Bupropion and paroxetine differentially influence cardiovascular and neuroendocrine responses to stress in depressed patients.

BACKGROUND: There exists a need to identify safe and effective treatments for depression in patients with coronary heart disease (CHD).
METHODS: Using a cross-sectional design, 17 depressed patients being treated with bupropion (200-450 mg/day) were compared with 17 depressed patients being treated with paroxetine (10-50 mg/day) and with a group of 15 unmedicated, non-depressed controls for cardiovascular, neuroendocrine and heart rate variability (HRV) measures at rest and in response to mental and physical stressors.
RESULTS: Regardless of treatment, both treated groups exhibited blunted plasma cortisol, plasma epinephrine, systolic blood pressure, cardiac output, and pre-ejection period responses to mental stressors relative to controls. Bupropion treated individuals exhibited greater total peripheral resistance (TPR) increases than either the paroxetine or control groups, and greater plasma norepinephrine (NE) increases to mental stressors than the paroxetine group. The bupropion group also displayed reduced HRV at rest relative to the controls and during orthostatic challenge relative to both the control and paroxetine groups. LIMITATIONS: Despite the fact that the treated groups were well matched for depression and other psychiatric histories, lack of randomization into treatment arms may be associated with a selection bias in the two treated groups.
CONCLUSIONS: Although both pharmacological treatments were associated with a blunting of some cardiovascular and neuroendocrine responses to stress relative to controls, which may be reflective of their therapeutic mechanisms of action, the results of our study also suggest that bupropion is associated with a more detrimental autonomic profile than paroxetine, as reflected in increased TPR and NE, and reduced HRV. The results of this study may have implications for the pharmacological treatment of depression in CHD patients.