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Effects of olopatadine hydrochloride on the release of thromboxane B2 and histamine from nasal mucosa after antigen–antibody reaction in guinea pigs


Correspondence: Dr Toshihiko Kaise, Department of Pharmacology, Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co. Ltd, 1188 Shimotogari, Nagaizumi-cho, Sunto-gun, Shizuoka 411-8731, Japan. Email:


Background: Various mediators, such as thromboxane (TX) A2, peptide leukotrienes (P-LT) and histamine, are involved in allergic nasal obstruction. The aim of the present study was to investigate the mechanism whereby olopatadine hydrochloride, a novel anti-allergic drug, ameliorated the allergic nasal obstruction.

Methods: The levels of TXB2, P-LT and histamine in nasal lavage fluid (NLF) were measured after intranasal antigen challenge in sensitized guinea pigs.

Results: Histamine and TXB2 levels in the NLF increased eight- and threefold, respectively, 10 min after antigen challenge, whereas the P-LT level was under the detection limit. Oral administration of olopatadine at 0.1, 1 and 3 mg/kg significantly inhibited the increases in TXB2 and histamine levels. At 3 mg/kg, olopatadine also ameliorated the nasal obstruction caused 10 min after antigen challenge, as determined by acoustic rhinometry.

Conclusions: These results suggest that the amelioration by olopatadine of the allergic nasal obstruction involves the inhibition of the release of TXA2 and histamine.