DOB

DOB (2,5-dimethoxy-4-bromoamphetamine; International Nonproprietary Name brolamfetamine) is a substituted phenethylamine and amphetamine derivative that acts as a potent, high-efficacy agonist at the serotonin 5-HT2A, 5-HT2B, and 5-HT2C receptors. First synthesized by Alexander Shulgin in 1967 and reported in the scientific literature in 1971, DOB occupies a historically significant position in psychedelic pharmacology as the compound that, for many years prior to the introduction of N-benzyl derivatives, was the most potent known phenethylamine hallucinogen, producing pronounced psychoactive effects in humans at oral doses of 1 to 3 milligrams with a duration of action of 18 to 36 hours. The compound binds the 5-HT2A receptor with low-nanomolar affinity (Ki approximately 0.6 to 81 nM across assay conditions), with comparable affinities at the 5-HT2B and 5-HT2C subtypes and approximately 1000-fold selectivity over 5-HT1A and other monoamine targets. Stereochemistry is pharmacologically significant: the R-(-)-enantiomer is the eutomer, producing pronounced effects at 0.5 to 1.5 milligrams in human bioassay, whereas the S-(+)-enantiomer exhibits markedly reduced potency with only threshold effects at 1.0 milligrams.

Beyond its psychoactive characterization, DOB has served as a foundational radioligand probe in serotonin receptor pharmacology. Tritiated [3H]-DOB labels a guanyl-nucleotide-sensitive, high-affinity agonist state of cortical 5-HT2 receptors, distinguishing it from antagonist radioligands such as [3H]-ketanserin that label total receptor populations irrespective of G-protein coupling state. The bromine-77-labeled R-(-)-enantiomer ([77Br]-R-(-)-DOB) was among the first agonist radioligands developed for in vivo characterization of 5-HT2 binding site subtypes. These radioligand applications have made DOB and its isotopologues essential tools in the elucidation of 5-HT2A receptor pharmacology, structure-activity relationships of hallucinogenic phenethylamines, and the broader understanding of serotonergic neurotransmission.

Pharmacokinetically, DOB exhibits good oral bioavailability with onset of effects at 1 to 2 hours, peak effects at 3 to 4 hours, and a prolonged plateau of 4 to 10 hours attributable to the metabolic stability conferred by the 4-bromo substituent. Hepatic metabolism proceeds principally through O-demethylation at the 2- and 5-positions (with CYP2D6 involvement), followed by oxidative deamination or reduction of the deaminated intermediate, with metabolites excreted in urine partly as glucuronide and sulfate conjugates. The compound is a Schedule I controlled substance in the United States (scheduled 1973), a Class A drug in the United Kingdom, and a Schedule I substance under the United Nations Convention on Psychotropic Substances. Toxicological case reports document fatalities at high doses (35 milligrams in one published case), with the principal life-threatening adverse effects being diffuse arterial vasospasm, peripheral ischemia progressing to gangrene in severe overdose, seizures, metabolic acidosis, and prolonged coma. This monograph reviews the chemistry, synthesis, and stereochemistry of DOB; the receptor pharmacology and signal transduction in molecular detail; the pharmacokinetic and metabolic record; the preclinical and clinical pharmacology including radioligand applications; sourcing and quality verification for laboratory use; reconstitution and handling; stack interactions; adverse-event and safety signal; and a comparative assessment of five structurally or functionally related 5-HT2A agonist phenethylamines (DOI, DOM, 2C-B, mescaline, 25B-NBOMe) against DOB on five competency standards.