Diphenhydramine hydrochloride (DPH) is a histamine H1 antagonist used as an antitussive and antiemetic. It is also used for pruritus and dermatoses, for hypersensitivity reactions, as an antiparkinson, a hypnotic, and as an ingredient in common cold preparations.

Diphenhydramine hydrochloride可阻断四氢咪唑敏感（TTX-S）和四氢咪唑抵抗（TTX-R）钠电流，其K(d)值分别为48 mM和86 mM。对于TTX-S钠电流，Diphenhydramine hydrochloride使电导-电压曲线向去极化方向移动，但对TTX-R钠电流的影响不大。Diphenhydramine hydrochloride还能使两种钠电流的稳态失活曲线朝超极化方向转移。当细胞以高频去极化脉冲重复刺激时，Diphenhydramine hydrochloride会产生明显的使用依赖性阻断。[1]Diphenhydramine hydrochloride以剂量依赖和时间依赖的方式在CCRF-CEM和Jurkat细胞线中诱导凋亡，而西米替丁在类似浓度下未能诱发显著效应。Diphenhydramine hydrochloride能抑制人外周血单核细胞的增殖而不诱导凋亡。[2]Diphenhydramine hydrochloride（500 nM）显著降低中脑导水管神经元的基线放电率，但对突触后电位频率无显著影响。高浓度Diphenhydramine hydrochloride抑制中脑导水管神经元，而低浓度下不影响基线放电率且阻断对神经肽和内侧前视区刺激的反应。[3]