Furthermore, the recent findings on genetic of hypertension taken together with the previous data on pathophysiology of hypertension and its cardiovascular complications are consistent with the notion that a variety of heterogeneous genetic-molecular mechanisms concur to develop the rather uniform clinical picture of primary hypertension. Drugs are small molecules that produce their effects by interacting with larger molecules (proteins) whose function or reactivity may vary from one patient to another because the variations within the gene encoding them. Therefore, it is logical to postulate that the consequence of this different interaction either in term of blood pressure reduction or cardiovascular risk prevention may vary from a patient to another according to the peculiar function of the proteins involved in a given patient.