The stuff on the market now is (assuming its even real) 4-FA... closely related to the rather toxic 4-MTA (the "flatliners" that killed a bunch of people when it was sold in Europe) and 4-MA (better known as PMA, which has also killed a bunch of people).
Although it is smart to push ppl to be very careful when new chems show up, you're exaggerating here Murple. 4-FA is very pharmacologically distinct from 4-MTA and 4-MA (both of which are already different from each other).
4-FA has been shown to be a dopamine releasing agent with little activity on the norepinephrine system. In humans this should translate as something that gives the amphetamine euphoria and mind clarity without the physical stimulating effects of speed.
4-MTA is a completely different animal as it's a strong 5-ht (serotonine) releasing agent which has been the cause for its lethal effects. Basically it creates a serotonine syndrome which has been described as taking an SSRI and an MAOI at the same time. The other 4-halogeno-amphetamine (4-CA, 4-IA, 4-BA ) seem to have a related pharmacological profile while 4-FA is in a different league.
As for 4-MA, it is a stimulant with a heavy cardiovascular push with very mild trippy effects.
3 different chems as you can see.
The 4-substituted amphetamines seem to be pretty high risk. Although existing research with 4-FA hasn't shown any neurotoxic activity, neither did early research with its more infamous relatives PMA and 4-MTA.
Again PMA (aka 4-MA), 4-MTA and 4-FA are three completely different animals completely unrelated as far as pharmacology is concerned. I agree that this doesn't prevent from being careful however.
[ 06 March 2003: Message edited by: Meilikhios ]