Ethylphenidate acts as both a dopamine reuptake inhibitor and norepinephrine reuptake inhibitor, meaning it effectively boosts the levels of the norepinephrine and dopamine neurotransmitters in the brain, by binding to, and partially blocking the transporter proteins that normally remove those monoamines from the synaptic cleft.
However, considering the close similarities between ethylphenidate and methylphenidate and the fact that methylphenidate, like cocaine, actually does not primarily act as a “classical” reuptake inhibitor, but rather as an “inverse agonist at the DAT” (also called a “negative allosteric modulator at the DAT”), it is at least very likely that ethylphenidate also primarily acts as an inverse DAT agonist instead of (or at least only secondarily) as a classical reuptake inhibitor (which could be called a “competitive antagonist at the DAT” using a similar terminology as “negative allosteric modulator at the DAT”, which per definition means that its mechanism is non-competitive).
There have been anecdotal reports of a perforated septum resulting from even just a few uses of ethylphenidate by insufflation (snorting). Some users also report the drug is extremely painful to insufflate. This is almost certainly due to the ethylphenidate that is sourced from grey market vendors containing caustic impurities. There is absolutely no evidence that pure ethylphenidate would have caustic effects, since ethylphenidate only differs from methylphenidate in that MPH’s methyl acetate is replaced with an ethyl acetate in EPH. Methyl acetate and ethyl acetate have exactly the same pKa of 25, which means that they are both even less acidic than water, which has a pKa of 14 (the lower the pKa the stronger the acid). Considering the fact that methylphenidate has been recreationally insufflated by 4% of the general population without any reports of perforated septums and since ethylphenidate is certainly not more corrosive than methylphenidate, it is clear that the cause for the pain caused can only be impurities.