| In Vitro | In vitro activity: Clemastine Fumarate inhibits histamine induced rise in [Ca2+]i in HL-60 cells with an IC50 of 3 nM as compared with that of chlorpheniramine or diphenhydramine with IC50 values of 20 nM and 100 nM, respectively. At concentrations of ≥25 μM, Clemastine Fumarate significantly blocks NK and ADCC reactions of lymphocytes against the human erythroleukemia cell line K562 and human B-lymphoblast cell line SB, respectively. Clemastine Fumarate inhibits histamine-induced contraction of guinea pig ileum with an IC50 of 231 nM. Clemastine Fumarate potently inhibits the HERG K+ channel in a concentration-dependent manner in HEK 293 cells stably expressing HERG channels with an IC50 of 12 nM, which can be attenuated by the Y652A or F656A mutation of HERG. Clemastine Fumarate significantly potentiates ATP-induced increase in [Ca2+]i in HEKhP2X7 cells not relying on histamine receptor blockage but on sensitizing P2X7 receptor in a concentration-dependent manner with an EC50 of 10 μM, and increases the IL-1β release from LPS-induced human macrophages. |
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| In Vivo | Administration of Clemastine Fumarate (5-20 mg/kg) displays significantly inhibitory effect on simultaneously induced zymosan paw oedema and croton oil ear oedema in rats in a dose-dependent manner, with the inhibition of 53.6% and 46.8%, respectively, at the dose of 20 mg/kg, and with ID50 values of 18.0 mg/kg and 20.5 mg/kg, respectively. Clemastine Fumarate treatment strongly reduces innate immune responses to Listeria monocytogenes in mice by interfering with the extracellular signal-regulated kinase (ERK)-mediated production of proinflammatory cytokines such as TNF-α and IL-6 surprisingly not dependent on blocking the histamine H1 receptor, leading to significantly higher mortality. |
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