[Problems in clinical testing of a psychotropic substance examplified by L-5-HTP-ester (author's transl)]

An i.v. injectable form of the serotonin-precursor L-5-hydroxytyptophan (Ro 3-5940) was investigated for its acute psychotropic effect. The difficulties are presented which had to be overcome as it was not known which effects could be expected. It was shown that for the intensive psychotropic effect found, it was not possible to use a long and detailed self-rating scale. The problem of informed consent is discussed.