MS-245 is a tryptamine derivative used in scientific research. It acts as a selective 5-HT<sub>6</sub> receptor antagonist with a K<sub>i</sub> of 2.3 nM, and was derived through structure-activity relationship development of the selective 5-HT<sub>6</sub> agonist EMDT. It has been used as a lead compound for further development of tryptamine-derived 5-HT<sub>6</sub> antagonists. In animal studies it has been shown to boost the activity of, but not substitute for, both amphetamine and nicotine.