A pilot study of the predictive value of the probenecid test in application of 5-hydroxytryptophan as antidepressant

In depressions, varying therapeutic effects have been obtained with 5-HT precursors. This is possibly due to the fact that the group of the depressions is pathogenetically heterogeneous; that, specifically, some types do and other types do not entail disturbances in the central 5-HT metabolism; and that only the former types are precursor-sensitive. This hypothesis was tested in a preliminary pilot study, and confirmed. The central 5-HT consumption was assessed on the basis of the probenecid test. In this experiment, 5-HTP was for the first time given in large doses over a considerable period of time.This study was supported by grants from the Netherlands Organization for Pure Research (Z.W.O.), the Preventie Fonds and the Merck Sharp & Dohme Research Laboratories (U.S.A.).