Microcrystalline Cellulose: The Inexhaustible Treasure for Pharmaceutical Industry

Abstract

Microcrystalline cellulose (MCC) is pure partially depolymerized cellulose synthesized from α-cellulose precursor. The MCC can be synthesized by different processes such as reactive extrusion, enzyme mediated, steam explosion and acid hydrolysis. The later process can be done using mineral acids such as H2SO4, HCl and HBr as well as ionic liquids. The role of these reagents is to destroy the amorphous regions remaining the crystalline domains. The MCC is a valuable additive in pharmaceutical, food, cosmetic and other industries. The MCC is one of the most important tableting excipients due to its outstanding dry binding properties of tablets for direct compression. Different properties of MCC are measured to qualify its suitability for such utilization, namely particle size, density, compressibility index, angle of repose, powder porosity, hydration swelling capacity, moisture sorption capacity, moisture content, crystallinity index, crystallite size and mechanical properties such as hardness and tensile strength. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) or differential scanning calorimetry (DSC) are also important to predict the thermal behavior of the MCC upon heat stresses. The degree of polymerization (DP) of the MCC is typically less than 400, while that for nanocrystalline cellulose is more than 400 extending to several thousands of (1→4)-β-d-glucopyranose units. The MCC particles with size lower than 5µm must not be more than 10% of the total particles. There are several types of the MCC, namely PHs 101, 102, 103, 105, 112, 113, 200, 301 and 302 based on the particle size and subsequent utilization.