The Evidence for 20 mg a day of Fluoxetine as the Optimal Dose in the Treatment of Depression

Fluoxetine, a selective serotonin-uptake inhibitor, has been shown to be effective in the treatment of depression. A series of studies found fluoxetine to be more effective than placebo and to be associated with equivalent efficacy to standard reference tricyclic antidepressants (Stark & Hardison, 1985; Feighner & Cohn, 1985). The selection of a dosage regime for fluoxetine in these studies was based on the information gathered from open dose-ranging investigations. In these studies, treatment starts with one dose level, which is then increased as indicated in the protocol or until increased doses are not tolerated due to side-effects. One of the weaknesses in this method of choosing the likely standard dose of a new antidepressant lies in the inherent bias towards the selection of the higher dose levels. This is particularly true for drugs which are well tolerated.