Combined Analysis of Mifepristone for Psychotic Depression: Plasma Levels Associated With Clinical Response

BACKGROUND Patients with psychotic depression exhibit elevated cortisol levels. Competitively antagonizing cortisol at the glucocorticoid receptor with mifepristone demonstrated therapeutic benefit in early studies of patients with psychotic depression. We present a combined analysis of all controlled phase 2 and 3 studies to report antipsychotic differences between treatment with mifepristone or placebo and to evaluate the relative contributions to response of attaining an a priori-defined, high mifepristone plasma level and markers of glucocorticoid receptor antagonism (increases in adrenocorticotropin hormone and cortisol) with treatment. METHODS Data from five similarly designed double-blind phase 2 or 3 studies evaluating the efficacy and safety of 7-day treatment with mifepristone for the psychotic symptoms of psychotic depression were pooled for analysis (mifepristone n = 833; placebo n = 627). Clinical assessments were performed at baseline and on days 7, 14, 28, 42, and 56. Mifepristone, adrenocorticotropin hormone, and cortisol samples were collected at baseline and day 7. RESULTS Combined results demonstrated meaningful efficacy (p < .004) for mifepristone in reducing psychotic symptoms with wide safety margins. Patients in the a priori-defined, high mifepristone plasma level group (≥1637 ng/mL) demonstrated a more significant treatment effect over placebo (p = .0004). A number needed to treat of 7 and 48 was observed in the high and low mifepristone plasma level groups, respectively. Adverse events were similar in mifepristone- and placebo-treated patients. CONCLUSIONS A high mifepristone plasma level carried the strongest association with response, followed by changes in adrenocorticotropin hormone and cortisol. Therapeutic plasma levels of mifepristone were most likely to be achieved with the 1200 mg/day dose.