Azelastine-¹³C-d₃is intended for use as an internal standard for the quantification of azelastine by GC- or LC-MS. Azelastine is a histamine H₁receptor antagonist (K_i= 1.26 nM in bovine cerebral cortex membranes).¹It is selective for histamine H₁over histamine H₃receptors (K_i= 158.49 nM), as well as α_1A- and α_1B-adrenergic receptors (K_i= 50.12 nM for both). Azelastine (0.14 µg/animal) reduces nose rubbing, sneezing, and nasal mucosa expression of IL-4 in a dust mite-induced mouse model of allergic rhinitis.²It also reduces infection by a lentivirus pseudotyped with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein, also known as the surface glycoprotein, in HEK293 cells expressing angiotensin-converting enzyme 2 (ACE2) when used at a concentration of 7 µg/ml.³Formulations containing azelastine have been used in the treatment of seasonal allergic rhinitis and vasomotor rhinitis.

1.Procopiou, P.A., Browning, C., Buckley, J.M., et al.The discovery of phthalazinone-based human H1 and H3 single-ligand antagonists suitable for intranasal administration for the treatment of allergic rhinitisJ. Med. Chem.54(7)2183-2195(2011) 2.Sun, S., Dean, R., Jia, Q., et al.Discovery of XEN445: A potent and selective endothelial lipase inhibitor raises plasma HDL-cholesterol concentration in miceBioorg. Med. Chem.21(24)7724-7734(2013) 3.Reznikov, L.R., Norris, M.H., Vashisht, R., et al.Identification of antiviral antihistamines for COVID-19 repurposingBiochem. Biophys. Res. Commun.538173-179(2021)