Dextromethorphan is a salt of the methyl ether dextrorotatory isomer of levorphanol, a narcotic (opioid) analgesic (and DXM itself is an isomer, i.e., a mirror image in the 3D space, of levomethorphan, a substance considered an opioid1
). It is chemically named as 3-methoxy-17-methyl-9(alpha), 13(alpha), 14(alpha)-morphinan hydrobromide monohydrate. DXM occurs as white crystals, is sparingly soluble in water, and freely soluble in alcohol. The drug is dextrorotatory in water (at 20 degrees Celsius, Sodium D-line) with a specific rotation of +27.6 degrees.