<p>Various approaches to increasing the stability of biogenic amines to degradation were considered. One such approach could be the production of various derivatives of the amino group of biogenic amines. Fatty acids, amino acids, peptides, and quinone fragments were used to create an amide bond. Preference was given to proline-containing compounds when using amino acids and peptides. Phosphinate analogs of peptides were also used to increase the stability of hybrid compounds containing dopamine and serotonin. The stability of the drugs was tested using amino- and carboxypeptidases, enzyme complexes, and cell cultures. The use of proline in these hybrid compounds could have other positive consequences because of the presence or absence of proline endopeptidase in various organs and tissues of the body. Therefore, hybrid molecules would be not only more stable in the bloodstream but also a source of biogenic amines, the amount of which in various organs and tissues of the body would be determined by the presence in them of proline endopeptidase. Thus, the effect of an additional fragment in hybrid compounds on the stability of biogenic amines was considered. In addition, data on the production of isotopically labeled analogs of hybrid compounds were provided. The results could lead to wider use of biogenic amines as drugs.</p>