2,4,5-Trihydroxyamphetamine (THA or THA-2), also known as ñ-methyl-6-hydroxydopamine (ñ-Me-6-OHDA) or as 2,4,5-TDM-TMA-2, is a neurotoxin and a metabolite of MDMA related to 6-hydroxydopamine. It comes from the ring hydroxylation of 3,4-methylenedioxyamphetamine (MDA). The drug may also be a metabolite of 2,4,5-trimethoxyamphetamine (2,4,5-TMA; TMA-2) via O-demethylation. In one study, it was shown to reduce hippocampal tryptophan hydroxylase activity by 54% after short-term treatment. In another study, it was shown to significantly reduce striatal tyrosine hydroxylase activity. THA was studied clinically as an antihypertensive agent but was never marketed. The drug did not produce hallucinogenic effects in humans at doses of up to 200mg orally.