How does one ideally extract DXM from cough formulae?
Add cough syrup to an equal volume of distilled water. (If a considerable amount of alcohol is present in the cough formula, heat to 95 C for 10 minutes to drive off the alcohol). With stirring, add 1.0N NaOH (or other convenient strength; it really isn’t that important) dropwise until the pH rises above 11 (do not increase above 13). Centrifuge, decant, and filter with slow-speed filter paper (optionally under mild vacuum). Wash the precipitate in several volumes of distilled water until the wash is no longer alkaline. The precipitate should be white to pink (depending on dyes) and fluffy or powdery. To purify, dissolve in methanol and filter, discarding any solids. Evaporate the methanol. The result should be a white to off- white solid. Expect a yield of 60-90%. If, after centrifuging, added NaOH causes further precipitation, you didn’t add enough beforehand. Avoid raising the pH too high; this is a major cause of failure.
