Olopatadine

Olopatadine (ALO4943A; KW4679) is an orally active histamine H1 receptor antagonist and mast cell stabilizer. Olopatadine exerts antiallergic effects by blocking histamine H1 receptor-mediated activities. Olopatadine inhibits exocytosis, chemokine release, F-actin polymerization, CXCL10-induced calcium influx, and T cell chemotactic activity. Olopatadine also reduces the expression levels of CXCR3 on the surface of CD4⁺ and CD8⁺ T cells. Olopatadine inhibits scratching behavior, improves dermatitis scores, and suppresses intraepidermal neurite outgrowth. Olopatadine simultaneously decreases the levels of inflammatory markers, growth factors, histamine, and specific IgE, while increasing the expression of ErbB3A/HER3A. Olopatadine can be used in research related to seasonal pollinosis, chronic rhinitis, urticaria, allergic conjunctivitis, alopecia areata, and atopic dermatitis^[1][2][3]. In Vitro: Olopatadine (1×10^-6-1×10^-5 M; 8 h) significantly inhibits the CXCL10-mediated chemotactic migration speed of CD4⁺ and CD8⁺ T cells isolated from patients with acute alopecia areata, with a stronger inhibitory effect at high concentrations than at low concentrations^[2].
Olopatadine (1×10^-6-1×10^-5 M) significantly reduces the CXCR3 expression level and F-actin polymerization on the surface of CD4⁺ and CD8⁺ T cells isolated from patients with acute alopecia areata^[2].
Olopatadine (1×10^-6-1×10^-5 M) significantly inhibits CXCL10-induced intracellular calcium influx in PBMCs isolated from one patient with acute alopecia areata, with a stronger inhibitory effect observed at the high concentration than at the low concentration^[2]. In Vivo: Olopatadine (3-10 mg/kg/day; p.o.; daily; 14 days) administered orally to Dermatophagoides farinae body (Dfb)-induced atopic dermatitis NC/Nga mice significantly reduces scratching behavior, intraepidermal neurite outgrowth, skin inflammatory markers, and Dfb-specific IgE, with the 10 mg/kg/day dose additionally improving dermatitis scores, reducing epidermal thickness, increasing epidermal sema3A expression, and producing a higher scratching inhibition ratio (86.5%)^[3].