Prophylactic effects of the histamine H ₁ receptor antagonist epinastine and the dual thromboxane A ₂ receptor and chemoattractant receptor-homologous molecule expressed on Th2 cells antagonist ramatroban on allergic rhinitis model in mice

The prophylactic use of anti-allergic drugs has been proposed to be effective in the treatment of seasonal allergic rhinitis in humans. However, there is little information regarding the prophylactic effect of thromboxane A ₂ (TXA ₂) receptor antagonist on allergic rhinitis. Recent studies revealed that a TXA ₂ receptor antagonist ramatroban could block the prostaglandin D ₂ (PGD ₂) receptor and chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). In the present study, we investigated the prophylactic effects of the histamine H ₁ receptor antagonist epinastine and the TXA ₂ receptor antagonist ramatroban and seratrodast on mouse models of allergic rhinitis. Female BALB/c mice were sensitized by an intraperitoneal injection of ovalbumin and alum on days 0, 5, 14 and 21. Seven days later, mice were sensitized by intranasal application of ovalbumin thrice a week. Drugs were administered once a day from day 22. The severity of allergic rhinitis was assessed by determining the extent of 2 nasal allergic symptoms (sneezing and nasal rubbing). Histamine sensitivity and eosinophil infiltration into the nasal mucosa were also determined. Epinastine and ramatroban significantly reduced nasal symptoms and the number of eosinophils in the nasal mucosa. Seratrodast showed no effect on nasal symptoms and eosinophil infiltration into the nasal mucosa. In addition, histamine sensitivity was reduced by epinastine and ramatroban. These results indicate that epinastine and ramatroban induce the prophylactic effect on allergic rhinitis.