Once-weekly fluoxetine

The relatively long half-life of the selective serotonin reuptake inhibitor fluoxetine has allowed the development of a delayed-release (enteric-coated) formulation containing 90 mg fluoxetine per capsule for once-weekly oral administration. The cumulative relapse rate in patients switched to once-weekly fluoxetine 90 mg for 25 weeks (after responding to 13 weeks of fluoxetine 20 mg/day) was similar to that in patients continuing to receive fluoxetine 20 mg/day and significantly lower than seen in patients switched to placebo. The efficacy of the once-weekly formulation was also similar to that of the daily formulation in other assessment parameters (modified 17-item Hamilton Rating Scale for Depression, Clinical Global Impressions - Severity of Illness Scale). Patient compliance (measured using an electronically monitored tablet bottle) was maintained at 87.5% in evaluable patients receiving once-weekly fluoxetine 90 mg for 12 weeks from a baseline of 85.4% after responding to 4 weeks of fluoxetine 20 mg/day; in contrast, compliance declined significantly (from 87.3% at baseline to 79.4%; p < 0.001) in patients continuing to receive 20 mg/day for 12 weeks. Once-weekly fluoxetine is well tolerated, with a tolerability profile similar to that of the immediate-release formulation.