Olopatadine: a drug for allergic conjunctivitis targeting the mast cell

Abstract IMPORTANCE OF THE FIELD: Ocular allergic diseases are characterized by specific activation of conjunctival mast cells with subsequent release of preformed and newly formed mediators. Mast cells are thus the first therapeutic target of ocular anti-allergic treatments. AREAS COVERED IN THIS REVIEW: In this review, a Medline literature search was conducted on conjunctival mast cells, their role in ocular allergy and mast cell stabilization by ocular anti-allergic compounds. WHAT THE READER WILL GAIN: Olopatadine hydrochloride, a mast cell stabilizer and histamine receptor antagonist, has been shown to inhibit mast cell activation in an in vitro model of human mast cell culture, reducing histamine and TNF-alpha release and upregulating proinflammatory mediators in conjunctival epithelial cells. In the in vivo conjunctival allergen challenge (CAC) model in allergic subjects, combined with objective evaluations of tear mediators and cytology, olopatadine reduced histamine tear levels and all aspects of allergic inflammation, confirming the positive clinical effects observed in active allergic patients. TAKE HOME MESSAGE: Mast cells play a central role in the pathogenesis of ocular allergy. The CAC model is ideal for assessing the mast cell stabilizing effects of anti-allergic compounds. This review of clinical studies demonstrates the superiority of olopatadine compared with other topical allergic drugs.