The development of novel drugs capable to prevent cell adhesion mediated by integrins is relevant to discover novel drug targets in the field of allergy/inflammation and cancer. This research group is interested to employ in vitro and in vivo assays with the aim to characterize novel integrin antagonists. Levocabastine is an antiallergic drug acting as a histamine H1-receptor antagonist. We have provided evidence that in a scintillation proximity assay levocabastine displaced ¹²⁵I-FN binding to human integrin a4b1 and, in flow cytometry analysis and antagonized the binding of a primary antibody to integrin a4 expressed on the Jurkat cell surface. Levocabastine binds the a4b1 integrin and prevents eosinophil adhesion to VCAM-I, FN or human umbilical vascular endothelial cells (HUVEC) in vitro. Similarly, levocabastine affects aLb2/ICAM-I-mediated adhesion of Jurkat cells. In a model of AC levocabastine eye drops reduced the clinical aspects of the late-phase reaction and the conjunctival expression of a4b1 integrin by reducing infiltrated eosinophils. We propose that blockade of integrin-mediated cell adhesion might be a target of the antiallergic action of levocabastine and may play a role in preventing eosinophil adhesion and infiltration in allegic conjunctivitis.The synthesis and the antiadhesion activity of libraries of peptidomimetics capable to recognize a(v)b(3) and a(5)b(1) and acting as inhibitors of fibronectin adhesion to SK-MEL-24 tumor cells is investigated.