α-Pyrrolidinoisohexanophenone (mainly known as A-PiHP or α-PiHP) is a
stimulant drug of the
cathinone class that has been sold online as a
designer drug. It is a
positional isomer of
pyrovalerone, with the methyl group shifted from the 4-position of the aromatic ring to the 4-position of the acyl chain. In a classic 2006 study of pyrrolidinyl cathinone derivatives by Meltzer et al. at
Organix, the alpha-isobutyl derivative of pyrovalerone, O-2494, was found to have the highest potency in vitro as an
inhibitor of the
dopamine transporter of the alpha substituted derivatives tested.[2] α-PiHP acts as a
norepinephrine–dopamine reuptake inhibitor. Compared to α-PVP and α-PHP, α-PiHP displays a higher selectivity for the dopamine transporter. Similar to other cathinones, use of α-PiHP can result in compulsive redosing, addiction, anxiety, paranoia, and psychosis. In July 2016 α-PHiP was first identified as a designer drug[3] when it was reported to the
EMCDDA by a forensic laboratory in Slovenia.[4][5]