Conclusions : International differences in prescriber behaviour may influence , and in turn be influenced by , the conduct of clinical trials .
Objective : International differences are thought to exist in dosages used by clinicians treating mood disorders .
This study examined international dosage differences in antidepressant clinical trials , using a data base formed and maintained as a component of a Cochrane review of comparative clinical trials of fluoxetine .
A Canadian multicenter, double-blind study of paroxetine and fluoxetine in major depressive disorder.
BACKGROUND Recent studies have suggested clinical differences among selective serotonin reuptake inhibitors . In a 12-week r and omized , multicenter , double-blind trial , the antidepressant and anxiolytic efficacy of the selective serotonin reuptake inhibitors paroxetine and fluoxetine was compared in patients with moderate to severe depression . METHODS A total of 203 patients were r and omized to fixed doses ( 20 mg/day ) of paroxetine or fluoxetine for the first six weeks of therapy . From week 7 - 12 , dosing could be adjusted biweekly , as required ( paroxetine 20 - 50 mg/day , and fluoxetine 20 - 80 mg/day ) . The mean prescribed doses were paroxetine 25.5 mg/day ( range 20.0 - 40.2 mg/day ) , and fluoxetine 27.5 mg/day ( range 20.0 - 59.5 mg/day ) . Emergence of motor nervousness or restlessness was assessed using the ESRS scale for akathisia . RESULTS Both active treatments demonstrated comparable antidepressant efficacy ( HAM-D , CGI ) . Anxiolytic activity of the two drugs ( COVI , STAI , HAM-D ) was also comparable . However , paroxetine was found to be superior to fluoxetine on two subscore measures at week 1 of therapy ( HAM-D Agitation item , p < 0.05 ; Psychic Anxiety item , p < 0.05 ) , with no differences detected after week 2 . The overall incidence of adverse effects was comparable in the two treatment groups . Constipation , dyspepsia , tremor , sweating and abnormal ejaculation were more common in paroxetine-treated subjects , whereas nausea and nervousness were more frequent in fluoxetine-treated patients . Weight loss was more common in the fluoxetine versus paroxetine group ( 11.88 % versus 2.94 % , respectively ) . ESRS scores for akathisia were low throughout the study and showed little change . LIMITATIONS Differences observed between the two drugs in antianxiety effects were limited to two measures of anxiety among several others . DISCUSSION The data indicate that paroxetine and fluoxetine have comparable antidepressant and anxiolytic efficacy .  Paroxetine appears to produce an earlier improvement in agitation and psychic anxiety symptoms compared with fluoxetine
Conclusions : International differences in prescriber behaviour may influence , and in turn be influenced by , the conduct of clinical trials .
Objective : International differences are thought to exist in dosages used by clinicians treating mood disorders .
This study examined international dosage differences in antidepressant clinical trials , using a data base formed and maintained as a component of a Cochrane review of comparative clinical trials of fluoxetine .