Carebastine-d5 is intended for use as an internal standard for the quantification of carebastine by GC- or LC-MS. Carebastine is an active metabolite of ebastine and a histamine H1 receptor antagonist (Ki = 75.86 nM). It inhibits histamine-induced contraction of isolated guinea pig trachea (IC50 = 120 nM). It also inhibits histamine release from isolated rat peritoneal mast cells and human basophils when used at concentrations ranging from 30 to 100 μM. Carebastine decreases production of chemokine (C-C motif) ligand 5 (CCL5) and CCL2 in human nasal epithelial cells isolated from patients with nasal allergies.
