Many releasing agents of both dopamine and norepinephrine (norepinephrine-dopamine releasing agents, or NDRAs) and of serotonin, norepinephrine, and dopamine are known (serotonin-norepinephrine-dopamine releasing agents, or SNDRAs), however. Serotonin-dopamine releasing agents are much rarer and are not selective for monoamine release. Examples of NDRAs include amphetamine and methamphetamine, and an example of an SNDRA is MDMA.