Bamirastine

Bamirastine inhibits ligand binding to recombinant human histamine H₁ receptors (rhH₁R) with an IC₅₀ value of 17.3 nM. IC50 & Target: IC50: 17.3 nM (rhH₁R)^[1] In Vitro: Bamirastine (TAK-427) reduces specific binding of [³H] pyrilamine to recombinant human H₁ receptors (rhH₁R) is seen in a concentration- dependent manner with an IC₅₀ value of 17.3 nM. The K_i value is calculated to be 7.35 nM. The affinity of Bamirastine is found to be as high as that of azelastine, 2 times lower than that of Epinastine, 8 times lower than that of ketotifen and 3 times higher than that of Terfenadine^[1]. In Vivo: Bamirastine (TAK-427) inhibits histamine induced skin reactions in guinea pigs and mice with an ID₅₀ value of 0.884 and 0.450 mg/kg, p.o., respectively; significant inhibition associated with 10 mg/kg of Bamirastine is still observed 24 h after dosing in guinea pigs. Even at 300 mg/kg, Bamirastine does not affect pentobarbital-induced sleeping time in mice. Bamirastine significantly inhibits passive cutaneous anaphylaxis (PCA) in mice and guinea pigs, and also inhibits antigen-induced ISRs in guinea pigs^[1].