Background: S-Adenosyl-L-methionine (SAMe), a natural compound, is the most important methyl donor in the central nervous system. In several clinical trials, SAMe showed antidepressant activity.
Objective: Two multicenter studies were conducted in patients with a diagnosis of major depressive episode [baseline score on the 21-item Hamilton Depression Rating Scale (HAM-D) >or=18] to confirm the efficacy and safety of SAMe in the treatment of major depression. In the first study (MC3), 1600 mg SAMe/d was given orally; whereas, in the second study (MC4), 400 mg SAMe/d was given intramuscularly. In both studies, the effects of SAMe were compared with those of 150 mg imipramine/d given orally in a double-blind design.
Design: In MC3, 143 patients received oral SAMe and 138 patients received imipramine for 6 wk. In MC4, 147 patients received SAMe intramuscularly and 148 patients received imipramine for 4 wk. In both studies the 2 main efficacy measures were the final HAM-D score and the percentage of responders to Clinical Global Impression at the endpoint. Secondary efficacy measures were the endpoint Montgomery-Asberg Depression Rating Scale scores and the percentage of responders, responders being those patients showing a decrease in HAM-D score of >or=50% from baseline.
Results: In both studies, the results of SAMe and imipramine treatment did not differ significantly for any efficacy measure. However, significantly fewer adverse events were observed in the patients treated with SAMe.
Conclusions: The antidepressive efficacy of 1600 mg SAMe/d orally and 400 mg SAMe/d intramuscularly is comparable with that of 150 mg imipramine/d orally, but SAMe is significantly better tolerated.