Ligand Potency, Efficiency and Drug-likeness: A Story of Intuition, Misinterpretation and Serendipity

: The concept of ligand potency is briefly discussed here as well as why this is still a challenge for its complete comprehension. In this context, we explain also the meaning of ligand efficiency (LE), which has been greeted with both enthusiasm and criticism among the drug design audience. A full understanding of LE requires the complex interpretation of the potency concept presenting the uncertainty similar to this of the Zeno paradox. In reality, the efficiency of LE is caused by the high degree of preference for slim pharma drug candidates.