Abstract
For over 50 years, cellulose derivatives have been used as excellent pharmaceutical excipients. Commercially, cellulose products are designated with viscosity grade, proportional to the molecular weight or chain length, which identifies the product numerically based on viscosity value (in mPa⋅s) measured at 2% w/v concentration in water at 20°C using an Ubbelohde viscometer. A wide range of viscosity grades are available.