The present invention relates to a kit and an intravenously administrable preparation, both with a signal transmitter precursor, an enhancer of precursor uptake, and an inhibitor of neurotransmitter reuptake or signal transmitter catabolism. The kit also contains an appropriate swab for obtaining oral cells suitable for allelic analysis. The intravenous formulation contains similar materials and, in some cases, ethanol. Either the kit composition or the intravenous formulation may be used as guided by a subjects allelic analysis. Collections of particular alleles, especially those relating to neural system are comprehensible in terms of likelihood of success in the administration of an intraveinous formulation or ingestion of components of the subject kit.