4-FA does not cause long-lasting depletion of brain serotonin, unlike its analogues 4-CA and 4-BA. This is thought to "reflect the inability of the fluoro-compound to be metabolized in the same way as the other haloamphetamines."[4]
Contrary to popular belief, neurotoxicity does not increase down the series of para-halogenated amphetamine derivatives, even though serotonin releasing potency does follow this trend. For example, 4-iodoamphetamine is less toxic than is 4-chloroamphetamine.[3][5] Hence, this property is not related to serotonin releasing potency as such, since PAL-287 was reported to be not at all neurotoxic even though it is a powerful 5-HT releasing agent.[6]