Carboxymethylcellulose Sodium is a semisynthetic water-soluble polymer in which CH2COOH groups are substituted on the glucose units of the cellulose chain through an ether linkage. Carboxymethylcellulose Sodium is the sodium salt of a polycarboxymethyl ether of cellulose, and it contains not less than 6.5 percent and not more than 9.5 percent of sodium (Na), calculated on the dried basis.