Techniques involved in Conversion of Powders into Granules-An Overview

Granulation is one of the most important unit operations in production of pharmaceutical oral dosage form. Granulation is defined as the size enlargement process in which fine and smaller particle are aggregated to form strong and stable particles called granules. A pharmaceutical organization uses different techniques such as direct compressing, wet-granulation, or dry granulation methods for the production of pharmaceutical products. The method of selection depends on the ingredients, individual characteristics and ability to flow properly, compresses, eject, and disintegrate. Granulation process transforms fine powders into free-flowing, dust-free granules that are easy to compress. Nevertheless, granulation poses numerous challenges due to high quality requirement of the formed granules in terms of content uniformity and physicochemical properties such as granule size, bulk density, porosity, hardness, moisture, compressibility, etc. apart from physical and chemical stability of the drug. Granulation process can be divided into two types: Wet granulation that utilize a liquid in the process and Dry granulation that requires no liquid. The type of process selection requires thorough knowledge of physicochemical properties of the drug, excipients, required flow and release properties. Among currently available technologies, spray drying, roller compaction, high shear mixing, and fluid bed granulation worth of note. Like any other scientific field, pharmaceutical granulation technology also continues to change, and arrival of novel and innovative technologies are inevitable. This review gives an overview of the granulation technologies with a short description about each development along with its significance and limitations.