Mepyramine maleate

Mepyramine maleate, a first generation antihistamine, is an antagonist of histamine H1 receptor, with K_ds of 0.8 nM, 5200 nM and >3000 nM for H1, H2, and H3 receptor, respectively, and a pK_d of 9.4 for H1 receptor. IC50 & Target: Kd: 0.8 nM (Histamine H1 receptor), 5200 nM (Histamine H2 receptor), >3000 nM (Histamine H3 receptor)^[1]
pKd: 9.4 (Histamine H1 receptor)^[2] In Vitro: Mepyramine maleate is an antagonist of histamine H1 receptor, with K_ds of 0.8 nM, 5200 nM and >3000 nM for H1, H2, and H3 receptor, respectively^[1], and a pK_d of 9.4 for H1 receptor^[2]. Mepyramine binds to the H1 receptor with different K_ds in Guinea pig brain (0.8 nM), rat brain (9.1 nM) and DDT1-MF-2 and BC3H1 cell (276 nM)^[1]. Mepyramine decreases the InsP levels in CHO-gpH1 cells, with log EC₅₀ of -7.94 ± 0.11, and reduces the the maximal response to ATP in CHO-gpH1 cells^[3]. In Vivo: Mepyramine obviously decreases the second phase of nociceptive response via i.p at 10 and 20 mg/kg, but shows no significant effect at 5 mg/kg in rats^[4].