine, or sertraline.

Method: Patients had met DSM-IV criteria for major depressive disorder prior to beginning treatment for their current episode, had received 6 to 52 weeks of treatment with citalopram (20-40 mg/day [N=83]), paroxetine (20 mg/day [N=77]), or sertraline (50-100 mg/day [N=86]), and had responded to that treatment (Clinical Global Impressions-Severity of Illness [CGI-S] score 2, modified 17-item Hamilton Rating Scale for Depression [HAM-D-17] score 10). Patients meeting these criteria (N=246) continued treatment with their current SSRI for 1 week, then were switched to open-label enteric-coated fluoxetine, 90 mg, taken once weekly for 12 weeks. Safety measures were comparisons of spontaneously reported and solicited treatment-emergent adverse events. Efficacy measures were percentages of patients who discontinued the study for relapse and lack of efficacy and comparison of change from baseline to endpoint in scores on the modified HAM-D-17, subscales of the HAM-D-28, and the CGI-S. Quality of life measures were assessed with the MOS 36-Item Short-Form Health Survey (SF-36). We hypothesized that the once-weekly administration of fluoxetine could be safely and effectively initiated among subjects who had been stabilized on daily SSRI treatment.

Results: Seventy-nine percent of patients successfully completed a switch to enteric-coated fluoxetine, 90 mg, with 9.3% discontinuing due to relapse or lack of efficacy. Enteric-coated fluoxetine at a once-weekly dose of 90 mg was well tolerated in all groups. No significant increases were found in the HAM-D-17 total, HAM-D-28 subscores, or CGI-S score. Patients showed improvement from baseline to endpoint in most of the SF-36 health concepts.

Conclusion: Enteric-coated fluoxetine taken once weekly appears to be well tolerated and efficacious in patients who responded to acute therapy with other SSRIs and were subsequently switched to fluoxetine once weekly for continuation/maintenance therapy.