Benzofurans

The APB and APDB series replace the methylenedioxy ring of the MDMA series with a benzofuran or a dihydrobenzofuran: 6-APB and 5-APB, the N-methyl forms 5-MAPB and 6-MAPB, 5-EAPB, and the dihydro compounds 5-APDB and 6-APDB. They release serotonin as the MDMA series does, which is why they are filed under Entactogens rather than with the psychedelic phenethylamines.

Two things separate them from MDMA in practice. Onset is slower and duration considerably longer, which is the redosing trap this family is known for. And the APB compounds are agonists at 5-HT2B, the receptor whose sustained stimulation by withdrawn appetite suppressants produced valvular heart disease — a repeated-dosing risk rather than an acute one, and not one shared with MDMA. Cardiovascular stimulation is marked, and the 5- and 6- isomers are not interchangeable.