Alcaftadine
Alcaftadine (R89674) is a histamine H1 receptor antagonist, which is used to prevent eye irritation brought on by allergic conjunctivitis. Alcaftadine is a broad-spectrum antihistamine displaying a high affinity for histamine H1 and H2 receptors and a lower affinity for H4 receptors. Alcaftadine also exhibits modulatory action on immune cell recruitment and mast cell stabilizing effects.