Chemical delivery systems for drugs containing an amino group: synthesis and properties of some pyridine derivatives of desipramine.

Seven chemical delivery systems (CDS) based on a dihydropyridine<-->quaternary pyridinium salt type redox system and analogous to the naturally occurring NADH<-->NAD+ coenzyme system were applied in the case of the antidepressant drug desipramine. The pyridine moiety-containing carriers were linked to the amino function of desipramine either as amides or substituted carbamates. Lipophilic properties were expressed in terms of chromatographic Rm values. Oxidative stability of the dihydropyridine forms of the CDSs were determined in vitro. The amide type derivatives were stable toward hydrolysis in buffers and in biological fluids, whereas the carbamates released the parent drug in a very efficient manner. In a behavioral despair test, the CDSs did not show improved activity when compared to desipramine. In vivo distribution studies of one of the CDS did not show more efficient delivery of the desipramine into the rat brain but did show a prolonged presence at a constant level.