Identification, Synthesis, and Characterization of β-Isomer as Process Related Impurity in production of Methocarbamol from Guaifenesin

J App Pharm Sci. 2020; 10(5): 10-15

doi: 10.7324/JAPS.2020.10502

Appala Raju Nemala, Sridevi Chigurupati, Kesavanarayanan Krishnan Selvarajan, Saurabh Bhatia, Sridevi Pingali, Anitha Sadula.

Abstract			Cited by 0 Articles
Methocarbamol is a CNS depressant with skeletal muscle relaxant properties indicated to treat spasms. During the synthesis of methocarbamol from guaifenesin, we observed an unknown impurity (0.050.1%, HPLC) along with the known potential impurities. The unknown impurity was separated using preparative liquid chromatography. Based on the complete spectral analysis (1H NMR, Mass, and IR), this new impurity was designated as 1-hydroxy-3-(2-methoxy phenoxy) propan-2-yl carbamate as β-isomer of methocarbamol. The impurity isolation, structure elucidation, and probable formation mechanism are discussed. Key words: β-isomer, 1-hydroxy-3-(2-methoxy phenoxy) propan-2-yl carbamate, Guaifenesin, Impurity, Methocarbamol.