Patient compliance with enteric-coated weekly fluoxetine during continuation treatment of major depressive disorder

Background: A once-weekly enteric-coated formulation of fluoxetine represen ts a new, effective option for the long-term treatment of clinically diagno sed depression. This study assessed compliance with the new once-weekly flu oxetine as compared with once-daily fluoxetine treatment. Method: Adult pat ients from the United Kingdom who had responded to fluoxetine treatment for a current episode of depression (DSM-IV criteria) were monitored for compl iance with daily and weekly dose administration of fluoxetine. The study co nsisted of 2 study phases. Study phase I was a baseline assessment of 20 mg of fluoxetine daily dosing for 4 weeks (N = 117). The second phase of the study consisted of randomly assigning patients to either once-weekly (90 mg /wk) or once-daily (20 mg/day) fluoxetine for 3 months (weekly, N = 56; dai ly, N = 53). Compliance with the dosing regimen was measured using an elect ronic Drug Exposure Monitor (eDEM, AARDEX Ltd., Zug, Switzerland). Results: For those patients randomly assigned to weekly fluoxetine, compliance was 85.4% during study period I while on treatment with daily fluoxetine and th en 87.5% while on treatment with weekly fluoxetine. This difference was not significant. For once-daily dosing, however, compliance declined from 87.3 % during period I to 79.4% during period II (p < .001). After adjusting for compliance during study period I, weekly compliance during study period II was 87.8% and daily compliance was 79.0%, a statistically significant diff erence (p = .006). Conclusion: Compliance with once-weekly fluoxetine was b etter than that with once-daily fluoxetine. Compliance decreased over time when patients remained on daily dosing; however, when patients switched fro m daily dosing to weekly dosing, compliance did not decrease. The results o f this study allay concerns about inferior compliance with a once-weekly re gimen compared with the conventional once-daily regimen.