Sympathomimetic drug
[1] The primary endogenous agonists of the sympathetic nervous system are the catecholamines (i.e., epinephrine [adrenaline], norepinephrine [noradrenaline], and dopamine), which function as both neurotransmitters and hormones.These drugs can act through several mechanisms, such as directly activating postsynaptic receptors, blocking breakdown and reuptake of certain neurotransmitters, or stimulating production and release of catecholamines.A primary or secondary aliphatic amine separated by 2 carbons from a substituted benzene ring is minimally required for high agonist activity.Dopaminergic stimulants such as amphetamine, ephedrine, and propylhexedrine work by causing the release of dopamine and norepinephrine, along with (in some cases) blocking the reuptake of these neurotransmitters.In addition to intended therapeutic use, many of these stimulants have abuse potential, can induce tolerance, and possibly physical dependence, although not by the same mechanism(s) as opioids or sedatives.