Ebastine-d₅is intended for use as an internal standard for the quantification of ebastine by GC- or LC-MS. Ebastine is a potent second generation histamine H₁receptor antagonist (IC₅₀= 45 nM) that does not cross the blood brain barrier.¹It undergoes extensive first-pass metabolism by hepatic cytochrome P450 3A4 into its active carboxylic acid metabolite, carebastine , which exerts most of the pharmacological effects.²At 10 μM, ebastine has been shown to inhibit T cell proliferation and the production of Th2-type pro-inflammatory cytokines by macrophages.³

1.Abou-Gharbia, M., Moyer, J.A., Nielsen, S.T., et al.New antihistamines: Substituted piperazine and piperidine derivatives as novel H1-antagonistsJ. Med. Chem.38(20)4026-4032(1995) 2.Vincent, J., Liminana, R., Meredith, P.A., et al.The pharmacokinetics, antihistamine and concentration-effect relationship of ebastine in healthy subjectsBr. J. Clin. Pharmacol.26(5)497-502(1988) 3.Nori, M., Iwata, S., Munakata, Y., et al.Ebastine inhibits T cell migration, production of Th2-type cytokines and proinflammatory cytokinesClin. Exp. Allergy33(11)1544-1554(2003)