The synthesis of 6-APB was first reported by a team led by the medicinal chemist and psychedelic researcher David E. Nichols at Purdue University. They were examining the role of the MDA dioxle ring structure in interacting with serotonergic neurons. It was also partly an effort to find an alternative to MDMA, which was gaining recognition as a potentially useful adjunct in psychotherapy, but was also being linked to neurotoxic effects. On November 28, 2013 the ACMD recommended that 6-APB and related benzofurans should become Class B, Schedule 1 substances. On March 5, 2014 the UK Home Office announced that 6-APB would be made a class B drug on 10 June 2014 alongside every other benzofuran entactogen and many structurally related drugs.
6-APB, also known as 6-(2-aminopropyl)benzofuran, is a synthetic molecule of the benzofuran class. The benzofuran class of substances are members of the amphetamine and phenylethylamine classes. Molecules of this class contain a phenethylamine core bound to an amino (NH2) group through an ethyl chain with an additional methyl substitution at Rα. 6-APB does not contain a methyl substitution on RN. It is composed of an an oxygen-substituted benzofuran ring fused at R3 and R4 of the phenyl ring.
Notably, 6-APB shares this benzofuran ring with related compounds such as 5-APB, 5-MAPB, and 6-MAPB.
Three distinct batches have been in circulation since its initial release to markets. Originally, only hydrochloride was available, and its dosage range shared characteristics most similar to that of MDA in terms of dose-response. However, succinate and fumarate batches both entered the market, and have very different effects by weight, and vastly different loose bulk densities.
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. 6-APB also possesses additional activity as a releasing agent of these monoamine neurotransmitters.
6-APB is a potent full agonist of the serotonin 5-HT2B receptor (Ki = 3.7 nM) Moreover, unlike MDMA, 6-APB shows 100-fold selectivity for the 5-HT2B receptor over the 5-HT2A and 5-HT2C receptors.
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.
The monoamine neurotransmitters known as serotonin, dopamine and noradrenaline are the global neurotransmitters that modulate the brain's ability to feel pleasure, motivation, reward, planning, attention, and focus. When their reuptake is inhibited or their release is promoted, these neurotransmitters accumulate in the synaptic cleft (gaps between neurons) to non-ordinary levels, which makes them able to be reused. The result is neuronal activation at a multitude of brain regions which has the net result of producing a combination of stimulating, relaxing, disinhibiting and euphoric effects.
Exposing compounds to the reagents gives a colour change which is indicative of the compound under test.
Due to only having a short history of human use, the toxicity and harm potential is not exactly known. Due to its similarity to MDMA, it is likely that the administration of repeated or high dosages of 6-APB may be both neurotoxic and cardiotoxic in some form.exact toxic dosage is unknown. It is strongly recommended that one use harm reduction practices when using this substance.
Short-term physical health risks of 6-APB consumption include dehydration, insomnia, and hyperthermia (overheating). Continuous activity without sufficient rest or rehydration may cause body temperature to rise to dangerous levels, and loss of fluid via excessive sweating puts the body at further risk as the stimulating and euphoric properties of the substance may render the user oblivious to their energy expenditure for quite some time. Diuretics such as alcohol may exacerbate these risks further.
Although it has not been formally studied, small changes in ambient temperature may cause large changes in 6-APB-induced serotonergic neurotoxicity as is the case with MDMA.
The neurotoxicity of 6-APB is subject to ongoing debate. It was specifically designed to be less neurotoxic than MDA or MDMA by circumventing the production of certain metabolic byproducts thought to underlie their toxicity (specifically alpha-methyl-dopamine). Although it is likely to be physically safe to try in a responsible context, it is completely possible that the administration of repeated or high dosages of 6-APB could result in neurotoxicity in some form, presenting as deficits in cognitive, affective and psychomotor function.
As with MDMA, the long-term, heavy usage of 6-APB (i.e. regular daily or weekly usage) is likely cardiotoxic and may lead to valvulopathy (heart valve issues) via its significant affinity for the 5-HT2B receptor. (List 4) substance. It may be used for research and restricted therapeutic purposes. (§ 1, d), 1. of Nařízení vlády č. 463/2013 Sb.)
France: 6-APB is classified as a narcotic since May 9, 2018, alongside other substances derived from benzofuran.
Germany: 6-APB is controlled under Anlage II BtMG (Narcotics Act, Schedule II) as of July 17, 2013. It is illegal to manufacture, possess, import, export, buy, sell, procure or dispense it without a license.
Italy: 6-APB is illegal in Italy.
Japan: 6-APB is a controlled substance in Japan effective December 17th, 2012.
Luxembourg:** 6-APB is not cited in the list of prohibited substances. Therefore, it is still a legal substance.
The Netherlands:** 6-APB is a controlled substance as of July 1, 2025.
Sweden: 6-APB is prohibited in Sweden as a "health hazard" as of 2009.
Switzerland: 6-APB is a controlled substance specifically named under Verzeichnis E.
Turkey:** 6-APB is a classed as drug and is illegal to possess, produce, supply, or import.
United Kingdom: On June 10, 2013, 6-APB and some analogues were classified as Temporary Class Drugs in the U.K. following an ACMD recommendation. On March 5, 2014, the U.K. Home Office announced that 6-APB would be made a class B drug on 10 June 2014 alongside every other benzofuran entactogen and many structurally related drugs.
United States: 6-APB is unscheduled in the United States, but not currently approved by the Food and Drug Administration for human consumption.
Responsible use
Research chemicals
Benzofuran
Entactogen
MDA
5-APB
6-APDB
6-APB (Wikipedia)
6-APB (Erowid Vault)
6-APB (Isomer Design)
6-APB (Drugs-Forum)
MDMA Wiki
Discussion
The Big & Dandy 6-APB Thread (Bluelight)
Greene, S. L. (2013). Benzofurans and benzodifurans. In Novel Psychoactive Substances (pp. 383-392). https://doi.org/10.1016/B978-0-12-415816-0.00016-X
