N-Methylpyrrolidone-d9 (NMP-d9) is deuterium labeled N-Methylpyrrolidone. N-Methylpyrrolidone (1-Methyl-2-pyrrolidinone), a five-membered cyclic amide, is an orally active organic polar solvent with teratogenicity and toxicity. N-Methylpyrrolidone is low in acute toxicity with a LD50 value of 3914 mg/kg in rats and of 4050 mg/kg in mice. N-Methylpyrrolidone is extensively used in the manufacture of adhesives, paints, fuels, and pharmaceuticals[1][2][3][4].