When the patent of a small molecule drug expires, generics may be introduced. They are considered therapeutically equivalent once pharmaceutical equivalence (i.e. identical active substances) and bioequivalence (i.e. comparable pharmacokinetics) have been established in cross-over volunteer study. However this generic paradigm cannot be applied to complex drugs as biologics. For copies of biologics EMA, and FDA, have introduced a new regulatory bio-similar pathway which mandate clinical trials to show therapeutic equivalence. However for some complex drugs, such as iron-carbohydrate drugs, low molecular weight heparins (named Non Biologic Complex Drugs [NBCD]), regulatory guidance is still mostly lacking. In this paper we will discuss therapeutic experiences with these different classes of complex drugs and their specificity, to provide scientific arguments for consideration for a new regulatory framework..