N-acetylcysteine (NAC), a glutathione precursor and glutamate modulator, has been shown to possess various clinically relevant psychopharmacological properties. Considering the role of glutamate and oxidative stress in depressive states, the poor effectiveness of antidepressant drugs (ADs) and the benefits of drug combination for treating depression, the aim of this study was to explore the possible benefit of NAC as an add on drug to treat major depression. For that matter we investigated the combination of subeffective and effective doses of NAC with subeffective and effective doses of several ADs in the mice tail suspension test.
The key finding of this study is that a subeffective dose of NAC reduced the minimum effective doses of imipramine and escitalopram, but not those of desipramine and bupropion. Moreover, the same subeffective dose of NAC increased the minimum effective dose of fluoxetine in the same model. In view of the advantages associated with using the lowest effective dose of antidepressant, the results of this study suggest the potential of a clinically useful interaction of NAC with imipramine and escitalopram. Further studies are necessary to better characterize the molecular basis of such interactions, as well as to typify the particular drug combinations that would optimize NAC as an alternative for treating depression.