MW: 370.3. Purity ≥98%. Background: Dextromethorphan (DXM) is a morphinan with structural similarity to levorphanol, codeine, and morphine. DXM binds to and inhibits NMDA (IC50 = 0.55 muM) and nicotinic receptors (IC50s = 0.7-3.9 muM) and blocks receptor-gated and voltage-gated calcium channels (IC50 = 60 muM) and voltage-gated sodium channels (IC50 = 78 muM). It is a Cytochrome P450 2D6 substrate and it is converted into the active metabolite dextrorphan in the liver.