Extending virtual screening approaches to deal with multi-target drug design and polypharmacology is an increasingly
important aspect in drug design. In light of this, the concept of accessible chemical space and its exploration
should be reviewed. The great advantages of re-using drugs with safe pharmacological profiles with favourable pharmacokinetic
properties highlights drug repositioning as a valid alternative to rational drug design, massive drug development
efforts, and high-throughput screening, especially when supported by in silico techniques. Here, we discuss some of the
advantages of multi-target approaches, and we review some significant examples of their application in the last decade to
that well known class of pharmaceutical targets, the G-protein coupled receptors.