Quinotolast sodium (FR71021) (Synonyms: FR71021)

Quinotolast sodium in the concentration range of 1-100 μg/mL inhibits histamine, LTC4 and PGD2 release in a concentration-dependent manner.

Quinotolast inhibits the release of histamine and the generation of leukotriene (LT) C4 and prostaglandin (PG) D2 from dispersed human lung cells. Quinotolast (100 μg/mL) significantly inhibits PGD2 and LTC4 release. Quinotolast inhibits PGD2 release by 100% and LTC4 release by 54%. The inhibitory effect of Quinotolast on histamine release from dispersed lung cells is largely independent of the preincubation period, no tachyphylaxis being observed. Quinotolast shows a significant inhibition of inflammatory mediators from human dispersed lung cells[1]. Quinotolast also shows strong inhibitory effects on histamine and peptide leukotrienes release from guinea pig lung fragments or mouse cultured mast cells. Quinotolast concentration-dependently inhibits pLTs release from cultured mast cells. The IC50 value for Quinotolast is 0.72 μg/mL[2].

Quinotolast potently inhibits such type I allergic reactions as passive cutaneous anaphylaxis (PCA) and anaphylactic bronchoconstriction in rats by both intravenous and oral dosing. When Quinotolast is given i.v. to rats, Quinotolast, dose-dependently inhibits PCA. The doses of Quinotolast required to inhibit the reaction by 50% (ED50) is 0.0063 mg/kg. Given p.o., Quinotolast inhibits the reaction. ED50 value for Quinotolast is 0.0081 mg/kg. Although almost complete inhibition is observed with Quinotolast at a dose of 0.32 mg/kg, its effect is slightly attenuated at a dose of 1 mg/kg[2].

[1]. Okayama Y, et al. Inhibition of histamine and eicosanoid release from dispersed human lung cells in vitro byquinotolast. Jpn J Pharmacol. 1995 Dec;69(4):375-80. [2]. Kobayashi K, et al. Effects of quinotolast, a new orally active antiallergic drug, on experimental allergic models. Jpn J Pharmacol. 1993 Sep;63(1):73-81.