Monometacrine (INNTooltip International Nonproprietary Name; developmental code name SD-735), also known as desmethyldimetacrine, is a drug of the tricyclic family described as an antidepressant which was never marketed.[1][2][3] It was first described in the literature by 1966.[1] The drug is the N-desmethyl analogue of dimetacrine and is a metabolite of dimetacrine.[1][3]