O-Desmethyl lacosamide is a potential impurity found in commercial preparations of lacosamide).1,2 1.Molleti, S., Rao, V., and Jayaveera, K.N.Stability indicating RP-UPLC method for the determination of lacosamide and its impurities in bulk drugs and its pharmaceutical dosage formsDer Pharma Chemica5(1)81-89(2013) 2.Yang, A., Hu, F., Chen, M., et al.Improved synthesis and impurity identification of (R)-lacosamideOrg. Proc. Res. Dev.23(5)818-824(2019)