Ephedrine

Ephedrine is a sympathomimetic agent belonging to the sympathomimetic amine class. It has both direct and indirect actions and can stimulate α and β adrenergic receptors. Its indirect action occurs when it enters sympathetic nerve terminals through the norepinephrine transporter, then enters norepinephrine storage vesicles through the vesicular monoamine transporter, displacing stored norepinephrine. The displaced norepinephrine is exchanged into the cytoplasm, and once cytoplasmic norepinephrine levels rise, it is released into the synaptic cleft by reverse transport through the norepinephrine transporter, where it activates postsynaptic α and β receptors. In addition, its direct action includes direct activation of α1, β1, and β2 receptors, although its receptor affinity is relatively weak.