PMA strongly acts as a selective serotonin releasing agent (SSRA) and very weakly on dopamine and norepinephrine (noradrenaline) systems in the brain and nervous system. However, it is not as potent in directly releasing serotonin in the same way as MDMA, and consequently is not particularly euphoric. Studies show that rodents do not seem to self-administer it in the same way as they do amphetamine and MDMA.
The other great difference between PMA/PMMA and other amphetamine-type substances is its inhibitory effect on the enzyme monoamine oxidase (MAO). It is 20 times more potent on this enzyme (specifically the ‘A’ variant) than amphetamine. MAO acts to breakdown compounds such as serotonin, dopamine, norepinephrine and epinephrine in the liver. This prevents toxic and potentially lethal levels of these ‘monoamines’ from building up in the blood. Although not fully understood, it is thought that the reason PMA and PMMA are fatal is due to a combination of this inhibitory effect on the MAO-A enzyme in preventing the metabolism of monoamines as well as an increase in serotonin centrally that causes the body to overheat.