ABSTRACT
The therapeutic concept of drug targeting is founded on Paul Ehrlich’s vision of ‘‘the magic bullet,’’ which he proclaimed at the beginning of the last century (1). Ehrlich’s notion was based on a concept of affinity between a drug acting as a ligand and a molecular target, e.g., a receptor (see Fig. 1). Even if the precise molecular targets for all of today’s drugs are not known, Ehrlich’s concept appears to be valid in principle.
