It is not much more than a hundred years ago that psychiatry started to become a scientific discipline in the sense of a modern medical science. This statement is especially true if we focus on psychiatry as a discipline of neurobiology/neuroscience. The key inventions in psychopharmacology were reached not earlier than the 50ies of the last century. The detection of antipsychotic, antidepressive, tranquilising and mood stabilising medication at that time can be regarded as a therapeutic revolution in psychiatry, given the fact that from today's point of view no meaningful biologically oriented treatment procedures were available apart from ECT. In this pioneer time of psychopharmacology, psychopharmacological treatment became one of the main treatment approaches. This was in principal a success story, however also several limitations such as unsatisfying efficacy, tolerability problems etc. were to be observed in the following decades. In the last 20 to 30 years second generation of antipsychotics and antidepressants entered the market, developed to overcome some of these problems.

There are still unmet needs in treating mental disorders with polypharmacy which can hopefully be reduced significantly in the near future. These unmet needs are related among others to delay of onset of therapeutic action, unsatisfying effect size, problems in treating medication refractory patients, side effect which are subjectively or objectively disturbing, some of them leading to problems e.g. in terms of metabolic issues. Although there has always been the theoretically based postulate that patients should be treated with monotherapy, clinicians tried to overcome at least some of these problems by switching strategies, comedication and augmentation strategies, believed to be meaningful due to clinical experience, although still lacking in evidence.