Epinastine-13C-d3 (hydrobromide)

Epinastine-¹³C-d₃ is intended for use as an internal standard for the quantification of epinastine by GC- or LC-MS. Epinastine is a histamine H₁ receptor antagonist (K_iapps = 1.41 and 1.62 nM using guinea pig cerebellar and lung membranes, respectively) and mast cell stabilizer.^1,2 It inhibits IgE-induced histamine, TNF-α, and IL-10 secretion in human cord blood stem cell-derived mast cells (CBMCs) when used at a concentration of 0.1 μg/ml.² Epinastine inhibits histamine-induced cutaneous vascular permeability in rats and bronchoconstriction in anesthetized guinea pigs (ID₅₀s = 5 and 0.1 mg/kg, respectively).³ It inhibits dye leakage into the conjunctiva in a rat model of passive anaphylaxis reaction-induced vascular hyperpermeability of the conjunctiva (ID₅₀ = 9.7 mg/kg, p.o.).⁴ Topical administration of formulations containing epinastine (0.05% three times per day) reduces lid edema, tearing, and redness, as well as the number of neutrophils and eosinophils in the lid fornix, in a mouse model of atopic conjunctivitis.² Formulations containing epinastine have been used in the prevention of itching associated with allergic conjunctivitis.

1.Ter Laak, A.M., DonnÉ-Op den Kelder, G.M., Bast, A., et al.Is there a difference in the affinity of histamine H1 receptor antagonists for CNS and peripheral receptors• An in vitro studyEur. J. Pharmacol.232(2-3)199-205(1993) 2.Galatowicz, G., Ajayi, Y., Stern, M.E., et al.Ocular anti-allergic compounds selectively inhibit human mast cell cytokines in vitro and conjunctival cell infiltration in vivoClin. Exp. Allergy37(11)1648-1656(2007) 3.Matsushita, K., Nobutoshi, A., and Aritake, K.Pharmacological studies on the novel antiallergic drug HQL-79: II. Elucidation of mechanisms for antiallergic and antiasthmatic effectsJpn. J. Pharmacol.78(1)11-22(1998) 4.Tamura, T., Sato, H., Miki, I., et al.Effects of orally administered olopatadine hydrochloride on the ocular allergic reaction in ratsAllergol. Int.52(2)77-83(2003)