Principle standards and problems regarding proof of efficacy in clinical psychopharmacology

Proof of efficacy of a psychotropic medicinal product is the key point of clinical psychopharmacology. This especially concerns the licensing of a new compound, but apart from this special case, lots of efficacy questions need to be answered in clinical psychopharmacology, such as, e.g. the question of the efficacy of a combination therapy. The methodology of the scientific proof of efficacy has already had a long tradition and has been developed further in the recent past under different aspects. Especially the double-blind randomised parallel group comparison has been developed as a design of highest methodological standard. However, often designs have their place and justification under certain conditions and in relation to certain questions. Although in the recent past, with the over-emphasis of so-called effectiveness studies, the inherent methodological limitations of these studies have not been addressed properly (Möller in Eur Arch Psychiatry Clin Neurosci 258:257–270, 2008), which in consequence devaluated the scientific merits of the classical double-blind randomised control group study designs in the view of those colleagues, who are not that experienced in study design issues. Therefore, it seems to be timely and necessary to review the principle standards and problems concerning the proof of efficacy in clinical psychopharmacology.