6-(2-aminopropyl)benzofuran (also known as 6-APB or by the brand-name Benzofury) is a popular synthetic entactogen of the phenethylamine and benzofuran chemical classes that produces a powerful, long-lived array of typical MDA-like entactogenic effects such as sedation, enhanced feelings of empathy, love, and sociability, muscle relaxation, anxiety relief and physical and cognitive euphoria when administered.
C11H13NO • HCl
A crystalline solid
207, 246, 276, 285 nm
6-APB is a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) with Ki values of 117, 150, and 2698 nM for the norepinephrine transporter (NET), dopamine transporter (DAT), and serotonin transporter (SERT), respectively. In addition, 6-APB not only blocks the reuptake of these monoamine neurotransmitters but is also a releasing agent of them; that is, it is a serotonin-norepinephrine-dopamine releasing agent (SNDRA). In addition to actions at the monoamine transporters, 6-APB is a potent full agonist of the serotonin 5-HT2B receptor (Ki = 3.7 nM), with higher affinity for this target than any other site. Moreover, unlike MDMA, 6-APB shows 100-fold selectivity for the 5-HT2B receptor over the 5-HT2A and 5-HT2C receptors. It is notably both more potent and more selective as an agonist of the 5-HT2B receptor than the reference 5-HT2B receptor agonist, BW-723C86, which is commonly used for research into the 5-HT2B receptor. Aside from the 5-HT2B receptor, 6-APB has also been found to bind with high affinity to the α2C-adrenergic receptor subtype (Ki = 45 nM), although the clinical significance of this action is unknown. 6-APB showed little other affinity at a wide selection of other sites.
The potent agonism of the 5-HT2B receptor makes it likely that 6-APB would be cardiotoxic with chronic or long-term use, as seen with other 5-HT2B receptor agonists such as the withdrawn serotonergic anorectic fenfluramine.