DOI or 2,5-dimethoxy-4-iodoamphetamine is a psychedelic hallucinogenic drug and a substituted amphetamine of the phenethylamine family. Despite being a substituted amphetamine it is not a stimulant. DOI has a stereocenter and R-(-)-DOI is the more active stereoisomer. In neuroscience research, [125I]-R-(-)-DOI is used as a radioligand and indicator of the presence of 5-HT2A serotonin receptors. When ingested recreationally, DOI is active at a dosage of 1.5 - 3.0 mg (orally) and has a duration of 16 - 30 hours (approximately twice as long as LSD). DOI's effects have been compared to LSD, although there are differences that experienced users can distinguish. Besides the longer duration, the trip tends to be more energetic than an LSD trip, with more body load and a different subjective visual experience. The after effects include residual stimulation and difficulty sleeping, which, depending on the dose, may persist for days. It is often sold as a substitute for LSD, or even sold falsely as LSD, which may be dangerous because DOI does not have the same established safety profile as LSD. Although there have been no known deaths due to DOI ingestion, it is relatively new on the recreational scene so long-term effects are not known.
The hallucinogenic effect of DOI is mediated by its partial agonistic activity at the 5-HT2A serotonin receptor, but DOI also has a high binding affinity for the 5-HT2B and the 5-HT2C serotonin receptors. DOI is often used as a tool compound in research when studying the 5-HT2 receptor family. The solubility of DOI-hydrochloride in H2O is 10 mg/ml, and in ethanol 2 mg/ml (source: www.sigmaaldrich.com MSDS)
DOI was first synthesized by Alexander Shulgin. The radioactive iodine-125 form of DOI was first developed in the lab of David E. Nichols. British Police recently reported that 3 young men had taken ill, reportedly, after taking DOI at a rave in Biggleswade, near Milton Keynes, and warned others who had taken it to seek medical attention. This would appear to the first indication that DOI has found more widespread use as a recreational drug in the UK.