In Vitro: Pheniramine maleate inhibits CYP2D6, the specific P450-isozymes, to delay metabolic time and prolong antihistaminic effects. Pheniramine maleate regulates cellular Ca2+ transmembrane action, and inhibits Ca2+ influx into BC3H-1 cells by inhibiting histamine with an IC50 value of 1.01 mM. Pheniramine maleate (0.5, 1.0 mM; 24 h) induces cell apoptosis in human T-cell acute lymphoblastic leukemia cell lines. Pheniramine maleate (1 μM-1 mM; 12-48 h) inhibits cell proliferation in a time-dependent manner and shows inhibitory concentration IC50s of 550 μM (CCRF-CEM cells) and 420 μM (Jurkat cells), respectively.
In Vivo: Pheniramine maleate (1.75 μM; i.t.) exerts local anesthesia effect and results spinal block in rats.