The role of serendipity in the discovery of the clinical effects of psychotropic drugs: beyond of the myth.

The serendipity is the faculty for making a discovery through a combination of accident and sagacity. In psychopharmacology, the serendipity played a key role in the discovery of many psychotropic drugs, although there are marked disputes in this regard, possibly due to semantic differences in relation to the meaning of this term. We have implemented an operational definition of serendipity based on the discovery of something unexpected or not sought intentionally, irrespective of the systematic process leading to the accidental observation. The present paper analyses some representative examples of discoveries in the field of psychopharmacology according to different serendipitous intervention patterns. Following this approach there would be four different imputability patterns: pure serendipitous discoveries (valproic acid/valproate); serendipitous observation leading to a non-serendipitous discoveries (imipramine); non-serendipitous discoveries secondarily associated with serendipitous observation (barbiturates); non-serendipitous discoveries (haloperidol). We can conclude that pure serendipitous discoveries in this field are not very frequent, most common being a mixed pattern; an initial serendipitous observation which leads to a non-serendipitous discovery of clinical utility. This is the case of imipramine, lithium salts, chlorpromazine or meprobamate.