Study of Spectroscopic, Thermal, Microscopic Characteristics and Extended-Release Application of Carboxymethyl Ethyl Cellulose

Carboxymethyl ethyl cellulose (CMEC), a pH-sensitive polymer listed in Japanese Pharmaceutical Excipients (JPE), 2013, has seldom been characterized and explored for drug delivery. The current work aimed at characterizing the polymer using spectroscopy, thermal techniques, and microscopy. To study the drug-release-retarding ability of CMEC, metformin hydrochloride (Met) tablets were prepared by wet granulation using hydroxy propyl methyl cellulose (HPMC) K100LV. The tablets were subjected to coating using coating solution comprising combinations of CMEC and HPMC E5 in various % ratios (93:7, 95:5, and 97:3). The coated tablets were subjected to in vitro drug release studies. Raman and FTIR spectra confirmed the presence of ethyl and carboxy groups on the polymer. PXRD and DSC studies confirmed the amorphous nature of CMEC. The microscopy studies revealed almost circular, solid, and smooth morphology of the polymer particles with D10, D50, and D90 of 31, 55, and 134 µ. The release profile of tablets coated with CMEC: HPMC E5 (97:3 ratio) up to 4% weight gain complied with the USP specifications for Met extended-release tablets and exhibited similarity to the marketed Met formulation. The work demonstrated the suitability of CMEC as a barrier film coating polymer and confirmed its release-retarding potential for a water-soluble, high-dose drug like Met, when used in combination with another release retardant like HPMC K100LV.