Gabapentin EP Impurity D

1-[(3-Oxo-2-azaspiro[4.5]dec-2-yl)methyl]cyclohexaneacetic Acid; [1-(3-Oxo-2-aza-spiro[4.5]dec-2-ylmethyl)cyclohexyl]acetic acid; Gabapentin Related Compound D (USP);