Betahistine

Betahistine is an orally active histamine H1 receptor agonist and a H3 receptor antagonist^[1]. Betahistine is used for the study of rheumatoid arthritis (RA)^[3]. In Vitro: Betahistine (0-10 μM) inhibits [¹²⁵I]iodoproxyfan binding to membranes of CHO (rH₃₍₄₄₅₎R) and CHO (hH₃₍₄₄₅₎R) cells with IC₅₀ values of 1.9 μM and 3.3 μM, respectively. Lead to K_i values of 1.4 μM and 2.5 μM, respectively^[2].
Betahistine (0-10 μM) has a regulating function on cAMP formation in CHO (rH₃₍₄₄₅₎R), CHO (rH₃₍₄₁₃₎R), and CHO (hH₃₍₄₄₅₎R) cells. At low concentrations, betahistine behaves an apparent inverse agonist, and progressively enhances cAMP formation with EC₅₀ values of 0.1 nM, 0.05 nM and 0.3 nM, respectively. In contrast, at concentrations higher than 10 nM, betahistine inhibits cAMP formation with an EC₅₀ value of 0.1 μM in CHO (rH₃₍₄₄₅₎R) and full agonist activity^[2].
In Vivo: Betahistine (intraperitoneal or oral administration; 0.1-30 mg/kg; single dose) with acute administration has increased tele-methylhistamine (t-MeHA) levels with an ED₅₀ of 0.4 mg/kg, indicating the inverse agonism. Besides, after acute oral administration, it increases t-MeHA levels with an ED₅₀ of 2 mg/kg in male Swissmice^[2].
Betahistine (oral adminstration; 1 and 5 mg/kg; daily for 3 weeks) attenuates the severity of arthritis and reduces the levels of pro-inflammatory cytokines in the paw tissues of CIA mice^[3].