NCIt definition : The maleate salt form of pheniramine, an alkylamine derivative with antihistaminic
and vasodilatory properties. Pheniramine maleate binds to histamine H1 receptors,
thereby inhibiting phospholipase A2 and production of endothelium-derived relaxing
factor, nitric oxide. Subsequent lack of activation of guanylyl cyclase through nitric
oxide results in decreased cyclic GMP (cGMP) levels, thereby inhibiting constriction
of smooth muscle tissue, and decreased capillary permeability and histamine-activated
allergic reactions.;