FHATHBIN, also known as 5-hydroxy-11-aminotetrahydrobenzindole or as 4,ñ-methylene-5-HT, is a serotonin receptor agonist of the partial ergoline group. It is a cyclized tryptamine and tricyclic derivative of serotonin (5-hydroxytryptamine) as well as a simplified analogue of LSD. The drug is known to act on the serotonin 5-HT<sub>1A</sub> receptor. FHATHBIN was first reported in the scientific literature by 1984.