4-Bromomescaline, also known as 4-bromo-3,5-dimethoxyphenethylamine (4-Br-3,5-DMPEA), is a serotonin receptor modulator of the phenethylamine and scaline families related to the psychedelic drug mescaline. It is the analogue of mescaline in which the methoxy group at the 4 position has been replaced with a bromine atom. The drug is also the phenethylamine (ñ-desmethyl) analogue of 4-Br-3,5-DMA and a positional isomer of 2C-B (4-Br-2,5-DMPEA).
In his book PiHKAL (Phenethylamines I Have Known and Loved), Alexander Shulgin briefly mentions 4-bromomescaline and states that it has never been tested in humans. As such, its properties and effects in humans are unknown.
4-Bromomescaline has been found to be a potent serotonin receptor agonist in the sheep umbilical artery ( = 185nM). It was 7.6-fold more potent than mescaline in this assay. In a subsequent study, the drug showed high affinity for the serotonin 5-HT<sub>2A</sub> receptor (K<sub>0.5</sub> = 45nM). Its affinity for this receptor was approximately 18-fold higher than that of mescaline.
Analogues of 4-bromomescaline include mescaline, desoxy (4-desoxymescaline; 4-methylmescaline; 4-Me-3,5-DMPEA), 4-O-desmethylmescaline (desmethyl; 4-hydroxymescaline; 4-OH-3,5-DMPEA), 2C-B (4-Br-2,5-DMPEA), and 4-Br-3,5-DMA, among others. 4-Br-3,5-DMA has been found to be a potent psychoactive drug in humans, though it did not produce clear hallucinogenic effects at tested doses of 3 to 10mg orally and instead produced pronounced analgesic and tactile anesthetic effects among others. On the other hand, desoxy (4-methylmescaline), a positional isomer of 2C-D, is a psychedelic drug similarly to mescaline at doses of 40 to 120mg orally, albeit with distinct effects.
Daniel Trachsel has expressed great interest in scaline-related compounds of the formula 4-X-3,5-DMPEA without an oxygen atom at the 4 position like desoxy (4-methylmescaline; 4-Me-3,5-DMPEA) and 4-bromomescaline (4-Br-3,5-DMPEA). He has described a variety of theoretical compounds of this class that could be explored, such as desoxyescaline (DE; 4-ethylmescaline; 4-Et-3,5-DMPEA), desoxytrifluoromescaline (DTFM; 4-trifluoromethylmescaline; 4-TFM-3,5-DMPEA), desoxytrifluoroescaline (DTFE; 4-trifluoroethylmescaline; 4-TFE-3,5-TMPEA), desoxyproscaline (DPR; 4-propylmescaline; 4-Pr-3,5-TMPEA), desoxyallylescaline (DAL; 4-allylmescaline; 4-AL-3,5-TMPEA), and desoxymethallylescaline (DMAL; 4-methallylmescaline; 4-MeAL-3,5-TMPEA), among others.
4-Bromomescaline was first described in the scientific literature by David E. Nichols and Shulgin and colleagues in 1977. Subsequently, it was described by Shulgin in PiHKAL in 1991.