Bupropion slow-release response in depression: diagnosis and biochemistry

Abstract

Background: Bupropion has been previously shown to be particularly beneficial in bipolar and atypical depression. Previous research has supported a possible association of response to plasma levels and to changes in plasma homovanillic acid (HVA). These findings were here extended to bupropion slow-release (SR), a formulation with slower release kinetics. Methods: Forty-one patients with major depressive disorder (DSM-III-R) completed 8 weeks of a fixed dose of 300 mg/day in two doses/day. Clinical outcome measures were the Hamilton Depression Rating Scale (HDRS) and Beck Depression Inventory (BDI). Biological parameters included plasma HVA and 3-methoxy-4-hydroxyphenylglycol (MHPG), as well as a final measurement of plasma bupropion and its metabolites. Results: Response to bupropion SR differed among the three groups: results for change in HDRS and in BDI were greater in the bipolar and atypical than in the “typical” depressed patients. Mean change in HDRS was, respectively, of 15.6, 17.1, and 7.6 ( F = 5.57, p < .01); mean change in the BDI, 21.1, 16.9, and 7.3 ( F = 3.32, p < .05). Threobupropion levels correlated with HDRS scores ( r = .47, p = .02, n = 23); plasma HVA and MHPG increased significantly ( t = 2.31, p = .03; t = 2.15, p = .04, n = 17). Bipolar depressed patients’ improvement in HDRS was related to increases in MHPG ( r = .87, p = .01) and in HVA ( r = .70, p = .08). Conclusions: This fixed-dose study indicates that there may be specific benefits for bupropion SR in atypical and bipolar depression, and that these benefits may be related also to plasma levels and biochemical changes in catecholamines. Due to the small sample size, replication is of key importance.