Extended-release quetiapine fumarate (quetiapine XR) monotherapy and quetiapine XR or lithium as add-on to antidepressants in patients with treatment-resistant major depressive disorder

BACKGROUND: Patients with treatment-resistant major depressive disorder (MDD) remain a common clinical challenge. METHODS: This 6-week, randomised, open-label, rater-blinded trial evaluated once-daily extended-release quetiapine fumarate (quetiapine XR; 300mg/day) as add-on to ongoing antidepressant and quetiapine XR monotherapy (300mg/day) compared with add-on lithium (0.6-1.2mmol/L) in patients with treatment-resistant MDD. Primary efficacy measure: change in Montgomery Åsberg Depression Rating Scale (MADRS) total score from randomisation to week 6 with a pre-specified non-inferiority limit of 3 points on the MADRS. RESULTS: At week 6, both add-on quetiapine XR (n=231) and quetiapine XR monotherapy (n=228) were non-inferior to add-on lithium (n=229); least squares means (LSM) differences (97.5% CI) in MADRS total score changes were -2.32 (-4.6, -0.05) and -0.97 (-3.24, 1.31), respectively. LSM MADRS total score change was numerically greater at day 4 for both quetiapine XR groups (add-on and monotherapy; p