4C-B, also known as 4C-DOB or DOB-B, as well as 4-bromo-2,5-dimethoxy-ñ-ethylphenethylamine, is a lesser-known psychedelic drug of the phenethylamine, phenylisobutylamine, and 4C families related to 2C-B (the 2C analogue) and DOB (the DOx analogue).
It is briefly mentioned in Alexander Shulgin's 1991 book PiHKAL (Phenethylamines I Have Known And Loved), but was never tested by Shulgin. Subsequently, the drug was tested by Daniel Trachsel and colleagues, and was found to be active in a dose range of 50 to 80mg orally with a duration of around 8hours. It produced pronounced psychedelic effects, though with generally milder effects than 2C-B or DOB.
The drug is a reasonably potent serotonin 5-HT<sub>2A</sub> receptor partial agonist with a K<sub>i</sub> of 7.6nM, but has relatively low efficacy (15% relative to 5-HT).
4C-B is a controlled substance in Canada under phenethylamine blanket-ban language, but is not explicitly controlled in the United States.