Multiple action agents and the eye: do they really stabilize mast cells?

Purpose of review Multiple action drugs, such as azelastine, epinastine, ketotifen and olopatadine, have recently been suggested to combine antihistaminic effect, mast cell stabilization and anti-inflammatory action. This pharmaceutical class is, therefore, rapidly becoming the first choice for prevention and treatment for allergic conjunctivitis. Recent findings Increasing in-vitro studies have been performed to investigate the mast-cell-stabilizing effect of multiple action drugs. Most of the study results agree that these drugs are able to inhibit histamine and several neoformed mediators, including cytokines and arachidonic acid-derived products, from mast cells. However, the mechanisms of action have not yet fully been elucidated. Most of the results from clinical trials as well as the in-vivo experimental studies, including the conjunctival provocation model, support the evidence of a stabilizing effect of these drugs. Summary Evidence of a different inhibitory effect of multiple action compounds on the pro-inflammatory mediators released from the mast cells suggests the possibility to target different phases of the allergic reaction, leading to a potential improvement in the management of allergic patients.