The piperazine scaffold for novel drug discovery efforts: the evidence to date

INTRODUCTION: Piperazine is a structural element present in drugs belonging to various chemical classes and used for numerous different therapeutic applications; it has been considered a privileged scaffold for drug design. AREAS COVERED: The authors have searched examples of piperazine-containing compounds among drugs recently approved by the FDA and in some research fields (nicotinic receptor modulators, compounds acting against cancer, and bacterial multidrug resistance), looking in particular to the design behind the insertion of this moiety. EXPERT OPINION: Piperazine is widely used due to its peculiar characteristics, such as solubility, basicity, chemical reactivity, and conformational properties. This moiety has represented an important tool to modulate pharmacokinetic and pharmacodynamic properties of drugs.